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Treatment: Surgery

The first step in deciding whether someone should have epilepsy surgery is to make sure that the seizures are medically refractory, or uncontrollable with anti-epileptic drugs.

After a patient’s seizures are confirmed to be medically refractory, a series of pre-operative diagnostic tests are performed to identify the area of the brain from which the seizures arise and the areas that control vital functions such as language, memory, movement, and sensation. Doctors hope to find that the seizures arise from an area that is not vital for intellectual or other important functions. Some areas of the brain can be removed without any observable or measurable changes in intellect, personality, or mood. The removal of other areas may be associated with slight deterioration or, in some cases, actual improvement in memory or other vital functions.

Many potential surgical candidates select the risks and benefits of surgery over the disadvantage and medication burden that accompanies refractory seizures. Over the past three decades, important strides have been made in developing new technologies and surgical techniques that have made surgical intervention both safe and effective.

Vagus Nerve Stimulation (VNS)
Vagus Nerve Stimulation is a non-drug treatment for epilepsy that utilizes the vagus nerve to send signals to the brain.  The vagus nerve, or cranial nerve X, is the longest cranial nerve which travels near the carotid artery and jugular vein from the brainstem, down the neck and into the chest and abdomen to influence activity in many organs.  It is a part of the autonomic nervous system, which controls functions of the body that are not under voluntary control, such as the heart rate and digestion.

Interestingly, neurologists in the 19th century noted that applying pressure on the carotid artery in the neck, and thus the vagus nerve, could stop seizures. Recent research has found that stimulation of the vagus nerve in animals decreases both epileptic activity in the EEG and the frequency and severity of seizures.  After proven seizure reduction in animals using VNS, several controlled human trials demonstrated a significant reduction in seizures with minimal side effects. In 1997, the FDA approved vagus nerve stimulation in patients older than 12 with refractory partial epilepsy. Mounting clinical experience also demonstrates efficacy and safety in children and in patients with generalized epilepsies.

The treatment consists of a patient having a VNS device implanted that will send small electrical signals from the device to the vagus nerve and therefore, up into the brain. The device is programmed by the doctor to deliver these signals (or “stimulate”) at periodic intervals.

What is Vagus Nerve Stimulation (VNS) Surgery?

Vagus Nerve Stimulation (VNS) surgery involves the surgical implantation of a stimulating device, a 6 centimeter wide disc which resembles a pacemaker. An incision is made along the outer, left side of the chest where the device is then implanted under the skin. A second incision is made horizontally in the lower neck, along a crease of skin, and the lead from the stimulator is wrapped around the vagus nerve.

Initially, stimulation is usually set to occur for 30 seconds every five minutes. The doctor then adjusts these parameters according to patient tolerance and seizure response in follow-up visits. The patient also has a degree of control over the VNS. Each patient receives a magnet that activates the device. When the patient or caregiver “swipes” over the device with the magnet, the VNS turns “on” and delivers a stimulus. This allows a patient who feels an aura coming on, or a caregiver who sees the start of a seizure, to try to stop the seizure.

Compared to standard epilepsy surgery, VNS surgery is relatively minor. The brain itself is NOT surgically involved in VNS surgery. The procedure takes 1-2 hours, requires general anesthesia, and most patients return home the same day of surgery. The device battery lasts for approximately 5 years, after which many patients choose to have repeat surgery to replace the battery.

Are There Any Risks Involved?
As with any treatment, you will need to discuss your risks with your doctor, however, the risks of implantation are low and mostly include the minor surgical risks of bleeding or infection (about 1-2%). Less than1% of implants cause some damage to the nerve supplying muscles in the voice box, which can result in intermittent hoarseness or a change in voice quality. This typically improves within a few months.

What Are the Side Effects of Vagus Nerve Stimulation?

At first, patients may notice a tingling in the neck during the 30 or so seconds that the stimulator is “on.” In addition, when the vagus nerve is stimulated, about one third of patients have some change in their voice quality, which is reversible by reducing the amount of stimulation or adjusting other stimulation features. Even without any change in the level of stimulation, the hoarseness and changes in voice quality tend to diminish and resolve over several weeks or months. Rare side effects include change in swallowing (usually during stimulation), cough or shortness of breath.

What is the Success Rate of VNS Therapy?
Studies have shown that:

• About 1/3 of patients have had the number of their seizures reduced by half or more; less than 5% of patients become seizure free.
• About 1/3 have shown benefit but have had their seizure frequency reduced by less than half.
• About 1/3 have had no worthwhile benefit.

Who is Eligible for VNS Surgery?
The vagus nerve stimulator was approved by the FDA for use in patients with refractory partial epilepsy who are 12 years of age or older. It was also approved for use in patients with refractory depression. Many centers have successfully used the device in younger children (as young as 1 year of age) and in patients with primary generalized epilepsy, Lennox-Gastaut syndrome, Landau-Kleffner syndrome, and other seizure disorders.

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Dr. Roy Sucholeiki, MD