Flexor Synergy Assessment and Therapy for Persons With Stroke Using the ULIX Low Impedance Robot.

Area of Science:

• Neurorehabilitation
• Biomechanics
• Robotics in Medicine

Background:

• Post-stroke flexor synergy causes involuntary distal muscle activation during shoulder flexion.
• This synergy impairs activities of daily living (ADLs) and functional independence.
• Robotic exoskeletons offer potential for synergy assessment and targeted therapy.

Purpose of the Study:

• To evaluate the efficacy of the Ultra Low Impedance eXoskelton (ULIX) in assessing flexor synergy post-stroke.
• To investigate the impact of varying gravity support levels on synergy assessment tasks.
• To assess the effectiveness of ULIX-based therapy modes in improving upper limb function during a reaching task.

Main Methods:

• Sixteen chronic stroke patients performed elbow extension and hand opening tasks with ULIX under varying gravity support.
• EMG data and joint kinematics were recorded during assessment and a free cup reaching task.
• Therapy modes were applied during the cup reaching task to evaluate their impact on movement.

Main Results:

• Increased gravity support during assessment led to greater elbow extension but reduced grip force.
• EMG ratios indicated increased distal muscle activation with higher gravity support.
• ULIX therapy modes enhanced range of motion and shoulder-elbow coordination during reaching compared to gravity support alone.

Conclusions:

• ULIX effectively assesses post-stroke flexor synergy and quantifies its relationship with functional tasks.
• Robotic therapy modes improve upper limb kinematics and range of motion in chronic stroke patients.
• Targeted assessment and therapy using exoskeletons show promise for neurorehabilitation.