Vagal nerve stimulation (VNS)
Vagal nerve stimulation therapy explained
VNS is not brain surgery; it involves implanting a device (similar to a pacemaker) under the skin just below the left collarbone or close to the armpit. A second small incision is made in the neck to attach two tiny wires to the vagus nerve. The wires are threaded invisibly up the neck from the device to the vagus nerve. The device (a pulse generator), will send small electrical pulses to the vagus nerve in the neck. These pulses are delivered to where the seizures are thought to start in the brain and may help to prevent the abnormal electrical activity that causes seizures. The pulse generator works at intervals 24 hours a day, every day.
Implanting the device is much less invasive than brain surgery for epilepsy. It involves a simple surgical procedure, which involves only a short stay in hospital.
People that have failed to adequately respond to several anti-epileptic medications or are thought to have epilepsy that is difficult to treat.
The benefits of VNS
It is less likely that you will become seizure free than with resective surgery. More than 40% of patients may have a 50% reduction in the number of seizures over time. You will also be given a magnet. By swiping the VNS therapy magnet over the pulse generator when you feel a seizure coming on or during a seizure, some people find it can stop or shorten the duration of the seizure. It may also improve the recovery period following a seizure.
The effects can take a few months or up to two years to reach their optimum level.
After the device has been implanted
Initially, you will be reviewed as an outpatient about once a month to have your seizure frequency reviewed. The epilepsy nurse specialist will read and adjust the stimulation settings. This is painless and can be done through your clothes. Over time, these visits may become less frequent. Once you have reached the best setting for you – which means your best level of seizure control with as few side effects as possible, you will be seen every six months to check the stimulator settings and to review the battery life.
The battery has a life of between three and eight years depending on your settings. When the battery is nearing the end of its life, it will be arranged for you to return to hospital to have a small operation to replace the battery.
For more information visit the Cyberonics website.
Image and text courtesy of 'VNS therapy an introduction for patients' a patient explanation brochure produced by Cyberonics who manufacture the VNS devices.