INTRODUCTION AND TERMINOLOGY
Epilepsy is a group of heterogeneous conditions, all of which include recurring seizures as an essential component. An epileptic syndrome is a constellation of symptoms, including seizures, signs, and other findings that tend to occur together and define a phenotype. The International Classification of Epileptic Syndromes and Epilepsies, published in 1989, organizes these into partial and generalized epilepsies as well as into idiopathic versus symptomatic epilepsies . Partial epilepsies are also referred to as focal or localization-related epilepsies. A revised terminology was published in 2010, but it has not been widely adopted .
Most of the partial epilepsies are either symptomatic (ie, the cause is known) or cryptogenic, which means there is a presumed focal structural cause that cannot be identified historically or be seen with current imaging techniques. If the patient undergoes epilepsy surgery, the cause is sometimes subsequently defined pathologically. Idiopathic partial epilepsies refer to a group of syndromes that usually present in childhood, are generally benign, and presumably have a genetic origin.
The causes, clinical manifestations, and electroencephalographic features of the localization-related epilepsies are reviewed here. The idiopathic focal epilepsies of childhood are discussed in detail separately. (See "Benign partial epilepsies of childhood".)
The management of partial epilepsy and other epilepsy syndromes are discussed separately. (See "Overview of the management of epilepsy in adults" and "Initial treatment of epilepsy in adults" and "Evaluation and management of drug-resistant epilepsy" and "Overview of the treatment of seizures and epileptic syndromes in children".)
Symptomatic localization-related epilepsies are, by definition, the result of a focal brain abnormality, even though this cannot always be identified. These cases represent the typical "adult-onset" epilepsy, although these are common in childhood as well. If the cause is found or otherwise known, it is said to be symptomatic epilepsy. If imaging studies are normal, the cause remains unknown, and they are said to be cryptogenic. Mesial temporal sclerosis is the most commonly identified cause of symptomatic partial epilepsy.