Vagus nerve stimulation

Vagus nerve stimulation (VNS) is a medical treatment that involves delivering electrical impulses to the vagus nerve. Initially developed by James Leonard Corning to compress or stimulate the carotid sheath, VNS typically refers to an implantable electrode. However, non-invasive VNS delivered transcutaneously via the auricular branch of the vagus nerve, or through the skin to the cervical nerve, is being investigated in clinical research. Invasive VNS is used as an adjunct treatment for certain types of intractable epilepsy, cluster headaches, migraine, treatment-resistant depression and stroke rehabilitation.

VNS is used to treat drug-resistant epilepsy. For refractive epilepsy, cervical VNS on the left side is FDA-approved.

In the United States, VNS is approved as adjunctive therapy for those 4 years of age or older with refractory focal onset seizures. In the European Union, VNS is approved as an adjunctive therapy for patients with either generalized or focal onset seizures without any age restrictions. It is recommended that VNS is only pursued following an adequate trial of at least 2 appropriately chosen anti-seizure medications and that the patient is ineligible for epilepsy surgery. This is because epilepsy surgery is associated with a higher probability of resulting in seizure freedom. Patients who have poor adherence or tolerance of anti-seizure medications may be good candidates for VNS.

VNS may provide benefit for particular epilepsy syndromes and seizure types such as Lennox-Gastaut syndrome, tuberous sclerosis complex related epilepsy, refractory absence seizures, and atonic seizures. There are also reports of VNS being successfully utilized in patients with refractory and super-refractory status epilepticus.

The UK National Institute for Health and Care Excellence (NICE) in the UK recommends VNS for cluster headaches. In 2017 the FDA approved the non-invasive gammaCore VNS system for treatment of episodic cluster headache and expanded its approved usage to acute treatment of pain associated with migraine. Two randomized, double-blind, and sham-controlled studies have administered nVNS to patients with episodic cluster headaches; both demonstrated a significant effect in reducing acute cluster attacks.

VNS is used to treat treatment-resistant major depressive disorder (TR-MDD). For treatment resistant depression, cervical VNS on the left side is FDA-approved. The UK NICE guidance (from 2020) stated that "Evidence on its efficacy is limited in quality" and encouraged further research studies "in the form of randomised controlled trials with a placebo or sham stimulation arm."

VNS has been used to treat chronic pain due to various causes, although the mechanisms for this relief have yet to be determined.

VNS has shown to be of value in the treatment of heart failure. One study did not show a reduction in death rates, but did show improvement in six-minute hall walk duration and quality of life.