Seizure types, epilepsy syndromes, etiology, and diagnosis

The clinical manifestation of epileptic seizures may vary widely from patient to patient, depending on the region of the brain involved. Over the centuries, many seizure classification systems have been used, and the current most widely used classification system is that of the International League Against Epilepsy (ILAE). The ILAE system divides seizures into those of partial onset and those of generalized onset, depending on whether the initial clinical manifestations indicate that one cortical region or both hemispheres are involved at the onset of the seizure. Partial seizures are then divided into simple partial seizures, in which a fully conscious state is retained, or complex partial seizures, in which consciousness is impaired. A more recent classification system based purely on symptom features and signs has been proposed, and this system may provide advantages for localization, and especially for surgical evaluation. Epilepsy is a condition characterized by recurrent unprovoked seizures. Epilepsy may be idiopathic, cryptogenic, or symptomatic. Idiopathic epilepsies are generally genetic, and while many such syndromes have been described, advances in molecular genetics will undoubtedly reveal many more syndromes in the near future. Cryptogenic epilepsies are those in which an underlying cause is suspected, but the etiology remains undetected. Epilepsies for which there is an underlying structural cause or major metabolic derangement are considered symptomatic. Common causes and diagnostic evaluation are described in this article.