Improving hand function in chronic stroke

Background: Recovery of function following stroke plateaus in about I year, typically leaving upper arm function better than that in the hand. Since there is competition among body parts for territory in the sensorimotor cortex, even limited activity of the upper arm might prevent the hand from gaining more control, particularly when the territory is reduced in size because of the stroke. Deafferentation of a body part in a healthy brain enhances cortical representations of adjacent body parts, and this effect is markedly increased by voluntary activity of the adjacent part. Objective: To explore whether deafferentation of the upper arm, produced by a new technique of regional anesthesia during hand motor practice, helps recovery of hand function in patients with long-term stable weakness of their hand following stroke. Methods and Results: Deafferentation, produced by a new technique of regional anesthesia of the upper arm during hand motor practice, dramatically improved hand motor function including some activities of daily living. The improvement was associated with an increase in transcranial magnetic stimulation-evoked motor output to the practice hand muscles. Conclusion: This is a novel therapeutic strategy that may help improve hand function in patients with long-term weakness after stroke.