Hauptmann B, Hummelsheim H
Klinik Berlin, Department of Neurological Rehabilitation, Free University of Berlin, Germany.
Electroencephalogr Clin Neurophysiol. 1996 Oct;101(5):387-94.
The influence of ongoing voluntary isometric contractions (ranging from 2.5% to 100% of maximum force production) on motor evoked potentials in the extensor carpi radialis muscle was investigated in 20 healthy subjects and 25 hemiparetic stroke patients using transcranial magnetic stimulation at threshold and at 90% of maximum stimulus intensity. In healthy subjects and in stroke patients, an initial sharp decay in response latencies was observed at low contraction levels. In hemiparetic patients, however, no significant further reduction of response latencies with increasing contraction levels was observed irrespective of whether threshold or 90% stimulus intensities were applied. The continuous decrease in latency in the healthy subjects is supposed to result from an enhanced involvement of rapidly conducting corticospinal neurones that are preferentially damaged in the patient group. In healthy subjects and in hemiparetic patients, however, the increase in response amplitudes runs in parallel with increasing force production, at least with threshold stimulus intensity. Contrary to response latencies, amplitude facilitation appears to be less dependent on the involved corticospinal fibre spectrum but to be predominantly based on temporal and spatial summation effects. The relevance of the latency and amplitude data obtained in healthy subjects and in stroke patients for physiology and localization of facilitatory processes, i.e. whether cortical or spinal, is discussed. For the rehabilitation of stroke patients it is concluded that the effect of slight voluntary contractions is indeed superior to most other facilitatory approaches. The functional relevance is discussed.
在20名健康受试者和25名偏瘫性中风患者中，使用阈刺激和最大刺激强度90%的经颅磁刺激，研究了持续的自愿性等长收缩（范围从最大力量产生的2.5%到100%）对桡侧腕伸肌运动诱发电位的影响。在健康受试者和中风患者中，在低收缩水平时观察到反应潜伏期最初急剧下降。然而，在偏瘫患者中，无论应用阈刺激强度还是90%刺激强度，随着收缩水平增加，均未观察到反应潜伏期进一步显著缩短。健康受试者中潜伏期的持续下降被认为是由于快速传导的皮质脊髓神经元参与增加所致，而这些神经元在患者组中优先受损。然而，在健康受试者和偏瘫患者中，反应幅度的增加与力量产生的增加平行，至少在阈刺激强度时如此。与反应潜伏期相反，幅度易化似乎较少依赖于所涉及的皮质脊髓纤维谱，而主要基于时间和空间总和效应。讨论了在健康受试者和中风患者中获得的潜伏期和幅度数据对于易化过程的生理学和定位（即皮质或脊髓）的相关性。对于中风患者的康复，得出的结论是轻微的自愿收缩的效果确实优于大多数其他易化方法。讨论了其功能相关性。
