Innovative Approaches To Autonomic Control: Comparison Of Open-Loop And Closed-Loop Auricular Vagus Nerve Stimulation With Potential Implications For Epilepsy Treatment
Kevin Gustavo dos Santos Silva1, Gabriella Maria de Faria2, Viviane Fajardo Filgueiras2, Henrique Amorim2, Lívia Bruni de Souza2, Fabiana Gomes Ferreira2, Nádia Bertoncello2, Karina Rabello Casali2, Tatiana Sousa Cunha2
1School of Medicine, Anhembi Morumbi University, 2Federal University of Sao Paulo
Objective:
To compare the effects of vagus stimulation on the autonomic control of healthy individuals using a commercial open-loop taVNS device (VitosⓇ) and our closed-loop taVNS prototype.
Background:
Transcutaneous auricular vagus nerve stimulation (taVNS), a non-invasive technique, activates autonomic control and produces therapeutic effects, particularly in epilepsy. The growing interest in these devices has led to variations to optimize vagal modulation and expand treatment options for patients unresponsive to conventional therapies. Studies show that stimulation synchronized with respiration enhances taVNS effects. Our group developed a closed-loop prototype that adjusts stimulation to respiratory patterns.
Design/Methods:
The study was approved by the Research Ethics Committee. A total of 6 healthy volunteers of both sexes (22-48 years old) were included in this blinded controlled study and randomized into two groups: open-loop device (OL; n=4) and closed-loop prototype (CL; n=2), both at 25Hz. Cardiac data was collected at three points: at rest, during intervention (20 minutes of use of OL or CL taVNS), and after intervention, using a continuous and non-invasive heart rate monitor (Polar V800 heart rate monitor). The autonomic nervous system was assessed by quantifying sympathetic (SM) and vagal (VM) modulations, estimated through spectral analysis applied to tachograms.
Results:
The taVNS, in both protocols, caused a significant increase in VM compared to baseline, in normalized units (nu) (OL_basal = 13.1±5.9; OL_during = 24.9±7.9; OL_post = 25.9±12.8; CL_basal = 13.6±0.8; CL_during = 46.7±3.5; CL_post = 25.1±2.9, p=0.001). CL taVNS produced a substantially greater increase in vagal activity during the maneuver compared to the OL device (p=0.006).
Conclusions:
Both vagus nerve stimulation through OL and CL taVNS resulted in a significant increase in vagal activity during the session, demonstrating the effectiveness of the developed prototype. CL had a more pronounced effect on immediate autonomic nervous system activation, reinforcing existing literature that suggests optimization and enhancement of vagal modulation effects.
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