What is the Vagus Nerve?
- The largest cranial nerve, which conveys sensory information from the body’s organs to the central nervous system
- Composed of 80% afferent sensory fibers and 20% efferent motor fibers
- Extends from the brainstem, through the neck within the carotid artery sheath into the chest and abdomen
- Plays a role in the function of nearly every organ and is a fundamental means by which the autonomic nervous system subconsciously and consciously monitors our physical state of being. It is often referred to as the neural superhighway.
History of Vagal Nerve Stimulation (VNS)
- In 1997 Cyberonics received the first FDA approval for a surgically implanted vagus nerve stimulator for the treatment of refractory epilepsy.
- Recipients of implanted VNS devices began reporting additional clinical benefits including reduction in depression symptoms and in 2005, Cyberonics was able to secure FDA approval for the treatment of refractory depression.
- For 25 years, implanted VNS has been safely and effectively used in over 100,000 patients to treat epilepsy (and depression in the US as of 2005).
What is Vagus Nerve Stimulation (VNS)?
- VNS is the use of electric currents to stimulate the vagus nerve.
- These electrical impulses can be applied directly through implanted electrodes or non-invasively to the vagus nerve
- Vagal sensory afferent cell bodies in the nodose ganglion project to the nucleus tractus solitarius (NTS).1
- The NTS has projections to many higher brain centers, including the amygdala, the dorsal raphe, locus coeruleus, the nucleus ambiguous, the dorsal motor nucleus of the vagus, the parabrachial nucleus, the hypothalamus, and the thalamus.2
- The recent development of a proprietary electrode configuration and signal allows for transcutaneous stimulation of vagus nerve afferents, which presents a novel therapeutic option in primary headache.
1. Groves & Brown, 2005, page 494
2. Hatton 2006, page 1243; Henry 2002, page 4