EEG monitoring of clinical coma: the compressed spectral array

Twenty-four comatose patients were studied by 16-hour compressed spectral array (CSA), made from four-channel portable EEG recordings. Causes of coma included head injury (15), anoxia (6), and brainstem strokes (3). CSA was classified on the basis of frequency and alternating or nonalternating patterns. Alternating CSA was significantly associated with survival (p less than 0.005) in the head-injured and anoxic group combined, and in the head-injured subgroup (p less than 0.013). The prognostic value of CSA equaled the Glasgow Coma Scale or neurologic examination and occasionally added prognostic information.