New neurophysiology and central nervous system dysfunction.

Abstract

PURPOSE OF REVIEW: The goal of this article is to summarize very recent technologic advances in neurophysiologic monitoring and to illustrate their potential benefit to critical care medicine. RECENT FINDINGS: Simplified, computer-processed electroencephalography devices now permit cost-effective, long-term critical care monitoring. They may be used alone to objectively assess sedation or coma level. In addition, these monitors serve as screening tools for more detailed electrophysiologic characterization of cortical dysfunction resulting from seizures, ischemia, or hypoxia. Somatosensory potentials broaden these capabilities to the entire neuraxis, whereas long-latency auditory evoked potentials facilitate measurement of changes in vigilance and cognition. Motor evoked potentials offer a sensitive and reliable method to determine the function of descending motor pathways in uncooperative or unresponsive patients. They may also yield a new measure of cortical excitability. New developments with transcranial Doppler ultrasonography promise noninvasive measures of cerebral perfusion pressure and particulate embolization. Near-infrared spectroscopy appears to enable noninvasive measurement of regional tissue oxygenation in both the brain and spinal cord. SUMMARY: When used together, these continuous measures of synaptic function, cerebral perfusion, and oxygenation give the clinician a vast amount of otherwise unobtainable information regarding the functional status of the central nervous system.