Epilepsy surgery is a procedure that removes an area of the brain where seizures occur.

Epilepsy surgery is most effective when seizures always occur in a single location in the brain. Epilepsy surgery is not the first line of treatment. But it might be an option when at least two anti-seizure medicines have failed to control seizures.

You might need several tests before surgery to find out whether epilepsy surgery is an option and what type of surgery to do.

Different areas of the brain control different functions. The risks vary depending on the surgical site and the type of surgery. The health care team explains the specific risks of the procedure, as well as the ways they can reduce the risk of complications. Risks may include:

• Memory and language problems that can affect the ability to understand and use language
• Visual impairment where the fields of vision of the eyes overlap
• Depression or other mood changes that can affect social relationships
• Headache
• Stroke

If someone is a possible candidate for epilepsy surgery, that person works with a health care team at a specialized epilepsy center. The health care team does several tests to:

• Determine the eligibility for surgery
• Identify the appropriate surgical site
• Understand in detail how that area of the brain functions

Some of these tests are done as outpatient procedures, while others require a hospital stay.

Evaluations to find the problem area

These procedures are standard tests used to identify the source of irregular brain activity.

• Baseline electroencephalogram (EEG). In this test, electrodes are placed on the scalp to measure electrical activity produced by the brain when a seizure is not present. This test can suggest general areas of the brain that may be affected and can be done while asleep or awake.
• Video EEG. A continuous EEG with video monitoring records seizures as they occur. Because seizure medicines have to be reduced or temporarily stopped so that seizures will occur, this test is done in the hospital. Evaluating the changes in the EEG with body movements during a seizure helps pinpoint the area of the brain where the seizures are starting.
• Magnetic resonance imaging (MRI). This imaging test uses a magnetic field and radio waves to create detailed images that allow health care providers to identify damaged cells, tumors or other irregularities that can cause seizures.

The surgical team may order additional tests to localize the source of seizures and to characterize the nature of the unusual activity. These tests may include:

• Invasive EEG monitoring. If an EEG test does not show where seizures begin, monitoring may be done with surgically placed electrodes. The surgeon places either grids or strips of electrodes on the surface of the brain or places electrodes deeper inside the brain. EEG monitoring is done while the person is unconscious.
• Video EEG with invasive electrodes. Surgically placed electrodes may also be needed for a video EEG procedure. After the surgery, the video and EEG data are captured during a hospital stay while the person is awake but not taking anti-seizure medications.
• Positron emission tomography (PET). This specialized imaging device is used to measure brain function when the person is seizure-free. The images alone — or combined with MRI data — can help identify the source of the seizures.
• Single-photon emission computerized tomography (SPECT). This procedure measures blood flow in the brain during a seizure. Typically, blood flow is higher in the part of the brain where seizures occur. People are admitted to the hospital to undergo this test.

Evaluations to understand brain function

Depending on the surgical site, the health care team may recommend tests to determine the precise areas of the brain that control language, sensation, motor skills and other important functions. This information helps the surgeon preserve function to the greatest extent possible when removing or altering a site in the brain.

The tests may include the following:

• Functional MRI. This test identifies regions of brain activity when someone is doing a particular task, such as listening or reading. This helps the surgeon know the precise locations in the brain that control a particular function.
• Wada test. With this test, an injected medicine temporarily puts one side of the brain to sleep at a time. Then a test for language and memory function is done. This test can help determine which side of the brain is dominant for language usage. While functional MRI has often replaced this test, it may be used if the imaging study isn't possible.
• Brain mapping. Small electrodes are surgically placed on the surface of the brain. When the person is alert after the surgery, a number of tasks are performed that are matched with measurements of the brain's electrical activity.
• Magnetoencephalography (MEG). This test analyzes the magnetic fields produced by the electrical currents in the brain. It is used with data from other sources to locate seizure sites.

Neuropsychological tests

Additionally, testing is usually recommended to measure verbal and nonverbal learning skills and memory function. These tests may provide additional insight into the area of the brain affected by seizures, as well as a baseline for measuring function after surgery.

Before the procedure

To avoid infection, hair is clipped short or shaved over the section of the skull that will be removed during the operation. A small, flexible tube is placed within a vein to deliver IV fluids, anesthetics or other medicines during the surgery.

During the procedure

Heart rate, blood pressure and oxygen levels are monitored throughout the surgery. An EEG monitor may record brain waves during the operation to better localize the part of the brain where seizures start.

Epilepsy surgery is usually done using general anesthesia. The person is unconscious during the procedure. In rare circumstances, the surgeon may awaken the person during part of the operation to help the team determine which parts of the brain control language and movement. In such cases, medicine is used to control pain.

The surgeon creates a relatively small window in the skull, depending on the type of surgery. After surgery, the bone is replaced and fastened to the remaining skull for healing.

After the procedure

The person is placed in a special recovery area to be monitored carefully after awakening from anesthesia. The person is usually placed in the intensive care unit the first night after surgery. The total hospital stay for most epilepsy surgeries is usually about three or four days.

After awakening, the head will be swollen and painful. Most people need to take pain medicine for at least the first few days. An ice pack on the head also may help. Most postoperative swelling and pain resolve within several weeks.

Most people are not able to return to work or school for about 1 to 3 months. Rest and relaxation are needed for the first few weeks after epilepsy surgery and then physical activity can be increased.

It's unlikely that intensive rehabilitation will be needed as long as the surgery was completed without complications such as a stroke or loss of speech.

The outcomes of epilepsy surgery vary depending on the type of surgery performed. The expected outcome is seizure control with medication.

The most common and best-understood procedure — resection of tissue in the temporal lobe — results in seizure-free outcomes for about two-thirds of people. Studies suggest that if a person takes seizure medicine and does not have a seizure in the first year after temporal lobe surgery, the likelihood of being seizure-free at two years is 87% to 90%. If there are no seizures in two years, the likelihood of being seizure-free is 95% at five years and 82% at 10 years.

If there are no seizures for at least one year, the health care provider may consider decreasing the anti-seizure medicine and eventually discontinuing it entirely. Most people who do experience a seizure after going off medicine are able to obtain seizure control by resuming medicine.