振動誘發之中風手部肌肉的內皮質神經迴路可激度改變

Abstract

過去研究指出，給予手指特定肌肉微幅振動刺激，會改變健康受測者大腦運動皮質可激度（Corticomotor Excitability）：其強化受振動手部肌肉的訊號同時抑制同手相鄰肌肉的運動神經訊號。長期中風病患因為手部肌肉不正常的協同作用（Abnormal Synergy），造成手指獨立動作能力下降，對此本研究欲了解，給予中風受測者患側與健側手部特定肌肉振動，對於大腦運動皮質可激度是否會產生影響，試圖以用來提升個別手指動作控制能力。三位平均中風達六個月以上的中風受測者參與本研究。我們使用電磁式振動機給予受測者特定肌肉振動（80Hz、振幅0.2~0.5mm），並透過經顱磁刺激器（Transcranial Magnetic Stimulation, TMS）分別給予大腦單一（Single-pulse）和成對（Paired-pulse）磁刺激，紀錄受測者在無振動和個別振動兩側手部三條肌肉（Abductor Pollicis Brevis, APB、First Dorsal Interossei, FDI、Abductor Minimi Digiti muscle, ADM）之運動誘發電位（Motor-evoked Potentials, MEPs），藉此來比較振動對大腦運動皮質之可激度、內皮質的短潛期抑制（Inhibition）和興奮（Facilitation）迴路是否有影響。結果發現若給予中風病人患側手部肌肉FDI肌肉振動時，患側三條手部肌肉的皮質脊髓徑MEPs彼此間有顯著差異，尤其與未振動時相比，患側手部肌肉FDI的MEPs顯著提升25%（p<0.05）。未來或許可針對個別中風病人，給予適當振動條件，並釐清振動誘發大腦神經迴路可激度改變與手指獨立性控制間的關係。此肌肉振動誘發MEP改變的方法或許可利用於中風復健上。

Previous studies have demonstrated that a small-amplitude muscle vibration could facilitate motor-evoked potentials (MEPs) of the vibrated muscle and inhibit the MEPs of non-vibrated adjacent muscles in intact individuals. However, the vibration-induced corticospinal modulations in individuals following stroke are unclear. Therefore, the purpose of this study was to investigate that whether individual muscle vibrations to unaffected or affected hand muscles would influence the excitability of affected motor pathways post stroke. Three individuals who experienced single stroke (aged 48±4.9yrs; >6 months post stroke) participated in the study. Muscle vibration (MV, 80Hz, 0.2~0.5mm peak-to-peak amplitude) was applied to the hand muscle by an electromagnetic vibrator. During MV, MEPs of three affected-hand muscles (abductor pollicis brevis, APB、first dorsal interossei, FDI、abductor minimi digiti muscle, ADM), and intracortical inhibition/facilitation were quantified by single and paired pulse TMS. The results showed that MV to the affected FDI induced different effects on the MEPs of the three affected-muscles (APB, FDI and ADM) (p<0.05). Especially, during MV to the affected FDI, the MEPs in the affected-FDI, compared to the no MV, were significantly facilitated (MEP increased by 25%, p<0.05). If we could further identify the relationship between MV-induced changes in the corticospinal excitability and the voluntary control of independent finger movements in stroke, muscle vibration might be a useful tool for stroke rehabilitation.