The goal of epilepsy surgery is to reduce or eliminate seizures in patients whose condition is not well controlled with medication. In some cases, surgery can actually cure epilepsy — in fact, surgery is the only known cure for epilepsy. In other cases surgery may reduce the frequency and severity of seizures. Since uncontrolled seizures can lead to brain damage or even death, surgery for epilepsy can be life-saving.
Surgery for epilepsy is both safe and effective when it’s performed on carefully selected patients by a neurosurgeon specializing in epilepsy surgery. Not all neurosurgeons have advanced training and expertise in epilepsy surgery, so it’s important to choose a surgeon who does. (See Doctors Who Treat Epilepsy.)
Mapping Brain Function Prior to Surgery
After determining the part of the brain responsible for the seizures (see (see Diagnosing and Treating Epilepsy), the epilepsy surgical team maps the brain to predict any major problems that may arise when a specific area is removed. The neurosurgical approach is tailored to obtain maximal seizure control and minimize any dysfunction afterward. The objective is always to improve quality of life. The first step of this brain mapping may include a Wada test, which involves injecting a drug called sodium amytal into an artery that supplies one part of the brain to put that part of the brain to sleep temporarily. The doctors can then lateralize language and memory functions in the brain.
The area of the brain responsible for seizures may include scar tissue, a tumor, or tissue that was improperly located in the brain during early development. The removal of this abnormal tissue may control the seizures without causing any change at all in the patient’s functioning. In other cases, however, the area of the brain that gives rise to seizures is located near important areas that control speaking, understanding, moving, remembering, or other critical human abilities. Careful testing during the brain mapping process helps protect those functions.
During brain mapping, the surgeon creates a centimeter-by-centimeter functional map of the brain to determine the exact function of the area being considered for surgical removal. Brain mapping occurs after the surgeon implants either a grid of electrodes on the surface of the brain or depth electrodes into the brain using robotic guidance. In some cases, the surgeon will briefly interrupt the function of that part of the brain and check to see whether the patient can still speak, understand, wiggle fingers, make puppets, cut sandwiches — in other words, do all the things he or she can ordinarily do. If no abilities are lost even though there has been interruption in that part of the brain, the surgeon can safely remove that portion and stop the seizures.
In some cases, the surgeon may identify some minor loss of function that will occur if the focus of the seizure is removed. It's critical to insure that the proposed surgery to control seizures will improve quality of life and not create any major long-term problems for the patient. The information gathered from functional mapping of the brain is shared with the patient and his or her family to help them make an informed choice regarding surgery.
Types of Surgery
There are two basic types of epilepsy surgery: curative and palliative.
The goal of curative surgery is to identify the specific area of the brain where seizures are generated and then to remove that area. A variety of specialized tests are performed prior to surgery to identify both the seizure-generating area of the brain as well as the specific functions of the brain. If the site of seizure onset can be removed safely, without neurological damage, then surgery can proceed safely with a high probability of a complete cure. For example, patients with temporal lobe epilepsy can often be cured with an anterior temporal lobectomy, which is a procedure that involves the complete removal of the affected portion of the temporal lobe. In patients who don’t reach a complete cure, an anterior temporal lobectomy often greatly reduces the number and severity of seizures. Another type of surgery is called laser interstitial thermal therapy (LITT). With LITT the surgeon can disrupt the seizure focus using a laser implanted into the brain through a very small incision. Although effective, LITT is only applicable to certain patients with highly localized seizure foci.
If the area of the brain generating the seizures is important for normal brain function, then surgery cannot be done safely and palliative surgery is considered.
The goal of palliative surgery is to reduce the frequency and severity of seizures in cases where curative surgery isn’t possible. Palliative operations often involve “disconnecting” parts of the brain where seizures start or spread. For example, the brain structure called the corpus callosum is a major route of communication between the hemispheres of the brain — and a pathway along which seizures can spread. A procedure called a corpus callosotomy eliminates that pathway by severing the corpus callosum. The brain has other routes of information flow between the two hemispheres, but they don’t allow the spread of seizures. Although information flow is reduced after a corpus callosotomy, patients do well and seizures are reduced.
Other options for palliative surgeries include:
Responsive Neural Stimulation (RNS) is a device that is implanted over the seizure focus. A small grid of electrodes attached to a computer records and then stimulates the seizure focus to disrupt seizures. This device can also be used for long term recording when the doctor is not sure which of two seizure foci is the most critical.
Multiple subpial transection may be used if the seizures originate in critical areas of the cerebral cortex, which is the four-lobed “gray matter” of the brain. The procedure is a series of fine cuts in the affected area of the cortex, cutting off communication and seizures between neighboring parts of the brain without causing any neurological damage to healthy brain tissue.
Vagal nerve stimulation (VNS) and deep brain stimulation (DBS) are other palliative options for epilepsy surgery. In these procedures, a neurosurgeon implants a device similar to a pacemaker to deliver electrical impulses to the part of the brain where the seizures originate. These electrical impulses decrease the frequency and severity of seizures.
Surgery for epilepsy is an advanced procedure that should only be performed by a neurosurgeon specializing in epilepsy surgery, after evaluation by a multidisciplinary team of epilepsy specialists. (See Doctors Who Treat Epilepsy.)
Dr. Theodore Schwartz is internationally known for his pioneering research in the field of epilepsy mapping and treatment. In his laboratory at the Weill Cornell Brain and Spine Center, Dr. Schwartz is leading a research effort investigating brain function — and dysfunction — as related to epileptic seizures. Find out more about the research, and how you can help support Dr. Schwartz's work.
Reviewed by Theodore Schwartz, M.D.
Last reviewed/last updated: September 2023