Fondazione Salvatore Maugeri-IRCCS, Divisione di Recupero e Rieducazione Funzionale, Istituto Scientifico di Veruno-NO, Italy.
Exp Neurol. 2012 Oct;237(2):407-17. doi: 10.1016/j.expneurol.2012.07.003. Epub 2012 Jul 15.
Early Parkinson's disease (PD), in which the motor disorder is mostly unilateral, allows to investigate the presence of side-related pathophysiological changes in the responses to balance perturbations prior to any confounding effect of therapy. These patients offer the possibility of answering the question whether the initial abnormalities affect spinal circuits or supra-spinal sensori-motor loops. Toe-down rotation of a supporting platform evokes in standing subjects a double-burst medium-latency response (MLR) in the stretched tibialis anterior (TA) muscle. The former burst (MLR1) is fed by group II spindle fibres through a spinal circuit, the latter (MLR2) travels through supraspinal pathways. This perturbation was used to separately test both reflex pathways in both the unaffected and affected side. Ten patients with unilateral PD (7 of which de-novo) and 10 normal subjects (NS) were recruited. 1. Body sway and centre of feet pressure (CFP) were recorded during quiet standing; 2. Rotations of the supporting platform were administered with both legs on the platform during free stance (Control) and 3. While holding onto a stable rail (Holding); 4. Separate perturbations to either leg (Leg-on or Leg-off) were also delivered to avoid the effect of concurrent ipsi- and contralateral inputs on MLR. The EMG of TA and Sol muscles were recorded bilaterally. 1. Position and sway of CFP were similar in NS and PD. 2. Under Control condition, there were no differences in area of TA MLR1 and MLR2 of both limbs between NS and PD. 3. During Holding, both bursts were reduced in amplitude in both NS and PD, but less so for the MLR1 on the PD affected side. 4. During single-leg perturbation, both bursts were reduced in amplitude in both NS and PD, both ipsi- and contralateral to the perturbation; however, in PD, MLR2 was much less reduced in the unperturbed affected side Leg-off. The differences in the responses to stretch between NS and early PD are not accounted for by changes in postural attitude, or by different amplitudes of the Control responses. The asymmetrical reduction of the MLR1 by Holding in PD indicates mostly unilateral impairment of the descending pathways modulatory to spinal group II circuits. Single-leg perturbation unveils a larger excitability of the supraspinal loop mediating the MLR2 on the affected side. These changes are early markers of basal ganglia malfunctions, and are related to both their descending effect on the spinal cord and their ascending influence onto the cortex.
早期帕金森病（PD）中，运动障碍主要为单侧，这使得我们能够在治疗任何干扰作用之前，研究平衡扰动时与侧相关的病理生理变化。这些患者为回答以下问题提供了可能性，即初始异常是否影响脊髓回路或脊髓上感觉运动回路。支撑平台的足趾向下旋转会在站立的受试者中引起伸展的胫骨前肌（TA）中的双爆发中潜伏期反应（MLR）。前爆发（MLR1）通过脊髓回路由 II 组梭形纤维供给，后爆发（MLR2）通过脊髓上途径传播。这种扰动用于分别测试未受影响侧和受影响侧的两种反射通路。招募了 10 名单侧 PD 患者（其中 7 名为首发）和 10 名正常受试者（NS）。1. 在安静站立期间记录身体摆动和足底压力中心（CFP）；2. 在自由站立时双腿放在平台上进行平台旋转（控制）；3. 同时握住稳定扶手（保持）；4. 也分别向单侧腿（单侧腿）施加单独的扰动，以避免同侧和对侧输入对 MLR 的影响。双侧记录 TA 和 Sol 肌肉的 EMG。1. NS 和 PD 之间的 CFP 位置和摆动相似。2. 在控制条件下，NS 和 PD 之间双侧肢体的 TA MLR1 和 MLR2 的面积没有差异。3. 在保持期间，NS 和 PD 双侧的两个爆发都减小了幅度，但 PD 受影响侧的 MLR1 幅度减小较小。4. 在单侧腿扰动期间，NS 和 PD 双侧的两个爆发都减小了幅度，无论是同侧还是对侧；然而，在 PD 中，未受扰的受影响侧腿（单侧腿）的 MLR2 减少幅度要小得多。NS 和早期 PD 对拉伸的反应差异不能用姿势态度的变化或控制反应的不同幅度来解释。PD 中保持时 MLR1 的不对称减少表明，对脊髓 II 组电路有下行调节作用的下行通路主要为单侧受损。单侧腿扰动揭示了受影响侧介导 MLR2 的脊髓上回路的兴奋性更高。这些变化是基底节功能障碍的早期标志物，与它们对脊髓的下行影响及其对皮质的上行影响有关。
