Vagus Nerve Stimulation (VNS)

Vagus nerve stimulation (VNS) is a form of neuromodulation used for patients with drug-resistant epilepsy. A thin wire is wrapped around the vagus nerve in the neck and connected to a small pulse generator implanted under the skin of the chest, similar in appearance to a cardiac pacemaker. The device delivers regular, intermittent electrical pulses to the vagus nerve, which in turn affects electrical activity in the brain in a way that can reduce the frequency and severity of seizures in many patients.

VNS is generally considered for patients with drug-resistant epilepsy who are not candidates for resective surgery (surgery to remove or disconnect a specific seizure focus), or for whom resective surgery has not been fully successful or is not desired.

VNS is generally considered for patients with confirmed drug-resistant epilepsy (seizures continuing despite adequate trials of appropriate anti-seizure medications) following evaluation by a multidisciplinary epilepsy team. It is most often used when imaging and seizure monitoring do not identify a single, safely removable seizure focus, or when a patient prefers not to pursue resective brain surgery.

A surgical evaluation for VNS is typically considered once drug resistance is established and resective surgery has been assessed as not appropriate, not desired, or not fully effective, following multidisciplinary epilepsy team review.

Implantation is generally a single, relatively brief outpatient or short-stay procedure performed under general anesthesia. A small incision is made in the neck to place a thin, spiral lead around the vagus nerve, and a second small incision below the collarbone allows the pulse generator to be implanted under the skin, connected to the lead by a wire tunneled under the skin. The device is programmed to deliver stimulation automatically on a set cycle (for example, a period of stimulation followed by a period of rest, repeating continuously), and most devices also allow the patient or a caregiver to trigger an extra dose of stimulation using an external magnet, for example at the first sign of a seizure (an “aura”), which can help shorten or lessen some seizures.

• Confirmation of drug-resistant epilepsy by an epilepsy specialist
• Video-EEG monitoring and brain MRI, to help confirm that resective surgery is not a more suitable option
• Multidisciplinary epilepsy team review
• General health assessment for a minor surgical implant procedure

The realistic goal of VNS is a meaningful reduction in seizure frequency or severity, and for some patients a reduction in how long seizures last or how long it takes to recover afterward. Complete seizure freedom is uncommon with VNS and is not the treatment’s usual goal. Benefit typically develops gradually over months as stimulation settings are adjusted, rather than immediately after implantation.

Surgical risks are generally modest and include infection, and rarely, temporary or persistent hoarseness or other voice changes, cough, or throat discomfort related to the nerve being stimulated, some of these effects can occur intermittently during each stimulation cycle rather than constantly. As with other implanted stimulators, the device has a battery that is eventually replaced in a further minor procedure. VNS does not work equally well for every patient, and, as noted above, complete seizure freedom is not the typical outcome.

Most patients go home the same day or after a short stay. Stimulation is usually started a few weeks after implantation and increased gradually over subsequent visits to a level that is effective and well tolerated, since higher stimulation intensity can increase voice-related side effects. Regular follow-up continues to adjust settings and assess seizure control over time, in coordination with the patient’s neurologist.