A Method for Quantifying Trunk Motor Control During Reaching in Individuals Post Hemiparetic Stroke^.

Area of Science:

• Neuroscience
• Rehabilitation Medicine
• Biomechanics

Background:

• Hemiparetic stroke causes upper limb motor impairments like weakness, spasticity, and abnormal joint torque patterns, notably the flexion synergy.
• These impairments, along with altered trunk motor control (weakness, instability, excessive movement), significantly limit reaching ability and daily activities.
• Existing research on stroke-related reaching deficits has not fully explored the interplay between trunk motor control and the flexion synergy, nor the impact of the flexion synergy on trunk postural control.

Purpose of the Study:

• To address the gap in understanding how trunk motor control deficits impact reaching ability and how the flexion synergy affects trunk postural control post-stroke.
• To develop and evaluate a novel system for investigating altered trunk control during reaching tasks, particularly when loads elicit the flexion synergy.

Main Methods:

• Development of an integrated system combining a robotic device for simulating reaching environments, surface electromyography (sEMG) for muscle activity measurement, and a 2-camera motion capture system for movement analysis.
• Evaluation of the system's feasibility and usability in two stroke participants and one healthy control during reaching tasks with varying shoulder abduction loads and trunk conditions (restrained vs. unrestrained).

Main Results:

• The developed system successfully simulated varied reaching environments and measured trunk and arm muscle activity and movement.
• Feasibility and usability were established, demonstrating the system's capability to monitor trunk postural control during reaching tasks in individuals post-stroke.
• The study design allows for the investigation of trunk deficits in the context of the flexion synergy, where arm loading impacts reaching and potentially trunk posture.

Conclusions:

• The presented system provides a novel method for monitoring changes in trunk postural control after hemiparetic stroke during reaching.
• This tool is a crucial first step towards a deeper understanding of trunk motor control alterations post-stroke.
• Further research using this system can lead to the development of more targeted and effective stroke rehabilitation interventions focused on trunk and upper limb coordination.