P300 auditory event-related potentials in nontraumatic coma. Association with Glasgow Coma Score and awakening

Auditory event-related potentials (ERPs) were performed in 20 patients with nontraumatic coma to determine the presence of a P300 ERP in coma and its association with the Glasgow Coma Score and awakening (Glasgow Outcome Score, > or = 3). A standard "oddball" paradigm was used: frequent tone, 1 kHz; rare tone, 2 kHz and 4 Hz; probability, 20%. The Glasgow Coma Score was determined concurrently with the P300 ERP. Thirty percent (6/20) of the comatose patients had a P300 ERP. The mean Glasgow Coma Score was significantly higher for those with a P300 ERP. Eighty-three percent (5/6) of those with a P300 ERP awoke. Presence of a P300 ERP was associated significantly with awakening, but absence of a P300 ERP did not preclude it.