Electroencephalography characteristics to predict one-year outcomes in pediatric anti-NMDA receptor encephalitis

Background: Electrographic characteristics (extreme delta brush, posterior dominant rhythm and slow waves) may predict outcomes in anti-NMDA receptor encephalitis (NMDARE). However, whether changes in EEG sleep architecture predict outcomes are unknown. We examine electrophysiological characteristics including sleep architecture in a pediatric NMDARE population and correlate with outcomes at one year.

Methods: Retrospective chart and EEG review was performed in pediatric NMDARE patients at a single center. Patients with first EEGs available within 48 h of admission, prior to treatment, and one-year follow-up data were included. EEGs were independently reviewed by two epileptologists, and a third when disagreement occurred. Clinical outcomes included modified Rankin scale (mRS) at one year.

Results: Nine patients (6 females) (range 1.9-16.7 years) were included. Five of nine patients had loss of posterior dominant rhythm (PDR) and three of nine patients had absent sleep architecture. Loss of PDR correlated with a worse mRS score at one year (2.8 versus 0.5, p = 0.038). Loss of PDR and loss of sleep architecture was associated with increased inpatient rehabilitation stay and in higher number of immunotherapy treatments administered. In multivariate analysis, absence of sleep architecture (p = 0.028), absence of PDR (p = 0.041), and epileptiform discharges (p = 0.041) were predictors of mRS at one year.

Conclusions: Loss of normal PDR, absence of sleep architecture, and epileptiform discharges are associated with worse outcomes at one year which has not been reported before. EEG characteristics may help prognosticate in NMDARE. Larger studies are needed to confirm these findings.