Anastasopoulos Dimitri, Nasios Gregor, Mergner Thomas, Maurer Christoph
Department of Physiology, School of Nursing, University of Athens, Athens, Greece.
J Neurol. 2003 May;250(5):546-55. doi: 10.1007/s00415-003-1034-z.
Proceeding from recent evidence for a sensory involvement in the pathophysiology of idiopathic spasmodic torticollis (ST), we asked whether the abnormal head posture of these patients is associated with distortions of their internal spatial reference frames due to abnormal processing of neck proprioceptive and/or vestibular input. Twelve ST patients were instructed to estimate, by adjusting a light pointer in the dark, their head and trunk mid-sagittal directions (as representatives of ego-centric references) and to reproduce a remembered target location in space (space centric reference). They did so before and after horizontal head and trunk rotations, which evoked isolated or combined vestibular and/or neck stimulation. In ST patients, unlike in normal controls, pre-stimulus estimates of the head and trunk mid-sagittal directions (baselines) showed a pronounced across-subjects variability, with essentially normal mean values. Their post-stimulus estimates in all tasks, after correction for the individual baseline errors, were normal with respect to both amplitude and variability, independent of stimulus direction, modality and rotation dynamics. Our findings suggest that ST patients have a rather inaccurate knowledge of their head posture, but can effectively use neck proprioceptive input and vestibular cues when estimating head and trunk displacements in ego-centric and space centric spatial orientation tasks. We propose that an offset of a non-sensory set point signal in the neck proprioceptive loop for head-on-trunk control may be responsible for the pathological head deviation in ST.
基于近期有关感觉参与特发性痉挛性斜颈（ST）病理生理学的证据，我们探讨了这些患者的异常头部姿势是否与由于颈部本体感觉和/或前庭输入处理异常导致的内部空间参考框架扭曲有关。12名ST患者被要求在黑暗中通过调整一个光指针来估计他们头部和躯干的矢状中线方向（作为自我中心参考的代表），并在空间中重现一个记住的目标位置（空间中心参考）。他们在水平头部和躯干旋转之前和之后进行了这些操作，这些旋转引发了孤立的或组合的前庭和/或颈部刺激。与正常对照组不同，ST患者在刺激前对头部和躯干矢状中线方向的估计（基线）在个体间显示出明显的变异性，但其平均值基本正常。在对个体基线误差进行校正后，他们在所有任务中的刺激后估计在幅度和变异性方面均正常，与刺激方向、模式和旋转动力学无关。我们的研究结果表明，ST患者对其头部姿势的认知相当不准确，但在以自我为中心和空间中心的空间定向任务中估计头部和躯干位移时，能够有效地利用颈部本体感觉输入和前庭线索。我们提出，颈部本体感觉回路中用于头对躯干控制的非感觉设定点信号的偏移可能是ST中病理性头部偏斜的原因。
