Alternating “Waking” and “Sleep” EEG Patterns in a Deeply Comatose Patient

This case-report of a deeply comatose patient with a pontine hemorrhage re-emphasizes that such patients may show an alpha type of background activity, that is, at times, reactive to external stimuli, but especially that such patients may “sleep” at night with normally appearing spindles and slow waves. Circadian variations of waking and sleep patterns were noted, although the cycle progressively increased in duration until electrocerebral silence was recorded. Electroencephalographers interpreting records from comatose patients must be aware that diffuse slow waves in these patients may not always reflect diffuse pathology, but may occasionally represent sleep rhythms, which may later disappear and then reappear.