Outcome of Chronic Idiopathic Meningitis

To record long-term follow-up data on patients with chronic idiopathic meningitis. We retrospectively reviewed the outcome of 49 patients who were examined at the Mayo Clinic between 1978 and 1990. For all patients, symptoms, signs, laboratory values, results of imaging studies, findings on biopsies, results of any empiric treatment, and results of autopsy, if applicable, were assessed. Some of these findings were stratified on the basis of good versus poor outcome of the patients and were analyzed statistically. Of the 49 patients who fulfilled the criteria for chronic idiopathic meningitis, 10 had a cause identified after repeated studies, brain biopsy, or autopsy (8 of these had a neoplasm). Of 21 brain biopsies, 5 (24%) yielded a diagnosis. Follow-up of the 39 undiagnosed cases showed that 33 (85%) had a good outcome despite an often prolonged illness. Two patients (5%) died of the meningeal process. Of the eight patients treated empirically with antituberculous medications, none responded. Corticosteroid therapy was effective in 52% of the patients thus treated, but it did not influence the outcome. In this study, 85% of undiagnosed cases of chronic meningitis were benign. No clinical or laboratory findings predicted those patients who had a fatal outcome. In our study population, the most useful empiric therapy was corticosteroids rather than antituberculous medications.