• Aya Kanno, Rei Enatsu, Satoshi Ookawa, Shouhei Noshiro, Shunya Ohtaki, Kengo Suzuki, Yuto Suzuki, Rintaro Yokoyama, Satoko Ochi, Yukinori Akiyama, Takeshi Mikami, Takuro Nakae, Takayuki Kikuchi, Takeharu Kunieda, Susumu Miyamoto, Riki Matsumoto, and Nobuhiro Mikuni.
• Department of Neurosurgery, Sapporo Medical University School of Medicine, Sapporo, Japan.
• World Neurosurg. 2018 Dec 1; 120: e628-e636.

BackgroundThe connection between the ventrolateral frontal and temporoparietal cortices has an important role in language function on the language-dominant side and spatial awareness on the nondominant side. However, the laterality of these pathways remains controversial. We investigated the laterality of this connection using corticocortical-evoked potentials (CCEPs).MethodsFrom April 2014 to March 2016, 27 patients who had undergone frontotemporal craniotomy were enrolled. With the patients under general anesthesia, subdural electrodes were placed on both frontal and temporoparietal areas intraoperatively. Alternating 1-Hz electrical stimuli were delivered to the pars opercularis and pars triangularis with a stimulus intensity of 10 mA. CCEPs were obtained from temporoparietal areas by averaging the electrocorticogram time-locked to the stimulus onset. The amplitudes and latencies of the CCEP N1 components were compared between the dominant and nondominant sides.ResultsThe median amplitudes of the CCEPs were 335.1 μV (range, 60.2-750) and 125.65 μV (range, 55.1-634) on the dominant and nondominant sides, respectively. The CCEP amplitudes were significantly larger on the dominant side than on the nondominant side (P = 0.013). In contrast, the median latency was 27.8 ms (range, 19.3-36.6) on the language-dominant side and 28.9 ms (range, 8.9-38.5) on the nondominant side. The latencies were not significantly different between the 2 sides (P = 0.604).ConclusionsThe CCEP amplitudes were significantly larger in the dominant hemisphere. These findings can lead to better hypotheses regarding the relationship between language functions and the development of the network connecting the frontal and temporoparietal cortices.Copyright © 2018. Published by Elsevier Inc.

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