Neurosarcoidosis: a review of its intracranial manifestation

Sarcoidosis is a multisystem disease of unknown cause and with a worldwide distribution. Involvement of the central nervous system occurs in a relativ ely small number of patients with sarcoidosis. Isolated neurosarcoidosis wi thout signs of systemic disease is a rarity. Because of its non-specific cl inical presentation and neuroradiological imaging characteristics, intracra nial neurosarcoidosis remains a very difficult diagnosis, particularly in t he absence of systemic signs of the disease. Intracranial neurosarcoidosis has a predilection for the basal leptomeninges commonly affecting the crani al nerves, but any part of the brain may be involved, resulting in a wide s pectrum of clinical syndromes. Cranial nerve involvement is the most common single symptom. Intracranial sarcoid manifests as nodular or diffuse lepto meningeal thickening and extra-or intra-axial parenchymatous lesions, intra cranial sarcoid may mimic various forms of meningitis, including carcinomat ous and intracranial mass lesions such as meningioma, lymphoma and glioma, based on neuroradiological imaging. Magnetic resonance imaging is a very se nsitive diagnostic tool for detecting intracranial abnormalities due to neu rosarcoidosis. Lumbar puncture is useful in ruling out other neurological d isorders, in particular infectious, but cerebrospinal fluid findings are no t specific. Angiotensin-converting enzyme in serum and cerebrospinal fluid may be increased, decreased or normal. Therapy consists of immunosuppressiv e agents and should be initiated with corticosteroids. Other immunosuppress ive drugs should be added in severe cases or after frequent recurrences. We review here all aspects of intracranial neurosarcoidosis from the clinical point of view, with special emphasis on presentation, diagnostic procedure s, differential diagnostic considerations and treatment.