Abstracts

Rationale: Anti-N-methyl-D-aspartate receptor (anti-NMDAr) encephalitis is an autoimune disorder that presents with psychiatric manifestations, abnormal movements, seizures and status epilepticus. Early recognition of the cardinal clinical features and aggressive treatment with immunomodulatory agents improves outcome. We describe a peculiar, and, possibly, characteristic electrographic pattern associated with anti-NMDAR encephalitis. Methods: Case series report of three young women that presented with cerebral spinal fluid (CSF) and serum anti-NMDAR antibodies in the setting of status epilepticus, coma, abnormal movements and psychiatric symptoms. Electroencephalogram (EEG) showed a unique pattern: monomorphic rhythmic delta activity. Results: Three young women (ages 13 to 34 years) were admitted to the Intensive Care Unit with new onset status epilepticus, that followed a subacute course of behavioral changes, confusion, abnormal movements and seizures that quickly evolved to status epilepticus. Magnetic resonance imaging exam was normal in all cases. CSF analysis showed a mild lymphomonocytic pleocytosis. Anti-NMDAR antibodies were present in the CSF and serum in all cases. None of the patients presented an underlying malignancy. In two cases status epilepticus was refractory to antiepileptic drugs, high dose intravenous steroids, and immunosuppressive agents. In all cases, a characteristic and unique EEG pattern was noted: monomorphic rhythmic theta-delta activity. Despite aggressive treatment with immunomodulatory agentes, one patient died and another patient evolved to a minimally conscious state. Conclusions: We describe a previously recognized characteristic EEG pattern associated with anti-NMDAR encephalitis: monomorphic rhythmic theta-delta activity. Awareness of this peculiar EEG pattern may allow early recognition of this condition, and lead early initiation of aggressive immunomodulatory therapy, with positive impact on prognosis.