Surgical treatment of medically refractory epilepsy in childhood

Twenty-five percent of children with epilepsy continue to seize despite the best medical management and may be defined as medically refractory. Many c hildren with medically refractory localization-related epilepsy. i.e. seizu res which originate in a particular area of the brain and secondarily sprea d to involve other brain regions, may benefit from a variety of surgical tr eatments including hemispherectomy. corpus callosotomy, focal cortical rese ction of the temporal lobe, focal cortical resection of extratemporal regio ns of the brain, and multiple subpial resections. A successful outcome from epilepsy surgery is generally defined as a seizure-free state with no impo sition of neurologic deficit. In order to achieve these twin goals two crit eria must be fulfilled. First, precise localization of the epileptogenic zo ne in the brain is necessary. The epileptogenic zone may be defined as the region of epileptogenic cerebral cortex whose removal will result in a seiz ure-free state. Second, one must determine the anatomic localization of elo quent cortex in the brain in order to spare these areas during any planned cortical excision of epileptogenic cortex. Several diagnostic measures may be used to achieve a successful surgical outcome. A clinical history to asc ertain the earliest symptom in the clinical progression of the seizure (sem iology) is imperative as is ictal and interictal scalp EEG, neuropsychologi cal testing, magnetic resonance imaging, positron emission tomography, sing le photon emission computerized tomography, and interictal magnetoencephalo graphy. In the typical child undergoing evaluation for epilepsy surgery, if the clinical, neuropsychological, EEG, and radiological data are all conco rdant and point to the same area of epileptogenicity in the brain, cortical excision of the suspected epileptogenic zone is undertaken. However, if th e data are discordant, and/or the epileptogenic zone resides wholly or in p art within eloquent cortex, invasive intracranial monitoring from depth and /or subdural electrodes during a seizure is required to map out the areas o f epileptogenicity in the brain. The assessment of potential risks and bene fits for this type of epilepsy surgery in children involves complex age-rel ated issues, including the possible impact of uncontrolled seizures, medica tion, or surgery on learning and development. (C) 2001 Elsevier Science B.V , All rights reserved.