Signs and Symptoms
Both amaurosis fugax (AF) and transient ischemic attack (TIA) are diagnosed almost exclusively by history alone. Patients with both AF and TIA are typically elderly with a history of diabetes, hypertension, or generalized atherosclerosis. Younger patients with these conditions may have a history of cardiac valve disease, blood constituent or coagulation abnormalities, or drug use.
Amaurosis fugax is a painless, monocular loss of vision, which may be total or sectorial. This is a traditional blackout of the patient’s vision. Amaurosis fugax can occur in isolation, antecedent, or crescendo and is unprovoked and unpredictable. Vision loss typically lasts only seconds, but may last for hours and will resolve completely. There are no other neurological symptoms or findings in association with AF.
Transient ischemic attacks can result in a total painless loss of monocular vision; however, TIA may occur with no ocular involvement whatsoever. Other significant neurological signs and symptoms associated with TIA include dysphasia, contralateral hemiparesis, and paresthesia. Temporary paresis most commonly involves the contralateral arm, leg, or both face and arm, or both arm and leg. Numbness typically involves the contralateral hand, foot, face, and contralateral half of the tongue. A TIA will typically last for 15 minutes, but may go for hours.
Pathophysiology
TIA and AF result from either an embolic, thrombotic, vasospastic, or hematological phenomenon. Thrombus development occurs via cholesterol deposition and atheroma formation within vessel lumens. From this process forms a thrombus, which may cause transient blood flow cessation and symptoms of TIA or AF. Also, inflammatory cell infiltration of the muscular walls of arteries in giant cell arteritis will lead to lumen narrowing and occlusion with resultant TIA or AF. More commonly, however, the thrombus ulcerates and releases particles which lodge within vessels and result in distal ischemia. This produces the signs and symptoms of TIA or AF. Occasionally, cholesterol emboli is seen lodged at a retinal arteriole bifurcation in patients experiencing AF. However, visible retinal emboli are often not observed as their very nature allows for the emboli to break up and move distally. This explains why cholesterol emboli typically result in transient neurologic deficits. Calcific emboli may dislodge from the heart and indicate valve disturbance. This type of emboli is not malleable and more likely to cause a permanent occlusion of the retinal arteriole.
Vasospastic causes of TIA and AF may be due to non-embolic idiopathic arterial narrowing or the possible release of an as-yet-unidentified vasospastic substance. Occasionally, use of exogenous sources such as cocaine may lead to localized vasospasm and TIA and AF.
Hematological causes of TIA and AF result when there are abnormalities in the normal blood constituents. Hematological causes include polycythemia, sickle cell disease, anemia, and hypercoagulable states.
Management
There is significant morbidity and mortality associated with TIA and AF. Patients experiencing uncomplicated AF have an 85 percent likelihood of full recovery while 10 to 15 percent will eventually develop a central retinal artery occlusion. The average untreated annual stroke rate of patients with untreated AF is 2 percent. Refer these patients to a neurologist or internist for carotid artery studies, such as Doppler imaging or magnetic resonance angiography. If there is significant stenosis of the carotid artery, consult a vascular surgeon for possible endarterectomy. However, these patients are typically medicatedwith blood thinners such as aspirin and they do quite well.
Patients experiencing hemispheric TIA are at more risk. The average annual untreated stroke rate in this group is 8 percent. Refer this patient to a neurologist since other neurological areas are involved in the attack. Typically, this patient requires carotid endarterectomy. The patient with hemispheric TIA has a 25 percent mortality rate within one month, 33 percent within six months, and 60 percent within seven years.
Patients who experience either TIA or AF and have retinal emboli visible at ophthalmic exam also have a high rate of mortality. In this group, the mortality rate is 15 percent within one year, 29 percent within three years, and 54 percent within seven years. In this group, cardiac death is more prevalent than stroke and thus these patients must be referred to a cardiologist.
Clinical Pearls
Amaurosis fugax in elderly patients may be the initial sign of giant cell arteritis. In these cases, devastating vision loss from anterior ischemic optic neuropathy likely ensues within several weeks of an episode of AF. These patients need an immediate Westgren ESR, and possible temporal artery biopsy, along with the requisite carotid studies.
Most cases of TIA and AF show no visible evidence at examination. These diagnoses can be made by history. Optimal management involves referral to the appropriate medical specialist.
The number one hematological cause of AF is sickle cell disease.
Showing posts with label education. Show all posts
Showing posts with label education. Show all posts
Sunday, November 13, 2011
Demyelinating Optic Neuropathy (Optic Neuritis, Retrobulbar Optic Neuritis)
Signs and Symptoms
Optic neuritis (ON) is defined as acute inflammation of the optic nerve. While etiologies include infection (syphilis, mumps, measles), infiltrative/ inflammatory disease (sarcoidosis, lupus), ischemic vascular disease (diabetes), the most common etiology is the demyelinating disease multiple sclerosis (MS). ON is the initial presenting sign in 20 to 25 percent of MS patients. Anywhere from 35 percent to 75 percent of patients who present with ON develop clinical MS. The risk of developing MS increases steadily during the first 10 years after the initial presentation of ON. The usual age range for the diagnosis of MS is 15 to 45 years. While some sources cite a predilection for females, the topic of sexual distribution remains controversial.
The clinical presentation of demyelinating optic neuropathy varies. Patients frequently present to the office with an acute loss of vision. The natural history of MS-related vision loss is rapidly progressive acuity loss for a period of 10 days, which then stabilizes and improves. Additional ocular signs include eye pain, tenderness of the globe, dyschromatopsia, decreased brightness sense, decreased color perception, a relative afferent pupillary defect, assorted visual field defects (altitudinal and central/cecocentral), phosphenes upon eye movement and optic disc swelling with or without vitreous cells. Often, the optic nerve is normal in appearance and the dysfunction is considered retrobulbar.
Systemic signs and symptoms may include headache, nausea, Uhtoff’s sign (decreased vision with or without limb weakness following exposure to increased temperatures i.e., a bath or exercise), Romberg’s sign (patient falls when they close their eyes), Pulfrich’s stereo phenomenon (beer barrel appearance to the environment) and fever.
Pathophysiology
Multiple sclerosis is an acquired, multifactorial, inflammatory demyelinating disease, which affects the white matter located in the central nervous system. Myelin is responsible for speeding electrical impulses along nervous tissues. Loss of myelin greatly slows nervous conduction and leads to the neurologic deficits seen in MS.
Although the exact cause of MS is presently unknown, many theories regarding its etiology exist. The most common theories involve the immune system. The immune system attacks and destroys antigens by two different mechanisms. One mechanism, known as cellular immunity, involves a response by macrophages and T-cells. The other mechanism, governed by B-cells and antibodies is known as humoral immunity. Evidence suggests that the cellular immune response contributes to the loss of myelin. This patchy demyelination is thought to be caused by a deposition of mononuclear cells such as macrophages and B-cells in perivascular regions. Demyelinating optic neuropathy can damage the fibers in both the visual and pupillary pathways. This damage interrupts nerve impulses within the pathways, producing decreased vision as well as an afferent pupillary defect.
Management
In the past, controversy existed as to whether or not to treat patients with ON with corticosteroids. The Optic Neuritis Treatment Trial (ONTT) supports the administration of intravenous methylprednisolone sodium succinate (Solumedrol, 250 mg. every 6 hours) for three days followed by oral prednisone (1 mg/kg per day) for 11 days for the purposes of accelerating visual recovery. This therapy did not improve visual outcome after one year but was found to increase the rate at which patients recover. The ONTT also determined that the use of oral prednisone (1 mg/kg per day) alone for 14 days is contraindicated. Patients receiving this therapy had a higher rate of new attacks of ON in both the initially affected and fellow eyes than did the intravenous/oral group and placebo group.
As recorded in the three-year follow-up of patients in the ONTT, treatment with intravenous methylprednisolone followed by oral corticosteroid regimens reduced the two-year rate of development of clinical MS, particularly in patients with signal abnormalities consistent with demyelination on MRI of the brain at the time of study entry. Serious side effects of glucocorticoid therapy are infrequent. Therefore, outpatient administration of high-dose intravenous glucocorticoids may be recommended.
Clinical Pearls
A number of other types of demyelinating disorders have been associated with ON. They are: acute transverse myelitis, Guillain-Barré syndrome, Devic’s neuromyelitis optica, Charcot-Marie-Tooth syndrome, multifocal demyelinating neuropathy, and acute disseminated encephalomyelitis.
Diseases such as syphilis, toxoplasmosis, histoplasmosis, tuberculosis, hepatitis, rubella, human immunodeficiency virus (HIV), Lyme borreliosis, familial Mediterranean fever, Epstein-Barr virus, herpes zoster ophthalmicus, paranasal sinus disorder, sarcoidosis, systemic lupus erythematosus, Bechet’s disease, and diabetes may cause optic neuropathy and should be considered before prematurely diagnosing demyelinating optic neuropathy.
In cases of optic neuropathy presumably secondary to demyelinating disease, MRI can assist in systemic diagnosis by identifying both old and acute demyelinating plaques within periventricular white matter.
Significant pain with eye movement is present in nearly every case of demyelinating optic neuropathy.
As the visual dysfunction is due to autoimmune destruction of myelin
Optic neuritis (ON) is defined as acute inflammation of the optic nerve. While etiologies include infection (syphilis, mumps, measles), infiltrative/ inflammatory disease (sarcoidosis, lupus), ischemic vascular disease (diabetes), the most common etiology is the demyelinating disease multiple sclerosis (MS). ON is the initial presenting sign in 20 to 25 percent of MS patients. Anywhere from 35 percent to 75 percent of patients who present with ON develop clinical MS. The risk of developing MS increases steadily during the first 10 years after the initial presentation of ON. The usual age range for the diagnosis of MS is 15 to 45 years. While some sources cite a predilection for females, the topic of sexual distribution remains controversial.
The clinical presentation of demyelinating optic neuropathy varies. Patients frequently present to the office with an acute loss of vision. The natural history of MS-related vision loss is rapidly progressive acuity loss for a period of 10 days, which then stabilizes and improves. Additional ocular signs include eye pain, tenderness of the globe, dyschromatopsia, decreased brightness sense, decreased color perception, a relative afferent pupillary defect, assorted visual field defects (altitudinal and central/cecocentral), phosphenes upon eye movement and optic disc swelling with or without vitreous cells. Often, the optic nerve is normal in appearance and the dysfunction is considered retrobulbar.
Systemic signs and symptoms may include headache, nausea, Uhtoff’s sign (decreased vision with or without limb weakness following exposure to increased temperatures i.e., a bath or exercise), Romberg’s sign (patient falls when they close their eyes), Pulfrich’s stereo phenomenon (beer barrel appearance to the environment) and fever.
Pathophysiology
Multiple sclerosis is an acquired, multifactorial, inflammatory demyelinating disease, which affects the white matter located in the central nervous system. Myelin is responsible for speeding electrical impulses along nervous tissues. Loss of myelin greatly slows nervous conduction and leads to the neurologic deficits seen in MS.
Although the exact cause of MS is presently unknown, many theories regarding its etiology exist. The most common theories involve the immune system. The immune system attacks and destroys antigens by two different mechanisms. One mechanism, known as cellular immunity, involves a response by macrophages and T-cells. The other mechanism, governed by B-cells and antibodies is known as humoral immunity. Evidence suggests that the cellular immune response contributes to the loss of myelin. This patchy demyelination is thought to be caused by a deposition of mononuclear cells such as macrophages and B-cells in perivascular regions. Demyelinating optic neuropathy can damage the fibers in both the visual and pupillary pathways. This damage interrupts nerve impulses within the pathways, producing decreased vision as well as an afferent pupillary defect.
Management
In the past, controversy existed as to whether or not to treat patients with ON with corticosteroids. The Optic Neuritis Treatment Trial (ONTT) supports the administration of intravenous methylprednisolone sodium succinate (Solumedrol, 250 mg. every 6 hours) for three days followed by oral prednisone (1 mg/kg per day) for 11 days for the purposes of accelerating visual recovery. This therapy did not improve visual outcome after one year but was found to increase the rate at which patients recover. The ONTT also determined that the use of oral prednisone (1 mg/kg per day) alone for 14 days is contraindicated. Patients receiving this therapy had a higher rate of new attacks of ON in both the initially affected and fellow eyes than did the intravenous/oral group and placebo group.
As recorded in the three-year follow-up of patients in the ONTT, treatment with intravenous methylprednisolone followed by oral corticosteroid regimens reduced the two-year rate of development of clinical MS, particularly in patients with signal abnormalities consistent with demyelination on MRI of the brain at the time of study entry. Serious side effects of glucocorticoid therapy are infrequent. Therefore, outpatient administration of high-dose intravenous glucocorticoids may be recommended.
Clinical Pearls
A number of other types of demyelinating disorders have been associated with ON. They are: acute transverse myelitis, Guillain-Barré syndrome, Devic’s neuromyelitis optica, Charcot-Marie-Tooth syndrome, multifocal demyelinating neuropathy, and acute disseminated encephalomyelitis.
Diseases such as syphilis, toxoplasmosis, histoplasmosis, tuberculosis, hepatitis, rubella, human immunodeficiency virus (HIV), Lyme borreliosis, familial Mediterranean fever, Epstein-Barr virus, herpes zoster ophthalmicus, paranasal sinus disorder, sarcoidosis, systemic lupus erythematosus, Bechet’s disease, and diabetes may cause optic neuropathy and should be considered before prematurely diagnosing demyelinating optic neuropathy.
In cases of optic neuropathy presumably secondary to demyelinating disease, MRI can assist in systemic diagnosis by identifying both old and acute demyelinating plaques within periventricular white matter.
Significant pain with eye movement is present in nearly every case of demyelinating optic neuropathy.
As the visual dysfunction is due to autoimmune destruction of myelin
Optic Nerve Head Drusen
Signs and Symptoms
A condition involving retained hyaline bodies in the anterior optic nerve, optic nerve head drusen (ONHD) has been referred to in the literature by many diverse and confusing names. Among the descriptive terms are congenitally elevated or anomalous discs, pseudopapilledema, pseudoneuritis, buried disc drusen, and disc hyaline bodies. ONHD is encountered in approximately 1 percent of the general population, and is bilateral in 70 percent of cases. The condition occurs primarily in Caucasians and is believed to demonstrate an autosomal dominant inheritance pattern with incomplete penetrance. Typically, patients with ONHD remain asymptomatic, and the finding is discovered only on routine ocular evaluation. In some instances, however, the condition can present with mildly decreased visual acuity and visual field defects. An afferent pupillary defect may be noted if the condition is both significant and asymmetric. Reports of recurrent, transient visual obscurations associated with disc drusen have also been documented.
