Hordacre Brenton, Bradnam Lynley V, Barr Christopher, Patritti Benjamin L, Crotty Maria
Department of Rehabilitation, Aged and Extended Care, Repatriation General Hospital, Flinders University Adelaide, SA, Australia.
Applied Brain Research Laboratory, Centre for Neuroscience, School of Medicine, Flinders University Adelaide, SA, Australia ; Discipline of Physiotherapy, School of Health Sciences, Flinders University Adelaide, SA, Australia ; Discipline of Physiotherapy, Graduate School of Health, University of Technology Sydney, NSW, Australia.
Front Hum Neurosci. 2015 May 19;9:276. doi: 10.3389/fnhum.2015.00276. eCollection 2015.
Reorganization of primary motor cortex (M1) is well-described in long-term lower limb amputees. In contrast cortical reorganization during the rehabilitation period after amputation is poorly understood. Thirteen transtibial amputees and 13 gender matched control participants of similar age were recruited. Transcranial magnetic stimulation was used to assess corticomotor and intracortical excitability of M1 bilaterally. Neurophysiological assessments were conducted at admission, prosthetic casting, first walk and discharge. Gait variability at discharge was assessed as a functional measure. Compared to controls, amputees had reduced short-latency intracortical inhibition (SICI) for the ipsilateral M1 at admission (p = 0.01). Analysis across rehabilitation revealed SICI was reduced for the contralateral M1 at first walk compared to discharge (p = 0.003). For the ipsilateral M1 both short and long-latency intracortical inhibition were reduced at admission (p < 0.05) and prosthetic casting (p < 0.02). Analysis of the neurophysiology and gait function revealed several interesting relationships. For the contralateral M1, reduced inhibition at admission (p = 0.04) and first walk (p = 0.05) was associated with better gait function. For the ipsilateral M1, reduced inhibition at discharge (p = 0.05) was associated with poor gait function. This study characterized intracortical excitability in rehabilitating amputees. A dichotomous relationship between reduced intracortical inhibition for each M1 and gait function was observed at different times. Intracortical inhibition may be an appropriate cortical biomarker of gait function in lower limb amputees during rehabilitation, but requires further investigation. Understanding M1 intracortical excitability of amputees undertaking prosthetic rehabilitation provides insight into brain reorganization in the sub-acute post-amputation period and may guide future studies seeking to improve rehabilitation outcomes.
长期下肢截肢者的初级运动皮层（M1）重组已有详尽描述。相比之下，截肢后康复期的皮层重组情况却知之甚少。招募了13名经胫骨截肢者和13名年龄相仿、性别匹配的对照参与者。采用经颅磁刺激双侧评估M1的皮质运动和皮质内兴奋性。在入院、假肢塑形、首次行走和出院时进行神经生理学评估。将出院时的步态变异性作为功能指标进行评估。与对照组相比，截肢者入院时同侧M1的短潜伏期皮质内抑制（SICI）降低（p = 0.01）。康复过程中的分析显示，与出院时相比，首次行走时对侧M1的SICI降低（p = 0.003）。同侧M1在入院时（p < 0.05）和假肢塑形时（p < 0.02），短潜伏期和长潜伏期皮质内抑制均降低。神经生理学和步态功能分析揭示了几个有趣的关系。对于对侧M1，入院时（p = 0.04）和首次行走时（p = 0.05）抑制降低与更好的步态功能相关。对于同侧M1，出院时抑制降低（p = 0.05）与步态功能差相关。本研究对康复期截肢者的皮质内兴奋性进行了特征描述。在不同时间观察到每个M1的皮质内抑制降低与步态功能之间存在二分关系。皮质内抑制可能是下肢截肢者康复期间步态功能的合适皮质生物标志物，但需要进一步研究。了解接受假肢康复的截肢者的M1皮质内兴奋性，有助于深入了解截肢后亚急性期的大脑重组，并可能为寻求改善康复结果的未来研究提供指导。
