NMDA-Receptor Encephalitis: An Unsual Case of Refractory Status Epilepticus (P6.286)

OBJECTIVE: We report a case of NMDA receptor encephalitis in a young man with early refractory status epilepticus and atypical radiological findings. BACKGROUND: Anti-NMDA receptor encephalitis is an autoimmune disorder characterized by psychiatric symptoms followed by dyskinesia, altered consciousness, and seizures due to antibodies to the NR1-NR2B heterodimer of NMDA receptor. On imaging, it typically presents with T2 hyperintensities in mesial temporal lobes, cerebral cortex and basal ganglia. We present a case with a dramatic clinical evolution and novel imaging findings. DESIGN/METHODS: Case report and review of imaging. RESULTS: A 29-year-old male of Carribean origin presented with 2 months of mood disturbance followed by new partial-complex seizures, facial dyskinesia and choreo-athetotic movements. His initial MRI showed subtle T2-hyperintensities in both mesial temporal lobes, without enhancement. The diagnosis of NMDA-receptor encephalitis was suspected and subsequently confirmed after CSF antibody detection. Prior to diagnostic confirmation, he developed status epilepticus refractory to multiple anti-convulsants, and concomitant signs of herniation. A repeated MRI showed increased T2-signal abnormalities of both thalami and mesencephalon, with cerebellar involvement and transtentorial and transforaminal herniation. Restricted diffusion was documented in the cerebellar cortex, thalami, putamina and caudate. He was treated with IV corticosteroids and hypertonic fluid which reversed the herniation, and halted the seizures. Follow-up imaging showed near resolution of the restricted diffusion and the signal abnormalities, except for persistent abnormalities of the hippocampal gyri, and posterior thalami. The patient remained clinically unchanged. CONCLUSIONS: To our knoweldge, this is the first case report of uncal and tonsillar herniation in the context of NMDA receptor encephalitissecondary to atypical, predominant cerebellar involvement in the context of NMDA receptor encephalitis. This case highlights a life-threatening manifestation that physicians might encounter, and also a possible role for high dose IV corticosteroids as an adjunct treatment in NMDA encephalitis with brain edema and seizures. Disclosure: Dr. Legault has nothing to disclose. Dr. Lapointe has nothing to disclose. Dr. Giacomini has received personal compensation for activities with Allergan, Inc., Biogen Idec, EMD Serono, Genzyme, Novartis, and Teva Neuroscience as a speaker, consultant, and/or advisory board member. Dr. Teitelbaum has nothing to disclose. Dr. La Piana has nothing to disclose. Dr. Tampieri has nothing to disclose. Dr. Romano has nothing to disclose.