Contralaterally Controlled Functional Electrical Stimulation Plus Video Games for Hand Therapy After Stroke

Inclusion Criteria: -\> 6 months since a first clinical cortical or subcortical, hemorrhagic or nonhemorrhagic stroke * age 21-80 years old * unilateral upper limb hemiparesis with finger extensor strength of grade \<=4/5 on the Medical Research Council (MRC) scale AND a score of \>=1 and \<=11/14 on the hand section of the upper extremity Fugl-Meyer Assessment * adequate active movement of the shoulder and elbow to position the hand in the workspace for table-top task practice (necessary for the lab task practice sessions) * able to follow 3-stage commands * able to recall 2 of 3 words after 30 minutes * surface stimulation of the paretic finger and thumb extensors produces functional hand opening without pain (this will exclude those who have degree of flexor hypertonia that prevents stimulated hand opening) * Functional passive range of motion (minimal resistance) at elbow, wrist, fingers, and thumb, i.e., there exists enough passive range of motion to reach and acquire table-top objects * intact vision and hearing * medically stable * full voluntary opening/closing of the contralateral (less affected) hand * demonstrate ability to follow instructions for operating the stimulator or have a caregiver who will assist them Exclusion Criteria: * co-existing neurologic diagnosis of peripheral nerve injury, Parkinson's disease, spinal cord injury, traumatic brain injury, or multiple sclerosis * uncontrolled seizure disorder * severely impaired cognition and communication * uncompensated hemineglect * arm or forearm skin breakdown or edema (to avoid edema-related shunting of current) * insensate forearm (to avoid risk of electrical burns) * history of potentially fatal cardiac arrhythmias with hemodynamic instability * implanted electronic systems (e.g. pacemaker) * botulinum toxin injections to any upper extremity muscle within 3 months of enrolling * pregnant women due to unknown risks of surface stimulation during pregnancy * participating in occupational therapy or other rehabilitation therapies to the upper extremity * severe shoulder or hand pain