ABNORMAL MUSCLE COACTIVATION PATTERNS DURING ISOMETRIC TORQUE GENERATION AT THE ELBOW AND SHOULDER IN HEMIPARETIC SUBJECTS
ABNORMAL MUSCLE COACTIVATION PATTERNS DURING ISOMETRIC TORQUE GENERATION AT THE ELBOW AND SHOULDER IN HEMIPARETIC SUBJECTS
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DOI：
10.1093/brain/118.2.495
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发表时间：
1995-04-01
期刊：
影响因子：
14.5
通讯作者：
RYMER, WZ
中科院分区：
文献类型：
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作者：
DEWALD, JPA;POPE, PS;RYMER, WZ
为了研究偏瘫中风中肌肉激活的异常空间模式，我们比较了 10 名偏瘫受试者在 1.5 秒自主等长收缩期间的偏瘫和对侧肘部和肩部肌肉的肌电图活动，并与 Jive 和八种不同的负载进行比较。参考与前臂长轴正交的平面，在八个方向上产生等长力，并由安装在手腕上的三自由度测力传感器记录。从每个受试者的受损上肢和对侧上肢记录六块肘部和六块肩部肌肉的表面和肌内肌电图。使用两种测量方法总结各个肌肉肌电图激活的空间特征。第一个称为“净合成肌电矢量”，是一种新的测量方法，用于计算八个方向中每个方向的肌电幅度的矢量和，第二个称为“肌电图焦点指数”，是对每个负载水平记录的肌电激活范围的测量。使用这些措施使我们能够定量描述空间肌电图特征，这是以前从未做过的。我们观察到受损肢体中所产生的肌电图矢量方向一致且具有统计显着性的变化，特别是在肩部和其他近端肌肉中。还发现肌电图活动的角度范围显着增加，并且在肘部最为明显。使用相关分析技术来评估不同肌肉对的共同激活程度。在所有受试者（正常和偏瘫）中观察到一致的肌电图共激活模式。然而，在痉挛麻痹肢体中，还记录了额外的新颖的共激活关系，特别是在肘屈肌/肩外展肌和肘伸肌/肩内收肌之间。这些新颖的共激活模式代表中风受试者的麻痹肢体中可能的肌肉组合数量或可能的“协同作用”数量的减少。 “协同效应”数量的减少可能是由于降序命令选项的丢失造成的；由于对残余脑干下行通路（例如网状脊髓和前庭脊髓投射）的依赖增加；来自脊髓间神经元兴奋性的变化；或来自其中几个因素的组合。讨论了这些假设的相对优点。
To study abnormal spatial patterns of muscle activation in hemiparetic stroke, we compared EMG activity in paretic and contralateral elbow and shoulder muscles of 10 hemiparetic subjects during 1.5-s voluntary isometric contractions, against Jive to eight different loads. Isometric forces were generated in eight directions, referenced to a plane orthogonal to the long axis of the forearm, and were recorded by a three degrees of freedom load cell, mounted at the wrist. Surface and intramuscular EMGs of six elbow and six shoulder muscles were recorded from both impaired and contralateral upper extremities of each subject The spatial characteristics of EMG activation of individual muscles were summarized using two measures. The first called the 'net resultant EMG vector' is a new measure which calculated the vector sum of EMG magnitudes for each of the eight directions, and the second, index of EMG focus, is a measure of the range of EMG activation recorded for each load level. Use of these measures permitted us to describe spatial EMG characteristics quantitatively, which has not been done previously. We observed consistent and statistically significant shifts in the resultant EMG vector directions in the impaired limb, especially in shoulder and other proximal muscles. Significant increases in the angular range of EMG activity were also identified and were most evident at the elbow. Correlation analysis techniques were used to assess the degree of coactivation of different muscle pairs. There were consistent EMG coactivation patterns observed across all subjects (both normal and hemiparetic). However in spastic-paretic limbs, additional novel coactivational relationships were also recorded especially between elbow flexors/shoulder abductors and elbow extensors/shoulder adductors. These novel coactivation patterns represent a reduction in the number of possible muscle combinations, or in the number of possible 'synergies' in the paretic limb of the stroke subject. This reduction in number of 'synergies' could result from a loss of descending command options; from an increased reliance on residual, descending brainstem pathways (such as the reticulospinal and vestibulospinal projections); from changes in spinal interneuronal excitability; or from a combination of several of these factors. The relative merits of these hypotheses are addressed.