Sarcoidosis is a multisystem, noncaseating granulomatous inflammation commonly diagnosed in young adults aged 20–40 years. In North America, the annual incidence for blacks is about 3 times the incidence for whites, and the disease is more common in women than in men. Although the lungs are involved most frequently, the eyes, heart, lacrimal glands, liver, lymph nodes, skin, and musculoskeletal system are also commonly affected. Neurologic manifestations, which occur in 5%–15% of patients, include CN involvement, meningitis, hydrocephalus, hypothalamic and pituitary involvement, encephalopathy, seizures, dural venous thrombosis, vasculitis, myelopathy, and peripheral neuropathy. However, 30%–60% of cases may be discovered incidentally on a routine chest radiograph.
Krumholz A, Stern BJ. Neurologic manifestations of sarcoidosis. Handb Clin Neurol. 2014; 119:305–333.
Intraocular manifestations of sarcoidosis
Iritis, cataract, vitritis, retinal vasculitis (“candlewax drippings”), and chorioretinitis can occur in sarcoidosis. For further discussion of these manifestations, see BCSC Section 9, Uveitis and Ocular Inflammation, and Section 12, Retina and Vitreous.
Acharya NR, Gonzales JA. Ocular sarcoidosis. Focal Points: Clinical Modules for Ophthalmologists. San Francisco: American Academy of Ophthalmology; 2014, module 10.
Neuro-ophthalmic manifestations of sarcoidosis
After the facial nerve, the optic nerve is the CN most frequently affected by sarcoidosis; it may manifest as either a papillitis or retrobulbar optic neuropathy. Less commonly, a sarcoid granuloma may occur at the optic nerve head (ONH) (see Chapter 4, Fig 4-13). Infrequently, sarcoidosis may cause neuroretinitis, optic perineuritis, or papilledema. Bitemporal and homonymous visual field defects may also occur from chiasmal and retrochiasmal visual pathway involvement. Sarcoidosis can also cause ocular motor CN palsy, gaze palsy, and a variety of pupillary abnormalities, including tonic pupil, Horner syndrome, and Argyll Robertson pupil.
Diagnosis and treatment of sarcoidosis
The diagnostic criteria for sarcoidosis include clinical symptoms and signs along with supporting, radiographic, and/or histologic results. Although most patients with neurosarcoidosis exhibit abnormalities on MRI scan, about 18% do not. The most common neuroimaging abnormalities are meningeal and leptomeningeal enhancing lesions. However, none of the abnormalities observed on MRI scan are specific for sarcoidosis, and establishing a definite diagnosis can be difficult.
Serum markers such as angiotensin-converting enzyme (ACE) and lysozyme have been associated with sarcoidosis. The sensitivity and specificity of ACE as a diagnostic test is 60% and 70% respectively. Hypercalcemia is seen in about 10%–13% of patients, whereas hypercalciuria is 3 times more common. A chest radiograph, usually a high-resolution CT scan, is typically obtained because of the frequent pulmonary involvement associated with sarcoidosis. Gallium scanning is a sensitive but nonspecific indicator of active inflammation in patients with sarcoidosis. Fluorodeoxyglucose positron emission tomography (FDG-PET) is a sensitive method to assess inflammatory activity and the extent of disease; it is especially helpful in assessing persistently symptomatic patients without abnormal serologic signs. Histologic studies of involved conjunctiva, lacrimal glands, lymph nodes, or lungs may demonstrate noncaseating granulomas.
Corticosteroids and other immunomodulatory therapies (in particular, methotrexate and tumor necrosis factor [TNF] blockers) are the mainstays of treatment.
Frohman LP. Treatment of neuro-ophthalmic sarcoidosis. J Neuroophthalmol. 2015;35(1):65–72. Phillips YL, Eggenberger ER. Neuro-ophthalmic sarcoidosis. Curr Opin Ophthalmol. 2010;21(6):423–429.
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.