Inclusion Criteria- Hemispheric stroke (ischemic or hemorrhagic), cortical or sub-cortical, documented by either a CT or MRI scan and associated with residual upper extremity weakness.
- Chronic stroke, occurring ≥12 months prior to subject enrollment.
- Age 18-80 years old.
- Inability to move any of the fingers of the affected hand more than 5.0 cm into extension.
- Finger-and-wrist impedance ≤3 on the Modified Ashworth Scale.
- Measureable EMG (>2 x baseline) in the long finger extensor muscle during attempted hand opening or closing.
- Physically and cognitively capable of consenting to and complying with the protocol (based on exam by Study Physician).
- Subject must be physically capable of communicating informed consent or must be accompanied by legally authorized representative to provide informed consent.
Exclusion Criteria- Complete flaccidity of the affected arm.
- Significant upper extremity proprioceptive deficit (<70% correct detection of the direction of passive finger movement with eyes closed).
- Pathological neurological/physical conditions, other than stroke, impairing the function of the impaired arm or resulting in pain in the arm.
- Spinal cord injury, arthritis, or fractures of affected arm that have resulted in loss of range of motion.
- Peripheral nerve injury or neuropathy resulting in significant motor or sensory loss in the tested arm.
- Cardiopulmonary compromise including but not limited to uncontrolled hypertension or angina, deep vein thrombosis, decompensated congestive heart failure, myocardial infarction, heart irregularities, or exercise intolerance.
- Major active psychiatric disorder.
- Cognitively or behaviorally unable to follow instructions including severe apraxia; inability to understand verbal (English) directions, or inability to communicate adequately with study personnel.
- Size of arm incompatible with the AMES device (checked by placing the limb in the device).
- Severe contractures or decreased range of motion or skin condition that would prohibit comfortable positioning or tolerance of the device or the vibrators.
- Any progressive neurodegenerative disorder affecting the upper extremity motor system.
- Uncontrolled seizure disorder.
- Current abuse of alcohol or drugs.
- Terminal illness with anticipated survival of <12 months.
- Current or planned concurrent participation in another study involving therapy to the impaired arm
- Planned initiation of or cessation of any kind of clinical therapy to the impaired limb just prior to or during the AMES treatment period.
- NIH Stroke Scale, following scores: Sensory Item score of >1; Neglect involving the affected limb score >1.
- Intent to receive Botox injections (5 months prior to or during enrollment), initiation of antispasmodic medication, or use of any other robotic (e.g., MANUS, Locomat) or electrical or vibratory stimulation device (e.g., Bioness) while participating in the AMES trial.
- Cognitively or behaviorally unable to follow instructions