Surgery as a Treatment for Medically Intractable Epilepsy

Background: \- Drug resistant epilepsy is the term used to describe epilepsy that cannot be controlled by medication. Many people whose seizures do not respond to medication will respond to surgical treatment, relieving seizures completely or almost completely in one-half to two-thirds of patients who qualify for surgery. The tests and surgery performed as part of this treatment are not experimental, but researchers are interested in using the data collected as part of routine standard epilepsy care to better understand epilepsy and its treatment. Objectives: \- To use surgery as a treatment for drug resistant epilepsy in children and adults. Eligibility: \- Children and adults at least 8 years of age who have simple or complex partial seizures (seizures that come from one area of the brain) that have not responded to medication, and who are willing to have brain surgery to treat their medically intractable epilepsy. Design: * Participants will be screened with a medical history, physical examination, and neurological examination. Imaging studies, including magnetic resonance imaging and computer-assisted tomography (CT), may also be conducted as part of the screening. Participants who do not need surgery or whose epilepsy cannot be treated surgically will follow up with a primary care physician or neurologist and will not need to return to the National Institutes of Health for this study. * Prior to the surgery, participants will have the following procedures to provide information on the correct surgical approach. * Video electroencephalography monitoring to measure brain activity during normal activities within a 24-hour period. Three to four 15-minute breaks are allowed within this period. * Electrodes placed directly in the brain or on the surface of the brain to measure brain activities and determine the part of the brain that is responsible for the seizures (seizure focus). * Participants will have a surgical procedure at the site of their seizure focu