The Role of Trans-spinal Direct Current Stimulation (tsDCS) in Treating Patients With Hand Spasticity After Stroke

Inclusion Criteria: 1. First single focal unilateral hemisphere lesion with diagnosis verified by brain imaging (MRI or CT scans) that occurred at least 6 months prior 2. Cognitive function sufficient to understand the experiments and follow instructions 3. A Modified Ashworth Scale score between 1-3 points for wrist flexor and extensor muscles 4. A minimum of 15 degrees wrist passive range of motion (ROM) for wrist flexion and extension from wrist neutral position Exclusion Criteria: 1. Focal brainstem or thalamic infarcts 2. Prior surgical treatments for spasticity of the upper limb 3. Ongoing use of central nervous system (CNS)-active medications 4. Ongoing use of psychoactive medications, such as stimulants, antidepressants, and anti-psychotic medications 5. Botox or phenol alcohol treatment within 12 weeks of enrollment 6. Pregnancy in women, as determined by self-report 7. History of spinal cord injury or weakness 8. Chronic pain 9. Peripheral neuropathy including insulin dependent diabetes as determined by case history 10. Presence of additional potential tsDCS risk factors: * Damaged skin at the site of stimulation (i.e., skin with ingrown hairs, acne, razor nicks, wounds that have not healed recent scar tissue, broken skin, etc.) * Presence of an electrically, magnetically or mechanically activated implant (including cardiac pacemaker), an intracerebral vascular clip, or any other electrically sensitive support system * Highly conductive metal in any part of the body, including metal injury to the eye (jewelry must be removed during stimulation) * Past history of seizures or unexplained spells of loss of consciousness during the previous 36 months