Meningoencephalitis as an initial manifestation of neuromyelitis optica spectrum disorder.

Two patients presented with initial symptoms of headache and fever, and two weeks later had disturbance of consciousness. Cerebrospinal fluid (CSF) showed pleocytosis >500×10²/L. Magnetic resonance imaging (MRI) showed multiple brain lesions at sites of high aquaporin-4 (AQP-4) expression. Case 1 presented optic neuritis four years after the first attack and case 2 had symptoms of myelitis three weeks after headache. Serum AQP-4 antibody was positive in both cases, and the diagnosis of neuromyelitis optica spectrum disorder (NMOSD) was made. Accordingly, NMOSD can initially present as meningoencephalitis mimicking intracranial infection, and the characteristic MRI imaging is quite critical for differentiation.