Schieppati M, Nardone A
Institute of Human Physiology II, University of Milano, Italy.
Brain. 1991 Jun;114 ( Pt 3):1227-44. doi: 10.1093/brain/114.3.1227.
Upright stance and its reflex control were studied in parkinsonian patients and in age-matched normal subjects. They stood unperturbed on a force-measuring surface (static conditions), or were displaced by movement of a supporting platform (dynamic conditions). During quiet stance the following variables were analysed, with eyes open or closed: position of the centre of foot pressure (CFP), average sway area, length of sway path, amplitude and distribution of tonic leg muscle EMG activity. Perturbations of stance were induced by toe-up or toe-down rotations, and by backward or forward translations of the platform. Amplitude of short, medium and long-latency EMG responses to displacement were measured in the tibialis anterior (TA) and in the three heads of the triceps surae (TS) muscle. The perturbations were produced during both free and supported stance (holding onto a stable structure), under which condition normal subjects suppress medium and long-latency responses. Under static conditions, the only significant finding in parkinsonians was represented by a shift in the position of the CFP. This was correlated with the severity of the disease (Webster scale), the less affected patients being shifted backwards and the more affected patients forwards, with respect to normals. Under dynamic conditions, the reflex responses to perturbations of free stance were similar in both groups. Only the medium-latency burst of gastrocnemius lateralis and the long-latency burst TA evoked by TS stretch were larger in parkinsonians. The amplitude of these responses, as well as of all the others, was not related to the Webster score. Within the patients' group, a relationship between position of CFP and area of EMG burst was found for both medium and long-latency TA responses evoked by forward translation and toe-up rotation, respectively. Under supported conditions, the capability to suppress all medium and long-latency muscle responses to any perturbation was lost or impaired in the parkinsonians. The degree of impairment was unrelated to the position of the CFP, but was significantly related to the severity of the disease. The suppression to 40% (supported/nonsupported), of TA response to toe-down rotation is proposed as the point of separation between normals and parkinsonians. The forward projection of the CFP, occurring in the severe stages of the disease, and the increase in amplitude of some responses to perturbations of free stance might be a compensatory adaptation to the anomalous upright posture.(ABSTRACT TRUNCATED AT 400 WORDS)
对帕金森病患者和年龄匹配的正常受试者的直立姿势及其反射控制进行了研究。他们在测力表面上安静站立（静态条件），或因支撑平台移动而产生位移（动态条件）。在安静站立期间，分析了以下变量，眼睛睁开或闭合：足压中心（CFP）位置、平均摆动面积、摆动路径长度、腿部肌肉紧张性肌电图（EMG）活动的幅度和分布。通过向上或向下转动脚趾以及平台向后或向前平移来诱发姿势扰动。测量胫骨前肌（TA）和腓肠肌三头肌（TS）三个头对位移的短、中、长潜伏期EMG反应的幅度。在自由站立和支撑站立（抓住稳定结构）期间都会产生扰动，在支撑站立条件下，正常受试者会抑制中、长潜伏期反应。在静态条件下，帕金森病患者唯一显著的发现是CFP位置的偏移。这与疾病严重程度（韦伯斯特量表）相关，相对于正常人，病情较轻的患者CFP向后偏移，病情较重的患者向前偏移。在动态条件下，两组对自由站立扰动的反射反应相似。只有帕金森病患者中，由TS拉伸诱发的外侧腓肠肌中潜伏期爆发和TA长潜伏期爆发更大。这些反应以及所有其他反应的幅度与韦伯斯特评分无关。在患者组中，分别发现向前平移和向上转动脚趾诱发的TA中、长潜伏期反应的CFP位置与EMG爆发面积之间存在关系。在支撑条件下，帕金森病患者丧失或受损了抑制所有对任何扰动的中、长潜伏期肌肉反应的能力。受损程度与CFP位置无关，但与疾病严重程度显著相关。将TA对向下转动脚趾反应的抑制率达到40%（支撑/非支撑）作为正常人与帕金森病患者的区分点。在疾病严重阶段出现的CFP向前投影以及对自由站立扰动的一些反应幅度增加可能是对异常直立姿势的一种代偿性适应。（摘要截于400字）
