transcranial direct current stimulation for improving gait training in stroke

Conditions: Stroke; Cerebral Vascular Accident

Summary: the purpose of this study is to determine if transcranial direct current stimulation (tdcs)applied over the lower extremity motor cortex in conjunction with assisted gait training is effective for improving gait in patients with chronic stroke.


Eligibility criteria:
inclusion criteria: * stroke survivors \> 3 months from most recent unilateral, stroke based on clinically or experimentally obtained mri brain scans and behavioral evidence of stroke (e.g., risk factors, hemiplegia, unilateral sensory impairment, or localized higher cortical dysfunction) by report or in the medical record. * age: \>21 years of age. * complete nih stroke scale. * sufficient endurance, motor ability and balance to ambulate at least 10 meters continuously with moderate or less assistance. * demonstrate gait impairment during ambulation such that gait instability or inefficient gait patterns \[gait pattern manifesting "dragging" or "catching" of the affected toes during swing phase of gait, or use of compensatory strategies such as circumducting the affected limb, vaulting with the unaffected limb or hiking the affected hip to clear the toes\] are exhibited. * pass the transcranial magnetic stimulation (tms) adult safety screen (tass) except for items related specifically to stroke and the treatment for stroke. exclusion criteria: * edema, skin breakdown, absent sensation of the affected lower limb which interferes with the peroneal nerve stimulator. * history of potentially fatal cardiac arrhythmias, such as ventricular tachycardia, supraventricular tachycardia, and rapid ventricular response atrial fibrillation with hemodynamic instability. * demand pacemakers or any other implanted electronic systems. * pregnant women, uncontrolled seizure disorder, parkinson's disease, spinal cord injury, traumatic brain injury with evidence of motor weakness, multiple sclerosis. * documented episode in the medical record of a seizure occurring 1 month or more post stroke for which the patient received consultation or treatment for said seizures. seizures occurring within the first month following a stroke are not exclusionary unless followed by another seizure. * fixed ankle plantar flexor contracture, peroneal nerve injury at the fibular head as the cause of foot-drop. * history of dementia, severely impaired cognition, communication or comprehension deficits. * presence of severe or frequent headaches * history of botulinum toxin (botox) injection to either of the lower extremities within the 3 month period preceding study entry. * have other medical conditions or are taking medications that compromise ambulation or balance. * failure to meet established screening criteria for tms or tdcs (i.e., tass) * principal investigator's or medical monitor's discretion not to include a participant. additional exclusion criteria for mri scan * claustrophobia, or the inability to lie still in a confined space * major medical disorders (e.g., hiv, cancer) * medications which may affect image quality (e.g., water pills) * magnetic metallic implants (such as screws, pins, shrapnel remnants, aneurysm clips, artificial heart valves, inner ear (cochlear) implants, artificial joints, and vascular stents), as these may heat, pull, or twist in the strong magnetic field of the mri scanner * non-removable dental implants, such as braces or permanent retainers, as these will distort the mri images we collect (note: filings, crowns, and silver or gold teeth are ok) * permanent makeup or tattoos with metallic dyes * a positive pregnancy test (for females), since the effect of strong magnetic fields on the developing fetus remains unknown and inconclusive. (we will conduct a pregnancy test for all female participants on the day of the mri scan.) * psychotic disorders (e.g., schizophrenia) * any other condition that the investigator believes might put the participant at risk