作業優先性與姿勢困難度對早期與中期巴金森氏症 患者雙重作業控制的影響

Abstract

研究背景與目的：姿勢-上姿勢作業為雙重作業情境中一種狀況，由於注意力資源的有限性，適當的注意力配置(亦即作業優先)性，為獲得較佳姿勢-上姿勢作業表現的重要因素。因巴金森症患者之大腦注意力資源下降及其於作業間注意力轉換較為困難，更加突顯作業優先性選擇的重要性。且姿勢作業的困難度與患者本身的平衡能力也是影響作業優先策略的重要關鍵。然而，目前關於不同平衡能力之巴金森症患者於不同站姿難度下，作業優先性(姿勢優先、上姿勢優先)對姿勢-上姿勢作業的表現影響及其相對應知神經生理機制仍尚未被探討。因此本研究將探討不同平衡能力之巴金森症族群(修正式侯-葉氏分期：1-2期與2.5-3期)，在不同姿勢難度下，使用姿勢優先策略或上姿勢優先策略對姿勢-上姿勢作業表現及神經活動的影響。研究方法：本研究共招募16位健康成年人受試者、17位早期巴金森症患者(修正式侯-葉氏分期：1-2期)及15位中期巴金森症患者(修正式侯-葉氏分期：2.5-3期)進行雙重作業站姿測試。受試者須於雙腳併攏(簡單姿勢)及前後站立(困難姿勢)的姿勢下，雙手持兩鐵環，使之不相碰撞(上姿勢作業)，並分別將主要注意力放置於維持姿勢平衡(姿勢優先)或維持鐵環不碰撞(上姿勢優先)。實驗過程紀錄姿勢作業及上姿勢作業表現、踝關節肌肉之肌電圖訊號及腦電圖訊號。本研究分析參數包含：姿勢作業身體晃動震幅與確定率(determinism)、鐵環總觸碰時間、踝關節肌肉同時活化數值、腦電圖(delta、theta、alpha)頻譜功率(relative power)及腦電圖(theta)同調性(coherence)。統計分析分別於雙腳併攏與前後站立姿勢情境下，使用3 × 3混合變異數分析(mixed ANOVA)及最小顯著差異法(least significant difference)進行事後檢定，探討作業優先性與不同組別對各行為表現參數、踝關節肌電圖及腦電圖的影響。結果與討論：本實驗為主要探討作業優先策略對於三組之影響。於簡單姿勢作業下，三組受試者均無發現有作業優先性之影響。於困難姿勢作業下可發現，相較於姿勢優先策略，使用上姿勢優先策略時，早期巴金森症患者有較低之鐵環總觸碰時間及前後向姿勢控制確定率，代表上姿勢優先策略可提升姿勢控制調整性；而上姿勢優先策略也會使中期巴金森症患者有較低之鐵環總觸碰時間，但卻有較高之踝關節同時活化數值，代表此時的踝關節較僵硬。在腦電圖結果上，則發現於困難姿勢作業下，使用上姿勢優先策略時早期巴金森症患者於額葉區有較高的theta同調性，反映早期巴金森患者在姿勢控制資源上運用較佳。結論與臨床應用：此結果反應早期巴金森症患者於雙重作業站立情境下以使用上姿勢優先策略較佳，但中期巴金森患者則利用增加踝關節僵硬度來維持身體穩定，因增加關節僵硬度可能有較高的跌倒風險，因此臨床上須再依中期巴金森患者平衡能力，決定最適當的作業優先策略。

Background and Purpose: Postural-suprapostural task is one kind of dual-task conditions with keeping balance and performing another task concurrently. Due to limited attentional, appropriate task prioritization (posture-focus or supraposture-focus) is required for better dual-task performance, especially in patients with Parkinson’s Disease (PD), who may have limited attentional resource or difficulty in resource switching between the two tasks. However, there is no study investigating task prioritization effects under dual-task standing paradigm for PD. Also, postural difficulty and individual’s balance ability are needed to concerned when choosing appropriate task prioritization strategy. The purpose of this study is to investigate the effects of task-priority strategies on postural-suprapoatural performance and its related neurophysiological activity in PD with different balance ability (modified H&Y stages: 1-2 vs. 2.5-3) under low and high posture challenging. Methods: Sixteen healthy adults, seventeen early-stage PD (modified H&Y: 1-2) and fifteen mid-stage PD (modified H&Y: 2.5-3) were recruited in this study. Each participant were asked to control two interlocking rings (suprapostural task) and maintain their balance in narrow stance (low challenging) and tandem stance (high challenging) with postural task or suprapostural task as the first-priority task. Both behavioral data (postural sway, total touching time of two interlocking rings), ankle muscle activity by electromyography (EMG) and cortical activity by electroencephalogram (EEG), were recorded. The outcome measures including postural sway amplitude and determinism (DET) in anterior-posterior (AP) and medial-lateral (ML) directions, total touching time of the two rings, co-activation index of ankle muscles, relative power of EEG (delta, theta, and alpha), and coherence of EEG (theta). Results: The task-priority effect on dual-task performance was only observed in the more challenging posture, but not in less challenging posture. Early-stage PD had smaller DET in the AP direction and total touching time with supraposture-focus (SF) strategy, and mid-stage PD also had less total touching time but had higher co-activation index in the ML direction. Early-stage PD also had higher theta coherence value around frontal area in more challenging posture. This results showed that early-stage PD had better control of the postural attention resources. Conclusion and Clinical Application: The SF strategy is the adequate strategy for the early-stage PD with enhancing postural flexibility and suprapostural performance. However, although the SF strategy also led to better suprapostural performance for the middle-stage PD, the increased ankle joint stiffness might increase falling probability during dual-task conditions. When choosing the appropriate task-priority strategy for mid-stage PD in clinic, we should further consider the dual-task situation for providing safe movement strategy.