Epilepsy Presurgical Evaluation

To determine if surgery is an option for your child, our team at the UCSF Epilepsy Center will conduct a series of tests and schedule an appointment to review test results and discuss treatment options, including potential benefits and risks.

Surgery is usually considered when anticonvulsant medications aren't effective in controlling seizures. Surgical procedures remove the area of the brain causing seizures, called the seizure focus. The goal is to improve seizure control and if possible, to stop seizures completely.

Test results, including those from electroencephalogram (EEG) video telemetry, help doctors better understanding your child's seizure focus, or area of the brain triggering seizures. If most seizures originate in a specific area of the brain, it may be possible to safely remove this area.

A specific procedure may be selected, depending on seizure type and history, and test results.

Types of Tests

Tests include:

  • Magnetic Resonance Imaging (MRI) Scan — This scan creates detailed pictures of the brain and surrounding nerve tissues
  • Magnetoencephalography (MEG) — This test identifies brain activity by measuring small electrical currents arising from the neurons of your child's brain and then pinpointing the location.
  • Neuropsychological Evaluation — This assessment for epilepsy patients is conducted by a neuropsychologist, a psychologist who specializes in the relationship between the brain and behavior. This testing may help determine the site of your child's seizures and predict possible cognitive changes, or changes in the process of thought, after surgery.
  • Positron Emission Tomography (PET) — A PET scan uses an injection of a radioactive tracer to measure your child's brain metabolism to help locate your child's seizure focus.
  • Wada Test — This test, conducted by a neuropsychologist, evaluates location of speech and memory functions in your child's brain. Sodium amytal is used to sedate one side of your child's brain while the other side is being tested. The results of the Wada test determine which side of your child's brain is the dominant area for speech and memory. It also determines if your child will need to be awake during part of surgery. The test, also called an "intracarotid sodium amobarbital procedure," is named after Dr. Jun Wada, the Japanese doctor who first performed the test.

Test Results

Information gathered from the tests help define and locate your child's seizure focus and determine if the seizure focus can be safely removed.

In some cases, results are inconclusive. If the initial EEG video telemetry monitoring doesn’t provide enough information, your child may need intracranial monitoring to record brain wave activity.

Intracranial Monitoring

Intracranial monitoring involves surgically placing electrodes on the surface of the brain or sometimes in the brain tissue, rather than pasting electrodes on the scalp as in EEG video telemetry monitoring.

These surgically placed electrodes may include one or more of the following:

  • Depth Electrodes (stereo-EEG) — These are fine, rigid electrodes placed into the brain tissue through burr holes. They record brain wave activity from a more precise area in the brain.
  • Subdural Grid Electrodes — A large number of these electrodes are placed onto the surface of one brain hemisphere. To access the brain, surgeons perform a craniotomy in which a bone flap is removed from the skull. Grid electrodes are typically used when the location of the seizure focus has been located, but more information is needed. The grid allows for additional testing at your child's bedside to define brain functions in and around the seizure focus.
  • Subdural Strip Electrodes — These flexible strands of electrodes are placed on the surface of the brain through burr holes to identify the side of the brain where seizures occur.

More Information

Please call the UCSF Epilepsy Center at (415) 353-2437 if you have any questions about your child's procedures, tests or scheduling.

 

Reviewed by health care specialists at UCSF Benioff Children's Hospital.

This information is for educational purposes only and is not intended to replace the advice of your doctor or health care provider. We encourage you to discuss with your doctor any questions or concerns you may have.

Related Information

UCSF Clinics & Centers

Pediatric Brain Center

Pediatric Epilepsy Center of Excellence
1825 Fourth St., Fifth Floor
San Francisco, CA 94158
Phone: (415) 353-2437
Fax: (415) 353-2400

Condition Information

Patient Experiences

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