Aseptic meningitis as an atypical manifestation of neuromyelitis optica spectrum disorder flare

Background: Inflammatory demyelinating disease of the central nervous system characterized by aseptic me- ningitis is rare and can be easily confused with intracranial infection. Here, we investigated the clinical features of neuromyelitis optica spectrum disorder (NMOSD) patients with a meningitis -like presentation. Methods: From a total of six attacks, five patients were identified. Their demographic, clinical, and magnetic resonance imaging (MRI) findings, as well as treatments and prognoses were retrospectively analyzed. Results: Five patients (two males with myelin oligodendrocyte glycoprotein [MOG] antibody and three females with aquaporin-4 [AQP4] antibody) experienced six attacks. Average age at onset was 31.5 ? 3.5 years -old. The earliest clinical manifestations included fever (6/6), headache (5/6), and meningeal irritation (6/6) ac- companied by leukocytosis and elevated protein levels (6/6) in cerebrospinal fluid. Two attacks initially man- ifested as meningitis alone. Meanwhile, following the onset of meningitis -like symptoms, four attacks were accompanied by transverse myelitis on the same day. One attack was associated with leptomeningeal en- hancement on MRI, four attacks with spinal meninges enhancement, and one with both leptomeningeal and spinal meninges enhancement. All patients were considered to have an intracranial infection at onset and consequently treated with anti -infective drugs. As the symptoms continuously deteriorated, flare-up of NMOSD was considered a more reasonable diagnosis. Application of glucocorticoids (with or without intravenous im- munoglobulin therapy) quickly relieved the symptoms. Subsequent re-examination of cerebrospinal fluid and MRI showed significant improvements. Conclusion: Aseptic meningitis may be an atypical phenotype of NMOSD flare that is easily confused with specific infection. Comprehensive evaluation to exclude an infective etiology and enable accurate diagnosis and timely immunotherapy are critical to prognosis.