iMRI machine

If your seizures do not get better with medication, surgery is an option. Surgeons at the OHSU Comprehensive Epilepsy Center perform many different surgical procedures for epilepsy; in fact, we are experts in a wider range of surgeries than any other center in the Pacific Northwest. Those procedures include new and advanced types of surgery that have been developed over the past several years.

Surgical procedures can be used to implant devices that help to minimize the electrical disturbances in your brain, or can remove the small part of the brain causing seizures – if removing that part will have no critical effect on how the brain functions.

Many of the epilepsy surgeries we perform – for children and adults – are aided by intraoperative magnetic resonance imaging using the iMRI suite at OHSU’s Doernbecher Children’s Hospital. Intraoperative MRI allows surgeons to create high-resolution brain scans during surgery, which gives surgeons finely detailed maps of a patient’s brain in real time during the surgery. In epilepsy surgeries, the iMRI allows surgeons to better see all of the small area of the brain that is causing seizures and allows surgeons to then remove all of that area while ensuring they don’t damage other parts of the brain or remove brain tissue that should not be removed.

Our neurosurgeons, neurologists and other medical experts work together to decide on the best type of surgery for you after careful assessment of your individual case and testing results.

Surgical options include

Temporal lobe surgery

About 60 percent of all people with epilepsy have temporal lobe epilepsy. The temporal lobe is one of four sections that make up the cerebrum, the largest part of a human brain. For those patients who do not respond to medication, surgeries removing a small part of the temporal lobe of their brain — while avoiding damage to areas responsible for critical brain functions — can significantly reduce or stop their seizures.

There are two primary surgeries that treat temporal lobe epilepsy: anterior temporal lobectomy and selective amygdalohippocampectomy, or SAH.

Anterior temporal lobectomy

Anterior temporal lobectomy is the most common type of surgery to control seizures that do not respond to medications. In this procedure, your surgeon removes a small portion of the anterior, or front, of the temporal lobe of the brain — which is a common place for seizures to start.

Selective amygdalohippocampectomy, or SAH

In selective amygdalohippocampectomy, or SAH, your surgeon removes only small portions of the medial, or inner, part of the temporal lobe of the brain.

Laser ablation

OHSU is one of only a few dozen centers in the United States that performs an advanced new procedure called laser ablation surgery for epilepsy. With this minimally invasive surgery, a laser fiber is guided from a small hole in the patient’s skull to the area of the brain where the seizures originate — often in the temporal lobe. Surgeons are aided by intraoperative magnetic resonance imaging, which gives a real-time picture of the brain as the laser is guided.

Once the surgeon has guided the laser to the appropriate site in the brain, the laser then precisely heats and destroys the very small area causing the seizures. Surrounding brain tissue is unharmed.

Laser ablation surgery can be as or more effective than other surgeries in stopping a patient’s seizures. Since the surgery does not involve opening a larger portion of the skull, recovery is much quicker and there are fewer side effects; patients often stay only one night in the hospital.


This surgery removes brain tissue that is abnormal and is causing the seizures. The abnormal tissue, called a lesion, may be from a benign brain tumor, injury, or other medical problem.  Before a lesionectomy, tests are performed to confirm the lesion is causing the seizures and pinpoint its location in the brain. Then, during the lesionectomy, the surgeon exposes that area of the brain using a procedure called a craniotomy. The patient is put to sleep with general anesthesia and the surgeon makes an incision in the scalp, removes a piece of bone and pulls back a section of the membrane that covers the brain. The surgeon can then see and have access to that pin-pointed brain area and use special instruments to remove the abnormal brain tissue while avoiding damage to other brain tissue.

Responsive neurostimulation and the RNS® System

OHSU is the only hospital in Oregon to offer an innovative and much less invasive surgical procedure to treat patients with seizures that can’t be controlled with medicine. The innovation is called responsive neurostimulation and the first FDA-approved device is called the RNS® System.

The device can be used in patients in whom surgery would be impossible — where the part of the brain where the seizures originate involves critical brain functions that cannot be safely removed with surgery.

The device is made up of a small neurostimulator and one or two very small lead wires. The surgeon places the neurostimulator under the scalp and within the skull of the patient and positions the wire or wires into the area of the brain where the patient’s seizures are originating. The neurostimulator continuously monitors the brain’s activity and is programmed by your doctor to detect specific activity that indicates a seizure is imminent. When that happens, the neurostimulator delivers a small burst of electrical stimulation that stops the seizure before it starts. The device’s settings for detection and stimulation are individualized to each patient and continually adjusted to improve its effectiveness.

Vagal nerve stimulation

Vagal nerve stimulation, or VNS, may be used when medicine cannot control a patient’s seizures. With vagal nerve stimulation, a device is implanted under the skin of the patient’s upper left chest with tiny wires attached to the vagus nerve in the patient’s neck. When operational, the device sends intermittent short bursts of electrical energy, which affects areas in the brain that produce the seizures. A good outcome with VNS therapy is having the frequency of seizures cut in half or better, and many patients achieve this goal.