Individuals with spinal cord injury (SCI) often experience reduced exercise capacity due to impaired cardiovascular control, which limits their participation in rehabilitation and daily activities. Although epidural spinal cord stimulation (eSCS) has demonstrated efficacy in restoring activity tolerance, its invasive nature and high cost hinder its widespread clinical adoption. To overcome these limitations, this research aims to develop a non-invasive, closed-loop transcutaneous spinal cord stimulation (tSCS) system that automatically adjusts stimulation levels based on real-time physiological signals. As a validation study for the hypothesis that exercise tolerance can be modulated using tSCS with activity dependent stimulation intensities, electrocardiogram and photoplethysmography data were collected from four SCI participants during exercise. I processed these cardiovascular signals using Fast Fourier Transform for heart rate variability (HRV) analysis in Python. I am also involved in developing a predictive machine learning model responsible for controlling tSCS intensity to improve exercise tolerance. It estimates exercise tolerance metrics, such as oxygen consumption volume, based on the HRV parameters. In the system, data are transmitted via Bluetooth Low Energy (BLE) protocols from physiological monitoring units to a processing unit, after on-board computation it then performs automatic adjustment of stimulation intensity. I have established a stable BLE connection within the system, and the final integrated system is anticipated to enhance rehabilitation outcomes by improving cardiovascular control during exercise and providing a clinically viable method to restore exercise capacity in individuals with SCI. Future studies will focus on optimizing algorithm efficiency for real-time performance and validating the system through clinical trials to further assess its impact on rehabilitation outcomes.

Following spinal cord injury (SCI), respiratory function is often impaired due to limited respiratory muscle function. Decreased respiratory function can lead to breathlessness, impaired coughing, reduced exercise tolerance, and increased respiratory infection risks. Previous studies have shown that transcutaneous spinal cord stimulation (tSCS) at cervical and lower thoracic levels can increase vital capacity by targeting respiratory and abdominal muscles in individuals with cervical SCI. This case series study aims to evaluate the effects of tSCS combined with arm crank exercise on respiratory function after SCI. We recruited three individuals with cervical motor-complete SCI, who were randomly assigned to the active tSCS or sham stimulation group. Two participants underwent 24 training sessions with active tSCS. One participant completed 24 training sessions training with sham stimulation. Spirometry was conducted with real-time tSCS at baseline at different spinal locations. Spirometry was also conducted without real-time tSCS before and after 24 training sessions to assess the long-term effect. Forced vital capacity (FVC), forced expiratory volume in one second (FEV1), and peak expiratory flow (PEF) were measured. Out of all locations tested, T6-T7 showed the largest improvement across all spirometry parameters. Participants in the active tSCS group showed improvements in all parameters after 24 sessions. The participant in the sham group showed decreased PEF. The data collected thus far suggests that tSCS may modulate the spinal neural network responsible for respiratory function. Furthermore, tSCS combined with exercise has potential to improve respiratory function in people living with SCI. A larger sample size is necessary to evaluate the long-term efficacy of this novel non-invasive therapy on respiratory function to improve health after SCI.

Multiple System Atrophy (MSA) is a fatal neurodegenerative disease caused by alpha-syn deposition in the brain and spinal cord. This results in severely declined autonomic and motor functions.  In rare cases of MSA, there is pure autonomic system failure, only including dysregulation of blood pressure (BP) control and pelvic organ functions including bowel movement. Blood pressure changes could be extremely dramatic, with uncontrolled drops below 60 mmHg and elevation sometimes over 250 mmHg, resulting in the inability to even stand for more than one minute without feeling faint. Overall, this greatly impacts an individual’s quality of life and mortality. On average, life expectancy after MSA diagnosis is about 6 to 10 years, though this can vary based on factors such as age at onset and symptom severity. Currently, treatment options primarily focus on mitigating symptoms. This case study reports the effect of non-invasive transcutaneous spinal cord stimulation, using on-skin electrodes, on cardiovascular and bowel function. We recruited a male in his 60’s with MSA diagnosed 15 years ago, showing pure autonomic system failure. We measured both acute and long-term effects of stimulation on blood pressure by monitoring continuous BP during stimulation and also had the patient maintain a 24-hour blood pressure log pre- and post-stimulation. Upon examining the data that I analyzed, cervical spinal cord stimulation elevated blood pressure more than thoracic or lumbar stimulation. The participant also recorded his bowel management and stool quality for 5-7 days before and after the sessions. Spinal cord stimulation initiated bowel movements immediately after the intervention. Further research is warranted to better understand the effects of cervical spinal stimulation on blood pressure regulation and bowel function.