EEG Findings in NMDA Encephalitis - A Systematic Review

Purpose: The clinical utility of EEG in cases of NMDA encephalitis is broad with many findings indicating not just epileptiform activity but also encephalopathy and potentially providing insights into pathophysiologic mechanisms of disease. We aimed to determine the frequency of different abnormalities described on EEG and their association with outcome in patients affected by NMDARE through a systematic review of all cases published.

Method: A systematic literature review of PubMed and Embase of all published cases of anti-NMDA receptor encephalitis with EEG results, was performed from inception to January 2018.

Results: A total of 446 cases of anti-NMDA receptor encephalitis with reported EEG findings were identified. 373 EEGs were abnormal, and this strongly correlated with ICU admission and time to recovery (p = 0.014 and 0.04 respectively). ICU admission and recovery were also correlated with delta range abnormalities including extreme delta brush (p = 0.007 and 0.03). Electrographic seizures correlated strongly with clinical seizures (p < 0.0001), however only 39 cases had EEG seizures captured, while there were 294 cases with clinical seizures.

Conclusions: EEG is useful in the clinical management and prognostication of cases on NMDA encephalitis. This is particularly true of certain findings which portend a higher likelihood of ICU admission or poorer outcome and this may assist in the decision to pursue more aggressive treatment options.