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

We call a hemiparetic hand with paralyzed finger extensors and volitional but spastic flexors a "spastic combination hand." Anecdotally, patients report hand-as-a-holder function with objects like pill bottles, motivating us to formally study spastic combination hand holding capacity using cylinders with different diameters. Nine participants with spastic hemiparesis and spastic combination hand more than 24 mos performed a standardized motor task with 10 cylinder diameters ranging between 1.3 and 9.5 cm and weighing 0.8 and 8.4 oz. Using the unaffected hand, participants attempted to insert a given cylinder into their spastic combination hand, holding it independently for 5 secs. Successful holds were counted during two sessions before and one session after botulinum toxin intervention of Ashworth 3 hand muscles. Findings revealed that a median capacity of six different cylinder diameters was successfully inserted into spastic combination hand at least once before block and a median capacity of 10 cylinders was inserted after block. A mixed-effect statistical model using fixed effects of cylinder diameter and session revealed that total number of successful holds was 43% higher after botulinum. We conclude that this proof-of-concept study does support the idea that spastic combination hand has holding capacity for cylindrical objects of specified diameter and weight and that botulinum neurotoxin offers potential for enlarging spastic combination hand capacity.