Evaluating upper limb impairments in multiple sclerosis by exposure to different mechanical environments

Area of Science:

• Neuroscience
• Rehabilitation Medicine
• Biomedical Engineering

Background:

• Multiple sclerosis (MS) is a chronic, autoimmune, neurodegenerative disease impacting motor functions.
• Upper limb motor impairments, including weakness and poor coordination, are common in MS.
• Robot-based assessments offer objective quantification of motor deficits.

Purpose of the Study:

• To quantify upper limb motor deficits in individuals with MS using a robot-based system.
• To analyze behavioral aspects and muscle synergies during reaching tasks in MS.
• To identify potential biomarkers and inform rehabilitative strategies for MS-related motor impairments.

Main Methods:

• 11 individuals with mild to moderate MS and 11 age/gender-matched controls performed planar reaching tasks using a robotic manipulandum.
• Tasks involved moving the upper limb or applying force in four different robotic environments (free space, assistive/resistive forces, rigid constraint).
• Activity of 15 upper body muscles was recorded, alongside behavioral data, for analysis of muscle synergies and coordination.

Main Results:

• Individuals with MS exhibited irregular movement trajectories during reaching tasks.
• Impaired coordination between shoulder muscles and arm movements was observed in MS.
• A notable co-activation of biceps and triceps muscles during extension and systematic differences in muscle synergy timing and organization were found in MS subjects.

Conclusions:

• Robot-based assessment effectively quantifies upper limb motor deficits in MS.
• Altered muscle synergies and coordination patterns are key indicators of motor impairment in MS.
• Findings support the development of novel biomarkers and targeted rehabilitative interventions for improving motor control in MS.