Stimulation Devices for Epilepsy Treatment

Epilepsy, EEG
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Medication has provided good control of seizures for the majority of people with epilepsy, but almost a third continue to have their lives disrupted by seizures. In addition to pharmaceuticals, other approaches using electrical devices are also being explored to control seizures in epilepsy. Existing techniques include vagal nerve stimulation, and responsive neurostimulation, and deep brain stimulation.

Vagal Nerve Stimulation (VNS)

VNS was approved by the US Food and Drug Administration in 1997 for treatment of partial-onset seizures, in combination with medication. The device looks something like a pacemaker, but instead of stimulating the heart muscle, it stimulates the vagal nerve. This large cranial nerve controls many important functions. For example, it relays parasympathetics to the heart to help slow down the heart rate and is also important in both speech and swallowing. Just why it helps reduce seizures when stimulated remains a bit unclear, but in selected patients, it can reduce seizures by up to 50%.  It is rare, however, that VNS stops seizures entirely.

A vagal nerve stimulator about 4 cm across is placed under the skin of the chest. A wire then runs to the vagal nerve in the neck. The device is typically activated 2-3 weeks after implantation. The timing and strength of the electrical stimulation can be tailored to the needs of each individual.

The device can also be triggered manually by means of a special magnet if someone feels as if they are about to have a seizure.

The implantation of the device is usually well tolerated. In about 1:1000 cases, the heart may slow or even stop. Vocal cord dysfunction may also occur. About 65% of people experience voice alteration due to the nerve’s stimulation.

VNS may also worsen any preexisting obstructive sleep apnea. For this reason, polysomnography should be considered before implanting VNS.

Deep Brain Stimulation (DBS)

Deep brain stimulation has been used quite successfully to treat diseases like Parkinson's and has also been explored for treatment of other problems like depression. In epilepsy, the idea is to manipulate the brain’s electrical rhythms in a manner that reduces the frequency and severity of seizure by stopping abnormal electrical rhythms. DBS has not yet been approved in the United States but has been explored to treat epilepsy in much of Europe.

The procedure involves two small wires threaded through holes drilled in the skull. The ends of these wires are placed in part fo the brain such as the anterior nucleus of the thalamus. Similar to VNS, it can take some time to find the right combination of stimulation settings to help each person.

In one large study, side effects of DBS included death, infection, hemorrhage, and status epileptics.

 Such serious side effects were rare, however. In one review, shortly after the surgery, 12.7% of patients suffered infection, and 4.5% had  intracranial hemorrhage. Once the stimulation began, about 22.7% had ​tingling and 3.5% had depression.

Responsive Neurostimulation (RNS)

The Neuropace RNS system (NeuroPa, Inc: Mountain View, CA) was approved by the FDA in 2013. This device is implanted under the skull and measures the brain’s electrical activity looking for signs of a coming seizure. If such abnormal electrical activity is found, the device tries to disrupt the aberrant signal with an electrical stimulation. As with VNS or DBS, a period of time is required while working with a programmer to find the best settings.

The median percentage of seizure reduction has been reported at about 39% at one year and 51% at 2 years. Few serious adverse events have been reported, though some patients did have pain and headache around the implant site. About 2.7% of patients had intracranial hemorrhage in another analysis.

In short, there are a number of different options available for people with epileptic seizures not fully controlled by medication, but who are unable to undergo more significant neurosurgery.


Casey H. Halpern, Uzma Samadani, Brian Litt, Jurg L. Jaggi, and Gordon H. Baltuch. Deep Brain Stimulation for Epilepsy. Neurotherapeutics. 2008 Jan; 5(1): 59–67.

Pawan V Rawal MD MHA, Side Effects of Epilepsy Treatment, The Neurology Report Volume 8 Number 1

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