A vagus nerve stimulator is a small, implanted medical device that sends programmed electrical pulses to the left vagus nerve in your neck. Think of it as a pacemaker for your brain: a pulse generator sits under the skin of your upper chest, connected by a thin wire that wraps around the vagus nerve. Every few minutes, it delivers a burst of electrical stimulation that travels up the nerve into the brainstem, modulating activity in regions that control seizures, mood, inflammation, and autonomic function.
How the Device Works
The standard implanted VNS system consists of two components: a titanium-encased pulse generator roughly the size of a silver dollar, and a lead wire with helical electrodes that coil around the left cervical vagus nerve. The left side is used because the right vagus nerve has more direct cardiac innervation, and stimulating it carries a higher risk of heart rhythm disturbances.
The generator delivers electrical pulses in cycles, typically 30 seconds on and 5 minutes off, though your neurologist programmes these parameters to your specific needs. Key settings include current intensity (usually 0.25 to 3.0 milliamps), pulse width (typically 250 or 500 microseconds), and frequency (usually 20 or 30 Hz). These are adjusted gradually over months to find the combination that provides the best benefit with the fewest side effects.
The electrical signals travel up vagal afferent fibres to the nucleus tractus solitarius (NTS) in the brainstem, which has projections to the locus coeruleus, thalamus, amygdala, and widespread cortical areas. This is how a nerve stimulator in your neck can influence brain circuits involved in seizure propagation, mood regulation, and neuroinflammation.
Approved Uses
The FDA first approved VNS for drug-resistant epilepsy in 1997, based on the E03 and E05 pivotal trials showing meaningful seizure reduction in patients who had failed multiple medications. A 2016 meta-analysis by Englot and colleagues, pooling data from over 5,500 patients, found that about 51% achieved a 50% or greater reduction in seizure frequency, with benefits continuing to improve over 1 to 2 years of use. VNS does not typically eliminate seizures entirely but can meaningfully reduce their frequency and severity.
In 2005, the FDA approved VNS for treatment-resistant depression in adults who had failed at least four adequate antidepressant treatments. The evidence here is more modest: initial controlled trials showed mixed results, but longer-term registry data suggested gradual improvement in depressive symptoms over 12 to 24 months. Response rates are lower than for epilepsy, and VNS for depression remains a last-resort option.
In July 2025, SetPoint Medical received FDA approval for a different type of implanted vagus nerve stimulator to treat rheumatoid arthritis, targeting the cholinergic anti-inflammatory pathway described by Kevin Tracey in 2002. This was the first non-neurological approval for VNS and marked a significant expansion of the technology’s clinical applications.
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The Implantation Procedure
VNS implantation is a relatively straightforward surgical procedure, typically performed under general anaesthesia and lasting 1 to 2 hours. The surgeon makes two small incisions: one on the left side of the neck to access the vagus nerve, and one on the upper left chest to create a pocket for the pulse generator. The lead wire is tunnelled under the skin between the two sites. Most patients go home the same day or the following morning.
The device is usually not turned on for 2 to 4 weeks after surgery, allowing the surgical site to heal. Stimulation then begins at low settings and is gradually increased over several clinic visits, a process called ramping that typically takes 3 to 6 months to reach therapeutic levels.
What It Feels Like
During the on-time (when the device is actively stimulating), most people feel a tingling or vibrating sensation in the throat and notice a change in their voice, often described as hoarseness or a slight catch. Some experience mild shortness of breath or a cough during stimulation. These sensations are generally mild and predictable since you know when each cycle is occurring. Many patients report that they stop noticing the sensations after several months.
The devices made by LivaNova (the primary manufacturer) include a handheld magnet that allows patients to trigger an extra burst of stimulation when they feel a seizure coming on, or to temporarily turn off stimulation during activities like public speaking or singing where voice changes would be problematic.
Current Devices and Battery Life
LivaNova’s current models include the SenTiva (approved 2017) and its successors, which offer features like scheduled stimulation changes, automatic detection of cardiac-rate changes associated with seizures (in the AspireSR model, approved 2015), and smaller generator sizes. Battery life depends on stimulation settings but typically ranges from 5 to 10 years, after which the generator is replaced in a minor outpatient procedure. The lead wire usually remains in place permanently.
Newer closed-loop systems aim to detect seizure-related biomarkers and deliver stimulation only when needed, rather than on a fixed schedule. This responsive approach could improve efficacy while reducing unnecessary stimulation and extending battery life.
Non-Invasive Alternatives
If you are interested in vagus nerve stimulation but not a candidate for surgery, non-invasive options exist. The gammaCore device (electroCore) delivers transcutaneous cervical VNS through the skin of the neck and has FDA clearance for cluster headache and migraine. Transcutaneous auricular VNS (taVNS) targets the auricular branch of the vagus nerve in the ear and is used in research settings for conditions from epilepsy to depression. These devices produce more modest effects than implanted VNS but carry essentially no surgical risk.
The choice between implanted and non-invasive stimulation depends on your condition, its severity, and what other treatments you have tried. Implanted VNS remains the option with the strongest evidence base, particularly for drug-resistant epilepsy, but it is reserved for cases where less invasive approaches have proven insufficient.
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