Monitoring Brain Failure Using Evoked Potentials

Abstract

It is 20 years since Brierley et al. reported their experimental work on brain damage induced by profound arterial hypotension in the rhesus monkey [1]. Their data indicate that “a story of the time course of the changes in the primary evoked potentials permits the prediction of the pathological outcome of an episode of hypotension”. They were the first to demonstrate that somatosensory evoked potentials (EPs) may be useful in the evaluation of brain damage in humans after severe hypotension and, more specifically, that EPs do reveal information on the functional state of the central nervous system after brain insult earlier that EEG recordings [2], Since then, many reports have been published dealing with the use of visual, auditory or somatosensory EPs in anesthesia, brain failure or brain death. This review concerns some of the new aspects of EP monitoring in the intensive care unit (ICU). For sake of clarity and conciseness we shall focus our attention predominantly on somatosensory EPs. This modality of EPs is particularly useful in the evaluation of comatose patients because the adequacy of the stimulus is precisely monitored over the peripheral and spinal nervous system. Many experimental studies published over the last 10 years have explored the influence of ischemia and/or hypoxia on the early cortical somatosensory EPs.