Technical aspects and future approaches in transcutaneous vagus nerve stimulation (tVNS)

Immediate effects and duration of a short and single application of transcutaneous auricular vagus nerve stimulation on P300 event related potential

“…Initially, bracket electrodes attached to the ear lobe or the tragus were used. They are easy to use, but high pressure of the brackets on the ear can cause discomfort, skin irritation, swelling and inflammation ( Bolz and Bolz, 2022 ). The NEMOS device initially focused in stimulating the tragus, and the electrode applicator of this device consisted of a silicone ring placed between the tragus and the antitragus and used a plastic spacer to position the electrode directly into the cymba conchae.…”

“…This fact, in which the received dose is well below what is theoretically expected, is possibly the most important factor of negative results. Instead of the constant voltage approach, it might be better to use a constant current output device (current controlled stimulation), with a closed loop regulator in which the output current is measured, and the output voltage is immediately adapted to keep the current constant (Bolz and Bolz, 2022). Our device was designed in such a manner, and in addition to allowing the reception of specific and equal electrical dose for all subjects, allows the data to be stored, computing the accumulated received dose in use of the taVNS over prolonged periods and enabling in future sessions to adjust doses depending on physiological response of the user.…”

Transcutaneous Auricular Vagus Nerve Stimulation in Pediatric Patients: A Systematic Review of Clinical Treatment Protocols and Stimulation Parameters

“…10 Recently suggested electrotechnical and software-based improvements to the state-of-the-art stimulators include the use of individualized tVNS therapy, using evolution algorithms that use device and subject data to optimize stimulation parameters. 16 One approach to determine stimulation parameters and protocols is the use of biomarkers of tVNS. 51 Frequently discussed biomarkers of tVNS include heart rate variability (HRV), 52 eventrelated (P300) or somatosensory evoked potentials, pupil dilation, or salivary alpha-amylase.…”

“…15 Critically, the development of tVNS devices, even though commercially available devices show no restrictions of application to exclusively adult populations, currently does not intend specific stimulation systems for children and young people. 16 This also might seem reminiscent of a past situation in which, alongside clinical practice experience in children and adolescents, the administration of psychotropic drugs in pediatric patients was usually guided by evidence extrapolated from adults, leading to substantial off-label use. 17 In part, this was due to a relative lack of high-quality pharmacokinetic, efficacy, and safety data, partly because drug regulatory authorities did not request evidence for this patient group until not much longer than a decade agowhich put pediatric patients at an increased risk of suboptimal treatment outcomes (eg, inefficacy of treatments, high rates of adverse effects).…”

“…Several comprehensive reviews of tVNS already exist, addressing, among others, current reporting standards and practice, 2 safety and tolerability, 3 the underlying anatomical rationale, 25 technical aspects and engineering, 16,26 physiological aspects, 27 neurophysiological underpinnings, 28 and clinical considerations 10,29,30 of tVNS. Yet none of these reviews specifically addresses aspects to be considered in the research and application of tVNS in pediatric patients.…”