Monitoring by compressed spectral array in prolonged coma.

Compressed spectral array (CSA) transforms the electroencephalogram into a succinct graphic display of changes in frequency and amplitude. We used CSA to monitor 51 comatose patients for at least 15 hours daily for up to 49 days. The crucial CSA feature was the presence or absence of a peak of activity within the theta or alpha frequency range (4.0 to 13 Hz). Persistence or return of this peak in the first 10 days of coma was seen in all patients who made a good recovery; continued absence of the peak for 10 days, or its return and loss, was associated with death or a residual disability.