Focal seizures in children with anti-NMDA receptor antibody encephalitis.

OBJECTIVE: We investigated the electroclinical features of seizures occurring in children with anti-NMDA receptor antibody encephalitis.

METHODS: Clinical features and video EEG recordings were analyzed from pediatric patients with anti-NMDA receptor antibody encephalitis at our center over a six year period.

RESULTS: We identified eight pediatric patients with anti-NMDA receptor antibody encephalitis. Video EEG captured multiple focal seizures in four patients. Ictal onset in all four patients consisted of a focal rhythmic sharpened 6-12Hz activity that subsequently spread to one or both hemispheres. When there was a clinical correlate, seizure semiology was limb posturing with or without dyscognitive features. While background abnormalities were noted at presentation in three cases, the initial EEG background was normal in five, including three patients presenting with seizures. The EEG background deteriorated with clinical progression.

CONCLUSIONS: Focal seizures are common in pediatric patients with anti-NMDA receptor antibody encephalitis and have a characteristic ictal onset pattern. Anti-NMDA receptor antibody encephalitis should be considered in the differential diagnosis of a child presenting with new onset focal seizures, irrespective of the EEG background, especially if accompanied by dyskinesia, psychiatric symptoms or impaired cognition.