Intraoperative neurophysiological monitoring under general anesthesia

Abstract

The early steps in determining cortical functional organization during neurosurgical procedures were performed in awake patients and date back into the early 1930s [12, 30]. At that time, the identification and assessment of cortical functional organization within the vicinity of a brain pathology (e.g., tumor, epileptic foci) was possible only by direct electrical stimulation of the cerebral cortex. The observation of the elicited interference with the awake patient's behavior, movement, and language performance served as guidance for the surgical tumor resection. Only in the late 1970s monitoring of somatosensory evoked potentials (SEP) and in the early 1990s monitoring of motor evoked potentials (MEPs) were introduced into the operating room. It was utilized in spine and spinal cord surgery and then for neurovascular procedures, before it was finally implemented into brain tumor surgery.