Evoked Responses and Electromyography in Intraoperative Monitoring in Neurosurgery

Abstract

The requirement that perioperative morbidity decrease in neurosurgerybecomes ever more pressing. A possible contribution may be made byintraolperative monitoring of conduction in important tracts duringgeneral anaesthesia. The techniques of central sulcus identification(somatosensory evoked potential, SEP phase reversal) and motor striplocation by cortical stimulation are well developed. Intraoperativemotor tract monitoring is advisable in the performance of resection ofintramedullary tumours. Monitoring of ascendant tracts and cranialnerves is an integral part of high-risk surgery in the cerebellopontineangle and in the brain stem. The techniques used for stimulation andrecording, as well as the ways in which responses and changes areevaluated, differ from common electromyographical practice. Closeteamwork among the prime movers in the operating theatre - theneurosurgeon, the anaesthesiologist and the neurophysiologist - is vitalto worthwhile and reliable monitoring.