Effects of Transcutaneous Spinal Cord Stimulation on Autonomic Nervous System Regulation

This study investigates the impact of transcutaneous spinal cord stimulation (TSCS) on the autonomic nervous system (ANS) by analyzing heart rate variability (HRV) metrics. TSCS, a non-invasive alternative to invasive spinal electrical stimulation, is used to treat motor disability or movement disorders. Despite its usage, the effects of TSCS on the ANS remain unclear, particularly its role in motor rehabilitation. The objective was to understand TSCS effects on HRV in healthy individuals. Electrocardiograms (ECGs) were recorded from 7 participants during baseline and tSCS stimulation periods at $7 \mathrm{~Hz}, 20 \mathrm{~Hz}$, and 45 Hz. Significant differences were found in parasympathetic markers between the control and 7 Hz stimulation, and between the control and 45 Hz stimulation. However, these differences disappeared when trimming the signal to eliminate start and end effects of stimulation blocks. This suggests that TSCS effects on ANS activity are transient, warranting further time-frequency analyses.