Electroencephalographic sleep patterns in post-anoxic stupor and coma

We analyzed EEGs performed over a 6-month period on patients with impaired consciousness following acute hypoxia or anoxia. There were 17 EEGs performed on 14 patients. Nine of the 17 records contained spindle activity. Spindles were present in 6/8 EEGs in stuporous patients, in 3/9 EEGs in comatose patients, in 6/10 patients who eventually died, and in 3/3 patients who regained consciousness. When spindle activity or background reactivity were absent, outcome was poor, ie, death or a persistent vegetative state. The presence of EEG spindle activity after hypoxic or anoxic injury did not indicate a favorable prognosis, but the absence of spindles or EEG background reactivity was associated with a poor outcome.