PREDICTIVE VALUE OF P300 EVENT-RELATED POTENTIALS COMPARED WITH EEG AND SOMATOSENSORY-EVOKED POTENTIALS IN NONTRAUMATIC COMA

Developments in ethical decision making are increasing demand for more accurate predictions of outcome in coma. New neurophysiologic tests a re needed to improve the ability to predict awakening as well as poor outcome. We have recently reported that the P300 event-related potenti al (P300) correlates with awakening and depth of nontraumatic coma. In this companion study, the predictive value of the P300 was compared w ith median nerve somatosensory evoked potentials (SEP) and EEG in 20 p atients in non-traumatic coma. We also evaluated the predictive value of a simplified grading scale for both the EEG and SEP (the USC SEP sc ale and USC EEG scale). The presence of a P300 was significantly assoc iated with higher Glasgow coma scores (GCS) and awakening. Severe abno rmalities of the somatosensory evoked potentials significantly correla ted with the absence of awakening and a low GCS. Moderate abnormalitie s of the SEP were significantly associated with awakening and higher G CS scores. the EEG was significantly associated with GCS score and sev ere abnormalities of the EEG were predictive of the absence of awakeni ng and very low GCS scores. The data indicates that the P300 and SEP a re more effective than the EEG in predicting awakening, and that the S EP and EEG are more effective than the P300 in predicting poor outcome . We conclude that, in addition to EEG and SEP, the P300 should be con sidered in the prognostic evaluation of patients in nontraumatic coma. Further, simplified scales for the EEG and SEP are predictive of dept h of coma and outcome.