The classic appearance of ONHD involves bilaterally elevated optic discs with irregular or "scalloped" margins, a small or nonexistent cup, and unusual vascular branching patterns that arise from a central vessel core. Often there are small, refractile hyaline deposits visible on the surface of the disc and/or in the peripapillary area. ONHD most often manifests on the nasal disc margin, but can be found within any part of the nerve head. In younger patients, the disc elevation tends to be more pronounced and the drusen less calcific, making them less visible ophthalmoscopically, and hence offering a more challenging diagnostic dilemma. Unlike true disc edema, ONHD very rarely presents with juxtapapillary nerve fiber edema, exudate, or cotton-wool spots.
Pathophysiology
There is no histopathological correlation between drusen of the optic nerve head and retinal drusen; the former represent acellular laminated concretions, often partially calcified, possibly related to accumulation of axoplasmic derivatives of degenerating retinal nerve fibers. As mentioned, ONHD tend to remain "buried" in children, but slowly become visible as they enlarge toward the disc surface and as the overlying retinal nerve fiber layer progressively thins. They are usually ophthalmoscopically detectable by the early to mid-teens, although these authors have seen patients in their mid-20s who continue to display "buried drusen". Within the optic nerve, the hyaline bodies are confined anterior to the lamina cribosa and thus can compress and compromise the nerve fibers and vascular supply, leading to visual field defects and disc hemorrhages. Along with slowly developing optic atrophy in extreme cases, disruption of the juxtapapillary tissue can result in choroidal neovascular membrane formation leading to subretinal hemorrhage and disciform retinal scarring.
Management
Although ONHD is typically classified as a benign condition, it can lead to modest visual compromise. First and foremost, ONHD must be clearly differentiated from acquired disc edema, which warrants immediate neurologic evaluation and treatment. Management of ONHD includes prompt and proper diagnosis, which is aided greatly by the use of ocular ultrasonography. The high reflectivity of the calcified hyaline bodies is dramatically evident on B-scan ultrasonography, even at particularly low gain levels. Careful evaluation of optic nerve function is imperative, and should include standard Snellen acuity, contrast sensitivity, color vision testing, and threshold visual fields. Photodocumentation should be obtained for future monitoring. It is also important for patients to self-monitor their vision periodically, particularly because of the risk of choroidal neovascular membrane formation. Should these membranes be noted or suspected, intravenous fluorescein angiography is recommended, followed by laser photocoagulation as indicated. More routine cases should be monitored every six to 12 months.
Clinical Pearls
Some suggest that the vast majority of congenitally anomalous, elevated optic discs are likely associated with nerve head drusen. Recognize the clinical features associated with ONHD in comparison to those features indicative of true optic disc edema. In ONHD, expect a typically "normal" pink to pinkish-yellow color, rather than a pale waxy disc or a hyperemic disc. In addition, a spontaneous venous pulsation is present in about 80 percent of patients with ONHD, but is absent in cases of true disc edema. Most importantly, recognize that while the disc margins may be irregular in ONHD, rarely are they blurred or obscured.
Ultrasonography is probably the single most important ancillary test to perform in adults with ONHD. This procedure should be performed on all adult patients presenting with elevated optic discs that are not definitively identifiable as true optic disc edema based upon ophthalmoscopic observation or history. Keep in mind, however, that optic disc drusen are generally not calcified in children and adolescents. Hence, ultrasonography may prove to be of little help in diagnosing these cases.
While visual fields are an important method of documenting and monitoring optic nerve compromise secondary to ONHD, they are neither uniform nor diagnostic. The more common patterns encountered in ONHD include nasal step defects, enlargement of the physiologic blindspot, arcuate scotomas, sectoral field loss, and altitu
A condition involving retained hyaline bodies in the anterior optic nerve, optic nerve head drusen (ONHD) has been referred to in the literature by many diverse and confusing names. Among the descriptive terms are congenitally elevated or anomalous discs, pseudopapilledema, pseudoneuritis, buried disc drusen, and disc hyaline bodies. ONHD is encountered in approximately 1 percent of the general population, and is bilateral in 70 percent of cases. The condition occurs primarily in Caucasians and is believed to demonstrate an autosomal dominant inheritance pattern with incomplete penetrance. Typically, patients with ONHD remain asymptomatic, and the finding is discovered only on routine ocular evaluation. In some instances, however, the condition can present with mildly decreased visual acuity and visual field defects. An afferent pupillary defect may be noted if the condition is both significant and asymmetric. Reports of recurrent, transient visual obscurations associated with disc drusen have also been documented.
The classic appearance of ONHD involves bilaterally elevated optic discs with irregular or "scalloped" margins, a small or nonexistent cup, and unusual vascular branching patterns that arise from a central vessel core. Often there are small, refractile hyaline deposits visible on the surface of the disc and/or in the peripapillary area. ONHD most often manifests on the nasal disc margin, but can be found within any part of the nerve head. In younger patients, the disc elevation tends to be more pronounced and the drusen less calcific, making them less visible ophthalmoscopically, and hence offering a more challenging diagnostic dilemma. Unlike true disc edema, ONHD very rarely presents with juxtapapillary nerve fiber edema, exudate, or cotton-wool spots.
Pathophysiology
There is no histopathological correlation between drusen of the optic nerve head and retinal drusen; the former represent acellular laminated concretions, often partially calcified, possibly related to accumulation of axoplasmic derivatives of degenerating retinal nerve fibers. As mentioned, ONHD tend to remain "buried" in children, but slowly become visible as they enlarge toward the disc surface and as the overlying retinal nerve fiber layer progressively thins. They are usually ophthalmoscopically detectable by the early to mid-teens, although these authors have seen patients in their mid-20s who continue to display "buried drusen". Within the optic nerve, the hyaline bodies are confined anterior to the lamina cribosa and thus can compress and compromise the nerve fibers and vascular supply, leading to visual field defects and disc hemorrhages. Along with slowly developing optic atrophy in extreme cases, disruption of the juxtapapillary tissue can result in choroidal neovascular membrane formation leading to subretinal hemorrhage and disciform retinal scarring.
Management
Although ONHD is typically classified as a benign condition, it can lead to modest visual compromise. First and foremost, ONHD must be clearly differentiated from acquired disc edema, which warrants immediate neurologic evaluation and treatment. Management of ONHD includes prompt and proper diagnosis, which is aided greatly by the use of ocular ultrasonography. The high reflectivity of the calcified hyaline bodies is dramatically evident on B-scan ultrasonography, even at particularly low gain levels. Careful evaluation of optic nerve function is imperative, and should include standard Snellen acuity, contrast sensitivity, color vision testing, and threshold visual fields. Photodocumentation should be obtained for future monitoring. It is also important for patients to self-monitor their vision periodically, particularly because of the risk of choroidal neovascular membrane formation. Should these membranes be noted or suspected, intravenous fluorescein angiography is recommended, followed by laser photocoagulation as indicated. More routine cases should be monitored every six to 12 months.
Clinical Pearls
Some suggest that the vast majority of congenitally anomalous, elevated optic discs are likely associated with nerve head drusen. Recognize the clinical features associated with ONHD in comparison to those features indicative of true optic disc edema. In ONHD, expect a typically "normal" pink to pinkish-yellow color, rather than a pale waxy disc or a hyperemic disc. In addition, a spontaneous venous pulsation is present in about 80 percent of patients with ONHD, but is absent in cases of true disc edema. Most importantly, recognize that while the disc margins may be irregular in ONHD, rarely are they blurred or obscured.
Ultrasonography is probably the single most important ancillary test to perform in adults with ONHD. This procedure should be performed on all adult patients presenting with elevated optic discs that are not definitively identifiable as true optic disc edema based upon ophthalmoscopic observation or history. Keep in mind, however, that optic disc drusen are generally not calcified in children and adolescents. Hence, ultrasonography may prove to be of little help in diagnosing these cases.
While visual fields are an important method of documenting and monitoring optic nerve compromise secondary to ONHD, they are neither uniform nor diagnostic. The more common patterns encountered in ONHD include nasal step defects, enlargement of the physiologic blindspot, arcuate scotomas, sectoral field loss, and altitu
Acquired Glaucomatous Changes of the Optic Nerve Head (Pictorial)
Baring of a circumlinear vessel
Pronounced rim thinning and rim loss in advanced glaucoma
Notching of the inferior temporal neuroretinal rim
Beanpotting
Vertical elongation of the optic cup with peripapillary atrophy
Beanpotting
Nerve fiber layer loss
Disc Hemorrhage
Pronounced rim thinning and rim loss in advanced glaucoma
Notching of the inferior temporal neuroretinal rim
Beanpotting
Vertical elongation of the optic cup with peripapillary atrophy
Beanpotting
Nerve fiber layer loss
Disc Hemorrhage
TONIC PUPIL
SIGNS AND SYMPTOMS
The patient often complains of unequal pupil sizes, and frequently of decreased vision at near. The patient may be any age, especially if there has been history of local trauma or orbital surgery. Often when a history of trauma is not apparent, the patient will be younger and female.
A tonic pupil may occur in one or both eyes. It is typically larger than the normal fellow pupil in normal illumination. However, there is no significant change in size of the tonic pupil when going from bright to dim illumination. The tonic pupil will appear fixed and unreactive to light.
When testing near accommodation, the tonic pupil will show a slow constrictive response. Biomicroscopy often reveals segmental paralysis and flattening of the pupil border, which gives the pupil an irregular shape. There may also be a vermiform movement of the non-paralyzed sections of the iris. In cases of idiopathic tonic pupils, deep tendon reflexes often diminish, particularly in young females.
PATHOPHYSIOLOGY
A tonic pupil results from damage to the ciliary ganglion within the orbit. In the ciliary ganglion, 93 percent of the post-ganglionic fibers innervate the ciliary body for accommodation; the remaining 7 percent innervate the iris sphincter for miosis during the light reflex. When the ciliary ganglion is damaged, there is an aberrant regeneration of fibers, with post-ganglionic fibers that originally innervated the iris sphincter now innervating the ciliary body. Thus, light response is diminished, but accommodative near constriction remains. However, near constriction is often slow and segmental, and accommodation is often diminished.
Trauma is the most common cause of a tonic pupil. Other causes associated with tonic pupils include viral illness, diabetes, syphilis and giant cell arteritis. When the etiology cannot be identified, particularly in young females, the condition is termed Adie's tonic pupil.
MANAGEMENT
There is no exact management plan for tonic pupils. Address each case individually. If the patient dislikes the cosmetic asymmetry of the pupils, consider opaque contact lenses. For a patient over 60 who develops a tonic pupil, order an erythrocyte sedimentation rate (ESR) to check for giant cell arteritis. If the patient is male, and has bilateral tonic pupils, order both a specific (FTA-ABS) and non-specific treponemal (RPR) test to examine for syphilis. In most cases, try to elicit a history of trauma.
CLINICAL PEARLS
Remember that a tonic pupil in an elderly patient can be caused by giant cell arteritis, and order an ESR. This can help diagnose a vision-threatening disease before severe vision loss ensues from ischemic optic neuropathy.
Incidence of syphilis is about 45 percent in cases of bilateral tonic pupils in males. Order both a specific and non-specific treponemal test for diagnosis.
In cases of Adie's tonic pupils, testing of patellar tendon reflexes can assist in the diagnosis.
Not all tonic pupils are Adie's tonic pupils. This term is mistakenly overused. The term "Adie's tonic pupil" refers to an idiopathic tonic pupil.
The patient often complains of unequal pupil sizes, and frequently of decreased vision at near. The patient may be any age, especially if there has been history of local trauma or orbital surgery. Often when a history of trauma is not apparent, the patient will be younger and female.
A tonic pupil may occur in one or both eyes. It is typically larger than the normal fellow pupil in normal illumination. However, there is no significant change in size of the tonic pupil when going from bright to dim illumination. The tonic pupil will appear fixed and unreactive to light.
When testing near accommodation, the tonic pupil will show a slow constrictive response. Biomicroscopy often reveals segmental paralysis and flattening of the pupil border, which gives the pupil an irregular shape. There may also be a vermiform movement of the non-paralyzed sections of the iris. In cases of idiopathic tonic pupils, deep tendon reflexes often diminish, particularly in young females.
PATHOPHYSIOLOGY
A tonic pupil results from damage to the ciliary ganglion within the orbit. In the ciliary ganglion, 93 percent of the post-ganglionic fibers innervate the ciliary body for accommodation; the remaining 7 percent innervate the iris sphincter for miosis during the light reflex. When the ciliary ganglion is damaged, there is an aberrant regeneration of fibers, with post-ganglionic fibers that originally innervated the iris sphincter now innervating the ciliary body. Thus, light response is diminished, but accommodative near constriction remains. However, near constriction is often slow and segmental, and accommodation is often diminished.
Trauma is the most common cause of a tonic pupil. Other causes associated with tonic pupils include viral illness, diabetes, syphilis and giant cell arteritis. When the etiology cannot be identified, particularly in young females, the condition is termed Adie's tonic pupil.
MANAGEMENT
There is no exact management plan for tonic pupils. Address each case individually. If the patient dislikes the cosmetic asymmetry of the pupils, consider opaque contact lenses. For a patient over 60 who develops a tonic pupil, order an erythrocyte sedimentation rate (ESR) to check for giant cell arteritis. If the patient is male, and has bilateral tonic pupils, order both a specific (FTA-ABS) and non-specific treponemal (RPR) test to examine for syphilis. In most cases, try to elicit a history of trauma.
CLINICAL PEARLS
Remember that a tonic pupil in an elderly patient can be caused by giant cell arteritis, and order an ESR. This can help diagnose a vision-threatening disease before severe vision loss ensues from ischemic optic neuropathy.
Incidence of syphilis is about 45 percent in cases of bilateral tonic pupils in males. Order both a specific and non-specific treponemal test for diagnosis.
In cases of Adie's tonic pupils, testing of patellar tendon reflexes can assist in the diagnosis.
Not all tonic pupils are Adie's tonic pupils. This term is mistakenly overused. The term "Adie's tonic pupil" refers to an idiopathic tonic pupil.
OPTIC PIT
SIGNS AND SYMPTOMS
Congenital pits of the optic nerve vary in size, shape, depth and location. They often appear as small, hypopigmented, yellow or whitish, oval or round excavated defects, most often within the inferior temporal portion of the optic cup. Approximately 20 to 33 percent are found centrally, with an average size of 500µm (one-third disc diameter).
Typically, optic pits occur unilaterally (85 percent). The optic disc in these patients appears larger than normal, and 60 percent of discs with optic pits also have cilioretinal arteries. These patients have a greater propensity to develop normal-tension glaucoma.
