Clinical significance of intraoperative bidirectional corticocortical evoked potential monitoring to evaluate language function.

in Journal of neurosurgery by Chie Kamada, Yusuke Kimura, Shoto Yamada, Ryohei Saito, Katsuya Komatsu, Rei Enatsu, Yukinori Akiyama, Nobuhiro Mikuni

TLDR

  • This study examined the use of bidirectional corticocortical evoked potential (CCEP) monitoring to evaluate intraoperative language function during awake brain tumor resection.

Abstract

Awake craniotomy is commonly used to resect lesions located near the language area during brain surgery. However, it is often difficult to perform language tasks due to several limitations such as difficulty in awakening during surgery and intraoperative seizures. This study investigated the clinical significance of bidirectional corticocortical evoked potential (CCEP) monitoring as a new approach to evaluate intraoperative language function. This study enrolled 12 patients who underwent awake brain tumor resection with intraoperative CCEP monitoring to assess language function. Electrodes were placed on the frontal and temporoparietal lobes based on the location of the arcuate fasciculus identified with preoperative diffusion tensor imaging to measure CCEPs intraoperatively in two directions: from the frontal lobe to the temporoparietal lobe of the language-dominant side, and vice versa. Correlations between CCEP amplitudes or latencies before and after tumor removal in each direction and postoperative language function assessed with the Western Aphasia Battery were analyzed. Nine of the 12 patients showed language-related CCEP responses in both directions before, during, and after tumor removal. One patient who showed decreased CCEP amplitudes in both directions after tumor removal exhibited aphasia for as long as 1 month postoperatively. In contrast, of the 6 patients whose CCEP amplitude in only a single direction was reduced or disappeared, 4 had no deterioration of language function and the other 2 had temporary deterioration of language function during the 1st postoperative week, which improved by 1 month postoperatively. This study indicated that bidirectional CCEP measurement may increase the precision of intraoperative language function monitoring.

Overview

  • The study investigated the clinical significance of bidirectional corticocortical evoked potential (CCEP) monitoring as a new approach to evaluate intraoperative language function.
  • The study enrolled 12 patients who underwent awake brain tumor resection with intraoperative CCEP monitoring to assess language function.
  • Electrodes were placed on the frontal and temporoparietal lobes based on the location of the arcuate fasciculus identified with preoperative diffusion tensor imaging to measure CCEPs intraoperatively in two directions.

Comparative Analysis & Findings

  • Nine of the 12 patients showed language-related CCEP responses in both directions before, during, and after tumor removal.
  • One patient who showed decreased CCEP amplitudes in both directions after tumor removal exhibited aphasia for as long as 1 month postoperatively.
  • Of the 6 patients whose CCEP amplitude in only a single direction was reduced or disappeared, 4 had no deterioration of language function and the other 2 had temporary deterioration of language function during the 1st postoperative week, which improved by 1 month postoperatively.

Implications and Future Directions

  • The study indicated that bidirectional CCEP measurement may increase the precision of intraoperative language function monitoring.
  • Future studies could investigate the use of CCEP monitoring in larger patient populations and examine its efficacy in more complex language surgery cases.
  • Additionally, the study suggests that the bidirectional CCEP measurement could be used to identify patients who are at risk of postoperative language deficits and optimize surgical strategies accordingly.
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