Cortical thumb orthosis for children with spastic hemiplegic cerebral palsy.

An orthosis was developed to control the position of the indwelling "cortical" thumb and improve function of the spastic hand of children with spastic hemiplegic cerebral palsy. A clinical evaluation was made of five children, 20 to 26 months old, with mild to moderate spastic hemiplegic cerebral palsy. All five children exhibited an indwelling thumb at rest and during reaching and grasping activities, using a "raking," ulnar type of prehension pattern. In all five children the orthosis was effective in changing the position of the thumb and improving the prehension pattern to a radial grasp in which objects were held between the thumb and the fingers, usually in a three-jaw chuck or large cylindrical prehension pattern, depending on the size of the object being manipulated. Possible explanations for the improved hand function include placement of the thumb in a more functional position, inhibition of muscle tone in thumb adductors and flexors, and the opportunity for increased sensory input and successful practice using the hand.