NMDA RECEPTOR ENCEPHALITIS MIMICKING SERONEGATIVE NEUROMYELITIS OPTICA

Abstract

NMDA receptor antibody encephalitis typically begins as a fulminant encephalopathy, with prominent neuropsychiatric manifestations, seizures, dyskinesias, and autonomic instability. After this often dramatic presentation, 1-3 relapses may occur. Most patients either die or recover from the disease.1 We describe a 15-year-old girl who initially presented with encephalopathy, hypoventilation, dyskinesias, and seizures. Her subsequent course was atypical, with more than 10 relapses during the next year, with longitudinally extensive transverse myelitis (LETM) and optic neuritis (ON) in addition to multifocal, contrast-enhancing gray and white matter lesions. These findings have not been previously reported in anti-NMDA receptor encephalitis. Her disease was ultimately controlled on an aggressive combined regimen of monthly plasmapheresis, pulse methylprednisolone and cyclophosphamide, and rituximab. ### Case report. A 15-year-old girl presented with headaches, photophobia, complex partial seizures, and encephalopathy dominated by hyporesponsiveness. Orofacial dyskinesias were noted. She required intubation for hypoventilatory failure. Her CSF demonstrated 420 leukocytes/mm3 (13% neutrophils, 79% lymphocytes, 8% monocytes). Protein was 103 mg/dL; glucose 38 mg/dL. MRI demonstrated a contrast-enhancing periatrial lesion (figure, A). After a 2-week hospitalization, she recovered without residual symptoms. Figure Features of atypical anti-NMDA receptor encephalitis MRI: (A) Initial contrast-enhancing lesion; (B) longitudinally extensive transverse myelitis; (C) continued development of contrast-enhancing lesions; (D) retrochiasmatic optic neuritis; (E, F) continued accumulation of T2/fluid-attenuated inversion recovery (FLAIR) hyperintense lesion burden, with sagittal FLAIR hyperintensities reminiscent of Dawson's fingers (E). Brain biopsy (from contrast-enhancing frontal lobe lesion): (G) perivascular infiltrate with associated reactive microgliosis; (H) widespread parenchymal destruction mediated by infiltrative lymphocytes and macrophages without selective demyelination; (I) prominent mixed perivascular infiltrate (macrophages, T- and B-lymphocytes with uncommon neutrophils and rare eosinophils). Western blot: (J) Western blot depicting the …