Most patients are unaware of the presence of an optic pit. Although as many as 60 to 70 percent of patients with optic pits possess some arcuate scotoma corresponding to the loss of retinal ganglion cells, their acuity is rarely affected. Patients may notice visual distortions, metamorphopsia or blurred vision. Those with temporal pits have the greatest risk for developing serous maculopathy.
PATHOPHYSIOLOGY
The origin of optic pits remains unclear. Optic pits have been associated with colobomatous lesions, suggesting that they result from incomplete closure of the fetal fissure. Others propose that they result from abnormal differentiation of primitive epithelia papilla. Arcuate visual field defects are the result of corresponding loss of retinal ganglion cells or secondary atrophy of attenuated nerve fibers.
Some 40 to 60 percent of patients with optic pits develop non-rhegmatogenous serous macular detachments. These fluid-filled cystic maculopathies can develop into lamellar macular holes. The origin of the fluid is unknown. There is a high incidence of posterior vitreous detachment associated with these serous maculopathies.
Previous theories concerning the origin of the subretinal fluid seen in optic pit-related serous macular detachment include liquefied vitreous penetration and leaking vessels within the pit. New findings strongly suggest that serous macular detachments secondary to optic pits develop due to pre-existing schisis-like lesions which connect the macula to the optic disc. Fluid, predominantly from the outer plexiform layer, enters an already edematous retina through the optic pit via the retinal stroma, producing a macular detachment.
MANAGEMENT
Begin the management of asymptomatic optic pit with a comprehensive eye examination, including threshold visual fields. Semi-annual intraocular pressure checks and dilated evaluations with drawings or photos are appropriate. Use home acuity assessment and home Amsler grid testing to monitor for the onset of maculopathy. Educate patients about the signs and symptoms of macular complications (e.g. blurred vision, visual distortions, metamorphopsia).
Treatment for optic pit-related macular detachment varies. Periodic monitoring, prophylactic laser photocoagulation, therapeutic laser photocoagulation after maculopathy has formed, oral steroids and vitrectomy have all been tried. The current trend is laser photocoagulation following the onset of maculopathy.
CLINICAL PEARLS
Differential diagnosis includes optic disc anomalies that mimic optic pit: choroidal and scleral crescent, tilted disc syndrome, circumpapillary staphyloma, hypoplastic disc and glaucomatous optic neuropathy. Idiopathic central serous retinopathy and subretinal neovascular membrane are alternative considerations for serous macular detachment.
Any change in appearance of the optic pit over time suggests that the lesion may be an acquired notch of the neuroretinal rim secondary to glaucomatous processes.
Congenital pits of the optic nerve vary in size, shape, depth and location. They often appear as small, hypopigmented, yellow or whitish, oval or round excavated defects, most often within the inferior temporal portion of the optic cup. Approximately 20 to 33 percent are found centrally, with an average size of 500µm (one-third disc diameter).
Typically, optic pits occur unilaterally (85 percent). The optic disc in these patients appears larger than normal, and 60 percent of discs with optic pits also have cilioretinal arteries. These patients have a greater propensity to develop normal-tension glaucoma.
Most patients are unaware of the presence of an optic pit. Although as many as 60 to 70 percent of patients with optic pits possess some arcuate scotoma corresponding to the loss of retinal ganglion cells, their acuity is rarely affected. Patients may notice visual distortions, metamorphopsia or blurred vision. Those with temporal pits have the greatest risk for developing serous maculopathy.
PATHOPHYSIOLOGY
The origin of optic pits remains unclear. Optic pits have been associated with colobomatous lesions, suggesting that they result from incomplete closure of the fetal fissure. Others propose that they result from abnormal differentiation of primitive epithelia papilla. Arcuate visual field defects are the result of corresponding loss of retinal ganglion cells or secondary atrophy of attenuated nerve fibers.
Some 40 to 60 percent of patients with optic pits develop non-rhegmatogenous serous macular detachments. These fluid-filled cystic maculopathies can develop into lamellar macular holes. The origin of the fluid is unknown. There is a high incidence of posterior vitreous detachment associated with these serous maculopathies.
Previous theories concerning the origin of the subretinal fluid seen in optic pit-related serous macular detachment include liquefied vitreous penetration and leaking vessels within the pit. New findings strongly suggest that serous macular detachments secondary to optic pits develop due to pre-existing schisis-like lesions which connect the macula to the optic disc. Fluid, predominantly from the outer plexiform layer, enters an already edematous retina through the optic pit via the retinal stroma, producing a macular detachment.
MANAGEMENT
Begin the management of asymptomatic optic pit with a comprehensive eye examination, including threshold visual fields. Semi-annual intraocular pressure checks and dilated evaluations with drawings or photos are appropriate. Use home acuity assessment and home Amsler grid testing to monitor for the onset of maculopathy. Educate patients about the signs and symptoms of macular complications (e.g. blurred vision, visual distortions, metamorphopsia).
Treatment for optic pit-related macular detachment varies. Periodic monitoring, prophylactic laser photocoagulation, therapeutic laser photocoagulation after maculopathy has formed, oral steroids and vitrectomy have all been tried. The current trend is laser photocoagulation following the onset of maculopathy.
CLINICAL PEARLS
Differential diagnosis includes optic disc anomalies that mimic optic pit: choroidal and scleral crescent, tilted disc syndrome, circumpapillary staphyloma, hypoplastic disc and glaucomatous optic neuropathy. Idiopathic central serous retinopathy and subretinal neovascular membrane are alternative considerations for serous macular detachment.
Any change in appearance of the optic pit over time suggests that the lesion may be an acquired notch of the neuroretinal rim secondary to glaucomatous processes.
OPTIC NERVE HEAD HYPOPLASIA
SIGNS AND SYMPTOMS
Because optic nerve head hypoplasia is congenital, it is typically diagnosed in younger patients at their initial eye examination. Visual acuity may range from normal to no light perception.
If the condition is unilateral, a relative afferent pupillary defect may be noted. Other dysfunctions of the afferent system, such as diminished color vision, red desaturation and brightness perception will likewise be present. Visual field defects may also be elicited but vary considerably-altitudinal loss, central and cecocentral scotomas, and other field defects have been documented. In addition, up to 50 percent of patients manifest a constant strabismus, most often esotropia.
Examination reveals a smaller-than-expected optic nerve, with the vasculature appearing large relative to the disc. If unilateral, there is a notable size difference in the nerve heads. A circumpapillary ring of white or yellowish scleral tissue is typically evident ("double-ring sign"). The normally bright reflex from the nerve fiber layer is diminished. A review of the patient's history may reveal associated brain disorders (e.g., absence of the septum pellucidum, pituitary dysfunction, porencephaly) and/or gestational disease, as well as a history of maldeveloped growth.
PATHOPHYSIOLOGY
The exact mechanism of optic nerve head hypoplasia is not completely understood. But the condition is believed to represent a dysplasia of the retinal ganglion cell layer with an associated loss of the nerve fiber layer, secondary to some interruption in fetal development. Underdevelopment of the optic nerve results, and the posterior scleral foramen "fills in" with connective and scleral tissues.
Many disorders have been implicated in this disorder, including gestational diabetes, maternal infection by cytomegalovirus, syphilis, rubella, fetal alcohol syndrome and other drug use by the mother while pregnant. ONH hypoplasia may be part of larger clinical syndromes such as septo-optic dysplasia, which is marked by short stature, congenital nystagmus and a hypoplastic disc. The majority of patients, however, have no associated systemic abnormalities.
MANAGEMENT
Remember, ONH hypoplasia is a congenital condition. Appropriate management begins with proper diagnosis. Use visual field testing to confirm your suspicions.
In addition, many clinicians photograph the posterior pole of the affected eye and measure the disc-macula/disc-disc (DM/DD) ratio; this allows them to compare the horizontal diameter of the nerve head to the distance between the fovea and the center of the nerve. In a normal eye, the DM/DD measures between 2:1 and 3.2:1. Ratios greater than this suggest hypoplasia.
In uncomplicated unilateral cases, manage the condition through patient education and protective eyewear. If the history or examination indicates any associated neurological manifestations, refer the patient for studies to rule out forebrain disease. Studies may include physical and neurologic evaluation, neuroimaging and endocrinologic assessment. In more profound cases where both eyes are affected, consider visual rehabilitation services.
CLINICAL PEARLS
Make sure to clearly distinguish this condition from amblyopia. Although both amblyopia and ONH hypoplasia can present with reduced acuity, strabismus and variable refractive error, the former remains a diagnosis of exclusion. In cases of ONH hypoplasia, the associated refractive and/or binocular findings are secondary findings rather than primary causes of the problem. Furthermore, conventional amblyopia therapy will not be helpful in ONH hypoplasia. Vision therapy is a lengthy, costly, yet fruitless option for these patients.
Because optic nerve head hypoplasia is congenital, it is typically diagnosed in younger patients at their initial eye examination. Visual acuity may range from normal to no light perception.
If the condition is unilateral, a relative afferent pupillary defect may be noted. Other dysfunctions of the afferent system, such as diminished color vision, red desaturation and brightness perception will likewise be present. Visual field defects may also be elicited but vary considerably-altitudinal loss, central and cecocentral scotomas, and other field defects have been documented. In addition, up to 50 percent of patients manifest a constant strabismus, most often esotropia.
Examination reveals a smaller-than-expected optic nerve, with the vasculature appearing large relative to the disc. If unilateral, there is a notable size difference in the nerve heads. A circumpapillary ring of white or yellowish scleral tissue is typically evident ("double-ring sign"). The normally bright reflex from the nerve fiber layer is diminished. A review of the patient's history may reveal associated brain disorders (e.g., absence of the septum pellucidum, pituitary dysfunction, porencephaly) and/or gestational disease, as well as a history of maldeveloped growth.
PATHOPHYSIOLOGY
The exact mechanism of optic nerve head hypoplasia is not completely understood. But the condition is believed to represent a dysplasia of the retinal ganglion cell layer with an associated loss of the nerve fiber layer, secondary to some interruption in fetal development. Underdevelopment of the optic nerve results, and the posterior scleral foramen "fills in" with connective and scleral tissues.
Many disorders have been implicated in this disorder, including gestational diabetes, maternal infection by cytomegalovirus, syphilis, rubella, fetal alcohol syndrome and other drug use by the mother while pregnant. ONH hypoplasia may be part of larger clinical syndromes such as septo-optic dysplasia, which is marked by short stature, congenital nystagmus and a hypoplastic disc. The majority of patients, however, have no associated systemic abnormalities.
MANAGEMENT
Remember, ONH hypoplasia is a congenital condition. Appropriate management begins with proper diagnosis. Use visual field testing to confirm your suspicions.
In addition, many clinicians photograph the posterior pole of the affected eye and measure the disc-macula/disc-disc (DM/DD) ratio; this allows them to compare the horizontal diameter of the nerve head to the distance between the fovea and the center of the nerve. In a normal eye, the DM/DD measures between 2:1 and 3.2:1. Ratios greater than this suggest hypoplasia.
In uncomplicated unilateral cases, manage the condition through patient education and protective eyewear. If the history or examination indicates any associated neurological manifestations, refer the patient for studies to rule out forebrain disease. Studies may include physical and neurologic evaluation, neuroimaging and endocrinologic assessment. In more profound cases where both eyes are affected, consider visual rehabilitation services.
CLINICAL PEARLS
Make sure to clearly distinguish this condition from amblyopia. Although both amblyopia and ONH hypoplasia can present with reduced acuity, strabismus and variable refractive error, the former remains a diagnosis of exclusion. In cases of ONH hypoplasia, the associated refractive and/or binocular findings are secondary findings rather than primary causes of the problem. Furthermore, conventional amblyopia therapy will not be helpful in ONH hypoplasia. Vision therapy is a lengthy, costly, yet fruitless option for these patients.
INTERNUCLEAR OPHTHALMOPLEGIA
SIGNS AND SYMPTOMS
Several underlying systemic diseases can cause this condition. There is a painless onset of visual disturbance, but often no diplopia in primary gaze. There will be horizontal diplopia in lateral gaze. The patient will manifest an adduction deficit on the involved side and a nystagmus of the fellow eye in extreme abduction.
Occasionally, the condition is bilateral with medial rectus palsy and adduction deficit in each eye and nystagmus upon abduction in both eyes (bilateral internuclear ophthalmoplegia, or BINO) While there appears to be medial recti palsy, most patients will be able to converge (posterior INO or BINO). In some cases, the patient will not be able to converge (anterior INO or BINO).
PATHOPHYSIOLOGY
To produce synchronous eye movements, cranial nerves III, IV and VI communicate through the medial longitudinal fasciculus (MLF), the neural pathway connecting the cranial nerve nuclei responsible for eye movements. In INO, a lesion disrupts this pathway, preventing communication between cranial nerves.
For example, for a patient to gaze to the left, the left supranuclear control center of horizontal eye movements [paramedian pontine reticular formation (PPRF)] must signal the left CN VI nucleus to turn the left eye outwards. At the same time, the PPRF must signal the right CN III nucleus, via the right MLF, to simultaneously turn the right eye inwards. A lesion of the right MLF would not allow the neural impulse to reach the right medial rectus. In this case, the left eye would abduct, but the right eye would not adduct. Further, the left eye would go into an abducting nystagmus.
Most lesions of the MLF are located in the pons, or caudal mesencephalon. Thus, patients with INO or BINO will be able to converge (posterior INO/BINO). However, if the lesion affects the MLF within the mesencephalon and involves the CN III nucleus, then the patient will not be able to converge (anterior INO/BINO).
Possible causes of INO/BINO:
multiple sclerosis
brainstem infarction
brainstem and fourth ventricular tumor
viral infection
trauma
syphilis
Lyme disease
drug intoxication (phenothiazines and tricyclic antidepressants)
subdural hematoma
Typically, multiple sclerosis causes a bilateral presentation, whereas ischemic vascular infarction causes a unilateral episode. Also, myasthenia gravis can produce a pseudo-INO/BINO with a motility pattern identical to true INO/BINO.
MANAGEMENT
Manage INO/BINO by identifying the underlying cause, and then obtaining appropriate medical treatment. In cases of ischemic vascular infarction, the motility pattern returns to normal over time. Appropriate testing includes MRI of the brainstem, FTA-ABS, VDRL, Lyme titre, fasting blood glucose, complete blood count with differential, blood pressure measurement, and toxicology screen.
CLINICAL PEARLS
Remember that myasthenia gravis can mimic the motility pattern of INO/BINO.
In younger patients, the etiology of INO/BINO is most commonly multiple sclerosis. In fact, INO/BINO is the most common ocular motility dysfunction in MS. Approximately 92 percent of patients who develop INO/BINO from demyelinization develop MS.
In older patients who develop INO/BINO, the most common etiology is ischemic vascular infarction. Beyond MRI studies, these patients need medical evaluation for ischemic vascular diseases such as diabetes and hypertension. These cases typically resolve over time.
