OBJECTIVE To measure axially-evoked postural reflexes in 11 Parkinson's disease (PD) subjects, both stable and unstable, and to compare these with 13 age-matched controls. METHODS We measured the short-latency electromyography (EMG) reflex effects of brief impulsive displacements applied to the upper sternum or C7 for tibialis anterior (TA) and soleus. Our subjects were studied standing normally and when leaning both forwards and backwards. RESULTS The initial mechanical effects of the stimuli were similar but the reflex responses for the unstable PD group were increased, even after allowing for the increased levels of tonic activation. For TA, unstable PD subjects had significantly larger responses than the stable PD group whose responses were in turn significantly larger than controls. For soleus, unstable PD subjects had significantly greater responses than controls. CONCLUSIONS These findings are consistent with previous evidence that exaggerated postural responses are characteristic of unstable PD subjects. SIGNIFICANCE Increased postural reflexes are characteristic of unstable PD subjects and may contribute to the instability seen for these patients in response to larger perturbations.

中文翻译：

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轴向扰动引起帕金森病伴姿势不稳定的姿势反射增加

目的 测量 11 名稳定和不稳定的帕金森病 (PD) 受试者的轴向诱发姿势反射，并将这些与 13 名年龄匹配的对照进行比较。方法我们测量了胫骨前肌 (TA) 和比目鱼肌上胸骨或 C7 的短暂脉冲位移的短延迟肌电图 (EMG) 反射效应。我们的受试者被研究正常站立和向前和向后倾斜时。结果 刺激的初始机械效应相似，但不稳定 PD 组的反射反应增加，即使在允许强直激活水平增加之后也是如此。对于 TA，不稳定 PD 受试者的反应明显大于稳定 PD 组，后者的反应又明显大于对照组。对于比目鱼，不稳定的 PD 受试者的反应明显高于对照组。结论 这些发现与先前的证据一致，即夸大的姿势反应是不稳定 PD 受试者的特征。意义 姿势反射增加是不稳定 PD 受试者的特征，可能导致这些患者对较大扰动的反应不稳定。