脊髓損傷患者執行雙項任務對上肢-軀幹協調性動作動態穩定度之影響

Abstract

目的：本研究目的在於比較健康人與脊髓損傷患者在同時執行上肢-軀幹協調性動作與聽算數減法時，其注意力需求對動態姿勢穩定之影響。 方法：本研究共徵召12位健康受試者(平均年齡37歲)與12位胸髓第7到12節完全損傷患者(T7-T12，平均年齡36.3歲)接受雙項任務測試。主要任務是在坐姿的情境下藉由移動軀幹來帶動上肢畫圈動作的上肢-軀幹協調性動作，次要任務是藉由聽到數字而快速回答減1答案的聽算數減法任務。受試者在單項上肢-軀幹協調穩定任務情境下，執行2回試驗，每回試驗上肢連續重複劃10圈。於單項聽算數減法任務情境下，每回受試者於靜態坐姿下回答所聽隨機出現6次雙位數字（10∼99）減1的答案。於雙項任務情境下，受試者在執行上肢-軀幹協調穩定任務同時隨機接受聽算數減法任務 (10圈隨機出現6次)共2回 (即上肢共劃20圈，其中有12次為雙項任務)。動態姿勢穩定表現是評估以身體壓心(COP)的動力學、上肢-軀幹協調性運動學與神經肌肉反應等變數。注意力需求則以對聽算數減法任務的口語反應時間為指標，在任務(單項對雙項)與組別(健康組對脊髓損傷組)雙變異數與Bonferroni adjustment分析，區別任務與組別效應。 結果：在單項主要任務(上肢-軀幹協調性動作)的表現比較上發現：(1)脊髓損傷組的身體壓心左右最大位移，身體壓心軌跡長度與其橢圓面積都明顯比健康組來的小(p<0.01)。(2)脊髓損傷組在執行軀幹-上肢協調動作時，比健康組使用較大的肩膀內收/外展的角度(p<0.001)，但軀幹前彎/後仰與骨盆前傾/後傾角度比健康組明顯較小(p<0.05)；且軀幹前彎/後仰與轉動的角速度都比健康組快(p<0.05)。(3)脊髓損傷組產生XY平面的圓筒尖端誤差與總誤差都比健康組多((p<0.05)。(4)當身體前彎時，脊髓損傷組的右側T6背直肌、腹斜肌與肩三角肌後段的肌肉活動於雙項任務與單項主要任務的情境下都比健康組大(p<0.025)；當身體後仰時，脊髓損傷組的左側T6背直肌、右腹斜肌與胸大肌的肌肉活動於雙項任務與單項主要任務的情境下都比健康組大(p<0.05)。在單項次要任務(聽算數減法)的表現比較上發現脊髓損傷組的口語反應時間顯著較健康組長(p<0.001)。在執行雙項任務情境時，兩組受試者於雙項任務情境下之口語反應時間顯著較單項任務情境時長(p<0.001)，且脊髓損傷組的口語反應時間都顯著較健康組長且差距大(p<0.001)。在雙項任務的表現上如下: (1)兩組的動作時間都顯著比單項任務情境時長(p<0.001)。(2)脊髓損傷組之身體壓心前後的最大變化量、軌跡長度與身體壓心橢圓面積都顯著比單項任務情境下增加(p<0.05)；但身體壓心軌跡長度與橢圓面積都小於健康組(p<0.005)。(3)兩組之XY平面與Z平面的圓筒尖端誤差、總誤差與軌跡長度都比單項任務情境下增加(p<0.05)且脊髓損傷組XY平面的圓筒尖端誤差與總誤差都比健康組大(p<0.05)。(4)脊髓損傷組的肩膀內收/外展、彎屈/伸直，及軀幹前彎/後仰、轉動與骨盆前傾/後傾的角度變化比單項主要任務表現較大(p<0.001)；但在健康組的肩膀內收/外展與彎曲/伸直角度變化(p<0.01)比單項主要任務表現較大。脊髓損傷組於雙項任務的情境下肩膀內收/外展的角度變化顯著比健康組大(p<0.001)；但在軀幹前彎/後仰、骨盆前傾、後傾與轉動的角度變化量在兩種情境下都比健康組小(p<0.012)。(5)當身體前彎時，脊髓損傷組的右側T6背直肌、腹斜肌與肩三角肌後段的肌肉活動比健康組大(p<0.025)；當身體後仰時，脊髓損傷組的右側與左側T6背直肌、右腹斜肌與胸大肌的肌肉活動都比健康組大(p<0.043)。無論身體前彎或後仰，脊髓損傷組的右側與左側T6背直肌、左腹斜肌、肩三角肌後段與胸大肌明顯比單項任務情境下增加(p<0.05)；相對的健康組只有肩三角肌後段與胸大肌明顯比單項任務情境下增加。 結論：脊髓完全損傷患者在執行雙項任務時上肢-軀幹協調性任務之動態姿勢穩定比同年齡之健康受試者需要較多的注意力需求。本研究顯示兩組在同時執行雙項任務時，超出中樞訊息處理容量，健康人的注意力多著重維持動態坐姿穩定而使得次要任務的表現變差，也發現所執行主要任務的動作時間較長，所以健康人動態坐姿平衡仍需依賴認知。但脊髓損傷患者在同時執行雙項任務時，不僅次要任務的表現變差，連主要任務的表現也變差，因此脊髓損傷患者在執行雙項任務時之動態姿勢穩定度所需的注意力比健康人高。本研究結果提供臨床物理治療師有關注意力與動態坐姿平衡的評估與訓練之參考。臨床上可以藉由雙項任務測試來分析健康人或脊髓完全損傷患者維持動態姿勢穩定時注意力需求度之不同，並了解注意力對姿勢控制的影響。

