Responsive Neurostimulation

What is responsive neurostimulation (RNS)?

Responsive neurostimulation (RNS) is a surgically implanted device that treats seizures. It delivers tiny amounts of electricity to your brain during periods of seizure activity. The RNS® System monitors and detects brain waves in the part of your brain where seizures start. When it notices abnormal electrical activity, it responds very quickly by stimulating that area of your brain with a series of electrical pulses. This electrical energy, over time, decreases your brain’s ability to generate seizures.

A healthcare provider can adjust the RNS System as needed to meet your treatment needs after a surgeon implants the device. A surgeon can also remove it if needed. The RNS System doesn’t cure epilepsy, but it may reduce how many seizures you experience.

What does responsive neurostimulation treat or manage?

RNS may help you manage seizures caused by epilepsy. A healthcare provider may consider this as a treatment option if antiseizure medications aren’t effective. They may also recommend this if other types of epilepsy surgery aren’t possible due to safety concerns or if the outcome of a previous surgery wasn’t successful.

The U.S. Food and Drug Administration (FDA) approved RNS to treat seizures that start in one part of the brain (focal seizures) and don’t respond to other types of treatment. It’s safe for people who are 18 years of age or older.

How should I prepare for responsive neurostimulation surgery?

Your surgeon will make sure you’re healthy enough for the procedure. They’ll perform a physical and a neurological exam, and review your medical history and seizure description history. Let them know if you have any allergies and bring a list of any medications or supplements you regularly take.

You’ll need to undergo testing before the date of your procedure to help your surgeon find the area of your brain where seizures start. This is where they’ll place the RNS electrodes that will help regulate any seizure activity. Your pre-surgery testing may include:

• Video-EEG monitoring
• MRI
• PET scan
• Magnetoencephalography (MEG)
• Ictal SPECT
• Neuropsychiatric testing
• Intracranial EEG monitoring (SEEG or subdural evaluation)

Your provider will also give you instructions specific to your situation. This may include:

• Getting other tests (like blood tests, for example)
• Making changes to the antiseizure medications you take (under your provider’s guidance only)
• Avoiding triggers that increase the likelihood of seizures
• Changing the foods you eat (like starting the ketogenic diet)

What happens during responsive neurostimulation surgery?

On the day of your surgery, an anesthesiologist will put you to sleep using general anesthesia. This is so you won’t feel any pain.

Once you’re in the operating room, your surgeon will:

1. Shave an area of your head where they’ll make a cut (incision). Don’t worry, your hair should grow back after the procedure.
2. Make an incision into your skin and an opening into your skull (craniectomy).
3. Guide very thin wires (electrodes*) to reach the part of your brain where seizures start. These electrodes will eventually be used to detect your brain’s electrical activity and deliver electrical pulses.
4. Place the RNS device just above your brain and in line with your skull. This device houses a computer that analyzes brain activity. Your provider will program it to deliver electrical pulses to your brain. The device is constantly recording information, which helps program the device.
5. Test the device to make sure it’s working properly.
6. Close the incision site.

*These electrodes may be depth electrodes, which your surgeon can place into deep structures of your brain. There’s another type of electrode, called strip or subdural electrodes, which your surgeon will place over the surface of your brain. Your surgeon will decide what type of electrode to use and where it will go before surgery begins.

How long does responsive neurostimulation surgery take?

It usually takes about two to four hours to implant an RNS device.

What happens after responsive neurostimulation surgery?

After surgery, you’ll rest in the hospital. You may need to stay overnight or up to three days in the hospital to make sure you’re healing as expected.

Typically, the device may begin the programming process during your surgery to begin “listening” or detecting potentially abnormal brain signals. The device is usually not programmed to deliver electrical pulses until after you heal from surgery. This could take two to four weeks. You’ll return to your provider’s office, and they’ll turn it on to begin the stimulation treatments.

Your provider will start the electrical stimulation pulses at a low setting. They may increase the settings slowly until they find a level that works well to manage your symptoms. They’ll also fine-tune the detection programming of your device so it better detects your specific abnormal epileptic brain signals.

There’s a lot of information that the device can provide to your physician. The data from the device can be downloaded when you’re home.

The RNS device company will provide you with a computer that has a wand. You place the wand over the device. The computer will download the data and send the data to a secure website called the Patient Data Management System (PDMS). Your physicians will have access to the PDMS data, and they can share details with you, such as how many seizures the device recorded and what time of day these seizures are occurring.

Physicians can use this data to make other decisions, like changing a medication dose during times when epileptic activity is more frequent. Your physician will also download data during your follow-up visits. They can show you and explain what the data looks like.

What are the benefits of responsive neurostimulation?

The benefits of an RNS device may include:

• You may have fewer seizures over time.
• You may need to take less antiseizure medications.
• It may give you longer periods without seizures.
• It may improve your quality of life (like physical health, cognitive functioning, stress and mental health).

What is the success rate of RNS?

The RNS System has a good success rate. Many people report fewer seizures in the years following surgery. In a nine-year study, the typical patient had about a 75% reduction in the amount of seizures over nine years of treatment. This means that if you had about 10 seizures per month prior to starting RNS, then you may be down to three seizures a month after nine years of treatment. There were 18% of study patients who were seizure-free for more than one year during the study.

What are the side effects of responsive neurostimulation?

RNS surgery comes with possible risks. While rare, these may include:

• Bleeding
• Infection
• Pain
• Brain damage
• Device stops working
• No improvement in seizures

There are typically no persistent side effects from electrical stimulation, as the stimulation is tested in the office with your physician to ensure that you’re tolerating it well.

When should I call my healthcare provider?

Contact your healthcare provider if you notice symptoms after surgery like severe pain, bleeding or swelling at the incision site.

Once your provider turns on the RNS device, let them know if you experience any symptoms that are uncomfortable like feeling lightheaded, vision changes or numbness. The RNS System is adjustable, so your provider can make changes to the amount of stimulation you receive if it’s unpleasant.

What is the recovery time for RNS surgery?

You should be able to return to your daily routine when you leave the hospital. Be careful not to overwork yourself and don’t participate in strenuous activities unless your provider approves it. You may return to work or school in two to four weeks. Your provider will make sure you’re healing as expected during follow-up visits. It could take up to eight weeks to make a complete recovery.

How long does an RNS device battery last?

The average RNS device battery, from the most recent device, can last up to eight to 10 years. The battery life varies based on frequency of use and type of battery. Your provider will let you know what you can expect.

To replace the battery, you don’t need to replace the entire device. A surgeon can perform a smaller procedure where they open the previous incision site, replace the battery and then, close the incision while leaving the original electrodes in place.