Chapter 6 - Intraoperative neurophysiologic monitoring during surgery

Neurologic deficits, intraoperative monitoring to avoidMapping techniques, intraoperativeIntraoperative neurophysiological monitoring (IONM)mapping inIntraoperative neurophysiological monitoring (IONM)functional feedback inIntraoperative neurophysiological monitoring (IONM)cranial nerve monitoring inFunctional feedback, in intraoperative monitoringCranial nerve monitoringIntraoperative neurophysiological monitoring (IONM) represents a valuable tool in the management of skull base meningiomas. First, through neurophysiological mapping techniques it is possible to identify, and spare, ambiguous neural structures that could be displaced or encased by the tumor. This is particularly valuable to identify cranial nerves when the anatomy is distorted. Second, the surgical manipulation of cranial nerves, perforating vessels, and brain or brainstem parenchyma may expose patients to substantial risk of neurological injury. In this perspective, IONM provides a continuous functional feedback on the functional integrity of motor, somatosensory, auditory, and visual pathways. Whenever warning criteria for changes in the evoked potentials are reached, the surgeon is informed of an impending injury and can adjust the surgical strategy in order to take corrective measures to reverse or minimize the risk of injury to the nervous system.Intraoperative neurophysiological monitoring (IONM)evoked potentials inEvoked potentialsin intraoperative monitoringThe combination of both mapping and monitoring techniques provides a multimodality approach, which offers the best chance to avoid neurological deficits. The application of different IONM strategies during skull base surgery must be tailored to the location of the tumor, according to the vascular and neural structures involved. This chapter will critically review the most common IONM techniques and their application during surgery for skull base meningiomas.