[Neurosarcoidosis]

Abstract

Signs and symptoms of neurosarcoidosis are variable and depend on location and size of granulomas. Clinical studies suggest a rate of 5% and autopsy results a rate of more than 25% of central nervous system (CNS) involvement in sarcoidosis. Statistical analysis of 57,789 patients admitted to the Department of Medicine in Lucerne over an 11-year period revealed 51 patients (0.9/1000) with the diagnosis of sarcoidosis. Six of these (12%) had sarcoidosis affecting the CNS. Neurosarcoidosis presented as: leptomeningeal granulomas, cranial nerve palsy, hypothalamic-pituitary syndrome, diabetes insipidus, pareses, paresthesia, pyramidal signs, dementia, urine retention, and asymptomatic granulomas. Neurosarcoidosis has predilections for the base of the brain, cranial nerves (facial nerve palsy is the most common) and meninges, but any part of the CNS may be affected. Therefore, the diagnosis of neurosarcoidosis may be extremely difficult, especially when it occurs as an isolated finding. Positive findings in transbronchial biopsy and lavage may demonstrate asymptomatic pulmonary involvement in as many as 50% of patients with neurosarcoidosis. Angiotensin-converting enzyme levels may be raised in the blood or cerebrospinal fluid in some 50% of cases. Kveim test has a low sensitivity in neurosarcoidosis and thus is of little use. Gallium uptake may demonstrate extracranial granuloma available for biopsy. All these tests, and also computed tomography and magnetic resonance imaging, may be helpful. However, when in selected cases with isolated CNS disease standard investigations are not conclusive, meningeal or cerebral biopsy may be required in order to exclude other causes such as other granulomatous disorders, tumor metastasis, lymphoma, vasculitis, Sjögren syndrome, infection, neurologic disease such as multiple sclerosis, or systemic diseases such as Whipple's disease. CNS involvement in the acute phase of the disease has a favorable prognosis, while chronic courses respond less well to therapy. Treatment is initiated most frequently with corticosteroids (0.5-1 mg/kg body weight/day or pulses of 1 g/day of methylprednisolone in severe cases). Improvement is seen within 1-2 months. Side effects of corticosteroids, aggressive disease or frequent recurrences may require other immunosuppressive drugs (methotrexate, azathioprine, chlorambucil, cyclosporine A). Cerebral irradiation may be successful in some cases when other treatments fail.