Netz J, Lammers T, Hömberg V
Neurological Therapy Centre, Heinrich-Heine-University Düsseldorf, Germany.
Brain. 1997 Sep;120 ( Pt 9):1579-86. doi: 10.1093/brain/120.9.1579.
Motor evoked responses to focal transcranial magnetic stimulation were investigated over the unaffected hemisphere in 15 patients with hemiparesis after ischaemic stroke and compared with data from normal control subjects. Whereas responses to muscles ipsilateral to the stimulated hemisphere could only be elicited at maximal intensities in two out of 12 normal control subjects, such ipsilateral responses were recorded after stimulation of the unaffected hemisphere in patients with poor recovery after stroke at significantly lower thresholds, but not in patients with good recovery. These responses occurred with a somewhat longer (on average 6 ms) latency than the typical contralateral response. The duration of the silent period ipsilateral to stimulation of the unaffected hemisphere was longer than in control subjects. Also the contralateral threshold for the unaffected hemisphere was elevated in comparison with the control group. In one patient, who developed mirror movements after stroke, the ipsilateral threshold was exceptionally low and the latency of the ipsilateral response identical to that seen contralaterally. It is concluded that the motor outputs in the unaffected hemisphere are significantly changed after stroke, including the unmasking of ipsilateral corticospinal projections. However, these pathways seem to be of little significance for recovery, as the existence of these responses was not correlated with clinical improvement. The unaffected hemisphere after stroke shows plastic changes in motor output organization after a contralateral lesion.
在15例缺血性中风后偏瘫患者的未受影响半球上，研究了对局部经颅磁刺激的运动诱发电位，并与正常对照受试者的数据进行了比较。在12名正常对照受试者中，只有2人在最大刺激强度下才能引出对受刺激半球同侧肌肉的反应，而在中风后恢复较差的患者中，刺激未受影响半球后能在显著更低的阈值下记录到这种同侧反应，但中风后恢复良好的患者则没有。这些反应的潜伏期比典型的对侧反应略长（平均6毫秒）。未受影响半球刺激同侧的静息期持续时间比对照组更长。与对照组相比，未受影响半球的对侧阈值也升高了。在一名中风后出现镜像运动的患者中，同侧阈值异常低，同侧反应的潜伏期与对侧所见相同。结论是，中风后未受影响半球的运动输出发生了显著变化，包括同侧皮质脊髓投射的暴露。然而，这些通路似乎对恢复意义不大，因为这些反应的存在与临床改善无关。中风后的未受影响半球在对侧病变后运动输出组织出现了可塑性变化。
