Grip aperture scaling to object size in chronic stroke

Area of Science:

• Neuroscience
• Rehabilitation Medicine
• Biomechanics

Background:

• Decreased dexterity in chronic stroke survivors significantly impacts hand function and quality of life.
• Understanding reach-and-grasp coordination is vital for developing effective rehabilitation strategies.

Purpose of the Study:

• To investigate reach-and-grasp coordination and aperture scaling in chronic stroke survivors with hand paresis.
• To compare performance between stroke survivors and controls across different grasp types and object sizes.

Main Methods:

• Participants performed reach-to-grasp movements with cylinders of varying sizes (33-55 mm) using whole-hand or fingertip grasps.
• Kinematic data were analyzed to assess reach-and-grasp coordination, aperture scaling, and movement timing.
• Subjects included chronic stroke survivors with varying degrees of hand paresis and healthy controls.

Main Results:

• Stroke survivors with severe hand paresis exhibited disrupted coordination and employed compensatory strategies.
• Survivors with mild to moderate paresis successfully scaled grip aperture to object size (p < .001) but demonstrated slower movements and increased trunk motion.
• The relative time to maximal grip aperture (TMA) was earlier in stroke subjects and for smaller objects (p < .002).

Conclusions:

• Chronic stroke survivors with mild to moderate hand paresis can retain grip aperture scaling abilities despite motor deficits.
• The findings suggest preserved sensorimotor control for object manipulation in some stroke survivors.
• Rehabilitation could focus on improving movement speed and reducing compensatory strategies to enhance functional hand use.