Several underlying systemic diseases can cause this condition. There is a painless onset of visual disturbance, but often no diplopia in primary gaze. There will be horizontal diplopia in lateral gaze. The patient will manifest an adduction deficit on the involved side and a nystagmus of the fellow eye in extreme abduction.
Occasionally, the condition is bilateral with medial rectus palsy and adduction deficit in each eye and nystagmus upon abduction in both eyes (bilateral internuclear ophthalmoplegia, or BINO) While there appears to be medial recti palsy, most patients will be able to converge (posterior INO or BINO). In some cases, the patient will not be able to converge (anterior INO or BINO).
PATHOPHYSIOLOGY
To produce synchronous eye movements, cranial nerves III, IV and VI communicate through the medial longitudinal fasciculus (MLF), the neural pathway connecting the cranial nerve nuclei responsible for eye movements. In INO, a lesion disrupts this pathway, preventing communication between cranial nerves.
For example, for a patient to gaze to the left, the left supranuclear control center of horizontal eye movements [paramedian pontine reticular formation (PPRF)] must signal the left CN VI nucleus to turn the left eye outwards. At the same time, the PPRF must signal the right CN III nucleus, via the right MLF, to simultaneously turn the right eye inwards. A lesion of the right MLF would not allow the neural impulse to reach the right medial rectus. In this case, the left eye would abduct, but the right eye would not adduct. Further, the left eye would go into an abducting nystagmus.
Most lesions of the MLF are located in the pons, or caudal mesencephalon. Thus, patients with INO or BINO will be able to converge (posterior INO/BINO). However, if the lesion affects the MLF within the mesencephalon and involves the CN III nucleus, then the patient will not be able to converge (anterior INO/BINO).
Possible causes of INO/BINO:
multiple sclerosis
brainstem infarction
brainstem and fourth ventricular tumor
viral infection
trauma
syphilis
Lyme disease
drug intoxication (phenothiazines and tricyclic antidepressants)
subdural hematoma
Typically, multiple sclerosis causes a bilateral presentation, whereas ischemic vascular infarction causes a unilateral episode. Also, myasthenia gravis can produce a pseudo-INO/BINO with a motility pattern identical to true INO/BINO.
MANAGEMENT
Manage INO/BINO by identifying the underlying cause, and then obtaining appropriate medical treatment. In cases of ischemic vascular infarction, the motility pattern returns to normal over time. Appropriate testing includes MRI of the brainstem, FTA-ABS, VDRL, Lyme titre, fasting blood glucose, complete blood count with differential, blood pressure measurement, and toxicology screen.
CLINICAL PEARLS
Remember that myasthenia gravis can mimic the motility pattern of INO/BINO.
In younger patients, the etiology of INO/BINO is most commonly multiple sclerosis. In fact, INO/BINO is the most common ocular motility dysfunction in MS. Approximately 92 percent of patients who develop INO/BINO from demyelinization develop MS.
In older patients who develop INO/BINO, the most common etiology is ischemic vascular infarction. Beyond MRI studies, these patients need medical evaluation for ischemic vascular diseases such as diabetes and hypertension. These cases typically resolve over time.
HORNER'S SYNDROME
SIGNS AND SYMPTOMS
Horner's syndrome is characterized by an interruption of the oculosympathetic nerve pathway somewhere between its origin in the hypothalamus and the eye. The classic clinical findings associated with Horner's syndrome are ptosis, pupillary miosis and facial anhidrosis. Other findings may include apparent enophthalmos, increased amplitude of accommodation, heterochromia of the irides (if it occurs before age two), paradoxical contralateral eyelid retraction, transient decrease in intraocular pressure and changes in tear viscosity.
Horner's syndrome has no predilection for age, race, gender or geographic location. Horner's syndrome of congenital origin is typically around the age of two years with heterochromia and absence of a horizontal eyelid fold or crease in the ptotic eye. Iris pigmentation (which is under sympathetic control during development) is completed by the age of two, making heterochromia an uncommon finding in Horner's syndromes acquired later in life. Old photographs can aid the clinician in distinguishing congenital Horner's by documenting heterochromia present at, or near, birth.
PATHOPHYSIOLOGY
Sympathetic innervation to the eye consists of a three neuron arc. The first neuron originates in the hypothalamus. It descends and travels between the levels of the eighth cervical and forth thoracic vertebrae (C8-T4) of the spinal cord. There, it synapses with second order neurons whose preganglionic cell bodies give rise to axons. These axons pass over the apex of the lung and enter the sympathetic chain in the neck, synapsing in the superior cervical ganglion. Here, cell bodies of third order neurons give rise to postganglionic axons that course to the eye via the cavernous sinus. These sympathetic nerve fibers course anteriorly through the uveal tract and join the fibers of long posterior ciliary nerves to innervate the dilator of the iris. Postganglionic sympathetic fibers also innervate the muscle of Mueller within the eyelid, which is responsible for the initiation of eyelid retraction during eyelid opening. Postganglionic sympathetic fibers, responsible for facial sweating, follow the external carotid artery to the sweat glands of the face. Interruption at any location along this pathway (preganglionic or postganglionic) will induce an ipsilateral Horner's syndrome.
The common etiologies of acquired preganglionic Horner's syndrome include, but are not limited to, trauma, aortic dissection, carotid dissection, tuberculosis and Pancoast tumor. Common causes of post-ganglionic Horner's syndrome include trauma, cluster migraine headache and neck or thyroid surgery.
The diagnosis and the localization of a Horner's syndrome is accomplished with pharmacological testing. Ten percent liquid cocaine (topically applied), works as an indirect acting sympathomimetic agent by inhibiting the re-uptake of norepinephrine at the nerve ending. A Horner's pupil will dilate poorly because of the absence of endogenous norepinephrine at the nerve ending. The test should be evaluated thirty minutes after the instillation of the drops to ensure accuracy. The cocaine test is used to confirm or deny the presence of a Horner's syndrome. However, a positive cocaine test does not localize the lesion.
To localize the lesion as either preganglionic or postganglionic, Paradrine 1% (hydroxyamphetamine) or Pholedrine 5% (n-methyl derivative of hydroxyamphetamine) can be instilled 48 hours later. Pholedrine and Paradrine act similarly by producing the forced release of endogenous norepinephrine from the presynaptic vesicles. If the third neuron is damaged, there will be no endogenous norepinephrine and the pupil will not dilate, thus indicating a postganglionic lesion. Dilation indicates first or second order neuron lesion. There is currently no method of topical testing to differentiate a first order preganglionic lesion from a second order preganglionic lesion.
MANAGEMENT
In general, the treatment for Horner's syndrome depends upon the cause. In many cases there is no treatment that improves or reverses the condition. Treatment in acquired cases is directed toward eradicating the disease that is producing the syndrome. Recognizing the signs and symptoms is tantamount to early diagnosis and expedient referrals to specialists.
CLINICAL PEARLS
The time frame for testing is important because cocaine has the ability to inhibit the uptake of Pholedrine and Paradrine into the presynaptic vesicle, reducing accuracy. There must be at least 48 hours between the tests.
Some of the older literature suggests employing Phenylephrine 1% solution for localization. This technique is rarely employed because patients with either preganglionic or postganglionic lesions become hypersensitive to the drug making results inaccurate.
There is a "dilation lag" in Horner's syndrome where the involved pupil will dilate slowly in dim illumination. That is, the degree of anisocoria diminishes as the patient sits in a dark room.
Post-ganglionic Horner's syndromes tend to occur from more benign causes and are typically vascular in origin.
If hemianalgesia and/or hemiparesis appear with Horner's syndrome, then the lesion is within the spinal cord or brain.
Isolated Horner's syndrome typically is vascular in nature.
Horner's syndrome is characterized by an interruption of the oculosympathetic nerve pathway somewhere between its origin in the hypothalamus and the eye. The classic clinical findings associated with Horner's syndrome are ptosis, pupillary miosis and facial anhidrosis. Other findings may include apparent enophthalmos, increased amplitude of accommodation, heterochromia of the irides (if it occurs before age two), paradoxical contralateral eyelid retraction, transient decrease in intraocular pressure and changes in tear viscosity.
Horner's syndrome has no predilection for age, race, gender or geographic location. Horner's syndrome of congenital origin is typically around the age of two years with heterochromia and absence of a horizontal eyelid fold or crease in the ptotic eye. Iris pigmentation (which is under sympathetic control during development) is completed by the age of two, making heterochromia an uncommon finding in Horner's syndromes acquired later in life. Old photographs can aid the clinician in distinguishing congenital Horner's by documenting heterochromia present at, or near, birth.
PATHOPHYSIOLOGY
Sympathetic innervation to the eye consists of a three neuron arc. The first neuron originates in the hypothalamus. It descends and travels between the levels of the eighth cervical and forth thoracic vertebrae (C8-T4) of the spinal cord. There, it synapses with second order neurons whose preganglionic cell bodies give rise to axons. These axons pass over the apex of the lung and enter the sympathetic chain in the neck, synapsing in the superior cervical ganglion. Here, cell bodies of third order neurons give rise to postganglionic axons that course to the eye via the cavernous sinus. These sympathetic nerve fibers course anteriorly through the uveal tract and join the fibers of long posterior ciliary nerves to innervate the dilator of the iris. Postganglionic sympathetic fibers also innervate the muscle of Mueller within the eyelid, which is responsible for the initiation of eyelid retraction during eyelid opening. Postganglionic sympathetic fibers, responsible for facial sweating, follow the external carotid artery to the sweat glands of the face. Interruption at any location along this pathway (preganglionic or postganglionic) will induce an ipsilateral Horner's syndrome.
The common etiologies of acquired preganglionic Horner's syndrome include, but are not limited to, trauma, aortic dissection, carotid dissection, tuberculosis and Pancoast tumor. Common causes of post-ganglionic Horner's syndrome include trauma, cluster migraine headache and neck or thyroid surgery.
The diagnosis and the localization of a Horner's syndrome is accomplished with pharmacological testing. Ten percent liquid cocaine (topically applied), works as an indirect acting sympathomimetic agent by inhibiting the re-uptake of norepinephrine at the nerve ending. A Horner's pupil will dilate poorly because of the absence of endogenous norepinephrine at the nerve ending. The test should be evaluated thirty minutes after the instillation of the drops to ensure accuracy. The cocaine test is used to confirm or deny the presence of a Horner's syndrome. However, a positive cocaine test does not localize the lesion.
To localize the lesion as either preganglionic or postganglionic, Paradrine 1% (hydroxyamphetamine) or Pholedrine 5% (n-methyl derivative of hydroxyamphetamine) can be instilled 48 hours later. Pholedrine and Paradrine act similarly by producing the forced release of endogenous norepinephrine from the presynaptic vesicles. If the third neuron is damaged, there will be no endogenous norepinephrine and the pupil will not dilate, thus indicating a postganglionic lesion. Dilation indicates first or second order neuron lesion. There is currently no method of topical testing to differentiate a first order preganglionic lesion from a second order preganglionic lesion.
MANAGEMENT
In general, the treatment for Horner's syndrome depends upon the cause. In many cases there is no treatment that improves or reverses the condition. Treatment in acquired cases is directed toward eradicating the disease that is producing the syndrome. Recognizing the signs and symptoms is tantamount to early diagnosis and expedient referrals to specialists.
CLINICAL PEARLS
The time frame for testing is important because cocaine has the ability to inhibit the uptake of Pholedrine and Paradrine into the presynaptic vesicle, reducing accuracy. There must be at least 48 hours between the tests.
Some of the older literature suggests employing Phenylephrine 1% solution for localization. This technique is rarely employed because patients with either preganglionic or postganglionic lesions become hypersensitive to the drug making results inaccurate.
There is a "dilation lag" in Horner's syndrome where the involved pupil will dilate slowly in dim illumination. That is, the degree of anisocoria diminishes as the patient sits in a dark room.
Post-ganglionic Horner's syndromes tend to occur from more benign causes and are typically vascular in origin.
If hemianalgesia and/or hemiparesis appear with Horner's syndrome, then the lesion is within the spinal cord or brain.
Isolated Horner's syndrome typically is vascular in nature.
CRANIAL NERVE VII (FACIAL NERVE) PALSY
SIGNS AND SYMPTOMS
The prevalence of idiopathic cranial nerve VII (CN VII) palsy ranges from 10/100,000 to 40/100,000 with an average of 21/100,000. Occurrences are highest in adults over 70. Recurrence of idiopathic CN VII palsy ranges between 6 to 11 percent.
Cranial nerve VII innervates the muscles of facial expression and the stapedius muscle of the inner ear. The orbicularis oculi, responsible for eyelid closure, is controlled by CN VII. Damage to the nerve or its peripheral course produces weakness or paralysis of one side of the face with an inability to close the ipsilateral eye. Additional findings on the affected side include flattening of the nasal labial fold, droop of the corner of the mouth, ectropion, lagophthalmos, decreased tear production, dry eye, conjunctival injection, corneal compromise, decreased sense of taste and hyperacusis (supersensitivity to sound).
Occasionally, following injury, some fibers of CN VII regenerate to erroneously innervate adjacent structures. The result is simultaneous movements of muscles (e.g. the corner of the mouth contracts on attempted eyelid closure) or the stimulation of glands supplied by the redistributed branches of CN VII when the nerve is activated (e.g. excessive lacrimation upon eating, known as crocodile tearing ).
PATHOPHYSIOLOGY
The muscles that close the eyes and wrinkle the forehead are bilaterally innervated. A unilateral lesion in the cortex or supranuclear pathway spares eyelid closure and forehead wrinkling but results in contralateral paralysis of the lower face. Since the area of the cortex associated with facial muscle function lies near the motor representation of the hand and tongue, weakness of the thumb, fingers and tongue ipsilateral to the facial palsy is not uncommon.
The facial nucleus contains four separate cell groups that innervate specific muscle groups. Lesions of the fibers of the superior salivatory and lacrimal nuclei (parasympathetic preganglionic fibers supplying the sublingual, submandibular and lacrimal glands) include temporal bone fractures and infections, schwannomas, neuromas (cerebellopontine angle tumors) and vascular compression, producing deficits in hearing, balance, tear production and salivatory flow.
Lesions that involve the ganglion include geniculate ganglionitis (Ramsey-Hunt syndrome: zoster oticus). Lesions such as acoustic neuroma that also involve cranial nerve VIII can impair hearing, facial nerve function and produce corneal hypoesthesia (CN V).
Lesions of the zygomatic and lacrimal nerves impair reflex tear secretion. Middle cranial fossa disease is indicated when defective tear production accompanies CN V (muscles of mastication) or CN VI palsy.
