The investigators proposed to evaluate the effectiveness of sustained peripheral nerve stimulation (PNS) to enhance the therapeutic effects of a modified form CIT (mCIT).

Stroke is one the most devastating and prevalent diseases, but efforts to limit the amount of tissue damaged in the acute phase have been disappointing, highlighting the need for effective therapeutic interventions after neurologic damage has occurred. A major goal of the research in stroke rehabilitation is to harness the capacity of the brain to reorganize after neurologic damage has occurred and thus ultimately lead to successful recovery of function. Data from animal and human models have suggested that sensory input plays an important role in motor output, possibly by influencing cortical plasticity. However, in spite of the advances to date, little is known about the extent to which sensory input in the form of peripheral nerve stimulation can be successfully combined to physical training. A new emerging approach called constraint-induced therapy (CIT) is an intensive functional motor training and has produced promising results in the field of stroke rehabilitation. CIT involves restraining the unaffected arm with a sling or glove combined with intense task-oriented therapy of the affected side for six hours daily during 2 weeks. This pilot study will evaluate the effectiveness of sustained peripheral nerve stimulation coupled with functional motor training to improve hand motor function. While the functional motor training follows identical principles of CIT, the length of daily training will be shortened to 4 hours daily and thus the investigators will refer in this proposal as a modified CIT. Preliminary data for this study demonstrated that peripheral nerve stimulation results in increased cortical motor excitability in normal subjects. In addition, learning and use-dependent plasticity can be substantially enhanced by a single session of 2 hours of peripheral nerve stimulation in chronic stroke patients. The goal of this study is to test the hypothesis that stroke patients treated with upper extremity peripheral nerve stimulation preceding CIT (intervention group) will have improved hand motor function compared to a group receiving lower extremity peripheral nerve stimulation and CIT (control group).

Inclusion Criteria:

• Chronic stroke patients
• Single stroke
• Chronic (more than 12 months after from stroke)
• At least 21 years old, but there is no upper age range for this project.
• Participants must be able to extend the affected metacarpophalangeal joints at least 10° and the wrist 20°.

Exclusion Criteria:

• History of carpal tunnel syndrome and conditions that commonly cause peripheral neuropathy, including diabetes, uremia, or associated nutritional deficiencies
• History of head injury with loss of consciousness, severe alcohol or drug abuse, psychiatric illness
• Within 3 months of recruitment, use of drugs known to exert detrimental effects on motor recovery
• Cognitive deficit severe enough to preclude informed consent
• Positive pregnancy test or being of childbearing age and not using appropriate contraception
• Participants with history of untreated depression.