What is responsive neurostimulation?

Responsive neurostimulation (RNS) is a surgical treatment for seizures in which a neurostimulator implant device monitors brain activity and delivers electronic stimulation when a seizure is detected. The mild electrical pulses act to prevent or shorten the seizure.

A small battery-powered device is implanted in the skull, under the scalp, with one or two wires leading to points on or within the brain where seizure activity is originating. The wire ends sense abnormal brain activity and give off electrical stimulation.

Who is a candidate for responsive neurostimulation?

Responsive neurostimulation is considered as a treatment for patients who have focal seizures originating from one or two points in the brain, that are not able to be controlled by medications, after at least two medications have been tried.

In some cases, seizures may originate deep in the brain or close to brain tissue that controls critical functions. In these cases, responsive neurostimulation can be an alternative to traditional surgical procedures that remove the brain tissue, reducing the risk of neurologic deficits.

How is responsive neurostimulation surgery performed?

At CHOP's Neuroscience Center, responsive neurostimulation surgery is performed while a child is under general anesthesia.

An incision is made in the scalp and an opening is cut in the skull just large enough to place the neurostimulator implant device. The wires are positioned with the leads at the points in the brain where the seizures originate. The neurostimulator device is attached to the skull to align with its outer surface, and the skin of the scalp is then closed over it.

How effective is responsive neurostimulation?

While everyone's seizures may respond differently, three out of four patients at CHOP who have had an RNS device for 6 months or more reported a 50% or more reduction rate in their seizures, and nine out of 10 patients reported less severe seizures compared to their baseline before their RNS device was implanted.

What to expect during responsive neurostimulation surgery

Before responsive neurostimulation surgery

Before starting responsive neurostimulation surgery, tests are done to identify the point or points in your child’s brain where the seizures originate. This usually includes stereo-electroencephalogram (sEEG). Imaging is performed before surgery to ensure the wires are robotically placed in the precise location of the onset of your child’s seizures. The neurostimulator implant device is placed where it will be least noticeable under your child’s hair.

On the day of the surgery and immediately after

On the day of the surgery, your child will undergo general anesthesia. At Children’s Hospital of Philadelphia (CHOP), you can trust our specially trained pediatric anesthesiologists to keep your child comfortable and safe before, during and after their procedure. Read more about our dedicated pediatric anesthesiology team.

The surgery itself takes three to four hours.

Your child will stay in our specialized Neuroscience Unit overnight for recovery and may be released the next day or two to three days later. No extended bed rest is required.

Going home after responsive neurostimulation implantation

Your child will be able to return to normal activities within a few days after returning home.

Once each day, you will use a remote monitor to collect data from the neurostimulator, a process that takes a few minutes. Once a week, you will upload the data to a secure Web database where your child’s medical team can review it.

When you or your child notice a seizure, you will swipe a special magnet over the device, which will prompt the device to store data about brain activity immediately before and after the seizure. That information will then be transmitted to your care team in the weekly upload. The medical team will use the data to fine-tune the sensing actions of the neurotransmitter over time, to detect and further reduce seizure activity.

Your child will return for follow-up appointments every four to six weeks to discuss seizure activity. Keeping a journal of seizure activity can help compare the data from the neurostimulator device with your child’s experiences and refine the programming of the device for greater effectiveness.

Responsive neurostimulation doesn’t end all seizure activity, but it reduces the number and severity of seizures experienced. By reviewing the data and fine-tuning the device’s seizure detection settings, seizure frequency can be reduced further over time.

Why choose CHOP for responsive neurostimulation

At Children’s Hospital of Philadelphia, your child will have access to pediatric experts from the Neuroscience Center, which is made up of neurologists, neurosurgeons and others who specialize in the care of children with epilepsy and seizures.

Our team of experts work closely with one another and with families to ensure that candidates are screened appropriately for responsive neurostimulation, and to provide the full range of supportive therapy before and after epilepsy surgery to optimize outcomes.