Effects of non-invasive trigeminal nerve stimulation frequency and duration on cardiovascular responses

This study investigated the effects of trigeminal nerve (TN) stimulation on cardiovascular responses in healthy individuals. Sixty-one participants received electrical stimulation to the ophthalmic and maxillary branches of the trigeminal nerve at different frequencies (2 Hz, 20 Hz, and 200 Hz) while heart rate (HR), pulse arrival time (PAT), and heart rate variability (HRV) were monitored. Results demonstrated frequency-dependent cardiovascular responses, with higher frequencies (particularly 200 Hz) producing more pronounced effects on both HR and PAT. HR showed significant decreases during stimulation, with recovery times proportional to stimulation frequency. PAT changes, which inversely reflect blood pressure alterations, occurred more rapidly than HR changes, suggesting baroreflex-mediated regulation. Notably, habituation effects were observed with repeated stimulation at 2-min intervals, but these effects were minimized when using shorter (30-s) stimulation periods. HRV analysis revealed a significant negative correlation between resting LF/HF ratio and stimulation-induced changes, indicating that TN stimulation particularly influences autonomic balance in individuals with sympathetic hyperactivity. These findings provide insights into the mechanisms of TN stimulation on cardiovascular function and suggest potential therapeutic applications for conditions characterized by autonomic dysregulation.