Abstract
Neurosurgeons still find it challenging to preserve brain functions during surgeries for lesions around the eloquent areas. In awake craniotomy, high-frequency electrical stimulation has been established to monitor and map intraoperative brain functions and preserve the eloquent areas. However, awake craniotomy cannot be performed in patients with preoperative language or cognitive dysfunction. Therefore, intraoperative electrophysiological monitoring is needed to preserve the integrity of the functional motor or language network.
Motor evoked potentials have been used in intraoperative methods to monitor motor function even under general anesthesia. We recently developed an in vivo electrical tract tracing method using cortico-cortical evoked potentials (CCEPs). In the intraoperative setting, we could map the supplementary motor area and dorsal language white matter pathway using the CCEP connectivity pattern. CCEPs potentially enable monitoring of brain function during surgery, even when general anesthesia is used. An intraoperative CCEP study also suggested that each subdivision of the inferior frontal gyrus had different connectivities to the temporal lobe with an anterior-posterior gradient, that is, the frontal lobe is newly connected to the temporal lobe through the limen insulae.
The development of an intraoperative electrophysiological monitoring system that can be used in parallel with general anesthesia during surgery is clinically useful for preserving brain function in patients who cannot undergo awake craniotomy.
