What do I need to know?

  • A vagus nerve stimulator does not require brain surgery 
  • Children who have tried fewer medications before VNS surgery have better results
  • The device is more successful if it is implanted less than five years after seizures start

  • Almost 75% of children experience a worthwhile benefit

  • 50% of children will have a 50% reduction in seizures
  • VNS is a palliative surgery. This means that it is not meant to stop seizures – only reduce them.

How does vagus nerve stimulation reduce seizures?

The vagus nerve is a long fiber that connects the brain to the throat, heart and digestive system. It controls heart rate, digestion, sweating, speech, chewing, and the gag reflex.

When the vagus nerve is stimulated with mild electrical impulses that are carried to the brain, seizures can slow down or reduce in frequency. This technique is known as vagal nerve stimulation (VNS).

What is a VNS device?

Vagus nerve stimulators are made by Livanova, a U.S. company based in Houston, Texas. Livanova makes severe different types of vagus nerve stimulators.

Device Name Description
Demipulse Open loop – requires the user or caregiver to swipe a magnetic wand over the device to generate the electrical impulse.
AspireHC Open loop – requires the user or caregiver to swipe a magnetic wand over the device to generate the electrical impulse.
AspireSR Closed loop – uses high heart rate (tachycardia) to sense seizure. Can be programmed to prevent seizures by providing electrical impulses to the vagus nerve on a schedule. It can also respond to an increase in heart rate, or stop/slow down a seizure by waving a wand over the magnet.
SenTiva Closed loop – uses high heart rate (tachycardia) to sense seizures and automatically provide a responsive electrical impulse to the vagus nerve.  Software logs low heart rate and whether child is lying face down. Can be programmed for different impulse frequency depending on day or night.  allows day-night programming, scheduled programming and logging of low heart rate and prone position events.

What is involved in surgery to implant a VNS device?

Surgery to implant a VNS device does not require brain surgery.

The VNS device is usually placed on the left side of the body. The surgeon will make a small pocket under the skin below the clavicle and above the pectoral muscle. The device is placed in the pocket. Sometimes it is placed on the right side of the chest.

Special leads from the device are tunneled under the skin and then wrapped around the vagus nerve in the neck by the surgeon.

VNS devices are battery-powered. The device is not activated until two weeks after surgery to avoid affecting the heart.

Surgery to implant a VNS device takes one to two hours under general anesthesia. It can be performed on an inpatient or outpatient basis.

The device’s battery lasts about six years. Surgery is required to replace the device with a new one with a fresh battery. This surgery involves opening up the chest wall with a small incision. It usually takes an hour or less for this surgery.

Who should consider VNS therapy?

Vagus nerve stimulation may be appropriate for patients:
  • with drug-resistant epilepsy (failed two adequate trials of two anti-seizure medications) and
  • who are not good surgical candidates or
  • who continue to experience seizures after resection.

What are the seizure control rates of VNS devices?

It’s important to understand that VNS devices do not cure seizures. These devices are considered palliative. This means they are designed to reduce or slow down seizures. However, about one in ten children do experience seizure freedom with VNS devices.

New research published in 2021 reports on VNS outcomes twenty years after surgery. The study looked at 76 children who had VNS devices implanted.

  • 51% of children had ≥ 50% reduction in seizure frequency;
  • Almost 75% experienced a “worthwhile benefit” or better;
  • 15% of children were seizure-free at follow-up.

When should a VNS device be placed in a child?

It’s clear that children with drug-resistant epilepsy benefit from early VNS. New research shows that VNS is most effective if placed within five years of epilepsy diagnosis. Children under six years old usually have the most dramatic benefit in seizure reduction.

Studies have found that patients with the best outcomes had:

  • shorter time having seizures before VNS therapy;
  • seizures started at a later age;
  • fewer anti-seizure medications were tried before VNS therapy.

Research shows that children have better outcomes than adults with VNS treatment.

Seizure outcomes by condition

Genetic mutations and other conditions often contribute to epilepsy. Some conditions have been studied more than others.

For example, VNS has been used for many children with tuberous sclerosis complex. Other conditions require more data before .

Research shows that the responder rate (at least a 50% reduction in seizures) by condition is as follows:

Condition % of children who responded to VNS
Dravet syndrome 41%
Doose syndrome 78%
Idiopathic epilepsy* 51%
Lennox-Gastaut syndrome 58%
Post-traumatic epilepsy 79%
Rett syndrome 82%
Tuberous sclerosis complex 68%

VNS has also been used to treat patients with mitochondrial disease, Landau-Kleffner syndrome, Aicardi syndrome, Angelman syndrome, ring chromosome 20 syndrome, hypothalamic hamartoma, lissencephaly, Down syndrome, autism, and absence and other primary generalized epilepsies.

VNS has a higher response rate in generalized epilepsy than partial epilepsy.

What age can a child have VNS surgery?

VNS is approved for children who are at least four years old; however, some surgeons are implanting the device “off-label” in younger children.

How soon before we see results?

A child’s response to VNS is not immediate. Instead, seizures usually improve over 12-18 months after the device is implanted. Though the device does not typically eliminate seizures, it can boost the effectiveness of other treatments and may be a good alternative to surgical procedures such as corpus callosotomy.

Researchers have found that VNS may also help improve the quality of life in children with seizures and other neurological challenges, even without seizure reduction. These improvements include:

  • daytime alertness;
  • reduction in behavioral challenges;
  • improved communication;
  • better mood (VNS is also FDA-approved for depression);
  • improved seizure severity, faster recovery from seizures, and less frequent seizures;
  • decreased status epilepticus (two years after implantation);
  • reduction in anti-seizure medication.

What are the risks of VNS device implantation?

Children with cognitive challenges may pick at or place fingers on the incision site. This can increase the chance of infection. About one in ten patients needed the device removed and reinserted because of this. To help these children, doctors have implanted the device in alternate locations, including under the pectoral muscles.

One of the most common side effects is voice hoarseness, which can affect 40 percent of children with VNS devices. These effects typically disappear within 5 years of implantation. Changing the location of the implant using a lower neck incision may reduce the risk of this side effect.

Children who have a hard time swallowing or are less alert before surgery are more likely than others to aspirate food and may need close supervision after VNS implantation.

Less than 1 in 10 children will experience complications from device implantation. These complications can include infection and fractured lead wires that require reoperation.

Corpus callosotomy vs. VNS for drop attack seizures

Patients with generalized epilepsy, particularly atonic or drop attack seizures, often consider vagus nerve stimulation or another surgical procedure called corpus callosotomy. Corpus callosotomy is when the surgeon disconnects the largest of the seven connections between the two hemispheres of the brain.

A 2021 study compared VNS to corpus callosotomy. They found that corpus callosotomy is more effective for certain tonic seizures. There’s about a 70% chance that drop attack seizures will improve with corpus callosotomy and a 20% chance with VNS.

A new approach to corpus callosotomy uses a laser ablation approach to avoid a craniotomy. Talk to your child’s neurosurgeon about the best approach for your child.

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