Mai N, Bolsinger P, Avarello M, Diener H C, Dichgans J
Max Planck Institute for Psychiatry, München, FRG.
Brain. 1988 Oct;111 ( Pt 5):973-98. doi: 10.1093/brain/111.5.973.
Control of isometric forces during grasping or handling of objects is an essential feature of all skilled manual performances. Previous studies of hand function in cerebellar patients were restricted to movements; force control was only investigated under isotonic conditions in combination with movements. Control of isometric forces during voluntary contraction of finger muscles was investigated in 31 patients with chronic cerebellar disease and in 20 normal controls. Eight patients with Friedreich's ataxia were considered to be typical for a disease affecting the afferents to the cerebellum; 4 patients with anterior lobe atrophy, which affects leg movements to a greater extent than finger movements, were compared with 3 patients with hemisphere lesions; 16 patients suffered from diffuse cerebellar atrophy. Using a recently developed microcomputer system for the continuous measurement of finger force, control of isometric force was studied in several tasks within the same subjects. The tasks included the maintenance of constant force output at different force levels with and without visual feedback, fast repetitive force changes, tracking of a sinusoidal target presented visually, and measurement of maximum grip force. The amount of voluntary contraction in terms of muscular power was normal in all patients; in all other tasks clear deficits were observed. The extent of the disturbances was highly variable between patients even within the same clinical subgroup. The detailed analysis of force traces revealed a great variety in types of disturbance. The frequently observed slowing of the speed in repetitive force changes can be attributed to different components in different patients and not only to difficulties at turning points as might be predicted from comparable movement studies. In addition, performance deficits across different tasks were not uniform, indicating dissociation of impairment. Deficits in maintaining force, which may be interpreted as dysmetria or due to tremor, do not necessarily imply an abnormality in diadochokinesis, as measured in fast repetitive force changes, nor does the converse apply.
在抓握或操作物体过程中对等长力的控制是所有熟练手部动作的一个基本特征。以往对小脑病变患者手部功能的研究仅限于运动方面；力的控制仅在等张条件下结合运动进行了研究。本研究对31例慢性小脑疾病患者和20名正常对照者在手指肌肉自主收缩时的等长力控制进行了研究。8例弗里德赖希共济失调患者被认为是影响小脑传入神经的典型疾病；将4例主要影响腿部运动而非手指运动的前叶萎缩患者与3例半球病变患者进行了比较；16例患者患有弥漫性小脑萎缩。使用最近开发的用于连续测量手指力的微机系统，在同一受试者内的多个任务中对等长力控制进行了研究。这些任务包括在有和没有视觉反馈的情况下在不同力水平维持恒定力输出、快速重复力变化、跟踪视觉呈现的正弦目标以及测量最大握力。所有患者在肌肉力量方面的自主收缩量均正常；在所有其他任务中均观察到明显缺陷。即使在同一临床亚组内，患者之间干扰的程度也有很大差异。对力轨迹的详细分析揭示了干扰类型的多样性。在重复力变化中经常观察到的速度减慢可归因于不同患者的不同因素，而不仅仅是如可比运动研究中可能预测的转折点处的困难。此外，不同任务中的表现缺陷并不一致，表明存在功能障碍的分离。维持力方面的缺陷，可能被解释为辨距不良或由于震颤，并不一定意味着在快速重复力变化中测量的轮替运动异常，反之亦然。
