Focal Resection

The most common surgical treatment for epilepsy involves removing (resecting) the small area of brain tissue where the patient's seizures originate. The goal is to reduce the frequency of seizures or stop them completely.

Before surgery, the medical team conducts an extensive evaluation to pinpoint the region of the brain that is triggering seizures. This region may adjoin or overlap areas of the brain used for language, memory, movement and emotion. To protect these functions, UCSF neurosurgeons use advanced brain mapping techniques to avoid or minimize any impact on the surrounding normal brain tissue.

When to Consider Surgery

Surgery is reserved for people whose epilepsy is not well controlled by seizure medications — what's called "medically refractory" or "drug-resistant" epilepsy. To be considered for surgery, the patient must have tried at least two anti-seizure medications, at sufficient dosing, without achieving satisfactory control of disabling seizures.

In the past, surgery wasn't considered unless the patient had tried multiple medications over several years or even decades. These days, surgery may be discussed after just one year of uncontrolled epilepsy, since evidence has shown that the earlier surgery is performed, the better the results.

You may be evaluated for surgery if you:

  • Have seizures that are not satisfactorily controlled by medication
  • Have drop (atonic) attacks
  • Have partial-onset (focal) seizures
  • Have structural brain problems — such as benign brain tumors, strokes or blood vessel malformations — that are causing seizures
  • Are experiencing intolerable side effects from your seizure medication


Patients being considered for surgery will undergo an extensive pre-surgical evaluation. At UCSF, this includes visits to the clinic, admission to our Epilepsy Monitoring Unit (EMU) and imaging tests to determine where your seizures arise — called the seizure onset zone — and if this region can be safely removed.

During the initial clinic visit, you will meet with an epilepsy specialist to review your medical history and previous epilepsy care and to plan your evaluation at UCSF. We will communicate with your primary care doctors and neurologist to discuss your care and any treatment changes throughout your evaluation.

Monitoring and Imaging Tests

Your epilepsy specialist may recommend that you be admitted to our Epilepsy Monitoring Unit (EMU) so we can record your seizures using video and electroencephalogram (EEG) monitoring. Patients generally stay in the EMU for three to five days. This allows us to determine your particular type of epilepsy and where your seizures may arise, if they originate in a single area of the brain.

In addition, you may undergo one or more of the following tests:

MRI — This non-invasive scan uses a magnet to form detailed pictures of your brain. UCSF's MRI has a very strong magnetic field — 3 Tesla — that is especially well suited to evaluating epilepsy. The Epilepsy Center has worked closely with the radiology department to develop a special MRI protocol that provides enough visual detail to identify even very subtle brain abnormalities that may cause seizures.

PET — Positron emission tomography (PET) is a brain scan used to help determine the presence and location of brain metabolic disturbances that may help us pinpoint the tissue responsible for seizures. The findings from PET help support or interpret findings from video-EEG or MRI. PET can be particularly helpful when no definite abnormalities appear on MRI. At UCSF, PET technology is combined with MRI for better accuracy.

SPECT — Single photon emissions computerized tomography (SPECT) is a brain scan that reflects blood flow. For the scan, a small amount of radioactive compound is injected intravenously as a seizure begins. This harmless compound acts as a tracer, glowing brightly in areas of increased blood flow related to seizure activity in the brain. This scan, called ictal SPECT, is compared to a scan obtained when the patient is not having a seizure. At UCSF, special analysis tools are used to map the statistically important differences between the two scans to that of the patient's MRI, resulting in a final scan that provides a remarkable "snapshot" of brain activity in the location of the seizures.

SPECT is usually reserved for patients with frequent seizures when other imaging tests have not conclusively pinpointed the seizure onset zone.

MEG — Magnetoencephalography (MEG) measures the tiny magnetic fields generated by the brain. This is very similar to the EEG, which records the electrical activity generated by the same neurons using electrodes pasted on the scalp. In contrast to EEG, the MEG measures are distorted less by tissues between the brain and scalp, and are recorded with much greater resolution than is typical with EEG. As a result, MEG can be used to locate the source of epilepsy-related electrical disturbances with greater precision than EEG. In fact, because of its accuracy, MEG is often used when other tests are inconclusive. Furthermore, MEG results can be combined with MRI and other brain imaging to provide a very comprehensive view of the brain function and structure.

MEG is available at only a few institutions in California, and UCSF has one the premier MEG laboratories in the U.S.

Neuropsychology Testing

In addition to imaging tests, most patients will meet with our neuropsychologist before surgery to go through a series of mental exercises that provide information on their language, memory and comprehension skills. This information helps the epilepsy team understand both where your seizures originate and how surgery may affect you. The testing is non-judgmental and done in a comfortable, welcoming environment by a neuropsychologist who specializes in epilepsy.