Lesions of the facial nerve disable the ability to dampen sound, producing hyperacusis. Lesions to sensory afferent fibers that transmit taste (fibers that also innervate the salivary glands) cause an interruption in salivatory flow and an inability to sense taste from the anterior two-thirds of the tongue.
The portion of the facial nerve that contains the motor fibers that innervate the muscles of facial expression exits the stylomastoid foramen and enters the substance of the parotid gland before distribution. Therefore, investigate lesions of the parotid gland also as part of the work up.
Lesions that occur within the cortical, extrapyramidal or brainstem levels are known as central lesions. Lesions outside the brain are referred to as peripheral. The common causes of peripheral CN VII palsy include cerebellopontine angle tumor (7 percent), trauma (21 percent), otitis media, herpes zoster oticus (Ramsey-Hunt syndrome), Lyme disease, sarcoidosis, parotid neoplasm, syphilis, diabetes mellitus, pregnancy and HIV.
MANAGEMENT
First obtain a complete history. Perform a cursory evaluation of the 12 cranial nerves as well as a comprehensive ocular examination with dilated fundus and optic nerve evaluation. Pay close attention to the affected eyelid's posture, corneal wetting (tear break up time), blink posture, tear quality (sodium fluorescein staining) and tear quantity (Schirmer tear testing). In cases where diagnosis is questionable, ask the patient to close both eyes while you try to open the lid. If one lid is significantly easier to open than the other, suspect CN VII palsy.
You can manage exposure keratopathy with ocular lubricating drops and ointments. Moisture chamber patches (e.g. Guibora eye patch) or eyelid taping are also possible solutions. Moisture chamber shields can be attached to spectacle temples to create a moist ocular environment and lessen tear evaporation. Since idiopathic facial nerve palsy is a diagnosis of exclusion, order laboratory testing (Lyme titer, rheumatoid factor, erythrocyte sedimentation rate, antinuclear antibody, echocardiogram, fluorescent treponemal antibody absorption test, HIV titer, chest X-ray), lumbar puncture (in patients with suspected neoplasm), CT and MRI and/or appropriate referrals (otolaryngology, neurology, neurosurgery).
CLINICAL PEARLS
Most cases (53 percent) of unilateral facial weakness are idiopathic. These lesions are thought to occur secondary to idiopathic inflammation, viral infection or vascular compression of CN VII. Given the extensive neurology of CN VII, idiopathic "Bell's Palsy" is a diagnosis of exclusion.
Patients with idiopathic facial nerve paralysis (Bell's Palsy) typically complain of acute (24 to 48 hours) unilateral facial weakness
The prevalence of idiopathic cranial nerve VII (CN VII) palsy ranges from 10/100,000 to 40/100,000 with an average of 21/100,000. Occurrences are highest in adults over 70. Recurrence of idiopathic CN VII palsy ranges between 6 to 11 percent.
Cranial nerve VII innervates the muscles of facial expression and the stapedius muscle of the inner ear. The orbicularis oculi, responsible for eyelid closure, is controlled by CN VII. Damage to the nerve or its peripheral course produces weakness or paralysis of one side of the face with an inability to close the ipsilateral eye. Additional findings on the affected side include flattening of the nasal labial fold, droop of the corner of the mouth, ectropion, lagophthalmos, decreased tear production, dry eye, conjunctival injection, corneal compromise, decreased sense of taste and hyperacusis (supersensitivity to sound).
Occasionally, following injury, some fibers of CN VII regenerate to erroneously innervate adjacent structures. The result is simultaneous movements of muscles (e.g. the corner of the mouth contracts on attempted eyelid closure) or the stimulation of glands supplied by the redistributed branches of CN VII when the nerve is activated (e.g. excessive lacrimation upon eating, known as crocodile tearing ).
PATHOPHYSIOLOGY
The muscles that close the eyes and wrinkle the forehead are bilaterally innervated. A unilateral lesion in the cortex or supranuclear pathway spares eyelid closure and forehead wrinkling but results in contralateral paralysis of the lower face. Since the area of the cortex associated with facial muscle function lies near the motor representation of the hand and tongue, weakness of the thumb, fingers and tongue ipsilateral to the facial palsy is not uncommon.
The facial nucleus contains four separate cell groups that innervate specific muscle groups. Lesions of the fibers of the superior salivatory and lacrimal nuclei (parasympathetic preganglionic fibers supplying the sublingual, submandibular and lacrimal glands) include temporal bone fractures and infections, schwannomas, neuromas (cerebellopontine angle tumors) and vascular compression, producing deficits in hearing, balance, tear production and salivatory flow.
Lesions that involve the ganglion include geniculate ganglionitis (Ramsey-Hunt syndrome: zoster oticus). Lesions such as acoustic neuroma that also involve cranial nerve VIII can impair hearing, facial nerve function and produce corneal hypoesthesia (CN V).
Lesions of the zygomatic and lacrimal nerves impair reflex tear secretion. Middle cranial fossa disease is indicated when defective tear production accompanies CN V (muscles of mastication) or CN VI palsy.
Lesions of the facial nerve disable the ability to dampen sound, producing hyperacusis. Lesions to sensory afferent fibers that transmit taste (fibers that also innervate the salivary glands) cause an interruption in salivatory flow and an inability to sense taste from the anterior two-thirds of the tongue.
The portion of the facial nerve that contains the motor fibers that innervate the muscles of facial expression exits the stylomastoid foramen and enters the substance of the parotid gland before distribution. Therefore, investigate lesions of the parotid gland also as part of the work up.
Lesions that occur within the cortical, extrapyramidal or brainstem levels are known as central lesions. Lesions outside the brain are referred to as peripheral. The common causes of peripheral CN VII palsy include cerebellopontine angle tumor (7 percent), trauma (21 percent), otitis media, herpes zoster oticus (Ramsey-Hunt syndrome), Lyme disease, sarcoidosis, parotid neoplasm, syphilis, diabetes mellitus, pregnancy and HIV.
MANAGEMENT
First obtain a complete history. Perform a cursory evaluation of the 12 cranial nerves as well as a comprehensive ocular examination with dilated fundus and optic nerve evaluation. Pay close attention to the affected eyelid's posture, corneal wetting (tear break up time), blink posture, tear quality (sodium fluorescein staining) and tear quantity (Schirmer tear testing). In cases where diagnosis is questionable, ask the patient to close both eyes while you try to open the lid. If one lid is significantly easier to open than the other, suspect CN VII palsy.
You can manage exposure keratopathy with ocular lubricating drops and ointments. Moisture chamber patches (e.g. Guibora eye patch) or eyelid taping are also possible solutions. Moisture chamber shields can be attached to spectacle temples to create a moist ocular environment and lessen tear evaporation. Since idiopathic facial nerve palsy is a diagnosis of exclusion, order laboratory testing (Lyme titer, rheumatoid factor, erythrocyte sedimentation rate, antinuclear antibody, echocardiogram, fluorescent treponemal antibody absorption test, HIV titer, chest X-ray), lumbar puncture (in patients with suspected neoplasm), CT and MRI and/or appropriate referrals (otolaryngology, neurology, neurosurgery).
CLINICAL PEARLS
Most cases (53 percent) of unilateral facial weakness are idiopathic. These lesions are thought to occur secondary to idiopathic inflammation, viral infection or vascular compression of CN VII. Given the extensive neurology of CN VII, idiopathic "Bell's Palsy" is a diagnosis of exclusion.
Patients with idiopathic facial nerve paralysis (Bell's Palsy) typically complain of acute (24 to 48 hours) unilateral facial weakness
CRANIAL NERVE IV PALSY
SIGNS AND SYMPTOMS
The patient will present with complaints of vertical diplopia, which is especially manifest as the patient tries to read. There may be an inability to look down and in. There may also be horizontal diplopia, as a lateral phoria occurs due to the vertical dissociation. The patient often has a head tilt contralateral to the affected superior oblique muscle. The chin is often tucked downwards as well. There is frequently concurrent hypertension and/or diabetes. The patient will present with a hyperphoric or hypertropic eye on primary gaze. On alternate cover test, the hyper-deviation will increase in contralateral gaze, reduce in ipsilateral gaze, increase on ipsilateral head tilt, and decrease on contralateral head tilt. Visual acuity is unaffected and there is very rarely pain. In bilateral cranial nerve IV palsy, the patient will manifest a hyper-deviation which reverses in opposite gaze.
PATHOPHYSIOLOGY
The fourth cranial nerve nucleus is located in the dorsal mesencephalon. From here, the nerve fibers then decussate and exit the brain stem dorsally into the subarachnoid space. The nerve then courses around the brain to enter the cavernous sinus, superior orbital fissure, orbit, and innervate the superior oblique muscle. Damage to the fourth nerve nucleus or its fascicles within the brain stem will give a contralateral fourth nerve palsy, along with the associated signs of light-near dissociated pupils, retraction nystagmus, up-gaze palsy, Horner's syndrome, and/or internuclear ophthalmoplegia. Bilateral fourth nerve palsies are possible as well. The main causes of damage to the fourth nerve in this area are hemorrhage, infarction, trauma, hydrocephalus and demyelinization.
The fourth nerve is especially prone to trauma as it exits the brain stem and courses through the subarachnoid space. In contrast to third nerve palsies within subarachnoid space, fourth nerve palsies are rarely due to aneurysm. The most common causes of damage to the fourth nerve in this region are trauma and ischemic vasculopathy. The most likely result from damage within subarachnoid space is an isolated fourth nerve palsy.
Due to the large number of other neural structures that accompany the fourth nerve as it travels through the cavernous sinus and superior orbital fissure, it is unlikely that the patient will exhibit an isolated fourth nerve palsy due to damage within these areas. More likely, there will be an associated palsy of cranial nerves III and VI. Common causes of damage to the fourth nerve in these areas are herpes zoster, inflammation of the cavernous sinus or posterior orbit, meningioma, metastatic disease, pituitary adenoma, and carotid cavernous fistula. Trauma to the head or orbit can cause damage to the trochlea, resulting in superior oblique muscle dysfunction.
MANAGEMENT
A fourth nerve palsy often presents suddenly, but may additionally result from decompensation of a longstanding palsy. In order to differentiate these two types of palsies, examine old photographs of the patient. A patient with a decompensated longstanding palsy will present with a compensatory head tilt in old photos. Further, patients with decompensated longstanding fourth nerve palsies will have an exaggerated vertical fusional ability. Longstanding fourth nerve palsies typically are benign and no further management is necessary.
In the case of complicated fourth nerve palsies, (i.e., those that present with other concurrent neurological dysfunction), the patient should undergo neuroradiological studies dictated by the accompanying signs and symptoms. In the case of isolated fourth nerve palsies caused by recent trauma, the patient should undergo an MRI or CT scan of the head to dismiss the possibility of a concurrent subarachnoid hemorrhage. If the fourth nerve palsy is not associated with recent trauma, investigate for a history of past trauma. If the fourth nerve palsy is due to previous trauma and has recently decompensated, you can manage the diplopia with vertical prisms.
If the patient is elderly and has a fourth nerve palsy of recent origin, perform an ischemic vascular evaluation to search for diabetes and hypertension. If the palsy is caused by vascular infarct, it will spontaneously resolve over a period of three to six months and the patient will not require further management beyond periodic observation and either temporary occlusion or press-on prism therapy.
CLINICAL PEARLS
Consider cases of true vertical diplopia to be a fourth nerve palsy until proven otherwise. In children, nearly all cases of isolated fourth nerve palsy are either congenital or traumatic in nature. In adults, approximately 40 percent of all isolated fourth nerve palsies are traumatic, 30 percent are idiopathic, 20 percent are due to vascular infarct, and only 10 percent are due to tumor or aneurysm.
The vast majority of fourth nerve palsies are benign. When encountering a sudden-onset isolated fourth nerve palsy, delay prescribing permanent prisms for at least three months in order to allow the palsy to recover.
The patient will present with complaints of vertical diplopia, which is especially manifest as the patient tries to read. There may be an inability to look down and in. There may also be horizontal diplopia, as a lateral phoria occurs due to the vertical dissociation. The patient often has a head tilt contralateral to the affected superior oblique muscle. The chin is often tucked downwards as well. There is frequently concurrent hypertension and/or diabetes. The patient will present with a hyperphoric or hypertropic eye on primary gaze. On alternate cover test, the hyper-deviation will increase in contralateral gaze, reduce in ipsilateral gaze, increase on ipsilateral head tilt, and decrease on contralateral head tilt. Visual acuity is unaffected and there is very rarely pain. In bilateral cranial nerve IV palsy, the patient will manifest a hyper-deviation which reverses in opposite gaze.
PATHOPHYSIOLOGY
The fourth cranial nerve nucleus is located in the dorsal mesencephalon. From here, the nerve fibers then decussate and exit the brain stem dorsally into the subarachnoid space. The nerve then courses around the brain to enter the cavernous sinus, superior orbital fissure, orbit, and innervate the superior oblique muscle. Damage to the fourth nerve nucleus or its fascicles within the brain stem will give a contralateral fourth nerve palsy, along with the associated signs of light-near dissociated pupils, retraction nystagmus, up-gaze palsy, Horner's syndrome, and/or internuclear ophthalmoplegia. Bilateral fourth nerve palsies are possible as well. The main causes of damage to the fourth nerve in this area are hemorrhage, infarction, trauma, hydrocephalus and demyelinization.
The fourth nerve is especially prone to trauma as it exits the brain stem and courses through the subarachnoid space. In contrast to third nerve palsies within subarachnoid space, fourth nerve palsies are rarely due to aneurysm. The most common causes of damage to the fourth nerve in this region are trauma and ischemic vasculopathy. The most likely result from damage within subarachnoid space is an isolated fourth nerve palsy.
Due to the large number of other neural structures that accompany the fourth nerve as it travels through the cavernous sinus and superior orbital fissure, it is unlikely that the patient will exhibit an isolated fourth nerve palsy due to damage within these areas. More likely, there will be an associated palsy of cranial nerves III and VI. Common causes of damage to the fourth nerve in these areas are herpes zoster, inflammation of the cavernous sinus or posterior orbit, meningioma, metastatic disease, pituitary adenoma, and carotid cavernous fistula. Trauma to the head or orbit can cause damage to the trochlea, resulting in superior oblique muscle dysfunction.
MANAGEMENT
A fourth nerve palsy often presents suddenly, but may additionally result from decompensation of a longstanding palsy. In order to differentiate these two types of palsies, examine old photographs of the patient. A patient with a decompensated longstanding palsy will present with a compensatory head tilt in old photos. Further, patients with decompensated longstanding fourth nerve palsies will have an exaggerated vertical fusional ability. Longstanding fourth nerve palsies typically are benign and no further management is necessary.
