Effect of Neural Constraints on Movement in Stroke

This study investigates the effects of Tizanidine on the voluntary movement controls of the arms of participants who have had a stroke and have not had a stroke by measuring medication-induced changes in upper extremity kinematics, pupillometry, and brain activity. Tizanidine is approved by the U.S. Food and Drug Administration. Understanding how different areas of the brain are involved in movement impairments may help rehabilitation efforts and assist in restoring healthy movement in individuals who have had a stroke.

Inclusion Criteria: * History of unilateral supratentorial ischemic stroke that occurred at least six months prior to enrollment * Age between 18-80 * Paresis confined to one side, with substantial motor impairment of the upper limb and some residual voluntary movement (Upper Extremity Fugl-Meyer Assessment in the range of 10-50/66) * Ability to communicate, understand, and provide informed consent * Ability to elevate their limb against gravity up to at least 75 degrees of shoulder flexion and to generate active elbow extension * MRI compatible * Intact skin on the hemiparetic arm * Ability to sit for three hours. Exclusion Criteria: * Motor or sensory impairment in the non-affected limb (FMA\3.6) * Any brainstem and/or cerebellar lesion * untreated cardiovascular disease * History of neurologic disorder other than stroke that affects the arms * Any acute or chronic painful condition in the upper extremities or spine, indicated by a score ≥5 on a 10-point visual analog scale * Current use of a pacemaker * History of seizure * Chemo denervation: botulinum toxin injection to any portion of the paretic upper extremity within the last 6 months, or phenol/alcohol injections \