[Methodologic aspects of the intraoperative monitoring of evoked potentials]

The aim of intraoperative monitoring methods is to obtain early information about central nervous function during critical phases of the operation. To this end it can be useful to accept modifications of the method or the technical parameters such as changes of the electrode positions, of the system's bandpass, the analysis time or the number of sweeps used for averaging. Additionally emphasis is laid upon the fact that there is no knowledge concerning the critical changes of potential which might indicate functional disturbances or impending postoperative neurological deficits. At the present time intraoperative EP-Monitoring is not an established method for clinical use. Evidence is lacking that supervision of the operation by these means results in a reduced operation risk.