Seizures are symptoms of a brain problem. They happen because of sudden, abnormal
electrical activity in the brain. When people think of seizures, they often think of convulsions in which a person's body
shakes rapidly and uncontrollably. Not all seizures cause convulsions. There are many types
of seizures and some have mild symptoms. Seizures fall into two main groups. Focal
seizures, also called partial seizures, happen in just one part of the brain. Generalized
seizures are a result of abnormal activity on both sides of the brain.
Most seizures last from 30 seconds to 2 minutes and do not cause lasting harm. However,
it is a medical emergency if seizures last longer than 5 minutes or if a person has many
seizures and does not wake up between them. Seizures can have many causes, including
medicines, high fevers, head injuries and certain diseases. People who have recurring
seizures due to a brain disorder have epilepsy.
NIH: National Institute of Neurological Disorders and Stroke