transcutaneous Vagus Nerve Stimulation
Invasive VNS has been successfully used for over ten years to treat patients with refractory epilepsies.
The cervical branch of the vagus nerve in the neck is exposed in a surgical procedure, and an electrode is placed to enclose it. The electrode is connected to a stimulator implanted under the skin, below the collarbone.1,2
The stimulus current is passed through the vagus nerve to the brainstem, from where it activates higher centres of the brain.1
Transcutaneous Vagus Nerve Stimulation (t-VNS®) uses the fact that the auricular branch of the vagus nerve (ABVN) supplies the skin of the concha in the human ear.3 This allows for transcutaneous electrical stimulation of the nerve fibers in this area. Intensity, pulse duration and frequency of the t-VNS stimulation have been optimized to induce signals in thick-myelinated Aβ fibres of the ABVN. Like those of the cervical branch of the vagus nerve, these project directly to the nucleus of the solitary tract (NTS) in the brainstem.4,5,6 The NTS is the starting point to activate a complex cerebral network, corresponding closely to that targeted by invasive VNS, and associated with the anticonvulsive effect.1,2,7
Anticonvulsive effects of t-VNS
The anticonvulsive effect of transcutaneous Vagus Nerve Stimulation has been demonstrated in various experiments. This includes animal experiments where seizures were induced by administering drugs, while recording epidural EEG. This revealed similar anticonvulsive effects of invasive and transcutaneous stimulation of the vagus nerve.8
Case Series: reduction in seizure frequency in drug-resistant epilepsy
In a prospective case series, conducted with the Erlangen Epilepsy Centre (Germany), seven patients who had suffered from drug-resistant epilepsy for many years used t-VNS for nine months. Stimulation was carried out for three hours a day, in sessions of at least an hour each. The primary endpoint of the study was the number of documented seizures. After nine months, a reduction in seizure frequency was found in 5 out of 7 patients. On the basis of investigations carried out so far, the authors of the study assessed t-VNS as safe and tolerable for long-term use. It may therefore offer an alternative treatment for patients with epilepsy that is refractory to other forms of therapy.9
Like most pharmaceutical and neuromodulatory treatments for drug-resistant epilepsy, t-VNS is not an acute therapy. For patients who respond to therapy with t-VNS, the anticonvulsive effect may occur with a latency of some weeks to a few months.
- Beekwilder JP, Beems T: Overview of the clinical applications of vagus nerve stimulation. J Clin Neurophysiol 2010;27:130-138.
- Amar AP, Levy ML, Liu CY, Apuzzo MLJ: Vagus Nerve Stimulation; in Krames ES, Peckham PH, Rezai AR, (eds): Neuromodulation. London, Academic Press, 2009, pp 625-637.
- Peuker ET, Filler TJ: The nerve supply of the human auricle. Clin Anat 2002;15:35-37.
- Nomura S, Mizuno N: Central distribution of primary afferent fibers in the Arnold's nerve (the auricular branch of the vagus nerve): a transganglionic HRP study in the cat. Brain Res 1984;292:199-205.
- Gao XY, Rong P, Ben H, Liu K, Zhu B, Zhang S: Morphological and electrophysiological characterization of auricular branch of vagus nerve: Projections to the NTS in mediating cardiovascular inhibition evoked by the acupuncture-like stimulation; Society for Neuroscience Abstracts, 2010;694.22.
Frangos E, Ellrich J, Komisaruk BR. Non-invasive access to the vagus nerve
central projections via electrical stimulation of the external ear: fMRI evidence
in humans. Brain Stimulation. 2014;DOI: 10.1016/j.brs.2014.12.003 ;In press.
Vonck K, Boon P, Van RD: Anatomical and physiological basis and mechanism of action of neurostimulation for epilepsy. Acta Neurochir Suppl 2007;97:321-328.
- He W, Zhu B, Rong P: A new concept of transcutaneous vagus nerve stimulation for epileptic seizure. Society for Neuroscience Abstracts 2009;539.4.
- Stefan H, Kreiselmeyer G, Kerling F, Kurzbuch K, Rauch C, Heers M, Kasper B, Hammen T, Rzonsa M, Pauli E, Ellrich J, Graf W, Hop-fengärtner R: Transcutaneous vagus nerve stimulation (t-VNS) in pharmacoresistant epilepsies: a proof of concept trial. Epilepsia 2012;53:e115-8.
Therapy device NEMOS®
In 2011 cerbomed received the European clearance (CE mark) for the transcutaneous vagus nerve stimulator NEMOS.