Investigation of the effects of unilateral right, unilateral left and bilateral applications of transcutaneous auricular vagus nerve stimulation on autonomic nervous system activity in healthy people

Transcutaneous auricular vagus nerve stimulation (VSS) is the stimulation of the vagal nerve through the ear conca and/or tragus with the help of superficial electrodes. It is as effective as invasive vagal stimulation methods. The superiority of the stimulations made from unilateral left, unilateral right or bilateral ears over each other is a matter of curiosity. This study determines the effects of unilateral left, unilateral right and bilateral auricular transcutaneous vagus nerve stimulation in healthy volunteer participants aged 18-65 years (n=30). Each participant was randomly assigned to each administration group at least 48 hours apart. Pulse, Systolic Blood Pressure, Diastolic Blood Pressure, RMSSD, SDNN, PNN50, LF/HF Rotatio, LF POWER, HF POWER and Galvanic Skin resistance parameters, which are indicators of sympathetic and parasympathetic branches in the autonomic nervous system, were evaluated. According to the application groups, biphasic vagus nerve stimulation was applied to the participants for 20 minutes with a Vagustim device in modulation mode at a frequency of 10 Hz and a pulse width of 300 microseconds. Since each participant is included in each application group, there is no difference between the groups in terms of age, height, weight and gender. In group comparisons; In the left ear application group, systolic and diastolic blood pressure decreased, while RMSSD and Galvanic Skin Resistance increased (p < 0.05). While Systolic and Diastolic Blood pressure decreased in the right ear treatment group, Galvanic Skin Resistance increased (p < 0.05). While Pulse and Diastolic Blood pressure decreased in the bilateral double ear application group, RMSSD, LN, LF and HF increased (p < 0.05). In the comparisons between the groups, the bilateral VSS application decreased the heart rate more than the applications performed in the right or left ear; RMSSD value increased LF Power value and HF Power value more (p < 0.05). The application increased the parasympathetic nervous system activity and the bilateral application group realized this increase more. Keywords: Vagus Nerve, Heart Rate Variability, Sympathetic Nervous System, Parasympathetic Nervous System