Sarcoidosis and the nervous system.

Neurologic involvement occurs in 5 per cent of patients with sarcoidosis and is a presenting symptom in about half of those affected. The neurologic symptoms are due to a granulomatous process that mirrors that seen in the systemic form. Its diagnosis is usually established by the demonstration of sarcoidosis in other systems and supported by clinical, radiographic, and laboratory evidence. Any and all portions of the nervous system can be involved in either an acute or a chronic fashion. Early acute presentations tend to have excellent outcomes and the overall prognosis for the disease is good. The cranial nerves, especially the facial nerve, are most frequently involved and have a good prognosis. CNS involvement, usually in the form of a meningoencephalitis involving the hypothalamic region, is usually chronic and associated with poor prognosis. Peripheral nerve and muscle involvement is frequently asymptomatic. Although neuropathy or myopathy may present acutely, the usual presentation is subacute or chronic. There have been no controlled studies of therapy in neurosarcoidosis. Early implementation of corticosteroids remains the mainstay of treatment. Evidence for improvement with treatment is anecdotally reported in many cases, but progression of the disease also occurs despite therapy.