Anti-N-methyl-D-aspartate receptor antibodies: A potentially treatable cause of encephalitis in the intensive care unit

Abstract

OBJECTIVE: To report the occurrence of an unusual neurologic disorder requiring admission to the intensive care unit. DESIGN: Analysis of an observational cohort study of 31 patients with encephalitis admitted over a 4-yr period. SETTING: Neurologic intensive care unit in a tertiary referral center. PATIENTS: We identified N-methyl-D-aspartate receptor antibodies in six patients (two male and four female). All seropositive patients presented with a psychiatric prodrome, before developing seizures and obtundation requiring intensive care unit admission. They exhibited limb and truncal stereotypies and orofacial dyskinesias upon weaning sedation. Two patients had ovarian tumors. INTERVENTIONS: Patients were treated with sedation, antiepileptic drugs, and immunotherapy. One patient received a magnesium infusion and ketamine. MEASUREMENTS AND MAIN RESULTS: N-methyl-D-aspartate receptor antibodies were identified in serum samples by an immunofluorescent cell-based assay. Three patients made a good but slow recovery; two were left with severe neurologic deficits; and one died after return to the referring hospital. These patients accounted for approximately 20% of all patients admitted with encephalitis to this referral center. CONCLUSIONS: N-methyl-D-aspartate receptor antibodies should be tested in patients with hyperkinetic encephalitis and neuropsychiatric prodrome admitted to the intensive care unit. The disorder is probably not rare and is potentially treatable.