Epilepsy is a chronic disorder that causes unprovoked, recurrent seizures. A seizure is a sudden rush of electrical activity in the brain. There are two main types of seizures. Generalized seizures affect the whole brain. Focal, or partial seizures, affect just one part of the brain. A mild seizure may be difficult to recognize. It can last a few seconds during which you lack awareness. Stronger seizures can cause spasms and uncontrollable muscle twitches, and can last a few seconds to several minutes. During a stronger seizure, some people become confused or lose consciousness. Afterward you may have no memory of it happening.