[Intraoperative monitoring for functional neurosurgery during intravenous anesthesia with propofol]

We studied the effects of propofol on electrophysiologic monitoring for functional neurosurgery. In six patients with intractable epilepsy, electrocorticograms (ECoGs) were monitored for epilepsy surgery, and in two of them, somatosensory evoked potentials (SEPs) were monitored because of the focus adjacent to the central sulcus. In four patients with hemifacial spasm, brain stem auditory evoked potentials (BAEPs) and abnormal muscle responses (AMRs) were monitored during microvascular decompression (MVD). In two patients with Parkinson's disease and in one patient with post-traumatic tremor, neural noise levels were recorded from microelectrodes during posteroventral pallidotomy and Vim thalamotomy. In each case of epilepsy surgery, during intravenous anesthesia with propofol, spike activity was recordable enough to identify the resective area and the residual spikes. SEP phase reversal was obtained in two patients and an exact determination of the central sulcus was possible. BAEPs and AMRs were obtained in all MVDs. To record neural noise levels, the infusion of propofol was decreased in two cases of posteroventral pallidotomy, and it was stopped in one case of Vim thalamotomy. In these patients, neural noise levels were recorded and were useful for identifying the target. Propofol is a potentially useful anesthetic agent for electrophysiologic monitoring during functional neurosurgery.