You may also meet with the neuropsychologist for a Wada test to evaluate where speech and memory functions are located in your brain. In a Wada test, one side of your brain is sedated while the other side is being tested. The results determine which side of the brain is the dominant area for the crucial functions of speech and memory. It will also determine if you will need to be awake during part of the surgery.

Intracranial Monitoring

In some cases, the diagnostic tests give the epilepsy team an idea as to where the seizures start but they are not conclusive. These patients may need further evaluation using intracranial monitoring. Intracranial monitoring records brain wave activity using electrodes placed surgically in or on the surface of the brain, rather than just pasting the electrodes to the scalp as with the initial video-EEG monitoring.

UCSF is one of a handful of medical centers in the U.S. to offer stereoelectroencelphalography (SEEG), a less invasive form of intracranial monitoring, as well as the standard subdural grid. Your surgical team will discuss SEEG with you if you are a potential candidate.

After the electrodes have been placed in the operating room and your condition is stable, you will be transferred to the Epilepsy Monitoring Unit for testing. If the intracranial monitoring provides enough information to proceed, the resection surgery is scheduled for the following week.

Epilepsy Surgery Conference

Before deciding on treatment recommendations, a team of UCSF epileptologists, neurosurgeons, neuropsychologists, advanced practice nurses, therapists and surgery coordination staff will meet to go over all aspects of your evaluation and determine the best treatment options for your particular case. After the conference, your doctor or epilepsy nurse specialist will contact you to discuss the risks and benefits of all treatment options, giving you the opportunity to make an informed decision that best suits your needs and lifestyle.


During the resection procedure, the neurosurgeon makes an incision in the scalp and removes a piece of the skull. The surgeon then pulls back the tough membrane covering the brain, called the dura.

The surgeon uses all the information from the pre-surgical evaluation to target only the area of the brain responsible for the seizures and to protect surrounding healthy brain tissue. In some cases, sedation is lightened during part of the procedure, so the surgeon can stimulate various areas of the brain while the patient performs simple tasks such as counting or identifying pictures. This helps the surgeon locate and avoid any areas of the brain that are necessary for important functions such as language or movement. The patient feels no discomfort or distress during this part of the procedure.

Once the seizure focus is removed, the surgeon will replace the dura and bone and close the scalp using stitches or staples. The night of the surgery is spent in the intensive care unit. By the next day patients should be able to eat and get up and walk with assistance. Pain is managed with intravenous medications until it is mild enough to be controlled with oral medications.

Most patients remain in the hospital for three to four days following a surgical resection. However, if intracranial monitoring is required before surgery, you will be hospitalized the week prior to the planned resection so we can perform an initial surgery to implant the electrodes. We will then record seizures and complete any brain mapping tasks that might be necessary.


After surgery, you can expect swelling and bruising on the scalp around the incision and, in some cases, on the face. This usually goes away within four to six weeks after surgery.

You will have your stitches or staples removed 10 to 14 days after surgery, either at UCSF or at your local doctor's office.

Most patients experience headaches during the first few weeks after surgery. The headaches will gradually become less frequent and less intense. Other effects of the surgery may include decreased ability to concentrate, forgetfulness and word finding difficulties. In most cases, these problems gradually improve over the first few weeks.

It's common for patients to tire very easily after the operation, especially in the first few days after discharge from the hospital. Most people feel back to normal and resume their usual activities about four to six weeks after surgery.

Most patients are put on steroids after surgery to minimize brain swelling. You will be tapered off of them two to three weeks after surgery. This can cause temporary withdrawal symptoms, including increased headache; slight stiffness in the neck, lower back or leg; low fever; irritability; and mild swelling under the incision.

You will continue to take the same anticonvulsant medications you took before surgery for at least two years, even if you're not having any seizures, unless your doctor instructs otherwise.

You will be given detailed post-operative instructions, as well as directions on how to contact the neurosurgery team with any questions or concerns, before you are discharged from the hospital.


Reviewed by health care specialists at UCSF Medical Center.

Related Information

How to Reach Us

For more information, please contact one of our epilepsy nurse specialists:

Maritza Lopez, (415) 353-2143

Mariann Ward, (415) 353-2347

UCSF Clinics & Centers

Neurology and Neurosurgery

Epilepsy Center
400 Parnassus Ave., Eighth Floor
San Francisco, CA 94143
Phone: (415) 353-2437
Fax: (415) 353-2837

400 Parnassus Ave., Eighth Floor
San Francisco, CA 94143
Phone: (415) 353-7500
Fax: (415) 353-2889

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