Neurological monitoring during anaesthesia and surgery

The ability to monitor the electrical activity of the central nervous system and to record responses to stimulation allows for a more immediate assessment of the functional integrity of the nervous system during anaesthesia than do conventional techniques. These monitoring methods, however, have been slow to find acceptance in clinical practice. The reasons include the difficulty with standardization and reproducibility of results from such monitoring techniques as the electroencephalogram (EEG) and evoked potentials, along with the level of expertise necessary for accurate interpretation of the voluminous data collected. Anaesthetic agents along with variations in physiological parameters can markedly alter the recordings not to mention the influence of diathermy, other electrical devices, muscle activity and artifact. Because of these inherent difficulties, most anaesthetists still rely on optimising such physiological parameters as arterial, venous and intracranial pressures, oxygen and carbon dioxide tensions, to ensure the functional integrity of the nervous system. This brief review explores the potential areas of application of electrophysiologic monitoring in surgery and anaesthesia.