EEG reactivity in the prognosis of severe head injury.

We compared reactivity of EEG to external stimuli--an easily and quickly available measure--with the central conduction time (CCT) of the somatosensory evoked potentials, currently the most-used electrophysiologic method to predict outcome in severe head injury (SHI), and with the initial Glasgow Coma Scale (GCS) score. In 50 patients, comatose subsequent to SHI, we measured EEG reactivity and CCT within 48 to 72 hours and compared them with the outcome after 1.5 years. Using discriminant analysis, EEG reactivity correctly classified 92%, CCT classified 82%, and both measures together classified 98% of the patients into globally good or bad outcome groups. GCS allowed a correct classification in only 72% and, combined with either of the two electrophysiologic measures, did not further increase predictability. EEG reactivity is an excellent long-term global outcome predictor in SHI, superior to CCT and GCS. When the two electrophysiologic measures are combined, a prognostic accuracy is achieved that is better than that of any other reported method.