This week was devoted entirely to Vagus Nerve Stimulation (VNS), which is an electrophysiology technique in which pulses of electrical activity are supplied to the vagal nerve (via implanted system) in order to address a growing number of medical problems.
VNS technology has been in place for about 20 years but its medical applicability has been accelerating in recent years. It was originally designed to treat pharmacologically intractable epilepsy and was shown to reduce both the frequency and severity of seizures.
In the process of studying VNS in epilepsy, patients reported that the VNS was improving their moods. It was therefore discovered that VNS can also be used to treat depression in certain intractable cases. From there the list goes on and on: migraines, chronic pain, eating disorders, multiple sclerosis, and inflammatory diseases such as rheumatoid arthritis. The literature is generally positive and not much in the way of side-effects are reported.
The vagus nerves "wonder" throughout the body, innervating the stomach and heart, as well as any number of structures in the head and neck. It strongly connects to the structures of the limbic system (largely responsible for emotion, memory, and smell), which provides a strong candidate for mechanism of action; despite widespread use, mechanisms of VNS functionality are not well understood.