In the case of complicated fourth nerve palsies, (i.e., those that present with other concurrent neurological dysfunction), the patient should undergo neuroradiological studies dictated by the accompanying signs and symptoms. In the case of isolated fourth nerve palsies caused by recent trauma, the patient should undergo an MRI or CT scan of the head to dismiss the possibility of a concurrent subarachnoid hemorrhage. If the fourth nerve palsy is not associated with recent trauma, investigate for a history of past trauma. If the fourth nerve palsy is due to previous trauma and has recently decompensated, you can manage the diplopia with vertical prisms.
If the patient is elderly and has a fourth nerve palsy of recent origin, perform an ischemic vascular evaluation to search for diabetes and hypertension. If the palsy is caused by vascular infarct, it will spontaneously resolve over a period of three to six months and the patient will not require further management beyond periodic observation and either temporary occlusion or press-on prism therapy.
CLINICAL PEARLS
Consider cases of true vertical diplopia to be a fourth nerve palsy until proven otherwise. In children, nearly all cases of isolated fourth nerve palsy are either congenital or traumatic in nature. In adults, approximately 40 percent of all isolated fourth nerve palsies are traumatic, 30 percent are idiopathic, 20 percent are due to vascular infarct, and only 10 percent are due to tumor or aneurysm.
The vast majority of fourth nerve palsies are benign. When encountering a sudden-onset isolated fourth nerve palsy, delay prescribing permanent prisms for at least three months in order to allow the palsy to recover.
CRANIAL NERVE III (oculomotor)PALSY
SIGNS AND SYMPTOMS
The patient will usually present with sudden onset unilateral ptosis (or rarely, a bilateral ptosis if the damage occurs to the third nerve nucleus), which is frequently accompanied by significant eye or head pain. The patient rarely complains of double vision because the ptosis obscures the vision in the affected eye; however, if the lid is manually elevated, the patient will experience diplopia. Acuity is typically unaffected unless damage occurs in the superior orbital fissure and cranial nerve II is also involved. The affected eye positions in a non-comitant exotropic, hypotropic position (down and out).
There will be limitation of elevation, depression and adduction. There is an underaction of the superior, inferior, and medial recti muscles and inferior oblique muscle, which may be total or partial. The pupil may be dilated and minimally reactive to light (pupillary involvement), totally reactive and normal (pupillary non-involvement), or may be sluggishly responsive (partial pupillary involvement). The patient is frequently elderly and often has concurrent diabetes and/or hypertension.
PATHOPHYSIOLOGY
Third nerve palsy results from damage to the oculomotor nerve anywhere in its course from the nucleus in the dorsal mesencephalon, its fascicles in the brainstem parenchyma, the nerve root in subarachnoid space, or in the cavernous sinus or posterior orbit. Damage to the third nerve nucleus results in an ipsilateral third nerve palsy with contralateral superior rectus under action and bilateral ptosis. Damage to the third nerve fascicles results in an ipsilateral third nerve palsy with contralateral hemiparesis (Weber's syndrome), contralateral intention tremor (Benedikt's syndrome), or ipsilateral cerebellar ataxia (Nothnagel's syndrome). Vascular infarct, metastatic disease and demyelinization are the common causes of brainstem involvement.
Damage to the third nerve within the subarachnoid space produces an isolated third nerve palsy. The main causes are compression of the nerve by an expanding aneurysm of the posterior communicating artery or the basilar artery, and ischemic vasculopathy. There will always be pain in aneurysmal compression and pupillary involvement is typical, though there have been infrequent cases of aneurysmal compression that did not initially affect pupillary function. In ischemic vascular nerve third palsies, pain is frequent and the pupil is typically normal and reactive.
Damage to the third nerve in the cavernous sinus, superior orbital fissure, or posterior orbit is unlikely to present as third nerve palsy due to the confluence of other structures in these areas. Cavernous sinus involvement may also include pareses of cranial nerves IV, VI and V-1, and an ipsilateral Horner's syndrome. The most common causes of damage in these areas include metastatic disease, inflammation, herpes zoster, carotid artery aneurysm, pituitary adenoma and apoplexy, and sphenoid wing meningioma.
MANAGEMENT
In complicated third nerve palsies where other neural structures are involved, have the patient undergo an MRI. In isolated third nerve palsies with no pupillary involvement where the patient is over 50, MRI scanning, an ischemic vascular evaluation, and daily pupil evaluation is indicated.
If the patient is under 50 and has a non-pupillary involved isolated third nerve palsy, intracranial angiography is indicated since ischemic vasculopathy is less likely to occur in this age group than is aneurysm. If the adult patient of any age presents with a complete or incomplete isolated third nerve palsy with pupillary involvement, consider this to be a medical emergency and have the patient undergo intracranial angiography immediately. In these cases, the cause is likely subarachnoid aneurysm and the patient may die if the aneurysm ruptures. Children under the age of 14 rarely have aneurysms; the majority of third nerve palsies in this age group are traumatic or congenital.
CLINICAL PEARLS
Isolated third nerve palsy due to ischemic vasculopathy will spontaneously resolve and recover over a period of three to six months. If the palsy fails to resolve in this time frame, repeat the MRI to search for the true etiology.
Myasthenia gravis has the ability to mimic virtually any cranial neuropathy, including isolated third nerve palsies. Myasthenia gravis must remain a possible diagnosis when encountering a third nerve palsy, especially when the course is variable or atypical.
The patient will usually present with sudden onset unilateral ptosis (or rarely, a bilateral ptosis if the damage occurs to the third nerve nucleus), which is frequently accompanied by significant eye or head pain. The patient rarely complains of double vision because the ptosis obscures the vision in the affected eye; however, if the lid is manually elevated, the patient will experience diplopia. Acuity is typically unaffected unless damage occurs in the superior orbital fissure and cranial nerve II is also involved. The affected eye positions in a non-comitant exotropic, hypotropic position (down and out).
There will be limitation of elevation, depression and adduction. There is an underaction of the superior, inferior, and medial recti muscles and inferior oblique muscle, which may be total or partial. The pupil may be dilated and minimally reactive to light (pupillary involvement), totally reactive and normal (pupillary non-involvement), or may be sluggishly responsive (partial pupillary involvement). The patient is frequently elderly and often has concurrent diabetes and/or hypertension.
PATHOPHYSIOLOGY
Third nerve palsy results from damage to the oculomotor nerve anywhere in its course from the nucleus in the dorsal mesencephalon, its fascicles in the brainstem parenchyma, the nerve root in subarachnoid space, or in the cavernous sinus or posterior orbit. Damage to the third nerve nucleus results in an ipsilateral third nerve palsy with contralateral superior rectus under action and bilateral ptosis. Damage to the third nerve fascicles results in an ipsilateral third nerve palsy with contralateral hemiparesis (Weber's syndrome), contralateral intention tremor (Benedikt's syndrome), or ipsilateral cerebellar ataxia (Nothnagel's syndrome). Vascular infarct, metastatic disease and demyelinization are the common causes of brainstem involvement.
Damage to the third nerve within the subarachnoid space produces an isolated third nerve palsy. The main causes are compression of the nerve by an expanding aneurysm of the posterior communicating artery or the basilar artery, and ischemic vasculopathy. There will always be pain in aneurysmal compression and pupillary involvement is typical, though there have been infrequent cases of aneurysmal compression that did not initially affect pupillary function. In ischemic vascular nerve third palsies, pain is frequent and the pupil is typically normal and reactive.
Damage to the third nerve in the cavernous sinus, superior orbital fissure, or posterior orbit is unlikely to present as third nerve palsy due to the confluence of other structures in these areas. Cavernous sinus involvement may also include pareses of cranial nerves IV, VI and V-1, and an ipsilateral Horner's syndrome. The most common causes of damage in these areas include metastatic disease, inflammation, herpes zoster, carotid artery aneurysm, pituitary adenoma and apoplexy, and sphenoid wing meningioma.
MANAGEMENT
In complicated third nerve palsies where other neural structures are involved, have the patient undergo an MRI. In isolated third nerve palsies with no pupillary involvement where the patient is over 50, MRI scanning, an ischemic vascular evaluation, and daily pupil evaluation is indicated.
If the patient is under 50 and has a non-pupillary involved isolated third nerve palsy, intracranial angiography is indicated since ischemic vasculopathy is less likely to occur in this age group than is aneurysm. If the adult patient of any age presents with a complete or incomplete isolated third nerve palsy with pupillary involvement, consider this to be a medical emergency and have the patient undergo intracranial angiography immediately. In these cases, the cause is likely subarachnoid aneurysm and the patient may die if the aneurysm ruptures. Children under the age of 14 rarely have aneurysms; the majority of third nerve palsies in this age group are traumatic or congenital.
CLINICAL PEARLS
Isolated third nerve palsy due to ischemic vasculopathy will spontaneously resolve and recover over a period of three to six months. If the palsy fails to resolve in this time frame, repeat the MRI to search for the true etiology.
Myasthenia gravis has the ability to mimic virtually any cranial neuropathy, including isolated third nerve palsies. Myasthenia gravis must remain a possible diagnosis when encountering a third nerve palsy, especially when the course is variable or atypical.
OPTIC DISC EDEMA & PAPILLEDEMA
SIGNS AND SYMPTOMS
Patients with optic disc edema may present asymptomatically, but this can vary depending upon the etiology of the nerve swelling. In cases of optic neuropathy due to inflammation, infiltration, ischemia or demyelinization, visual acuity is often significantly diminished. Papilledema, a specific form of disc edema resulting from elevated intracranial pressure, generally exhibits a minimal acuity deficit, but may demonstrate transient visual obscurations associated with postural changes. Patients with papilledema also may report headache, intermittent diplopia, vomiting and/or nausea, and pulsatile tinnitus. Visual field defects vary widely as well.
In general, you may observe an enlarged physiologic blind spot in any form of disc edema which displaces the peripapillary photoreceptors. Arcuate scotomas are also common when the inferior and superior poles of the disc are compromised. Altitudinal defects may be seen in ischemic and demyelinating neuropathies; central and cecocentral scotomas are common in primary optic nerve inflammations and infections. If disc swelling is unilateral and vision is poor, expect to find a relative afferent pupillary defect in the involved eye.
True bilateral papilledema will not present with an afferent pupillary defect. The earliest signs of disc edema include striations within the nerve fiber layer in conjunction with blurring of the superior and inferior margins of the neural rim tissue. The disc itself will, in time, protrude from the retinal surface. In cases of inflammation or papilledema, it may display hyperemia and capillary dilation. In ischemic optic neuropathy, the disc is swollen and elevated, but characteristically pale. In more severe presentations of optic disc edema, the retinal venules become engorged and tortuous, hemorrhages and/or cotton wool spots form in the peripapillary area, and you'll see circumferential retinal microfolds (Paton's lines) in the region surrounding the disc. Chronic disc edema may ultimately result in atrophy of the nerve head, with associated pallor and gliosis of the rim tissue.
PATHOPHYSIOLOGY
Optic disc edema results primarily because of axoplasmic stasis, or slowed cellular conduction along the nerve. When this occurs, intracellular fluids and metabolic by-products accumulate and are eventually regurgitated at the level of the optic nerve head. Mechanical compression, infiltration, infection, inflammatory disease, demyelinating disease, or compromised vascular perfusion to the nerve may all lead to disc edema. Papilledema is not a primary neural inflammation but rather a direct sequela of elevated intracranial pressure. In this disorder, cerebral edema is effectively transmitted along the common meningeal sheaths of the brain and optic nerve producing an engorged, swollen disc. The condition is bilateral in almost all cases. True papilledema is a critical sign of intracranial hypertension, a potentially life-threatening situation.
MANAGEMENT
Management of optic disc edema begins with a correct diagnosis. Most importantly, it is crucial to distinguish between papilledema and the many other forms of optic disc edema, including "masqueraders" such as buried optic disc drusen. Consider the acuity, visual fields, ophthalmoscopy findings and especially the laterality of presentation carefully in the initial work-up. Order or perform a B-scan ultrasound, which is invaluable in differentiating swelling of the nerve head from infiltration by hyaline bodies (drusen).
If the signs indicate an optic neuropathy such as papillitis or anterior ischemic optic neuropathy, management is aimed at treating the underlying disorder. Often, this involves systemic steroids, particularly when the etiology is inflammatory. You must obtain a CT or MRI scan of the brain within 24 hours of any tentative diagnosis of papilledema (i.e., when you suspect that increased intracranial pressure is the cause of the disc edema). These tests may help to identify an intracranial mass lesion, such as tumor, hemorrhage or abscess; in addition, the appearance of the cerebral ventricles may indicate hydrocephalus or pseudotumor cerebri. In the absence of positive radiographic studies, lumbar puncture may yield information regarding meningitis, encephalitis, or spinal cord tumors. Neurological consultation and co-management is obligatory in all cases of intracranial hypertension.
The treatment of papilledema and its underlying causes may be medical or surgical, depending upon the disorder. Neuro-ophthalmologists have attempted surgical therapy of the optic nerve using optic nerve sheath decompression to alleviate fluid retention within the surrounding meninges by creating a small fenestration site within the intraorbital portion of the nerve. While this procedure has yielded some positive results, it is extremely complex work and may fail in up to one-third of all cases.
CLINICAL PEARLS
There are two critical points to remember: (1) Not all swollen optic discs constitute optic disc edema and (2) Not all cases of optic disc edema constitute papilledema. Many benign clinical entities can simulate an edematous nerve head, even to the most experienced practitioners. Malinserted discs, congenitally full discs (seen often in hypermetropes), or especially buried drusen may sometimes be mistaken for optic disc edema, even though all are non-pathological conditions.
By the same token, many primary inflammations of the optic nerve whic
Patients with optic disc edema may present asymptomatically, but this can vary depending upon the etiology of the nerve swelling. In cases of optic neuropathy due to inflammation, infiltration, ischemia or demyelinization, visual acuity is often significantly diminished. Papilledema, a specific form of disc edema resulting from elevated intracranial pressure, generally exhibits a minimal acuity deficit, but may demonstrate transient visual obscurations associated with postural changes. Patients with papilledema also may report headache, intermittent diplopia, vomiting and/or nausea, and pulsatile tinnitus. Visual field defects vary widely as well.
In general, you may observe an enlarged physiologic blind spot in any form of disc edema which displaces the peripapillary photoreceptors. Arcuate scotomas are also common when the inferior and superior poles of the disc are compromised. Altitudinal defects may be seen in ischemic and demyelinating neuropathies; central and cecocentral scotomas are common in primary optic nerve inflammations and infections. If disc swelling is unilateral and vision is poor, expect to find a relative afferent pupillary defect in the involved eye.
