Odergren T, Iwasaki N, Borg J, Forssberg H
Department of Neurology, Karolinska Hospital, Stockholm, Sweden.
Brain. 1996 Apr;119 ( Pt 2):569-83. doi: 10.1093/brain/119.2.569.
Six subjects with writer's cramp and six healthy control subjects were examined while lifting a small instrumented object with variable weight and friction using the precision grip. The isometric grip and load forces were sampled at 400 Hz and stored in a flexible laboratory computer system for later analysis. Quantitative measurement of vibration and temperature sensibility showed normal sensory perception in the writer's cramp subjects. They exhibited an impaired programming of the grip-lift force co-ordination, while the ability to generate unimodal force-rate trajectories and to characterize the pattern of the force output according to memory representations of weight and friction of the object were intact. The capacity to terminate quickly the programmed grip force in lifts erroneously programmed too high was impaired. Writer's cramp subjects also employed excessive grip force during the static phase of the lift, and some patients had a short grip force latency after sudden unpredicted load increases, indicating a disinhibited spinal reflex response. The results indicate an impaired capacity in writer's cramp subjects to integrate sensory information in the motor programming and force regulation during precision grip tasks, despite a normal sensibility.
六名患有书写痉挛的受试者和六名健康对照受试者在使用精确抓握方式提起一个带有可变重量和摩擦力的小型仪器化物体时接受了检查。等长握力和负载力以400赫兹的频率进行采样，并存储在一个灵活的实验室计算机系统中以供后续分析。对振动和温度敏感性的定量测量显示，书写痉挛受试者的感觉感知正常。他们在抓握-提起力协调的编程方面存在受损，而产生单峰力率轨迹以及根据物体重量和摩擦力的记忆表征来刻画力输出模式的能力是完好的。在错误编程过高的提起动作中快速终止编程握力的能力受损。书写痉挛受试者在提起动作的静态阶段也会使用过大的握力，并且一些患者在突然出现不可预测的负载增加后握力潜伏期较短，这表明脊髓反射反应受到抑制。结果表明，尽管感觉正常，但书写痉挛受试者在精确抓握任务中整合感觉信息以进行运动编程和力调节的能力受损。
