皮质脑电小波分析定位人脑语言区的方法研究

We are the first team in china to employ intraoperative direct electrical stimulation(DES) for mapping of the eloquent areas under awake anaesthesia in 2002 in order to achieve not only maximal but also safe resection of tumors in cerebral eloquent areas. We found that DES provided a real-time, reliable, precise and safe method for brain mapping, but it was time-consuming, epilepsy inducing, resulting in false positive and false negative sometimes. It couldn't be suitable for patients who do not cooperate. ..To study the specific accurate spectral change of electrocorticography(ECoG) during language processing make it possible to intraoperatively map the language cortices by ECoG. In one of our previous studies, significant u-band change could be detected correctly in 28/30 cases(sensitivity of 93%) with a specificity of 84%. This confirms the the feasibility of this methods and suggest the research directions( improving the sensitivity and specificity).. .This study will focus on mapping of the language related cortices by ECoG.The ECoG signals of rest-state and performing language tasks(naming, counting, reading and verb generation tasks) are obtained from patient with brain lesions who undergo awake surgery. The language-related cortices were confirmed by DES. The ECoG signals are decomposed and reconstructed in multilevel by wavelet transform. Single or combined parameters of reconstructed signal was extracted to be the feature parameter with construction a specific threshold for mapping of language cortices. ..This study will provide a new tool for functional human brain mapping of language areas in operation, and then improve the accuracy and convenience of intra-operative mapping of eloquent areas, and will improve quality of resection in surgery of patient with lesions near eloquent areas.

我们于2002年在国内首先采用术中直接电刺激在唤醒麻醉下定位脑功能区，旨在保留功能的前提下最大程度的切除病变。实践中发现电刺激费时、会诱发癫痫、出现假阳性和假阴性结果，且无法适合不能配合的病人。研究脑电信号在语言活动时出现的特异性变化规律，使术中脑电图定位脑功能区成为可能。前期研究发现单一频段定位运动区皮层的敏感性93%，特异性84%，提示该方法的可行性及需要完善的内容。本研究拟对大脑手术病人在清醒状态下获取静息和语言任务状态下（数数，命名，阅读和动词联想）皮质脑电信号，皮质直接电刺激确定语言区皮质，利用小波分析方法分析脑电信号，提取单一参数和多维参数及其相应特定阈值，获得皮质脑电定位语言区的特异性参数，建立皮质脑电实时定位语言区皮质新方法，为皮质脑电定位语言区探索新方法。该项目将提高功能区手术中功能区的定位准确性和便利性，提高手术切除质量。

我们于2002年在国内首先采用术中直接电刺激在唤醒麻醉下定位脑功能区，旨在保留功能的前提下最大程度的切除病变。实践中发现电刺激费时、会诱发癫痫、出现假阳性和假阴性结果，且无法适合不能配合的病人。皮质脑电图是一种利用内源性信号定位脑皮质功能的方法，研究脑电信号在语言活动时出现的特异性变化规律，使术中脑电图定位脑功能区成为可能。. 我们对8例功能区病变病人采用术中脑功能区胶质瘤病人进行全麻术中唤醒状态下手术，术中皮质电刺激（inomed皮层电刺激仪，双极，双向方波，频率60Hz，波宽1000us，电流2-5mA）定位运动区和语言区皮质，语言任务采用数数和图片命名。采集静息、数数任务和命名任务状态下皮质脑电信号（4*5盘状电极），然后采用矢量多分类的方法，对脑电信号进行小波分解并重构各单子频段信号，以任务事件前后的各单子频段信号能量差别作为特征量，构建多维时频域矢量；最后采用基于决策树的支持向量机多分类算法对多维时频域矢量进行分类，从而识别各电极导联上脑电信号的特异性，完成大脑皮能区脑电特异性的检测。.. 所有病人皮层电刺激均定位运动区和语言区皮层，命名状态下可见命名不能区的皮质脑电图信号70Hz-120 Hz频带相对活跃，以滑动对数功率和为特征值，与直接皮层电刺激结果相符合。数数任务状态下，数数中断区（Broca区）、命名区和运动区等功能区皮层脑电在70Hz-120 Hz频带相对活跃，而非功能区皮层在此频段相对抑制。采用这种方法对8例病人的语言区功能皮质检测的灵敏性可达93.8%，但特异性稍差，对其特异性进行分析，平均真阳性率：54.0%；平均真阴性率：95.8%。进一步分析将命名区和数数区都归于语言区，重新取样本建模，可以大大提高正确检出率，平均真阳性率提高了12.9%，达66.9%。如果排除血管和术中任务状态干扰，检出率和误检率有望进一步改善。.. 皮质脑电信号分析定位语言区皮质操作简单，在语言任务过程中有一定特征，有望成为一种新的语言区皮质定位方法。另外，由于临床数据采集的局限性，研究过程中发现皮质脑电的特异性研究有待在动物学进行验证。