Of the variety of immune system–mediated disorders that produce neuro-ophthalmic signs and symptoms, giant cell arteritis, multiple sclerosis, myasthenia gravis, thyroid eye disease, and sarcoidosis are the most common.
Giant Cell Arteritis
Giant cell arteritis (GCA), or temporal arteritis, is a systemic inflammatory granulomatous vasculitis that involves large- and medium-sized arteries and affects mainly white people over 50 years of age almost exclusively. The incidence of the disease increases with age; it is 20 times more common in the ninth decade than the sixth decade. GCA is 2–4 times more likely to affect women than men, and it is more common in people of Northern European and Scandinavian descent. Early diagnosis and treatment of GCA can limit or prevent permanent vision loss.
Clinical presentation of giant cell arteritis
Systemic symptoms of GCA include headache and tenderness of the temporal artery or scalp. Jaw or tongue claudication (a cramping pain that develops while chewing or talking) is the symptom most specific for the disorder; other symptoms include malaise, anorexia and weight loss, fever, new neck pain, ear pain, and joint and muscle pain. Systemic sequelae can include cerebrovascular ischemia, myocardial infarction, and aortic aneurysm or dissection.
Visual symptoms may include diplopia or transient or permanent vision loss. The most common cause of vision loss is arteritic anterior ischemic optic neuropathy (AAION) (see Chapter 4, Fig 4-10), but central retinal artery occlusion (CRAO), cilioretinal artery occlusion, posterior ischemic optic neuropathy, choroidal infarction, ocular ischemic syndrome, and orbital ischemia also occur. Ischemia of the ocular motor cranial nerves (CNs), extraocular muscles, or brainstem can result in transient or constant diplopia.
Diagnosis of giant cell arteritis
When evaluating patients over age 50 with the visual symptoms just described, a high level of suspicion of GCA is paramount. Diagnostic evaluation begins with laboratory tests of the erythrocyte sedimentation rate (ESR), complete blood count (CBC), and C-reactive protein (CRP). Most cases of GCA show marked elevation of the Westergren ESR (mean 70 mm/hr; often >100 mm/hr), but the level may be normal in up to 16% of cases. The ESR rises with anemia and with increasing age; levels above the laboratory’s listed upper limit of normal are common in patients older than 70 years without arteritis. A more accurate estimate of the upper normal value can be obtained by using these formulas: [age]/2 (men) or [age + 10]/2 (women). Measurement of CRP level, which may be more specific and less affected by increasing age and anemia, may increase diagnostic accuracy and is typically obtained in conjunction with the ESR. Thrombocytosis (increased platelet count) may suggest active disease. A normochromic normocytic anemia may be present.
Whenever clinical suspicion or laboratory studies suggest the possibility of GCA, temporal artery biopsy (TAB) should be performed, ideally at a site of localized tenderness and/or on the side of the vision loss (see BCSC Section 4, Ophthalmic Pathology and Intraocular Tumors). The TAB needs to be done as soon as possible, ideally within 2 weeks, but in some cases remains positive for months after initiation of therapy. A unilateral TAB can be falsely negative in approximately 3%–15% of cases. Factors that may produce a false-negative unilateral TAB include discontinuous arterial involvement (“skip areas”), missed lesions, or inadequate sections (under 2 cm long). If the index of suspicion remains high, a contralateral TAB is typically performed. Other imaging strategies such as color Doppler ultrasonography, positron emission tomography (PET), and magnetic resonance imaging (MRI) may provide additional useful diagnostic clues; however, TAB remains the gold standard for GCA diagnosis.
El-Dairi MA, Chang L, Proia AD, Cummings TJ, Stinnett SS, Bhatti MT. Diagnostic algorithm for patients with suspected giant cell arteritis. J Neuroophthalmol. 2015;35(3):246–253.
Treatment of giant cell arteritis
Corticosteroids are the mainstay of treatment of GCA; they should be initiated immediately when GCA is suspected. Approximately 50% of patients with GCA and vision loss in 1 eye will lose vision in the opposite eye within 7 days if the GCA is left untreated. Intravenous methylprednisolone (1 g/day for the first 3–5 days) is often recommended when vision loss is present. For patients with suspected GCA but without loss of vision, oral prednisone 60–100 mg/day may be sufficient. Treatment is also required for patients with severe, bilateral vision loss because GCA is a systemic disease. The clinical response to corticosteroids is often dramatic; symptoms may be reduced within days. The corticosteroids are generally tapered slowly, depending on response, and patients typically continue therapy for at least 1–2 years, sometimes longer. Patients undergoing long-term corticosteroid therapy should be monitored and treated as necessary for osteopenia and osteoporosis as well as prophylaxis of gastrointestinal effects; it is recommended that these patients be comanaged with a rheumatologist or internist. Corticosteroid treatment does not generally improve vision, but it may prevent new ischemic events from occurring. The risk of recurrent or contralateral optic nerve involvement during withdrawal from corticosteroid treatment has been reported at 7%; thus, as mentioned, tapering must be done slowly and carefully. Patients must also be monitored for thoracic and aortic aneurysms, which are associated with GCA. Additionally, these patients are at increased risk of cerebrovascular and cardiovascular ischemia; thus, low-dose aspirin administration should be considered.
Excerpted from BCSC 2020-2021 series: Section 5 - Neuro-Ophthalmology. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.