Implantable neuromodulation devices for drug resistant epilepsy

If you’ve been diagnosed with epilepsy, there are several kinds of treatments available. One option is neuromodulation. This includes devices that are approved for the treatment of drug resistant (also known as ‘intractable’ or ‘refractory’) focal epilepsy in the United States.

There are several kinds of neuromodulation devices, but currently only implanted devices are approved for the treatment of drug-resistant epilepsy. Implanted neuromodulation devices send an electrical signal to the nervous system. For some people, this can significantly reduce the number of seizures they have.

Neuromodulation devices are an add-on therapy. This means this therapy is used together with anti-seizure medications and people continue taking their medications while using the device.

If you have any questions about neuromodulation, talk to your doctor. In this article, you’ll learn about what neuromodulation is, and the three kinds of neuromodulation devices approved to treat drug resistant epilepsy.

What is neuromodulation?

The human nervous system is made up of billions of cells working together in highly complex ways. These cells send electrical and chemical signals through the brain and throughout the body to control everything from heart rate to digestion to movement and much more.

Epilepsy is a condition where the brain's nerve cells send the wrong signals. This lack of regulation of electrical activity in the brain can lead to seizures.

Some types of epilepsy can be treated by using neuromodulation devices. These devices work in different ways, but generally deliver small pulses of electricity into the nervous system.

In addition to drug-resistant epilepsy, neuromodulation has also been explored in other neurological conditions, including:

• Movement disorders
• Chronic pain
• Psychiatric disorders
• And more

Implanting the devices

To implant a neuromodulation device, you will need to have surgery. Epilepsy specialists will do tests to work out if neuromodulation is suitable for you. If it is, they’ll decide on which kind of device is best suited to your needs.

The implantation method is a bit different depending on the type of device - see more details in each section below.

What kinds of epilepsy are neuromodulation devices approved for?

Neuromodulation devices are not suitable for treating all kinds of epilepsy. Ask your doctor if they think they would be suitable for you. Using neuromodulation devices may be suitable if:

• ⁠You have drug resistant epilepsy: Neuromodulation devices may be an option if you have drug resistant epilepsy. This is when you have tried two or more appropriately-chosen anti-seizure medications (ASMs) but you haven’t achieved seizure freedom while using them. While ASMs can help many people to manage their seizures, roughly one third of adults have drug resistant epilepsy. If medication doesn’t appear to be stopping your seizures, talk to your doctor. Depending on your situation, your doctor may suggest other kinds of epilepsy treatment - including neuromodulation therapy.

• You have focal seizures: In the United States, neuromodulation devices are currently approved for people who have focal epilepsy. These devices are used as add-on treatments, which means you will still need to take your anti-seizure medications (ASMs).

Neuromodulation devices for drug resistant epilepsy

In the United States, there are three kinds of neuromodulation devices that are approved to treat drug resistant focal epilepsy. These are:

• Deep brain stimulation (DBS)
• Responsive neurostimulation (RNS)
• Vagus nerve stimulation (VNS)

Here is an overview of the three kinds of neuromodulation devices approved for epilepsy treatment in the United States. If you have any questions about these devices, ask your doctor.

Deep brain stimulation (DBS)

With DBS, two tiny wires are inserted deep into the brain. The wires are connected to an ‘extension’ wire outside the skull that is attached to a pulse generator. The generator is usually placed under the surface of the skin near the collarbone.

The DBS generator sends regular electrical pulses deep into the brain.

Important to know:

• It was approved by the FDA in 2018
• In the USA, it’s approved for adults (18+)
• It’s approved for focal seizures or for focal seizures that turn into generalized seizures
• It is approved for patients that have tried three or more ASMs but continue to have seizures
• It is approved for patients who averaged 6+ seizures per month for the previous three months

Responsive neurostimulation (RNS)

With RNS, the device is placed flush with the skull. Then, tiny wires are fed to the part of the brain where doctors believe your seizures start from (the wires can go to one or two places or ‘foci’).

This generator monitors brain activity continuously and is programmed to recognize the individual’s seizure patterns and automatically respond to these abnormal patterns by sending an electrical pulse. It only delivers brain stimulation when it detects abnormal brain activity.

Important to know:

• It was approved by the FDA in 2013
• In the USA, it’s approved for adults (18+)
• It’s approved for people with frequent and disabling focal seizures, with or without secondary generalized seizures
• It is approved for patients that have tried two or more ASMs but continue to have seizures
• It is approved for patients who average 3 or more disabling seizures per month over the three most recent months

Vagus Nerve Stimulation (VNS)

With VNS, the pulse generator is placed under the skin in your chest. A wire is then fed to the left vagus nerve in your neck. The VNS generator sends regular electrical pulses that stimulate the nerve, which then sends stimulation into the brain.

VNS devices also come with a magnet, which can be swiped across the implant in the wearer’s chest. This swipe then sends an extra pulse of electricity to the nerve which may help stop or shorten a seizure if the person feels one coming on.

Important to know:

• It was approved by the FDA in 1997
• In the USA,VNS is approved for people aged 4+
• It’s approved for people with focal seizures
• It is approved for patients that have tried two or more ASMs but continue to have seizures
• There is not a minimum number of seizures you must have to be a candidate for VNS

Considering neuromodulation devices for epilepsy

Neuromodulation devices can be added as an additional therapy to help people whose epilepsy is not controlled by ASMs alone to improve seizure control. If you are interested in this kind of treatment, talk with your doctor. If these devices are suitable for you, your doctor may refer you to an epilepsy center, where specialists will perform tests to determine which neuromodulation device is right for you.