Prediction of awakening from hypothermic postanoxic coma based on auditory discrimination

Objective Most of the available clinical tests for prognosis of postanoxic coma are informative of poor outcome. Previous work has shown that an improvement in auditory discrimination over the first days of coma is predictive of awakening. Here, we aimed at evaluating this test on a large cohort of patients undergoing therapeutic hypothermia and at investigating its added value on existing clinical measures. Methods We recorded electroencephalographic responses to auditory stimuli in 94 comatose patients, under hypothermia and after rewarming to normal temperature. Auditory discrimination was semiautomatically quantified by decoding electroencephalographic responses to frequently repeated versus rare sounds. Outcome prediction was based on the change of decoding performance from hypothermia to normothermia. Results An increase in auditory discrimination from hypothermia to normothermia was observed for 33 of 94 patients. Among them, 27 awoke from coma, resulting in a positive predictive value of awakening of 82% (95% confidence interval = 0.65–0.93). Most nonsurvivors showing an improvement in auditory discrimination had incident status epilepticus. By excluding them, 27 of 29 patients with improvement in auditory discrimination survived, resulting in a considerable improvement of the predictive value for awakening (93%, with 95% confidence interval = 0.77–0.99). Importantly, this test predicted the awakening of 13 of 51 patients for whom the outcome was uncertain based on current tests. Interpretation The progression of auditory discrimination from hypothermia to normothermia has a high predictive value for awakening. This quantitative measure provides an added value to existing clinical tests and encourages the maintenance of life support. Ann Neurol 2016;79:748–757