Central nervous system demyelinating overlapping syndrome such as Neuromyelitis Optica Spectrum Disorder (NMOSD) and Anti-N-methyl-D-aspartate receptor encephalitis (NMDARe) have been reported. Here we present an interesting case of a triple antibody-positive autoimmune neurological syndrome patient who manifested clinical features of NMOSD, NMDARe, and myasthenia gravis (MG), hence manifested both central and peripheral nervous system immune-mediated neurological syndrome.

A 43-year-old woman with a history of AQP4 positive NMOSD (initially tested negative for anti-AQP4 IgG) on mycophenolate 1 g twice a day presented with severe fatigue and right eye ptosis (3 months since NMOSD diagnosis) and tested positive for AchR binding antibody. Later (6 months since NMOSD diagnosis) patient presented with subacute progressive cognitive decline, behavioral changes, imbalance, anxiety/panic attacks, and paranoid delusions. NMDARe was suspected, and she tested positive for CSF NMDAR antibodies. The patient received a high dose of IV methylprednisolone 1 g for 3 days but had a poor response. She received rituximab 1 g, 2 doses 2 weeks apart, and reported significant improvement in her symptoms shortly after the second dose. Initial Brain and cervical spine MRI at the time of NMOSD diagnosis revealed T2 hyperintensities, periventricular to the 4th ventricle, bilateral hypothalamic regions, and patchy T2 signal changes from cervico-medullary junction to C2.

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We present an unusual case of patient testing positive for serological markers of NMOSD, MG, and NMDARe while also displaying the clinical manifestations of these three disorders. Therefore, clinicians need to be vigilant about the overlap neurological syndromes affecting central and peripheral nervous systems to avoid delays in the diagnosis and treatment to prevent poor clinical outcomes. It is equally important to address poor response to the first-line immunosuppressive therapy as the continuation of these therapies may not be effective in some cases.