Quantitative EEG In The Evaluation Of The Prognosis Of Anti-N-methyl-D-aspartate Receptor Encephalitis

BACKGROUND&PURPOSE:There is currently no reliable marker that can predict the prognosis of anti-NMDA receptor encephalitis at the early stage.This study aims to use quantitative electroencephalography(qEEG)to monitor anti-NMDA receptor encephalitis and to study the relationship between qEEG parameters and severity as well as prognosis of anti-NMDA receptor encephalitis.METHODS:This single-center,observational study was conducted from April 2014 to May 2017 at Peking Union Medical College Hospital.Patients diagnosed with anti-NMDA receptor encephalitis who met the criteria were included.Patients were further divided into critically ill subgroup and non-critically ill subgroup based on whether they stayed in ICUs for more than 48 hours due to severe encephalitis' symptoms.Patients'outcomes were measured by mordified Rankin Scale combined with recurrent events.The short-term and long-term outcomes were measured at 3 months and 12 months after onse,respectively.All patients at peak stage and 10 healthy volunteers received 2 hours of qEEG monitoring.qEEG parameters in this study included amplitude-integrated electroencephalogram(aEEG),SEF-95,total power,absolute band powers(ABP)as well as relative band powers(RBP)of ?,?,? and ? bands at F3-F4 and P3-P4 montages.The clinical information and qEEG data were compared between critically ill and non-critically ill subgroup,and between the groups of different outcomes.The logistic regression model was used to assess the predictive value of qEEG parameters.RESULTS:In total,26 patients completed one-year follow-up,including 11(42.3%)males and 15(57.7%)females.The median age was 20 years and the median hospital stay was 38 days.There were 14 cases in critically ill subgroup and 12 cases in non-critically ill subgroup.7 patients had good short-term outcomes,19 had poor short-term outcomes.16 patients had good long-term outcomes,and 10 had poor long-term outcomes.Compared with the background activity of healthy control group,the parietal RBP-? of the anti-NMDA receptor encephalitis group significantly increased(P=0.024),while the parietal RBP-? significantly decreased(P=0.006).No significant differences in qEEG parameters were observed between critically ill and non-critically ill patients as well as between good and poor short-term outcome groups.There existed anterior-to-posterior gradient differences in RBP-?,ABP-? and ABP-? in anti-NMDA receptor encephalitis,and these differences were not significant in the critically ill subgroup.A narrower parietal aEEG bandwidth correlated with better long-term outcomes(odds ratio 37.9,P=0.044),with an optimal cutoff value of 1.7 ?V and corresponding sensitivity and specificity of 90.00 and 56.25%,respectively.CONCLUSIONS:The qEEG background activity of anti-NMDA receptor encephalitis shows a unique pattern.Any single qEEG parameter does not reflect the clinical severity of anti-NMDA receptor encephalitis disease at peak stage.The parietal aEEG bandwidth is able to predict the long-term outcome of anti-NMDA receptor encephalitis at an early stage with good sensitivity.