locomotor function following transcutaneous electrical spinal cord stimulation in individuals with hemiplegic stroke

Conditions: Stroke

Summary: this study has two interventional components, the first is a cross-over design and the second is a randomized control trial. both will evaluate the effectiveness of transcutaneous (non-invasive) spinal cord stimulation on gait and balance function for individuals with hemiplegia due to stroke.

objectives: * exploratory phase: identify a systematic, methodical approach to identifying the optimal stimulation parameters and gait training protocol for each individual patient with stroke. * aim 1: evaluate short-term effects of transcutaneous spinal cord stimulation + gait training on gait symmetry, gait performance, and corticospinal circuitry in individuals with chronic stroke. * aim 2: evaluate and predict long-term effects of transcutaneous spinal cord stimulation + gait training on gait symmetry, gait performance, and corticospinal circuitry in individuals with chronic stroke * aim 3: identify parameters that distinguish responders from non-responders to transcutaneous spinal cord stimulation in individuals with chronic stroke.

Eligibility criteria:
inclusion criteria * age 18 years or older * able and willing to give written consent and comply with study procedures * at least 6 months' post-stroke * hemiplegia secondary to a single stroke * functional ambulation category of 2 or greater - i.e., subject needs continuous or intermittent support of one person to help with balance and coordination. * not currently receiving regular physical therapy services * physician approval to participate exclusion criteria * ataxia * multiple stroke history * botox injection in lower extremity within the last 4 months * modified ashworth score of 3 or greater in lower extremity * pregnant or nursing * using a powered, implanted cardiac device for monitoring or support of heart function (i.e. pacemaker, defibrillator, or lvad) or anti-spasticity implantable pumps * active pressure sores * unhealed bone fractures * peripheral neuropathies * painful musculoskeletal dysfunction due to active injuries or infections * severe contractures in the lower extremities * medical illness limiting the ability to walk * active urinary tract infection * clinically significant depression, psychiatric disorders, or ongoing drug abuse * active cancer or cancer in remission less than 5 years * orthopedic dysfunction, injury, or surgery that would impact an individual's ability to use the lower extremity. * traumatic brain injury or other neurological conditions that would impact the study. tms-specific exclusion criteria: tms will be utilized for both aims. the sub-set of participants who meet these criteria will participate in this component of the studies. * medicated with agents known to increase (e.g., amphetamines) or decrease motor system excitability (e.g., lorazepam) * implanted cardiac pacemaker * metal implants in the head or face * suffers unexplained, recurring headaches * had a seizure in the past unrelated to the stroke event, or has epilepsy * skull abnormalities or fractures * a concussion within the last 6 months * unstable cardiorespiratory or metabolic diseases (e.g. cardiac arrhythmia, uncontrolled hypertension, uncontrolled diabetes, or chronic emphysema)