Intraoperative neurophysiological mapping: the effect of general anaesthetic impact on brain cortex affectability

Neuron irritation lies at the heart of intraoperative motor mapping and varies with the general anaesthetic type and dose. Basing on the analysis of 63 cases (male/female 25/38, aged 21–69) of brain tumors (glial tumors, metastasis, cavernous angiomas) the study explores the role of propofol and sevoflurane in the affectability of cortex neurons during the intraoperative neurophysiological mapping. The study has clearly demonstrated that the liminal current strength is notably higher when inhalation anaesthesia (sevoflurane) is used, than in the case of TIVA (propofol). The propofol activity in the doses causing brain activity depression results in a sharp increase in the excitability threshold. In contrast, sevoflurane causes a steady dose-related rise in the liminal current strength during the motor area galvanic stimulation due to the suppression of affectability and conduction in the nervous system.