Brain Stimulation and Rehabilitation Lab, School of Science and Health, Western Sydney University, Sydney, New South Wales, Australia.
Brain Stimulation and Rehabilitation Lab, School of Science and Health, Western Sydney University, Sydney, New South Wales, Australia; School of Biomedical Science, Queensland University of Technology, Brisbane, Queensland, Australia.
J Pain. 2024 Apr;25(4):1000-1011. doi: 10.1016/j.jpain.2023.10.020. Epub 2023 Oct 29.
Accumulating evidence demonstrates that pain induces adaptations in the corticomotor representations of affected muscles. However, previous work has primarily investigated the upper limb, with few studies examining corticomotor reorganization in response to lower limb pain. This is important to consider, given the significant functional, anatomical, and neurophysiological differences between upper and lower limb musculature. Previous work has also focused on unilateral corticomotor changes in response to muscle pain, despite an abundance of literature demonstrating that unilateral pain conditions are commonly associated with bilateral motor dysfunction. For the first time, this study investigated the effect of unilateral acute hamstring pain on bilateral corticomotor organization using transcranial magnetic stimulation (TMS) mapping. Corticomotor outcomes (TMS maps), pain, mechanical sensitivity (pressure pain thresholds), and function (maximal voluntary contractions) were recorded from 28 healthy participants at baseline. An injection of pain-inducing hypertonic (n = 14) or pain-free isotonic (n = 14) saline was then administered to the right hamstring muscle, and pain ratings were collected every 30 seconds until pain resolution. Follow-up measures were taken immediately following pain resolution and at 25, 50, and 75 minutes post-pain resolution. Unilateral acute hamstring pain induced bilateral symptom development and changes in corticomotor reorganization. Two patterns of reorganization were observed-corticomotor facilitation and corticomotor depression. Corticomotor facilitation was associated with increased mechanical sensitivity and decreased function bilaterally (all P < .05). These effects persisted for at least 75 minutes after pain resolution. PERSPECTIVE: These findings suggest that individual patterns of corticomotor reorganization may contribute to ongoing functional deficits of either limb following acute unilateral lower limb pain. Further research is required to assess these adaptations and the possible long-term implications for rehabilitation and reinjury risk in cohorts with acute hamstring injury.
越来越多的证据表明，疼痛会引起受影响肌肉的皮质运动代表区的适应性变化。然而，之前的工作主要集中在上肢，很少有研究研究下肢疼痛对皮质运动重组的影响。这一点很重要，因为上肢和下肢肌肉在功能、解剖和神经生理学上有很大的差异。之前的工作也主要集中在单侧皮质运动变化对肌肉疼痛的反应上，尽管有大量文献表明单侧疼痛状况通常与双侧运动功能障碍有关。本研究首次使用经颅磁刺激（TMS）映射技术研究了单侧急性腘绳肌疼痛对双侧皮质运动组织的影响。在基线时，从 28 名健康参与者中记录皮质运动结果（TMS 图谱）、疼痛、机械敏感性（压痛阈值）和功能（最大自主收缩）。然后向右侧腘绳肌注射引起疼痛的高渗（n=14）或无疼痛的等渗盐水（n=14），并每隔 30 秒收集一次疼痛评分，直到疼痛缓解。在疼痛缓解后立即进行后续测量，并在疼痛缓解后 25、50 和 75 分钟进行测量。单侧急性腘绳肌疼痛引起双侧症状发展和皮质运动重组变化。观察到两种重组模式-皮质运动易化和皮质运动抑制。双侧皮质运动易化与机械敏感性增加和功能下降有关（均 P<0.05）。这些影响在疼痛缓解后至少持续 75 分钟。观点：这些发现表明，个体皮质运动重组模式可能导致单侧急性下肢疼痛后四肢持续存在功能缺陷。需要进一步研究这些适应机制以及对急性腘绳肌损伤队列康复和再损伤风险的可能长期影响。
