Abnormal coordination of upper extremity during target reaching in persons post stroke

Area of Science:

• Neuroscience
• Rehabilitation Medicine
• Biomechanics

Background:

• Understanding abnormal upper extremity (UE) synergy in stroke survivors is crucial for identifying motor impairments.
• Stroke often leads to difficulties in coordinating multiple arm joints during functional tasks.

Purpose of the Study:

• To investigate the extent to which stroke survivors can coordinate multiple arm joints during a reaching task.
• To quantify kinematic and kinetic coordination patterns in stroke survivors compared to healthy controls.

Main Methods:

• Utilized an exoskeleton robot to record arm joint angles and torques in 37 stroke survivors and 13 healthy controls during reaching.
• Quantified kinematic and kinetic coordination patterns by partitioning variances into task-irrelevant (TIV) and task-relevant (TRV) components.
• Calculated the index of synergy (IS) for kinematic (ISθ) and kinetic (ISτ) patterns.

Main Results:

• Stroke survivors exhibited significantly lower kinematic ISθ and kinetic ISτ compared to controls, indicating impaired UE reaching ability.
• Reduced kinematic ISθ was mainly due to lower TIVθ, while reduced kinetic ISτ resulted from higher [Formula: see text] and lower TIVτ.
• Stroke survivors demonstrated abnormal kinetic synergistic movement deficits, particularly during outward arm movements.

Conclusions:

• Stroke survivors have impaired ability to coordinate multiple UE joints for reaching, characterized by reduced kinematic and kinetic synergy.
• Abnormal kinetic synergy patterns, especially during outward movements, are a significant motor deficit post-stroke.
• Findings suggest the need for impairment-specific treatments to improve UE synergies in stroke rehabilitation.