针刺治疗面肌痉挛的大脑运动皮层功能重组机制研究

Hemifacial spasm (HFS) is a movement disorder with unilateral, involuntary and intermittent contractions of facial muscles. HFS initially occurs in the orbicularis oculi muscle, gradually spreads to other facial muscles. HFS is difficult to recover spontaneously and easy to recrudesce not physically disabling, leading to psychological disorders including self-abasement, frustration, depression and anxiety and dangerous to patients’ physical and mental health. No optimal therapeutic modality has been found yet. Studies on brain plasticity indicated that there was competitive inhibitory effect between hand and face representation in motor cortex. Moreover, our previous work also showed that there was specific relationship between Hegu acupoint and orofacial area and acupuncture at Hegu acupoint regulated the interaction between hand and face representation in the cortex. Therefore, we proposed the scientific hypothesis of the project: acupuncture at Hegu acupoint may produce competitive inhibitory effect (i.e., facilitating excitability and area in hand representation and simutaneously inhibiting that in face representation), which will result in functional reorganization in hand and face representation and promote recovery of HFS. Techniques of brain functions including Transcranial Magnetic Stimulation (TMS) and functional magnetic resonance imaging (fMRI) and some novel designs such as cross-over design and double-blinded, sham-controlled, randomized, parallel-group study will be used in this study to investigate the biological mechanism of HFS, which can be programmed to benefit the treatment of HFS.

面肌痉挛是一侧面部肌肉阵发性、不自主抽搐为特征的面神经疾患，难以自行缓解且易反复发作，导致患者出现自卑、挫折感、抑郁、焦虑等心理精神障碍，严重危害患者的身心健康，目前缺乏理想的治疗手段。脑可塑性的最新研究成果表明，大脑运动皮层手面区之间存在竞争性的抑制作用。我们的前期工作亦证实，合谷穴和口面部之间存在特异性联系，针刺合谷穴可能对手面区间的相互作用具有调节作用。为此，我们提出科学假说：针刺合谷穴可能产生竞争性抑制效应（兴奋被过度抑制的运动皮层手区，同时抑制相毗邻且过度兴奋的面区），导致运动皮层手区和面区发生功能重组，抑制面部肌肉的过度兴奋，从而促进面肌痉挛恢复。本研究应用经颅磁刺激（TMS）和功能磁共振（fMRI）等脑功能研究手段，采用交叉设计和随机双盲平行试验等设计，从大脑运动皮层功能重组这一全新的角度探讨针刺治疗面肌痉挛的生物学机制，国内外尚无人涉及，对面肌痉挛的治疗具有重要的临床意义。

周围神经的损伤可导致中枢神经系统的可塑性变化，且神经损伤后的修复与脑可塑性密切相关，调节脑可塑性变化逐渐成为周围神经损伤的治疗策略。“面口合谷收”是经络理论与临床实践结合的典范，且针刺对脑可塑性具有显著的调节作用。因此，本研究在中医经络理论和现代科学脑可塑性理论的指导下，应用经颅磁刺激（TMS）、功能磁共振（fMRI）和临床神经电生理等技术手段，以健康志愿者和患者（面肌痉挛及面瘫）为观察对象，从三个方面（①针刺对健康志愿者脑可塑性变化的作用机制、②针刺对面肌痉挛脑可塑性变化的调节作用、③针刺对面瘫患者脑可塑性变化的调节作用）开展研究工作。.研究发现：（1）生理状态下，电针手部穴位能诱发手面区的可塑性变化，即兴奋运动皮层手区，抑制运动皮层面区，同时抑制脑干的兴奋性；联合运动训练，无协同效应，表现为自稳态的再可塑性。（2）病理状态下（面肌痉挛，HFS），同侧脑干（瞬目反射BR）和对侧运动皮层面区（运动诱发电位MEPs）的兴奋性明显高于健康志愿者；电针HFS同侧合谷和鱼际穴，临床症状明显改善，抑制同侧脑干BR，同时兴奋对侧手区MEPs，抑制对侧面区MEPs；电针同侧太阳和四白穴无明显治疗效应，表现为同侧BR增强，对侧面区MEPs兴奋。而rTMS直接抑制运动皮层，无诱发皮层及脑干的可塑性变化，且对电针所诱发的脑干和皮层面区效应无明显影响。（3）电针治疗周围性面瘫患者的效应与HFS相反，即电针患侧口面部穴位改善症状的同时，显著增强脑干的兴奋性，同时兴奋对侧面区，抑制对侧皮层手区；电针同侧合谷穴无明显效应。.上述研究结果表明，远端选穴（患侧合谷和鱼际）对HFS具有明显的治疗作用，其主要作用机制在于抑制脑干的兴奋性，而皮层手面区的兴奋性变化只是脑干兴奋性变化的上游反应而已。本研究首次证实了针刺治疗HFS的脑可塑性机制，对HFS的治疗具有重要的临床指导意义。