Epilepsy surgery involves removing a portion of the brain from which seizures occur. When seizures occur in a single region in the brain, epilepsy surgery is most successful. However, when at least two anti-seizure drugs have failed to control seizures, epilepsy surgery is considered a last resort. A variety of pre-surgical tests are required to assess whether you are eligible for epilepsy surgery and how the procedure is performed. When medications fail to control seizures, a condition is known as medically refractory epilepsy or drug-resistant epilepsy; epilepsy surgery may be possible. With or without the use of medicine, the purpose of epilepsy surgery is to stop or reduce the intensity of seizures.