GIANT CELL ARTERITIS

SIGNS AND SYMPTOMS
The patient is invariably elderly, with the mean age of 75 years. Incidence increases with advancing age. An associated condition, known as polymyalgia rheumatica (PMR), involves pain and stiffness of the muscles of the proximal limbs, particularly upon waking. In fact, PMR is likely within the same spectrum as giant cell arteritis (GCA). There is a 2:1 female to male ratio, and a higher incidence in whites.

Systemic manifestations may include malaise, weight loss and anorexia, headache in the temporal or occipital region, pulseless and indurated temporal artery, night sweats, tongue necrosis and oral ulceration, dental abscess, scalp pain, scalp necrosis and jaw claudication when eating. Other systemic manifestations include depression, mental disturbance, breast masses, gynecological disorders, persistent flu-like illness, chronic pharyngitis, vertigo, muscle aches, cardiac arrhythmia, congestive heart failure, and myocardial infarction.

Ocular manifestations include anterior ischemic optic neuropathy (AION), posterior ischemic optic neuropathy (PION), central retinal artery occlusion (CRAO), cilioretinal artery occlusion, ophthalmic artery occlusion, amaurosis fugax, diplopia and opthalmoplegia. Further ocular manifestations are tonic pupil, Horner's syndrome, ocular hypotony, chronic uveitis, episcleritis and scleritis, conjunctivitis, ocular ischemic syndrome, visual hallucinations, posterior chiasmal field loss, cortical blindness, and ocular ischemic syndrome.

PATHOPHYSIOLOGY
GCA is an idiopathic inflammation of medium and large arteries where the muscular wall of these vessels is infiltrated by monocytes, histiocytes, plasma cells, and multinucleate giant cells. Significant infiltration can lead to vessel occlusion with resultant ischemia and dysfunction of the organ system fed by the vessel. GCA is a multi-system, multi-symptom disorder-virtually any vessel within the body may be involved.

The degree of ischemia tolerated varies by system, and symptoms often appear for a period of months before diagnosis. In the eye, ischemia often manifests by amaurosis fugax, intermittent diplopia and ophthalmoplegia prior to complete occlusion of the posterior ciliary, retinal or ophthalmic arteries. When ocular symptoms occur, there is a much shorter time interval to severe permanent vision loss.

MANAGEMENT
Optimal management of giant cell arteritis means recognizing GCA as a potential cause of the above mentioned findings in an elderly patient. Once recognized, order a Westegren erythrocyte sedimentation rate (ESR) to confirm suspicions. The ESR is a non-specific index of illness, but is frequently elevated in cases of GCA. If the ESR is elevated, then refer for a temporal artery biopsy in order to conclusively diagnose GCA. Remember, however, that a small number of GCA cases do not manifest an elevated ESR. In these cases, the findings and systemic history become more diagnostically important.

GCA requires systemic steroids to preserve vision and reduce morbidity. However, do not withhold steroids pending biopsy results. If exam findings and ESR indicate GCA, then start steroids immediately. Biopsy results, though, will not be affected for several weeks after you initiate steroid therapy.

The dosage of steroids is controversial. Rheumatologists recommend low doses of prednisone, typically 10-20mg per day. However, it is argued that rheumatologists see patients with milder forms of the disease. When vision loss ensues, the patient should receive 1-2mg IV methylprednisolone for several days, with high dose (80-120mg) daily oral prednisone tapered over several weeks. Afterwards, these patients must be maintained on low dose oral prednisone for two to four years.

CLINICAL PEARLS

Vision loss from GCA is an emergency. Untreated, progression to the fellow eye occurs in a high number of cases within hours to days. Frequently, vision loss in GCA is devastating and irreversible. Don't wait until the second eye is involved to take action. You must have an emergency plan in your office in order to handle this disease.

You must consider GCA in elderly patients with AION, PION, amaurosis fugax, intermittent diplopia, CRAO, and cilioretinal occlusion and manage accordingly.

In cases of retrobulbar optic neuropathy in an elderly patient, don't be fooled into diagnosing retrobulbar optic neuritis (as seen in multiple sclerosis) as this is a disease of younger patients. Consider PION, which is typically caused by GCA and tends to involve the fellow eye.

In cases where there are multiple clinical presentations, such as combined cilioretinal artery occlusion and AION, bilateral AION, bilateral CRAO, or CRAO and contralateral tonic pupil (among others), then aggressively investigate GCA in the elderly patient.

Giant cell arteritis and its visual manifestations should not be handled by a primary care optometrist, or even a general ophthalmologist. As the prognosis is grim and morbidity high, these patients should be managed by a neurologist (or neuro-ophthalmologist) specifically skilled in the treatment of GCA. Identify such an individual well in advance, since time is crucial once the GCA patient enters your office.