Sarcoidosis localized in the central nervous system.

Purpose. - Current knowledge on central nervous system sarcoidosis. Current knowledge and key points. - Sarcoidosis is localized in the central nervous system in 5 to 16% of the cases. Various neurological manifestations are observed inluding: seizures, cognitive or psychic manifestations, hypothalamic and pituitary involvement, local pseudotumors, and hydrocephalus very frequently associated with asymptomatic lymphocytic meningitis and with cranial nerve palsy, particularly palsy of the seventh nerve, occurring less regurlarly. CNS localization is most often an early manifestation of the disease, unmasking sarcoidosis. Ii is often part of primary or secondary systemic polyvisceral sarcoidosis. The diagnosis is mainly based on two arguments: confirmation of the existence of systemic sarcoidosis and clinical and paraclinical compatibility of neurological abnormalities (particularly at magnetic resonance imaging [MRI]). Neurological histopathology is rarely necessary to confirm the diagnosis. Corticotherapy is indicated in all symptomatic cases and most often leads to a more or less complete clinical response evidenced by regression of active lesions identified on MRI. The treatment must often be prolonged for several years, and clinical and MRI evolution help guide therapeutical choices for dosages and threshold doses. CNS involvement is potentially severe with mortality and morbidity rates that are not insignificant. Limiting of iatrogenic risks requires adequate follow-up. Perspectives and projects. - Multicenter studies are necessary to determine factors influencing the incidence and long-term prognosis of CNS sarcoidosis treated with corticotherapy. The efficacy of treatments other than corticotherapy must be evaluated. (C) 1998, Elsevier, Paris.