True bilateral papilledema will not present with an afferent pupillary defect. The earliest signs of disc edema include striations within the nerve fiber layer in conjunction with blurring of the superior and inferior margins of the neural rim tissue. The disc itself will, in time, protrude from the retinal surface. In cases of inflammation or papilledema, it may display hyperemia and capillary dilation. In ischemic optic neuropathy, the disc is swollen and elevated, but characteristically pale. In more severe presentations of optic disc edema, the retinal venules become engorged and tortuous, hemorrhages and/or cotton wool spots form in the peripapillary area, and you'll see circumferential retinal microfolds (Paton's lines) in the region surrounding the disc. Chronic disc edema may ultimately result in atrophy of the nerve head, with associated pallor and gliosis of the rim tissue.
PATHOPHYSIOLOGY
Optic disc edema results primarily because of axoplasmic stasis, or slowed cellular conduction along the nerve. When this occurs, intracellular fluids and metabolic by-products accumulate and are eventually regurgitated at the level of the optic nerve head. Mechanical compression, infiltration, infection, inflammatory disease, demyelinating disease, or compromised vascular perfusion to the nerve may all lead to disc edema. Papilledema is not a primary neural inflammation but rather a direct sequela of elevated intracranial pressure. In this disorder, cerebral edema is effectively transmitted along the common meningeal sheaths of the brain and optic nerve producing an engorged, swollen disc. The condition is bilateral in almost all cases. True papilledema is a critical sign of intracranial hypertension, a potentially life-threatening situation.
MANAGEMENT
Management of optic disc edema begins with a correct diagnosis. Most importantly, it is crucial to distinguish between papilledema and the many other forms of optic disc edema, including "masqueraders" such as buried optic disc drusen. Consider the acuity, visual fields, ophthalmoscopy findings and especially the laterality of presentation carefully in the initial work-up. Order or perform a B-scan ultrasound, which is invaluable in differentiating swelling of the nerve head from infiltration by hyaline bodies (drusen).
If the signs indicate an optic neuropathy such as papillitis or anterior ischemic optic neuropathy, management is aimed at treating the underlying disorder. Often, this involves systemic steroids, particularly when the etiology is inflammatory. You must obtain a CT or MRI scan of the brain within 24 hours of any tentative diagnosis of papilledema (i.e., when you suspect that increased intracranial pressure is the cause of the disc edema). These tests may help to identify an intracranial mass lesion, such as tumor, hemorrhage or abscess; in addition, the appearance of the cerebral ventricles may indicate hydrocephalus or pseudotumor cerebri. In the absence of positive radiographic studies, lumbar puncture may yield information regarding meningitis, encephalitis, or spinal cord tumors. Neurological consultation and co-management is obligatory in all cases of intracranial hypertension.
The treatment of papilledema and its underlying causes may be medical or surgical, depending upon the disorder. Neuro-ophthalmologists have attempted surgical therapy of the optic nerve using optic nerve sheath decompression to alleviate fluid retention within the surrounding meninges by creating a small fenestration site within the intraorbital portion of the nerve. While this procedure has yielded some positive results, it is extremely complex work and may fail in up to one-third of all cases.
CLINICAL PEARLS
There are two critical points to remember: (1) Not all swollen optic discs constitute optic disc edema and (2) Not all cases of optic disc edema constitute papilledema. Many benign clinical entities can simulate an edematous nerve head, even to the most experienced practitioners. Malinserted discs, congenitally full discs (seen often in hypermetropes), or especially buried drusen may sometimes be mistaken for optic disc edema, even though all are non-pathological conditions.
By the same token, many primary inflammations of the optic nerve whic
ANTERIOR ISCHEMIC OPTIC NEUROPATHY (AION)
SIGNS AND SYMPTOMS
The patient will typically be elderly and will present with a unilateral, painless loss of vision and visual field. The field defect traditionally is a superior, altitudinal defect. Visual acuity may in rare instances be quite good; however, acuity is usually in the range of 20/200 to no light perception. Visual loss may progress rapidly over several days.
The patient generally has significant systemic disease. In the case of non-arteritic anterior ischemic optic neuropathy, the patient usually has a systemic vascular disease (hypertension, diabetes, atherosclerosis) or collagen vascular disease. In the arteritic form of the disease, the patient will usually present with early signs of anorexia, weight loss, decreased appetite, jaw claudication, scalp tenderness and malaise.
Often several instances of amaurosis fugax (transient blindness) may precede the arteritic AION by up to six months. This is due to giant cell arteritis (GCA), an idiopathic systemic inflammation of medium-sized arteries. The patient with arteritic AION is, on average, 75 years old while the patient with non-arteritic AION is, on average age, 62 years old. Non-arteritic patients will present with a relative afferent pupil defect and a swollen, hyperemic optic disc. Patients with the arteritic form will present also with afferent pupil defect, but the swollen disc is usually pale with associated splinter hemorrhages.
PATHOPHYSIOLOGY
Anterior ischemic optic neuropathy is caused by infarction of the short posterior ciliary arteries supplying the anterior optic nerve. In the non-arteritic form, these vessels are compromised by vascular disease and arteriolosclerosis. In the case of arteritic AION, these vessels, as well as the ophthalmic and central retinal arteries, are compromised by an idiopathic infiltration of the vessels walls by inflammatory macrophages, lymphocytes, and multinucleate giant cells. As most arteries are affected in GCA, there usually is a constellation of systemic symptoms. Due to the widespread involvement in GCA, there is a propensity for the fellow eye to become similarly involved within days, causing severe bilateral vision loss.
MANAGEMENT
Collect a thorough ocular and systemic history and immediately order an erythrocyte sedimentation rate (ESR). Typically, this will be grossly elevated in arteritic AION and normal in non-arteritic AION. If the ESR is elevated and you suspect GCA and arteritic AION, have the patient undergo a temporal artery biopsy to examine for inflammatory cells in the arteries.
If the patient is either suspected to have, or diagnosed with, GCA and arteritic AION, begin treatment with systemic steroids to prevent vision loss from progressing to the other eye. Typically, it's best to hospitalize the patient and place him or her on 1-2g I.V. methylprednisolone for two to three days, followed by oral steroids (60 to 100mg QD of prednisone). Following hospital release, taper the oral steroids but maintain therapy for two to four years. Despite aggressive therapy, GCA frequently progresses to the fellow eye, giving this disease a poor prognosis.
In the case of non-arteritic AION, the prognosis is guarded but much better than with arteritic AION. The rate of progression to bilateral involvement is significantly lower (32 months, on average). There is no direct treatment for non-arteritic AION or the vasculopathy that causes it. The systemic vascular diseases that precipitate the condition must be well controlled by the patient's internist in hopes of preventing or delaying bilateral involvement.
CLINICAL PEARLS
Suspect GCA and arteritic AION in any patient over age 65 with sudden unilateral vision loss and a swollen disc. This is a true emergency, and warrants immediate consultation with a neurologist or neuro-ophthalmologist. You also must evaluate any elderly patient presenting with headache, head pain or, especially, amaurosis fugax for giant cell arteritis.
Central retinal artery occlusion (CRAO), while usually caused by embolism, occurs due to GCA in two to 10 percent of cases. Assume that any patient over age 65 presenting with CRAO has giant cell arteritis until proven otherwise. This means that the patient must immediately have an ESR. If the ESR is abnormal, or if there are systemic signs or symptoms of GCA, the patient must undergo temporal artery biopsy.
The patient will typically be elderly and will present with a unilateral, painless loss of vision and visual field. The field defect traditionally is a superior, altitudinal defect. Visual acuity may in rare instances be quite good; however, acuity is usually in the range of 20/200 to no light perception. Visual loss may progress rapidly over several days.
The patient generally has significant systemic disease. In the case of non-arteritic anterior ischemic optic neuropathy, the patient usually has a systemic vascular disease (hypertension, diabetes, atherosclerosis) or collagen vascular disease. In the arteritic form of the disease, the patient will usually present with early signs of anorexia, weight loss, decreased appetite, jaw claudication, scalp tenderness and malaise.
Often several instances of amaurosis fugax (transient blindness) may precede the arteritic AION by up to six months. This is due to giant cell arteritis (GCA), an idiopathic systemic inflammation of medium-sized arteries. The patient with arteritic AION is, on average, 75 years old while the patient with non-arteritic AION is, on average age, 62 years old. Non-arteritic patients will present with a relative afferent pupil defect and a swollen, hyperemic optic disc. Patients with the arteritic form will present also with afferent pupil defect, but the swollen disc is usually pale with associated splinter hemorrhages.
PATHOPHYSIOLOGY
Anterior ischemic optic neuropathy is caused by infarction of the short posterior ciliary arteries supplying the anterior optic nerve. In the non-arteritic form, these vessels are compromised by vascular disease and arteriolosclerosis. In the case of arteritic AION, these vessels, as well as the ophthalmic and central retinal arteries, are compromised by an idiopathic infiltration of the vessels walls by inflammatory macrophages, lymphocytes, and multinucleate giant cells. As most arteries are affected in GCA, there usually is a constellation of systemic symptoms. Due to the widespread involvement in GCA, there is a propensity for the fellow eye to become similarly involved within days, causing severe bilateral vision loss.
MANAGEMENT
Collect a thorough ocular and systemic history and immediately order an erythrocyte sedimentation rate (ESR). Typically, this will be grossly elevated in arteritic AION and normal in non-arteritic AION. If the ESR is elevated and you suspect GCA and arteritic AION, have the patient undergo a temporal artery biopsy to examine for inflammatory cells in the arteries.
If the patient is either suspected to have, or diagnosed with, GCA and arteritic AION, begin treatment with systemic steroids to prevent vision loss from progressing to the other eye. Typically, it's best to hospitalize the patient and place him or her on 1-2g I.V. methylprednisolone for two to three days, followed by oral steroids (60 to 100mg QD of prednisone). Following hospital release, taper the oral steroids but maintain therapy for two to four years. Despite aggressive therapy, GCA frequently progresses to the fellow eye, giving this disease a poor prognosis.
In the case of non-arteritic AION, the prognosis is guarded but much better than with arteritic AION. The rate of progression to bilateral involvement is significantly lower (32 months, on average). There is no direct treatment for non-arteritic AION or the vasculopathy that causes it. The systemic vascular diseases that precipitate the condition must be well controlled by the patient's internist in hopes of preventing or delaying bilateral involvement.
CLINICAL PEARLS
Suspect GCA and arteritic AION in any patient over age 65 with sudden unilateral vision loss and a swollen disc. This is a true emergency, and warrants immediate consultation with a neurologist or neuro-ophthalmologist. You also must evaluate any elderly patient presenting with headache, head pain or, especially, amaurosis fugax for giant cell arteritis.
Central retinal artery occlusion (CRAO), while usually caused by embolism, occurs due to GCA in two to 10 percent of cases. Assume that any patient over age 65 presenting with CRAO has giant cell arteritis until proven otherwise. This means that the patient must immediately have an ESR. If the ESR is abnormal, or if there are systemic signs or symptoms of GCA, the patient must undergo temporal artery biopsy.
Friday, November 11, 2011
RETINAL DETACHMENT
RETINAL DETACHMENT
SIGNS AND SYMPTOMS
There are three forms of retinal detachment:
1. Rhegmatogenous retinal detachment (RRD), which results from a retinal break. The vast majority of rhegmatogenous detachments are symptomatic, with patients reporting photopsiae, floating spots, peripheral visual field loss, central blurring of vision or metamorphopsia.
2. Exudative or serous retinal detachment (ERD), which results from fluid accumulation under the sensory retina without a retinal break. Exudative detachments do not generally present with photopsiae but may be associated with moderate vision loss, metamorphopsia or a visual field deficit.
3. Tractional retinal detachment (TRD), which results from the pull of proliferative fibrovascular vitreal strands. Tractional detachments are typically asymptomatic unless central vision is threatened, in which case the patient can suffer severe and abrupt vision loss.
In cases of extensive unilateral retinal detachment, you may observe a relative afferent pupillary defect. Intraocular pressure may be reduced in eyes with acute retinal detachment.
Ophthalmoscopy in cases of RRD usually reveals a clumping of pigment cells within the anterior vitreous (Shaffer's sign). There may be an area of white or grayish elevated retina adjacent to the instigating retinal break. If a significant area of the retina is involved, you may note a milky, lackluster appearance with undulating retinal folds.
A rhegmatogenous detachment will not change position with changes in body posture, however it may shift and then return to its original orientation with quick eye movements. Associated findings may include posterior vitreous detachment and preretinal or vitreal hemorrhage. Retinal pigment epithelial hyperplasia may be noted in cases of long-standing retinal detachment (pigment demarcation line), and is a good prognostic feature.
ERD appears clinically as a focal, serous elevation of the retina, which shifts position with changes in posture and eye movement. The subretinal fluid obeys gravity, always affecting the lowest aspect of the eye. Ophthalmoscopy reveals a smooth, translucent, dome-shaped protrusion of the retina. There are usually no hemorrhages, except in cases of associated retinal vasculopathy.
TRD is always associated with vitreal strands and membranes. It appears as a concave, smooth-surfaced detachment with marginal fibrovascular bands emanating into the vitreous body. It is sometimes difficult to assess where the necrotic retina ends and the vitreal membranes begin. Very often, this area encircles an intact posterior pole, resulting in a retinal "pseudo-hole." TRDs are dense and immobile. This motility lends itself well to ancillary testing with ultrasonography.
PATHOPHYSIOLOGY
All retinal detachments involve the sensory retina dissecting from the underlying pigment epithelial layer by subretinal fluid. In rhegmatogenous detachments, this fluid is liquefied vitreous, which accesses the subretinal space via a retinal break. In exudative detachments, the fluid is derived from the choroid, passing through a defective Bruch's membrane. The origin of the subretinal fluid in tractional detachments is unknown. Both passive and active movement of subretinal fluid induce progression of retinal detachments, leading to partial or total loss of vision in some patients.
Retinal breaks are the predisposing factor in patients with rhegmatogenous detachment. These may result from preexisting conditions or ocular trauma. Some of the more common entities associated with RRD include lattice degeneration, flap tears, atrophic holes, operculated retinal breaks, and acquired retinoschisis with both inner and outer holes. As the retinal tissue loses its connection to the RPE, it becomes edematous and dysfunctional. Without surgical intervention, death of this tissue occurs within 48 to 72 hours.
Exudative detachments are relatively rare, occurring in association with subretinal disorders that damage the RPE layer. These may include choroidal neoplasms, Vogt-Koyanagi-Harada syndrome, posterior scleritis, congenital optic disc anomalies (optic pits, morning glory syndrome, etc.), Coat's disease and uveal effusion syndrome.
Transudation of fluid through the RPE defects causes detachment of the otherwise normal sensory retina. As the fluid shifts with eye and head movements, the involved portion of the retina changes. This explains why most patients with ERDs suffer significantly less devastating visual compromise than those with RRDs or TRDs.
