胶质瘤与锥体束交界区脑白质超微结构定点观察

The ultrastructure observation of nerve fiber in brain white matter between glioma and pyramidal tract

目的观察胶质瘤瘤周脑白质神经纤维的超微结构,为研究神经纤维束功能保护提供组织学依据。方法对8例功能区胶质瘤,术前行扩散张量成像(DTI),标记锥体束与肿瘤交界区的神经影像兴趣区,利用神经导航系统中扩散张量成像-纤维束示踪(DTI-FT)图像、脑穿刺留置着色明胶海绵矫正脑漂移技术、直接电刺激技术等,定点采集影像兴趣区标本,进行常规透射电镜观察。结果成功定点采集标本13块,术后患者运动功能均保持术前状态或改善。胶质瘤周边脑白质内有髓神经纤维存在三类超微结构改变:单纯髓鞘病理改变、单纯轴索病理改变及髓鞘-轴索共同病变。结论针对术前神经影像兴趣区,定点留取大脑半球内手术病理标本的方法,为研究神经影像信号与手术神经病理间关系提供了重要方法。轴索变性、坏死是肿瘤周边脑白质功能障碍的重要原因,而仅有髓鞘病变的有髓神经纤维是术后神经功能改善的基础。

Objective To observe the ultrastructure of nerve fiber between glioma and the pyramidal tract. Methods In eight glioma patients, DTI data were obtained on a 1.5 T Siemens scanner before the operation. The regions of interested （ROI） on anisotropy fraction （FA） image were fused in neuronavigation. In operation, techniques of diffusion weighted imaging-fiber tractography （I）TI-FT） in neuronavigation, navigated brain puncture with methylene blue stained gelatin sponge, and direct electrical stimulation were used to obtain the specified specimens of the ROIs on FA images. The specimens were observed with transmission electron microscope. Results A total of 13 specimens were obtained. The patients＂ motor function was the same as or better than that before operation. Three types of ultrastueture pathological changes in the myelinated nerve fibers in the region between tumor and the pyramidal tract were identified. Firstly only the myelin sheath change, secondly only change in axon, the last both of them. Conclusion The method that obtains specified specimen defined by neuroradiological image in deep brain during neurosurgery would be an important way to study the relationship between image signals and pathological findings. The degeneration or necrosis of axon is the main cause for fiber tract dysfunction. The myelinated nerve fibers that only suffer myelin sheath pathological changes are the reason for neurological function improvement after tmnor resection.