Capacity for Hand-as-a-Holder Function of the Spastic Combination Hand: A Proof-of-Concept Study.

Area of Science:

• Neuroscience
• Rehabilitation Medicine
• Biomechanics

Background:

• Hemiparetic hands often present with impaired motor control, specifically paralyzed finger extensors and spastic flexors, termed 'spastic combination hand'.
• Patients anecdotally report functional hand-as-a-holder capabilities, suggesting potential for object manipulation despite spasticity.

Purpose of the Study:

• To formally investigate the object-holding capacity of the spastic combination hand using cylindrical objects of varying diameters.
• To evaluate the effect of botulinum toxin intervention on the hand's capacity to hold cylindrical objects.

Main Methods:

• Nine participants with chronic spastic hemiparesis and spastic combination hands performed a standardized motor task involving holding cylinders of 10 different diameters (1.3-9.5 cm) and weights (0.8-8.4 oz).
• Object holding capacity was assessed before and after botulinum toxin intervention targeting Ashworth 3 spastic hand muscles.
• Successful holds were quantified across two pre-intervention sessions and one post-intervention session.

Main Results:

• Before intervention, participants could successfully hold a median of six different cylinder diameters.
• Following botulinum toxin intervention, the median capacity increased to holding ten different cylinder diameters.
• A mixed-effect statistical model indicated a 43% increase in the total number of successful holds after botulinum toxin treatment.

Conclusions:

• The spastic combination hand demonstrates a capacity for holding cylindrical objects within a specified range of diameter and weight.
• Botulinum neurotoxin intervention shows potential for enhancing the object-holding capacity of spastic combination hands in individuals with hemiparesis.