Clinical significance of mismatch negativity in predicting the awakening of comatose patients after severe brain injury.

We assessed the clinical significance of mismatch negativity (MMN) in predicting the awakening of comatose patients with severe brain injury. The clinical data of patients with severe brain injury, admitted to the neurosurgical intensive care unit of Xiangya Hospital of Central South University from July 2018 to March 2020, who underwent auditory MMN examinations within 28 days after coma onset, were reviewed. Correlations between clinical factors and prognosis [Glasgow Outcome Scale (GCS) for 3 mo] were analyzed. Fifty-three patients were included; 37 (69.8%) had favorable outcomes. A univariate analysis revealed the Glasgow Coma Scale (GCS) and absolute MMN amplitudes at electrodes Fz and Cz were significantly correlated with prognosis. Only GCS scores and MMN amplitude at Fz were independent predictors in multivariate logistic regression analysis (area under the curve 0.744 vs. 0.753, respectively); both combined, improved accuracy to 84.6%. MMN amplitudes at Fz were dichotomized at a value of 1.08 μV with a sensitivity and specificity of 81.1% and 68.7%, respectively, for predicting comatose patients' awakening. In conclusion, MMN amplitude at Fz is a reliable prognostic indicator for comatose patients with severe brain injury; the prediction value improved when combined with GCS. Thus, an event-related potential component with a clear site and cutoff value may support prognostication in severe brain injury. NEW & NOTEWORTHY Mismatch negativity (MMN) can assess the prognosis of comatose patients after severe brain injury, especially for MMN amplitude. In addition, MMN analysis at electrode Fz best predicts recovery of consciousness in patients with severe brain injury. Importantly, a quantitative approach (cutoff value of 1.08 μV) may improve the use of MMN for prognostication.