Cortico-cortical and subcortico-cortical evoked potentials during general anesthesia

Objective In brain tumor surgery, gross total and supramarginal resections are sought to maximize survival, while maintaining neurological integrity. Cortico-cortical evoked potentials (CCEPs), initially introduced for intraoperative mapping of language pathways during awake surgery, have been recently applied to asleep procedures. The present work reports a review on CCEPs and subcortico-cortical evoked potentials (SCEPs) performed in brain surgery under general anesthesia. Methods PRISMA guidelines were applied. All records published up to March 2025, were searched through PubMed, Cochrane Library, Web of Science, and Google Scholar databases, with detailed search strings. Results Fourteen studies were found to which five were added because they also contained the search strings. Among them, thirteen focused on the language pathway, particularly the arcuate fasciculus, and four on the visual pathway. Seven studies investigated the SCEPs, while fifteen reported CCEPs. All studies applied single electrical pulse stimulation (SPES), 0.3-1 ms in duration, if monophasic, alternating their polarity, repeated at a rate of 0.3-9 pulses per second, usually in bipolar configuration. The recordings were usually done from subdural electrodes. The N1 peak latencies were shown to be dependent on the stimulation and recording sites. In addition, under general anesthesia, the latter N2 peak latencies were not detected. Conclusions The present work highlights the feasibility of CCEPs and SCEPs during general anesthesia, in their different roles: monitoring the integrity of the tracts with CCEPs and detecting their proximity with SCEPs. Significance CCEPs and SCEPs are promising tools for monitoring eloquent cognitive functions that may be at risk during neurosurgery performed under general anesthesia.