臂丛神经损伤后不同部位肌肉萎缩的检测和机制探讨

目的 研究臂丛神经损伤后不同部位的失神经骨骼肌的萎缩规律，并探讨细胞凋亡和肌卫星细胞的变化在失神经萎缩骨骼肌中发挥的作用。方法 臂丛神经损伤后手术治疗患者50例，术中切取不同部位的失神经骨骼肌80块，按肌肉部位分为A、B两组，A组为小指展肌34块，B组为肱二头肌46块，每块分别进行HE染色、Masson染色、失神经萎缩肌肉中凋亡细胞核的免疫组化染色和透射电镜观察。结果 （1）随时间的延长，肌细胞萎缩愈加明显，A、B组在各时间段比较，差异均无显著性意义。（2）失神经后骨骼肌中染成牟胶原纤维增多，早期增生并不明显，失神经支配1年以上的肌肉中胶原增生更为显著。不同时间组胶原纤维与骨骼肌细胞面积比较，差异有显著性意义（P＜0.05），同一时间段内A、B组比较，差异均无显著性意义。（3）正常的骨骼肌细胞鲜见凋亡细胞核，失神经后骨骼肌随时间延长，其凋亡细胞核的数量增加，而小指展肌中上升速度较肱二头肌快。（4）随着失神经时间的延长，肌卫星细胞含量迅速下降，小指展肌中肌卫星细胞下降速度较肱二头肌快。结论 不同部位的肌肉失神经支配后，萎缩的肌纤维截面积及胶原纤维的增生情况相似，胶原纤维的增生只在晚期才成为影响神经修复手术疗效的原因之一。细胞凋亡与失神经肌萎缩相关，小指展肌中凋亡细胞核数上升较肱二头肌快，提示细胞凋亡导致的肌细胞核数量减少可能是影响神经修复手术疗效的主要原因之一；肌卫得细胞含量的迅速下降可能也是造成其疗效欠佳的另一原因。

Examination and mechanism of different muscles atrophy after brachial plexus injury

Objective To observe the morphological changes of different muscles after brachial plexus injury and to investigate the role of cell apoptosis in denervation atrophy. Methods Fifty patients of brachial plexus injuries were involved. Eighty denervated muscles were harvested intraoperatively and divided into two groups: Group A (abductor digiti minimi) and Group B (biceps brachii). The slice was stained by HE staining, Masson staining and immunohistochemical staining of apoptotic nucleus. Samples were also observed under electronmicroscope for counting the satellite cells. Results There was a sharp decrease in the muscle fiber cross sectional area. There was no significant difference between Groups A and B. In both Groups A and B, a longer denervation time resulted in a more collagen fibers. The difference between Group A and Group B of same denervation time was not statistically significant. Apoptotic nucleus was rarely seen in normal skeletal muscle. With elongation of denervation time, the number of apoptotic nucleus increased. The number of abductor digiti minimi increased more rapidly than that of biceps brachii. The number of satellite cells increased slightly after denervation. Then they decreased with the elongation of denervation time, the declination of satellite cells in digiti minimi was faster than that of biceps brachii. Conclusions The changes of myofiber cross sectional area and collagen fiber content in different muscles are similar. Hyperplasia of collagen fiber only affects the treatment outcome of nerve repair in late stage. Apoptosis is closely related to muscle atrophy. Apoptosis inducing decrease of nucleus may be one of the factors influencing treatment outcome in peripheral nerve repair. And the decline of satellite cells is another reason for the poor treatment outcome.