肌肉振動對中風病人手部動作獨立性的影響

Abstract

研究指出給予健康人手部特定肌肉微幅振動，可以增強受振動肌肉運動神經的訊號強度（motor-evoked potential），同時也會抑制相鄰未受振動肌肉的訊號。本實驗室之前研究亦顯示此形式微肌肉振動，亦可改變中風病人患側手部肌肉神經的訊號強度。因此本研究想知道，給予手部特定肌肉振動，造成運動神經訊號的增強或抑制對手指做外展屈曲的獨立活動能力是否會造成影響。五位中風受測者及十位健康受測者參與本研究。使用電磁式振動機給予受測者80Hz、0.1~0.7mm振幅的振動，記錄受測者在（1）未受任何肌肉振動與（2）振動患側（慣用手）或非患側（非慣用手）Abductor pollicis brevis（APB）, first dorsal interossei（FDI）, Abductor digiti minimi（ADM）肌肉，共七種條件下，手指外展屈曲的移動狀況及肌肉活動情形。計算其individuation index（Iind值）及Index of selective activation（ISA值），比較給予肌肉振動及未給予肌肉振動時，手指獨立活動能力的差異。健康受測者雖手指獨立動作控制能力較好，仍看到肌肉振動對動作控制能力較差的無名指有所改善，振動前後進步約2%（p<0.05）。對個別中風病人來說，振動可以使部份手指獨立動作能力提升（進步最多可達20%）或是些微打破肌肉不正常協同作用（abnormal synergy），在給予非患側FDI振動時，可增進患側FDI肌肉的控制能力約66%（p<0.05）。未來或許可針對個別中風病人，給予適合的振動條件，以改善手指控制獨立性，完成日常生活中較具功能性的手指動作。

Previous studies had demonstrated in intact individuals that small-amplitude muscle vibration (MV) could increase the motor pathway excitability of the vibrated hand muscle and inhibit the excitability of motor pathways of neighboring non-vibrated muscles in healthy individuals. Our previous study also found that MV could selectively modulate motor pathway excitability of stroke-affected hand muscles. However, the link between MV-induced neurophysiological changes and voluntary control of finger movements is unclear. Therefore, the purpose of this study is to examine the effect of MV on the independency of finger movements. We hypothesized that MV to three hand intrinsic muscles (Abductor pollicis brevis, APB; first dorsal interossei, FDI; Abductor digiti minimi, ADM) would affect the individual finger movement when performing abduction/adduction movements. We tested five chronic stroke subjects and ten health control subjects (aged 18-26 yrs). The subjects were asked to perform repeated abduction/adduction finger movements with and without individual MV to each of the three hand muscles of both hands. We calculated individuation index (Iind) and Index of selective activation (ISA) values to examine the effect of MV on finger independency and muscle selectivity. For healthy subjects, MV could increase the finger independently of ring finger about 2% of Iind (p<0.05). For stroke subjects, we found that MV to non-affected FDI would increase the ISA of FDI about 66% in the affected hand (p<0.05). Muscle vibration to selected hand muscles would increase the ability to perform more independent finger movements and muscle selectivity. If we could identify the patterns of MV-induced modification of finger movement control in stroke, muscle vibration might be a useful tool for stroke hand rehabilitation.