Surgical resection of tumors located in subcortex of language area

Object. Although functional mapping facilitates the planning of surgery in and around eloquent areas, the resection of tumors adjacent to language areas remains challenging. In this report, we took notice that the language areas (Broca's and Wernicke's) present at the perisylvian fissure. We posit that if there is non-essential language area on the inner surface of the Sylvian fissure, safe tumor resection may be possible even if the tumor is located under the language cortex. Methods. The study population consisted of 5 patients with intrinsic brain tumors (frontal glioma, n = 3; temporal cavernous angioma, n = 1; primary malignant central nervous system lymphoma, n = 1) located in the perisylvian subcortex, in the language-dominant hemisphere. All patients underwent awake surgery and we performed intra-operative bipolar cortical functional language mapping. When the tumor was located under the language area, the Sylvian fissure was opened and the inner surface of the opercular cortex was exposed with the patient asleep, and additional functional mapping of that cortex was performed. This enabled us to remove the tumor from the non-functioning cortex. In our series, 4 of 5 patients had not language function on the inner surface of the operculum. Only one patient, a 52-year-old man with frontal glioblastoma (Case 3) had language function on the inner surface of the frontal operculum. Conclusion. We suggest that even perisylvian tumors located in the subcortex of the language area may be resectable via the nonfunctioning intrasylvian cortex by a transopercular approach without resultant language dysfunction.