Language-associated cortical regions in non-proficient Chinese–English bilinguals with glioma

• Distribution characteristics of language-associated cortical region are explored.
• Non-proficient Chinese–English late bilinguals have bilingual cortical regions.
• BOLD-fMRI cannot replace positioning by direct cortical electrical stimulation.

In fluent bilingual patients with glioma, brain mapping for the two languages is necessary because the language areas for both languages may not completely overlap. However, whether or not non-fluent bilingual patients with glioma should undergo the same procedure has yet to be determined. In this study, the distribution characteristics of language-associated cortical regions in non-fluent Chinese–English bilinguals (CEBs) with glioma were explored. Six unskilled Chinese–English late bilingual patients with glioma in eloquent cortical regions underwent awake brain surgery. Preoperative blood-oxygen-level dependent functional magnetic resonance imaging (BOLD-fMRI) was performed to position bilingual regions. Direct cortical electrical stimulation (DCES) was conducted for intraoperative positioning of bilingual cortical regions. The identified language-positive regions were protected during tumor resection to preserve language function after surgery, and BOLD-fMRI and DCES results were compared. Results showed that 71 points were stimulated in 6 CEB patients. Three specific language regions (4.2%), including 2 specific English language regions (2.8%) and 1 specific Chinese language region (1.4%), were located in the frontal and temporal lobes. Comparisons between BOLD-fMRI and DCES showed a sensitivity, specificity and consistency of 75.0%, 30.9% and 40.9%, respectively. Non-fluent Chinese–English late bilinguals have specific bilingual cortical regions, and the test for both languages during surgery is necessary. The language region positioning results of BOLD-fMRI cannot replace the position accuracy provided by DCES.