Grünewald R A, Yoneda Y, Shipman J M, Sagar H J
Department of Clinical Neurology, University of Sheffield, Royal Hallamshire Hospital, UK.
Brain. 1997 Dec;120 ( Pt 12):2179-85. doi: 10.1093/brain/120.12.2179.
As muscle spindles are involved in the sensation of position and movement of the body, we tested their involvement in the pathophysiology of idiopathic focal dystonia. Twenty patients with torticollis, nine with writer's cramp, two with blepharospasm and 16 healthy control subjects participated. In the first task, the blindfolded subject matched the position of the passively moved forearm with the opposite forearm when the elbow joint was slowly flexed. In a second matching task, passive movement was replaced by stimulation of one biceps tendon with a 50-Hz vibratory stimulus (a selective stimulus for muscle spindle Ia afferents). In normal individuals, this stimulus produces flexion of the vibrated arm around the elbow joint. Movement in both arms was recorded electronically. In experiments without vibratory stimuli, dystonic subjects showed normal movement of the tracking arm during attempts to match the position of the passively moved arm and no difference between the arms in the initial and final steady state positions. In experiments using vibratory stimuli, vibration of biceps tendons in normal subjects elicited flexion of the stimulated arm at the elbow and a matching movement of the opposite arm. In patients with dystonia, there was a similar flexion response to the vibratory stimulus in the stimulated arm but movement of the tracking arm was reduced. Taken together, these experiments suggest that there is abnormal perception of motion, but not position, in dystonic subjects. Dystonic subjects showed bilateral abnormalities of perception of the tonic vibration reflex which were remote from the clinically affected site. These findings are discussed in relationship to the role of muscle spindle Ia afferents in focal dystonia.
由于肌梭参与身体位置和运动的感知，我们测试了它们在特发性局灶性肌张力障碍病理生理学中的作用。20名斜颈患者、9名书写痉挛患者、2名眼睑痉挛患者和16名健康对照者参与了研究。在第一个任务中，蒙眼受试者在肘关节缓慢屈曲时，将被动移动的前臂位置与对侧前臂相匹配。在第二个匹配任务中，用50赫兹的振动刺激（一种对肌梭Ia传入纤维的选择性刺激）刺激一侧肱二头肌肌腱，以取代被动运动。在正常个体中，这种刺激会使受振动的手臂围绕肘关节屈曲。双臂的运动通过电子方式记录。在没有振动刺激的实验中，肌张力障碍受试者在试图匹配被动移动手臂的位置时，追踪手臂的运动正常，且双臂在初始和最终稳态位置上没有差异。在使用振动刺激的实验中，正常受试者肱二头肌肌腱的振动会引起受刺激手臂在肘部屈曲以及对侧手臂的匹配运动。在肌张力障碍患者中，受刺激手臂对振动刺激有类似的屈曲反应，但追踪手臂的运动减少。综上所述，这些实验表明，肌张力障碍受试者存在运动感知异常，但位置感知正常。肌张力障碍受试者表现出双侧对紧张性振动反射的感知异常，且这些异常远离临床受累部位。本文结合肌梭Ia传入纤维在局灶性肌张力障碍中的作用对这些发现进行了讨论。
