脑卒中恢复期患者小腿肌肉功能的速度编码相位对比磁共振观察

目的 探讨恢复期脑卒中患者小腿前后肌群在体动力学变化的特点,为偏瘫患者肌肉功能在体评估提供新方法.方法 2008年5月至2009年5月在中山大学附属第三医院、广州军区陆军总院、广州医学院附属第二医院康复科就诊的脑卒中患者中,选取26例恢复期偏瘫患者,另招募21名年龄和性别与之相匹配的正常对照者.受试者平卧于磁共振仓内,进行周期性踝关节主动屈伸运动.采集患者双侧小腿及正常对照左侧小腿胫骨前肌(TA)、腓肠肌内侧头(MG)和比目鱼肌(SOL)的速度编码相位对比磁共振图像(VE-PC MRI).测量上述小腿肌肉的收缩速度,采用Berg平衡量表(BBS)评估患者平衡功能并进行相关性分析.结果 周期性踝关节主动屈伸运动时,患者患侧与正常对照比较,TA(1-8时相,8.900～21.120 mm/s比12.99～34.50 mm/s)、MG(12-19时相,13.60～13.28 mm/s比25.85～18.38 mm/s)及SOL(12-16时相,18.63～33.62 mm/s比27.68～47.22 mm/s)作为主动肌的收缩速度均明显下降(P＜0.05);踝背伸时,患侧与正常对照比较,SOL/TA(2-9时相,0.81～0.82比0.27～0.44)、MG/TA(2-9时相,0.73～0.58比0.10～0.11)共同收缩水平均明显大于正常对照.患者BBS评分与患侧小腿TA平均收缩速度(r=-0.69,P=0.001)及MG平均收缩速度(r=-0.47,P=0.01)成负相关,与健侧小腿TA平均收缩速度(r=-0.60,P=0.001)及MG平均收缩速度(r=-0.49,P=0.01)成负相关.结论 踝关节进行周期性屈伸运动时,脑卒中患侧TA、MG及SOL作为主动肌收缩功能下降,患侧踝关节背伸共同收缩水平增高,进而导致患者平衡功能下降.VE-PC MRI技术可以反映卒中后小腿肌群的功能变化,为肌肉功能在体评估提供新方法.

Abstract：

Objective To compare the difference of muscle dynamic characteristics for the ankle dorsiflexors and plantarflexors between stroke patients at the chronic stage and healthy controls so as to provide a new method of assessing thein vivo muscle function in patients with hemiplegia. Methods From May 2008 to May 2009, 26 stroke patients and 21 age-and gender-matched normal controls were recruited. All subjects were positioned on a scanner table and requested to perform the voluntary movement of ankle flexion-extension. The velocity encoded phase contrast magnetic resonance imaging (VE-PC MRI )provided the images of tibialis anterior muscle ( TA), medial head of gastrocnemius muscle (MG) and soleus muscle (SOL) during a movement cycle. By measuring the calf muscle contraction velocity, the balance function was assessed by Berg balance scale(BBS). The correlation between scores of BBS and the mean maximum velocity were compared and analyzed. Results The peak velocity of TA( 1-8 phase,8. 900-21. 120 mm/s vs 12.99-34.50 mm/s), MG(12-19phase,13.60-13. 28 mm/s vs 25.85-18.38 mm/s)and SOL(12-16 phase,18. 63-33. 62 mm/s vs 27.68-47.22 mm/s) was lower in the affected side than that in the controls during ankle extension(P ＜0. 05 ); During ankle dorsiflexion, the co-contraction index of SOL/TA(2-9 phase,0. 81-0. 82 vs 0. 27-0. 44)and the co-contraction index of GM/TA(2-9 phase,0. 73-0. 58 vs 0. 10-0. 11 ) was markedly higher in the affected side than the controls. The patient score of BBS was negatively correlated with the mean velocity of TA ( r = - 0. 69, P = 0. 001 ) and GM ( r = - 0. 47, P =0. 01 ) in the affected side. There was correlation between TA ( r = - 0. 60, P = 0. 001 ) and GM ( r =-0. 49 ,P =0. 01 )in the unaffected side. Conclusion During the movement of active ankle flexionextension, the velocities of TA, SOL and MG are lower in the affected side. The co-contraction index is markedly higher in the affected side during ankle dorsiflexion. This in turn leads to a decline of balance function in patients. VE-PC MRI can provide quantitative in vivo measurements of lower extremity muscle function in stroke patients.

Study of lower extremity muscle function in stroke patients by velocity-encoded phase-contrast magnetic resonance imaging

Objective To compare the difference of muscle dynamic characteristics for the ankle dorsiflexors and plantarflexors between stroke patients at the chronic stage and healthy controls so as to provide a new method of assessing thein vivo muscle function in patients with hemiplegia. Methods From May 2008 to May 2009, 26 stroke patients and 21 age-and gender-matched normal controls were recruited. All subjects were positioned on a scanner table and requested to perform the voluntary movement of ankle flexion-extension. The velocity encoded phase contrast magnetic resonance imaging (VE-PC MRI )provided the images of tibialis anterior muscle ( TA), medial head of gastrocnemius muscle (MG) and soleus muscle (SOL) during a movement cycle. By measuring the calf muscle contraction velocity, the balance function was assessed by Berg balance scale(BBS). The correlation between scores of BBS and the mean maximum velocity were compared and analyzed. Results The peak velocity of TA( 1-8 phase,8. 900-21. 120 mm/s vs 12.99-34.50 mm/s), MG(12-19phase,13.60-13. 28 mm/s vs 25.85-18.38 mm/s)and SOL(12-16 phase,18. 63-33. 62 mm/s vs 27.68-47.22 mm/s) was lower in the affected side than that in the controls during ankle extension(P ＜0. 05 ); During ankle dorsiflexion, the co-contraction index of SOL/TA(2-9 phase,0. 81-0. 82 vs 0. 27-0. 44)and the co-contraction index of GM/TA(2-9 phase,0. 73-0. 58 vs 0. 10-0. 11 ) was markedly higher in the affected side than the controls. The patient score of BBS was negatively correlated with the mean velocity of TA ( r = - 0. 69, P = 0. 001 ) and GM ( r = - 0. 47, P =0. 01 ) in the affected side. There was correlation between TA ( r = - 0. 60, P = 0. 001 ) and GM ( r =-0. 49 ,P =0. 01 )in the unaffected side. Conclusion During the movement of active ankle flexionextension, the velocities of TA, SOL and MG are lower in the affected side. The co-contraction index is markedly higher in the affected side during ankle dorsiflexion. This in turn leads to a decline of balance function in patients. VE-PC MRI can provide quantitative in vivo measurements of lower extremity muscle function in stroke patients.