Objective: The purpose of this study was to examine the effects of attentional demands on dynamic postural stability between subject with spinal cord injured and age-matched healthy adults during arm-trunk coordinated movement combined with arithmetic subtraction task. Method: Twelve age-matched healthy adults (mean age= 37 years) and 12 subjects with complete T7-T12 thoracic cord injury (mean age= 36.3 years) were recruited. They received dual task paradigm test at seated position. The primary task was an arm-trunk coordinated movement by using the body and shoulder to performed repetitive arm circular drawing movement on sitting position. The secondary task was an auditory arithmetic subtraction task by listening two-digit number and answering minus one quickly. In the single, primary task condition, subjects performed 2 sets of arm-trunk coordinated stability task with totally 10 repetitive circles/set. In the single, secondary task condition, subjects performed 2 sets of auditory arithmetic subtraction task, and two-digit number (10~99) appeared randomly in 6 trials per set during quiet sitting. In the dual task condition, subjects performed 2 sets arm-trunk coordinated stability task combined with arithmetic subtraction task randomly. (i.e., totally 20 circles with 12 dual trials). The performance of dynamic postural stability was reflected by kinetics of center of pressure (COP), kinematics of arm-trunk coordinated movement, and neuromuscular electromyographic (EMG) responses. The attentional demand was reflected by verbal reaction time (VRT). A two-way repeated measure ANOVA and Bonferroni adjustment were performed to determine the group effect and task effect for each variable. Results: In the performance of single, primary arm-trunk coordinated task, the main findings included: (1) the COP maximal M-L displacement, the COP path and COP elliptical area were smaller (p<0.01) in the SCI group than the healthy group, (2) the shoulder adduction/abduction angle of the SCI group was bigger than the healthy group (p<0.001), but trunk flexion/extension angle, pelvic anterior/posterior tilt angle and rotation angle of SCI group were smaller than healthy group (p<0.05), (3) the SCI group increased significantly (p<0.016) their cylinder tip error of x-y-component and total cylinder tip error, compared with the healthy group, (4) the NARMS right erector spinae (RT6PS), right abdominal oblique (ROA) and posterior deltoid (PD) were larger (p<0.025) in SCI group than the healthy group when trunk flexion. The NARMS of left erector spinae (LT6PS), right abdominal oblique (ROA) and pectoralis major (PEC) were larger (p<0.05) in SCI group than the healthy group conditions when trunk extension. In the performance of single, secondary auditory arithmetic subtraction task, it was found that VRT was significantly longer than the healthy group (p<0.001). In the dual task condition, the VRTs of the both groups were significantly longer than single task, and the VRT of the SCI group was longer than the healthy group. In the performance of arm-trunk coordinated dual task, the main findings were as follows. (1) The movement time (MT) of each cycle was significantly longer (p<0.001) in both groups comparison with the single task condition. (2) The COP maximal A-P displacement, the COP path and COP elliptical area increased significantly (p<0.05) in the SCI group compared with a single task performance, but smaller than the healthy groups (p<0.005). (3) Both the groups displayed an arm circular drawing trajectory with a significantly larger total cylinder tip error, cylinder tip error of x-y-dimension and z- dimension (p<0.05) than single task condition. The SCI group increased significantly (p<0.05) their cylinder tip error of x-y-component and total cylinder tip error, compared with the healthy group. (4) The SCI group displayed an arm-trunk movement with a significantly larger shoulder adduction/abduction angle, shoulder flexion/extension angle, trunk flexion/extension, rotation and pelvic anterior/posterior tilt (p<0.001) than single task condition, but the healthy group displayed significantly larger shoulder adduction/abduction and flexion/extension angles (p<0.01) than single task condition. (5) The NARMS of RT6PS, ROA and PD were larger (p<0.025) in SCI group than the healthy group when trunk flexion. The NARMS of RT6PS, LT6PS, ROA and PEC were larger (p<0.05) in SCI group than the healthy group during trunk extension. The NARMS of RT6PS, LT6PS, left abdominal oblique (LOA), PEC, and PD in SCI group (p<0.05) were increased more than single task condition whenever trunk in flexion or extension. In contrast, The NARMS of PEC, and PD were increased more than single task condition whenever trunk in flexion or extension. Conclusions: The attentional demand for dynamic postural stability during arm-trunk coordinated circular movement in subjects with SCI was more than that in age-matched healthy adults during performing dual task. This study indicated that both groups would exceed the central processing capacity during performing dual task. The attention of healthy subjects focused more in maintaining dynamic sitting stability which made a less efficient performance in secondary task, and also needed longer movement time in performing primary task, so dynamic sitting stability of healthy subjects depended on attentional demand. When SCI subjects performed dual task, not only the performance of secondary task became less efficient, their performance in primary task also became less efficient. Therefore, SCI subjects needed more attentional demand than healthy subjects in maintaining dynamic sitting stability during dual task. This study provided clinical physical therapists in assessment and training with deficits in attention and dynamic sitting stability. In clinical practice, we could assess the attentional demand in maintaining dynamic sitting stability by dual task test, and understood the effect of attention on postural control.