Tractional detachments occur only in proliferative vitreoretinopathies. The most common of these is proliferative diabetic retinopathy, but many TRDs are associated with ischemic retinal vein occlusions, sickle cell retinopathy, retinopathy of prematurity, toxocariasis and trauma.
The etiology of TRD involves fibrotic scaffolding of the vitreous along proliferative vascular networks which induce strong anterior tractional forces through vitreal shrinkage. These forces induce the sensory retina to separate from the underlying RPE.
Unlike rhegmatogenous or exudative detachments which tend to be abrupt, TRDs are often slow and insidious, progressing at the same rate as the associated fibrovascular proliferation. Peripheral TRDs are therefore rarely if ever noticed by the patient. Macular TRDs, on the other hand, tend to be symptomatic, unless the underlying disease process has already compromised visual acuity.
SIGNS AND SYMPTOMS
There are three forms of retinal detachment:
1. Rhegmatogenous retinal detachment (RRD), which results from a retinal break. The vast majority of rhegmatogenous detachments are symptomatic, with patients reporting photopsiae, floating spots, peripheral visual field loss, central blurring of vision or metamorphopsia.
2. Exudative or serous retinal detachment (ERD), which results from fluid accumulation under the sensory retina without a retinal break. Exudative detachments do not generally present with photopsiae but may be associated with moderate vision loss, metamorphopsia or a visual field deficit.
3. Tractional retinal detachment (TRD), which results from the pull of proliferative fibrovascular vitreal strands. Tractional detachments are typically asymptomatic unless central vision is threatened, in which case the patient can suffer severe and abrupt vision loss.
In cases of extensive unilateral retinal detachment, you may observe a relative afferent pupillary defect. Intraocular pressure may be reduced in eyes with acute retinal detachment.
Ophthalmoscopy in cases of RRD usually reveals a clumping of pigment cells within the anterior vitreous (Shaffer's sign). There may be an area of white or grayish elevated retina adjacent to the instigating retinal break. If a significant area of the retina is involved, you may note a milky, lackluster appearance with undulating retinal folds.
A rhegmatogenous detachment will not change position with changes in body posture, however it may shift and then return to its original orientation with quick eye movements. Associated findings may include posterior vitreous detachment and preretinal or vitreal hemorrhage. Retinal pigment epithelial hyperplasia may be noted in cases of long-standing retinal detachment (pigment demarcation line), and is a good prognostic feature.
ERD appears clinically as a focal, serous elevation of the retina, which shifts position with changes in posture and eye movement. The subretinal fluid obeys gravity, always affecting the lowest aspect of the eye. Ophthalmoscopy reveals a smooth, translucent, dome-shaped protrusion of the retina. There are usually no hemorrhages, except in cases of associated retinal vasculopathy.
TRD is always associated with vitreal strands and membranes. It appears as a concave, smooth-surfaced detachment with marginal fibrovascular bands emanating into the vitreous body. It is sometimes difficult to assess where the necrotic retina ends and the vitreal membranes begin. Very often, this area encircles an intact posterior pole, resulting in a retinal "pseudo-hole." TRDs are dense and immobile. This motility lends itself well to ancillary testing with ultrasonography.
PATHOPHYSIOLOGY
All retinal detachments involve the sensory retina dissecting from the underlying pigment epithelial layer by subretinal fluid. In rhegmatogenous detachments, this fluid is liquefied vitreous, which accesses the subretinal space via a retinal break. In exudative detachments, the fluid is derived from the choroid, passing through a defective Bruch's membrane. The origin of the subretinal fluid in tractional detachments is unknown. Both passive and active movement of subretinal fluid induce progression of retinal detachments, leading to partial or total loss of vision in some patients.
Retinal breaks are the predisposing factor in patients with rhegmatogenous detachment. These may result from preexisting conditions or ocular trauma. Some of the more common entities associated with RRD include lattice degeneration, flap tears, atrophic holes, operculated retinal breaks, and acquired retinoschisis with both inner and outer holes. As the retinal tissue loses its connection to the RPE, it becomes edematous and dysfunctional. Without surgical intervention, death of this tissue occurs within 48 to 72 hours.
Exudative detachments are relatively rare, occurring in association with subretinal disorders that damage the RPE layer. These may include choroidal neoplasms, Vogt-Koyanagi-Harada syndrome, posterior scleritis, congenital optic disc anomalies (optic pits, morning glory syndrome, etc.), Coat's disease and uveal effusion syndrome.
Transudation of fluid through the RPE defects causes detachment of the otherwise normal sensory retina. As the fluid shifts with eye and head movements, the involved portion of the retina changes. This explains why most patients with ERDs suffer significantly less devastating visual compromise than those with RRDs or TRDs.
Tractional detachments occur only in proliferative vitreoretinopathies. The most common of these is proliferative diabetic retinopathy, but many TRDs are associated with ischemic retinal vein occlusions, sickle cell retinopathy, retinopathy of prematurity, toxocariasis and trauma.
The etiology of TRD involves fibrotic scaffolding of the vitreous along proliferative vascular networks which induce strong anterior tractional forces through vitreal shrinkage. These forces induce the sensory retina to separate from the underlying RPE.
Unlike rhegmatogenous or exudative detachments which tend to be abrupt, TRDs are often slow and insidious, progressing at the same rate as the associated fibrovascular proliferation. Peripheral TRDs are therefore rarely if ever noticed by the patient. Macular TRDs, on the other hand, tend to be symptomatic, unless the underlying disease process has already compromised visual acuity.
RETINITIS PIGMENTOSA
SIGNS AND SYMPTOMS
Patients with retinitis pigmentosa (RP) may present with varying symptoms. The onset is often gradual and insidious, and many patients fail to recognize the manifestations of this condition until it has progressed significantly. When patients do report symptoms, they commonly include difficulty with night vision (nyctalopia) as well as loss of peripheral vision.
Many patients with RP also experience photopsiae as the disorder progresses; typically they report small flashes of light or a twinkling, shimmering sensation in the midperipheral or peripheral field. These are believed to represent aberrant electrical impulses from the degenerating retina.
Central visual acuity is generally not affected until the very late stages of RP, although variants have been encountered that cause devastating macular compromise early in the disease course (e.g., X-linked recessive RP). Color vision is typically remains intact as long as visual acuity is better than 20/40.
Attenuation of the retinal arterioles is the earliest observable sign in RP. Retinal pigmentary changes occur in the form of fine mottling or granularity with surrounding areas of atrophy. Later, stellate pigment hyperplasia may be noted at perivascular locations in the midperipheral retina. These hyperplastic formations are often referred to as "bone spicules."
As the disorder progresses, general atrophy of the RPE and choriocapillaris ensues, exposing the larger choroidal vessels. The optic nerve head is often normal in early RP, but may demonstrate a waxy yellow or pale appearance later. RP has a strong correlation with acquired optic disc drusen. The macula, like the optic nerve, is usually unaffected in the early stages, but in some forms of RP may demonstrate preretinal gliosis ("cellophane maculopathy"), cystoid macular edema or focal RPE defects. Additional findings in RP include pigment cells in the vitreous ("tobacco dust sign"), posterior vitreous detachment and posterior subcapsular cataracts.
Most patients with retinitis pigmentosa are myopic, and many have keratoconus as well. Electrodiagnostic testing in RP shows a significantly diminished scotopic ERG as well as an abnormal EOG and dark adaptometry.
PATHOPHYSIOLOGY
Retinitis pigmentosa is believed to stem from a genetic defect, which leads to a disturbance in the retinal pigment epithelium (RPE) and the breakdown of the photoreceptors' outer segment disc membranes. The resultant accumulation of metabolic by-products disrupts retinal function, and manifests as lipofuscin deposition, retinal gliosis, photoreceptor loss, choriocapillaris occlusion and RPE hyperplasia. These RPE changes compromise the blood-retina barrier, resulting in subretinal leakage and macular edema in later stages. Because the affected photoreceptor cells in most cases are rods, the patient typically experiences visual difficulty under dark conditions, as well as peripheral field constriction.
There are many forms of retinitis pigmentosa, and while most present with similar findings and outcome, some presentations are atypical. RP may be classified on the basis of inheritance pattern (autosomal dominant, autosomal recessive, X-linked, simplex, multiplex), age of onset (congenital, childhood onset, juvenile onset, adult onset), predominant photoreceptor involvement (rod-cone, cone-rod), or location of retinal involvement (central, pericentral, sectoral, peripheral).
MANAGEMENT
Since there is no known treatment for retinitis pigmentosa, management calls for prompt diagnosis and subsequent counseling to maintain quality of life.
Always obtain visual fields and electrodiagnostic testing to confirm the diagnosis of RP; order serology if the diagnosis is unclear or other disorders are suspected.
Most experts recommend a pedigree analysis of patients once RP has been diagnosed. This is critical to determine the exact inheritance pattern of the patient's condition. Individuals should know the risk for their progeny or other family members developing the disease.
Recommend genetic counseling to help the patient deal with these issues. Implement low-vision services as the disorder begins to affect visual function. Field-expansion devices, infrared blocking sun lenses and contrast enhancing filters may be helpful. Periodic optometric follow-up is also important. Perform visual fields several times a year, and evaluate for cataract or macular edema at least annually.
CLINICAL PEARLS
Most patients with RP are diagnosed in the second or third generation of life. Because of the insidious nature of the disorder, the earliest indicators are often objective findings rather than subjective complaints. Some presentations are extremely subtle, particularly in the early stages. Perform a critical evaluation on all patients presenting with complaints of nyctalopia or peripheral field loss.
The diagnosis of RP is often based upon appearance, but many "masqueraders" exist, including rubella retinopathy, syphilitic retinopathy, CMV retinopathy, toxoplasmosis, cancer-associated retinopathy, retinal drug toxicity secondary to thioridazine, chlorpromazine or chloroquine, pigmented paravenous retinochoroidal atrophy, and traumatic retinopathy.
Understandably, the untreatable progressive nature of retinitis pigmentosa is extremely unsettling for the patient and their loved ones; it is often beneficial to recommend psychological or family counseling early in the disease.
Impress upon these patien
Patients with retinitis pigmentosa (RP) may present with varying symptoms. The onset is often gradual and insidious, and many patients fail to recognize the manifestations of this condition until it has progressed significantly. When patients do report symptoms, they commonly include difficulty with night vision (nyctalopia) as well as loss of peripheral vision.
Many patients with RP also experience photopsiae as the disorder progresses; typically they report small flashes of light or a twinkling, shimmering sensation in the midperipheral or peripheral field. These are believed to represent aberrant electrical impulses from the degenerating retina.
Central visual acuity is generally not affected until the very late stages of RP, although variants have been encountered that cause devastating macular compromise early in the disease course (e.g., X-linked recessive RP). Color vision is typically remains intact as long as visual acuity is better than 20/40.
Attenuation of the retinal arterioles is the earliest observable sign in RP. Retinal pigmentary changes occur in the form of fine mottling or granularity with surrounding areas of atrophy. Later, stellate pigment hyperplasia may be noted at perivascular locations in the midperipheral retina. These hyperplastic formations are often referred to as "bone spicules."
As the disorder progresses, general atrophy of the RPE and choriocapillaris ensues, exposing the larger choroidal vessels. The optic nerve head is often normal in early RP, but may demonstrate a waxy yellow or pale appearance later. RP has a strong correlation with acquired optic disc drusen. The macula, like the optic nerve, is usually unaffected in the early stages, but in some forms of RP may demonstrate preretinal gliosis ("cellophane maculopathy"), cystoid macular edema or focal RPE defects. Additional findings in RP include pigment cells in the vitreous ("tobacco dust sign"), posterior vitreous detachment and posterior subcapsular cataracts.
Most patients with retinitis pigmentosa are myopic, and many have keratoconus as well. Electrodiagnostic testing in RP shows a significantly diminished scotopic ERG as well as an abnormal EOG and dark adaptometry.
PATHOPHYSIOLOGY
Retinitis pigmentosa is believed to stem from a genetic defect, which leads to a disturbance in the retinal pigment epithelium (RPE) and the breakdown of the photoreceptors' outer segment disc membranes. The resultant accumulation of metabolic by-products disrupts retinal function, and manifests as lipofuscin deposition, retinal gliosis, photoreceptor loss, choriocapillaris occlusion and RPE hyperplasia. These RPE changes compromise the blood-retina barrier, resulting in subretinal leakage and macular edema in later stages. Because the affected photoreceptor cells in most cases are rods, the patient typically experiences visual difficulty under dark conditions, as well as peripheral field constriction.
There are many forms of retinitis pigmentosa, and while most present with similar findings and outcome, some presentations are atypical. RP may be classified on the basis of inheritance pattern (autosomal dominant, autosomal recessive, X-linked, simplex, multiplex), age of onset (congenital, childhood onset, juvenile onset, adult onset), predominant photoreceptor involvement (rod-cone, cone-rod), or location of retinal involvement (central, pericentral, sectoral, peripheral).
MANAGEMENT
Since there is no known treatment for retinitis pigmentosa, management calls for prompt diagnosis and subsequent counseling to maintain quality of life.
Always obtain visual fields and electrodiagnostic testing to confirm the diagnosis of RP; order serology if the diagnosis is unclear or other disorders are suspected.
Most experts recommend a pedigree analysis of patients once RP has been diagnosed. This is critical to determine the exact inheritance pattern of the patient's condition. Individuals should know the risk for their progeny or other family members developing the disease.
Recommend genetic counseling to help the patient deal with these issues. Implement low-vision services as the disorder begins to affect visual function. Field-expansion devices, infrared blocking sun lenses and contrast enhancing filters may be helpful. Periodic optometric follow-up is also important. Perform visual fields several times a year, and evaluate for cataract or macular edema at least annually.
CLINICAL PEARLS
Most patients with RP are diagnosed in the second or third generation of life. Because of the insidious nature of the disorder, the earliest indicators are often objective findings rather than subjective complaints. Some presentations are extremely subtle, particularly in the early stages. Perform a critical evaluation on all patients presenting with complaints of nyctalopia or peripheral field loss.
The diagnosis of RP is often based upon appearance, but many "masqueraders" exist, including rubella retinopathy, syphilitic retinopathy, CMV retinopathy, toxoplasmosis, cancer-associated retinopathy, retinal drug toxicity secondary to thioridazine, chlorpromazine or chloroquine, pigmented paravenous retinochoroidal atrophy, and traumatic retinopathy.
Understandably, the untreatable progressive nature of retinitis pigmentosa is extremely unsettling for the patient and their loved ones; it is often beneficial to recommend psychological or family counseling early in the disease.
Impress upon these patien
Subscribe to:
Posts (Atom)