双语脑语言转换和语言代表区的术中直接电刺激研究(附2例分析)

Language switching and direct cortical electrical stimulation to the language representation area in Chinese-English bilinguals:report of 2 cases

目的通过对双语病人进行术中直接电刺激研究,探讨参与双语过程的脑结构。方法对2例左额叶低级别胶质瘤汉-英双语病人在术中唤醒麻醉下进行中文、英文以及双语转换任务的脑定位,依据功能边界切除肿瘤。评价术前、术后语言功能。结果2例病人均定位出Broca区,无语种特异性,但两种语言的命名阳性点是分离的;在前额叶背外侧区发现负责双语转换的阳性点,并在皮质下找到相应的特异性纤维;电刺激尾状核头表现为双语转换障碍。术后MRI显示肿瘤全切除。术后语速减慢1例,另1例自发言语减少,3个月后均恢复,未遗留语言转换障碍。结论大脑存在负责语言转换的脑结构。在实施语言功能区定位手术时,应对每种语言及其转换进行监测。

Objective To explore the brain regions participating in the process of language switching by intraoperative direct cortical electrical stimulation in 2 Chinese-English bilingual glioma patients. Methods Two bilingual patients with low-grade glioma in left frontal lobe were operated on and received brain mappings for Chinese, English and switching between the two kinds of languages under anesthesia with waking state. Tumor resection was performed according to individual functional boundaries. Preoperative and postoperative language functions were evaluated. Results The Broca area was located in both patients, which were shared by the two languages. However, the oral naming sites were separate corresponding to each language. The sites for language switching were spotted in dorsolateral prefi＇ontal cortex and corresponding special subcortical tracts were found in the subcortex. Stimulations to the caudate head revealed the difficulty of language switching. Enhanced MRI showed total resection in both the patients. One patient presented with weakened language fluency immediately after the operation, and the other had reduction of spontaneous speech ability; both of them fully recovered after three months. Conclusion There are structures responsible for language switching in the brain, thus each single language and language switching should be monitored when bilingual patients receive the surgery for localization of eloquent brain area of language.