Muscle Synergy Analysis for Clinical Characterization of Upper Limb Motor Recovery After Stroke

Area of Science:

• Neuroscience
• Rehabilitation Medicine
• Biomedical Engineering

Background:

• Stroke frequently causes upper limb motor impairment, necessitating effective rehabilitation.
• Muscle synergies, patterns of muscle activation, are crucial for motor control and can be altered post-stroke.

Purpose of the Study:

• To analyze muscle synergy patterns (similarity, merging, fractionation) in stroke survivors who responded or did not respond to upper limb motor treatment.
• To identify potential biomarkers for predicting treatment response in stroke rehabilitation.

Main Methods:

• Secondary analysis of a multicenter randomized controlled trial involving 62 stroke patients with upper limb motor impairment.
• Muscle synergy patterns were extracted from surface electromyography data collected during reaching tasks before and after 4 weeks of conventional, virtual reality, or robot-assisted therapy.
• Synergy patterns (similarity, merging, fractionation) were analyzed for both affected and unaffected upper limbs.

Main Results:

• Overall, patients showed significant improvement in upper limb motor function (Fugl-Meyer Assessment-Upper Extremity score improved).
• Responders (n=34) exhibited decreased synergy merging compared to non-responders.
• Non-responders showed improved synergy similarity, while responders did not show this pattern.

Conclusions:

• Changes in muscle synergy merging patterns may serve as a potential marker to distinguish between responders and non-responders to upper limb motor rehabilitation in stroke patients.
• This finding could inform personalized rehabilitation strategies by identifying patients likely to benefit from specific interventions.