The objective of this study was to explore motor impairment of the index finge r following stroke. More specifically, the kinetics and kinematics of the index finger were analysed throughout its workspace. Twenty-four...The objective of this study was to explore motor impairment of the index finge r following stroke. More specifically, the kinetics and kinematics of the index finger were analysed throughout its workspace. Twenty-four stroke survivors wit h chronic hemiparesis of the hand participated in the trials, along with six age -matched controls. Hand impairment was classified according to the clinical Che doke-McMaster Stage of Hand scale. Subjects were instructed to generate fingert ip force in six orthogonal directions at five different positions within the wor kspace. Split-plot analysis of variance revealed that clinical impairment level had a significant effect on measured force (P < 0.001), with the weakness in st roke survivors being directionally dependent (P < 0.01). Electromyographic recor dings revealed altered muscle activation patterns in the more impaired subjects. Unlike the control subjects, these subjects exhibited peak muscle excitation of flexor digitorum superficialis, extensor digitorum communis and first dorsal in terosseous during the generation of fingertip fexion forces. Subjects also attem pted to reach locations scattered throughout the theoretical work-space of the index finger. Quantification of the active kinematic workspace demonstrated a re lationship between impairment level and the percentage of the theoretical worksp ace that could be attained (P < 0.001). The stroke survivors exhibited a high co rrelation between mean force production and active workspace (R=0.90). Thus, our data suggest that altered muscle activation patterns contribute to directionall y dependent weakness following stroke. Both the modulation of muscle excitation with force direction and the independence of muscle activation seem to be reduce d. These alterations translate into a significantly reduced active range of moti on for the fingers.展开更多
文摘The objective of this study was to explore motor impairment of the index finge r following stroke. More specifically, the kinetics and kinematics of the index finger were analysed throughout its workspace. Twenty-four stroke survivors wit h chronic hemiparesis of the hand participated in the trials, along with six age -matched controls. Hand impairment was classified according to the clinical Che doke-McMaster Stage of Hand scale. Subjects were instructed to generate fingert ip force in six orthogonal directions at five different positions within the wor kspace. Split-plot analysis of variance revealed that clinical impairment level had a significant effect on measured force (P < 0.001), with the weakness in st roke survivors being directionally dependent (P < 0.01). Electromyographic recor dings revealed altered muscle activation patterns in the more impaired subjects. Unlike the control subjects, these subjects exhibited peak muscle excitation of flexor digitorum superficialis, extensor digitorum communis and first dorsal in terosseous during the generation of fingertip fexion forces. Subjects also attem pted to reach locations scattered throughout the theoretical work-space of the index finger. Quantification of the active kinematic workspace demonstrated a re lationship between impairment level and the percentage of the theoretical worksp ace that could be attained (P < 0.001). The stroke survivors exhibited a high co rrelation between mean force production and active workspace (R=0.90). Thus, our data suggest that altered muscle activation patterns contribute to directionall y dependent weakness following stroke. Both the modulation of muscle excitation with force direction and the independence of muscle activation seem to be reduce d. These alterations translate into a significantly reduced active range of moti on for the fingers.
