Neuroscience Research Australia, Randwick, 2031, NSW, Australia.
School of Medical Sciences, University of New South Wales, Randwick, 2031, NSW, Australia.
Tremor Other Hyperkinet Mov (N Y). 2023 Jan 3;13:1. doi: 10.5334/tohm.731. eCollection 2023.
Essential tremor (ET) is characterized by abnormal oscillatory muscle activity and cerebellar involvement, factors that can lead to proprioceptive deficits, especially in active tasks. The present study aimed to quantify the severity of proprioceptive deficits in people with ET and estimate how these contribute to functional impairments.
Upper limb sensory, proprioceptive and motor function was assessed inindividuals with ET (n = 20) and healthy individuals (n = 22). To measure proprioceptive ability, participants discriminated the width of grasped objects and the weight of objects liftedwith the wrist extensors. Causal mediation analysis was used to estimate the extentthat impairments in upper limb function in ET was mediated by proprioceptive ability.
Participants with ET had impaired upper limb function in all outcomes, and had greater postural and kinetic tremor. There were no differences between groups in proprioceptive discrimination of width (between-group mean difference [95% CI]: 0.32 mm [-0.23 to 0.87 mm]) or weight (-1.12 g [-7.31 to 5.07 g]). Causal mediation analysis showed the effect of ET on upper limb function was not mediated by proprioceptive ability.
Upper limb function but not proprioception was impaired in ET. The effect of ET on motor function was not mediated by proprioception. These results indicate that the central nervous system of people with ET is able to accommodate mild to moderate tremor in active proprioceptive tasks that rely primarily on afferent signals from muscle spindles.
特发性震颤（ET）的特征是肌肉活动异常和小脑受累，这些因素可导致本体感觉缺失，尤其是在主动任务中。本研究旨在量化 ET 患者本体感觉缺失的严重程度，并估计这些缺失如何导致功能障碍。
评估了 20 名 ET 患者和 22 名健康个体的上肢感觉、本体感觉和运动功能。为了测量本体感觉能力，参与者辨别了抓握物体的宽度和腕伸肌提起物体的重量。因果中介分析用于估计 ET 患者上肢功能障碍在多大程度上受到本体感觉能力的影响。
ET 患者在所有结果中均出现上肢功能障碍，且姿势性和运动性震颤更为严重。两组在宽度（组间平均差异[95%CI]：0.32 毫米[-0.23 至 0.87 毫米]）或重量（-1.12 克[-7.31 至 5.07 克]）的本体感觉辨别方面无差异。因果中介分析表明，ET 对上肢功能的影响不受本体感觉能力的影响。
ET 患者的上肢功能受损，但本体感觉不受影响。ET 对运动功能的影响不受本体感觉的影响。这些结果表明，ET 患者的中枢神经系统能够适应主动本体感觉任务中的轻度至中度震颤，这些任务主要依赖于肌梭传入信号。
