Evoked Responses and Impaired Consciousness

Abstract

The EEG is generally accepted as a good indicator of gross level of alertness. Alerting stimuli desynchronize the alpha rhythm recorded during the resting awake state, and sleep is associated with marked EEG changes. When evoked-response recording became possible, investigators soon sought to determine whether the responses also reflected level of alertness. This chapter will deal with states of impaired consciousness: sleep, delirium, and coma. Phenomena related to states of heightened alertness will be considered in the subsequent chapter.