Autonomic Effects of Stimulation in SCI

This study aims to determine the effects of transcutaneous spinal cord stimulation to increase blood pressure and use that device to increase exercise endurance time and heart rate recovery during arm cycle ergometry. In addition, the investigators will see if the stimulation helps regulate body temperature when in a cool environment.

This study aims to determine the effects of transcutaneous spinal cord stimulation to increase blood pressure and use that device to increase exercise endurance time and heart rate recovery during arm cycle ergometry. In addition, the investigators will see if the stimulation helps regulate body temperature when in a cool environment. The study will consist of 7 visits, that will be between 3-4 hours in duration, separated by no less than 3 days. Visit 1 will consist of determining baseline autonomic function and screening visit. The participant will undergo a sit up set to determine hypotension and orthostatic hypotension and complete a couple surveys. Visits 2 and 3 will determine which site the stimulation parameters should be on the spine, either T7-T8 or T11-12. The site that increases seated systolic blood pressure will be used for the rest of the study. Visits 4 and 5 will consists of putting the electrode at the optimal spot on the spine and completing a submaximal arm ergometry exercise and the other visit will be a sham visit. Visits 6 and 7 will consist of assessing core temperature when in a cool environment with the stimulator on and off.

All participants will complete an orthostatic tilt without stimulation, then go through transcutaneous stimulation mapping sessions to determine the optimal parameters. During the study 1 visits, the participants will complete an arm ergometry exercise with the optimal stimulation parameters and without (sham). During study 2 visits, the participants' body core temperature will be measured about being exposed to a cool environment with stimulation and without (sham).

The visits during Study 1 (4&5) and Study 2 (6&7), the participants will be blinded to the order of completing the study with and without stimulation.

For study 1, exercise endurance time and heart rate recovery will be measured after arm ergometry without stimulation. For study 2, body core temperature and thermal comfort will be reported without stimulation.

For study 1, exercise endurance time and heart rate recovery will be measured after arm ergometry with stimulation. For study 2, body core temperature and thermal comfort will be reported with stimulation.

Electrodes will be placed on the vertebral midline at the spinous process (T7/T8, T11/12). Determine the best electrode placement on the spine that increases blood pressure to around 120/80 mmHg in the seated position.

Amplitude of the stimulation will start at 5mA and increase in increments of 5mA to determine the best amplitude to normalize blood pressure. The same spinous process sites (T7/T8, T11/12) will be used. The best amplitude will be used to increase blood pressure during Study 1 (arm ergometry) and Study 2 (cool environment).

Determine if TSCS shortens the amount of time for HR recovery (return to baseline) compared to no stimulation.

Determine if TSCS helps maintain body core temperature in a cool environment compared to no stimulation.

To determine if TSCS helps improve subjective reporting on thermal comfort and thermal sensation compared to no stimulation.

Inclusion Criteria: injury more than 1 year ago, non-ambulatory level of lesion C3-T1, AIS A or B stable prescription medication regimen for at least 30 days must be able to commit to study requirements of 7 visits within a 60-day period Exclusion Criteria: extensive history of seizures ventilator dependence or patent tracheostomy site history of neurologic disorder other than SCI history of moderate or severe head trauma contraindications to spine stimulation significant cardiovascular disease active psychological disorder recent history (within 3 months) of substance abuse open skin lesions over spine at levels targeted for stimulation (T7/8, T11/12) and pregnancy