Chen Robert, Anastakis Dimitri J, Haywood Catherine T, Mikulis David J, Manktelow Ralph T
Division of Neurology, Toronto Western Research Institute, University Health Network, University of Toronto, Toronto, Ont., Canada.
Clin Neurophysiol. 2003 Dec;114(12):2434-46. doi: 10.1016/s1388-2457(03)00283-9.
Although motor system plasticity in response to neuromuscular injury has been documented, few studies have examined recovered and functioning muscles in the human. We examined brain changes in a group of patients who had a muscle transfer.
Transcranial magnetic stimulation (TMS) was used to study a unique group of 9 patients who had upper extremity motor function restored using microneurovascular transfer of the gracilis muscle. The findings from the reconstructed muscle were compared to the homologous muscle of the intact arm. One patient was also studied with functional magnetic resonance imaging (fMRI).
TMS showed that the motor threshold and short interval intracortical inhibition was reduced on the transplanted side while at rest but not during muscle activation. The difference in motor threshold decreased with the time since surgery. TMS mapping showed no significant difference in the location and size of the representation of the reconstructed muscle in the motor cortex compared to the intact side. In one patient with reconstructed biceps muscle innervated by the intercostal nerves, both TMS mapping and fMRI showed that the upper limb area rather than the trunk area of the motor cortex controlled the reconstructed muscle.
Plasticity occurs in cortical areas projecting to functionally relevant muscles. Changes in the neuronal level are not necessarily accompanied by changes in motor representation. Brain reorganization may involve multiple processes mediated by different mechanisms and continues to evolve long after the initial injury.
Central nervous system plasticity following neuromuscular injury may have functional relevance.
尽管已有文献记载运动系统对神经肌肉损伤的可塑性，但很少有研究在人体中检查恢复并发挥功能的肌肉。我们研究了一组接受肌肉移植患者的大脑变化。
采用经颅磁刺激（TMS）对一组独特的9例患者进行研究，这些患者通过股薄肌的显微神经血管移植恢复了上肢运动功能。将重建肌肉的研究结果与健侧上肢的同源肌肉进行比较。还对1例患者进行了功能磁共振成像（fMRI）研究。
TMS显示，移植侧在静息状态下运动阈值和短间隔皮质内抑制降低，但在肌肉激活时未降低。运动阈值的差异随术后时间的延长而减小。TMS图谱显示，与健侧相比，运动皮层中重建肌肉代表区的位置和大小无显著差异。在1例由肋间神经支配重建肱二头肌的患者中，TMS图谱和fMRI均显示运动皮层的上肢区域而非躯干区域控制重建肌肉。
投射到功能相关肌肉的皮质区域会发生可塑性变化。神经元水平的变化不一定伴随着运动代表区的变化。脑重组可能涉及由不同机制介导的多个过程，并且在初始损伤后很长时间仍在持续演变。
神经肌肉损伤后中枢神经系统的可塑性可能具有功能相关性。
