Conditions in which there are recurrent seizures. Such conditions are also known as epilepsy; the isolated occurrence of a seizure, however, is not designated as epilepsy. A seizure (ictus) is an event in which there is a sudden alteration in function of nerve cells, most commonly involving excessive electrical activity of the cells. This sudden change in nerve cell function is usually relatively brief, lasting seconds to minutes. Soon after a seizure, the brain may function quite normally. The manifestation of a seizure varies depending on which area of the brain is involved.