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Surgical treatment of medically refractory epilepsy in childhood
1Department of Pediatrics, Bloorview Epilepsy Program, University of Toronto, Ontario, Canada. csnead@sickkids.on.ca
Insights
For children with medically refractory epilepsy, surgery can offer a seizure-free outcome. Precise identification of the epileptogenic zone and sparing eloquent cortex are key to successful epilepsy surgery.
Area of Science:
- Pediatric Neurology
- Neurosurgery
- Epileptology
Background:
- Approximately 25% of children with epilepsy have medically refractory seizures, persisting despite optimal medical management.
- Medically refractory localization-related epilepsy may be treated with various surgical interventions.
- Successful epilepsy surgery aims for a seizure-free state without neurological deficits.
Purpose of the Study:
- To outline the diagnostic measures and surgical considerations for children with medically refractory epilepsy.
- To emphasize the importance of precise localization of the epileptogenic zone and eloquent cortex.
- To discuss the complexities of risk-benefit assessment in pediatric epilepsy surgery.
Main Methods:
- Clinical history (seizure semiology)
- Scalp electroencephalography (EEG)
- Neuropsychological testing
- Neuroimaging (MRI, PET, SPECT)
- Interictal magnetoencephalography (MEG)
- Invasive intracranial monitoring (depth/subdural electrodes) when non-invasive data is discordant or epileptogenic zone is in eloquent cortex.
Main Results:
- Concordant clinical, neuropsychological, EEG, and radiological data allow for cortical excision of the epileptogenic zone.
- Discordant data or epileptogenic zones within eloquent cortex necessitate invasive intracranial monitoring for precise mapping.
- Surgical success hinges on accurately identifying and removing the epileptogenic zone while preserving critical brain functions.
Conclusions:
- Epilepsy surgery offers a potential pathway to seizure freedom for refractory cases in children.
- Accurate pre-surgical evaluation, including advanced neurophysiological and imaging techniques, is crucial.
- Age-related factors significantly influence the assessment of risks and benefits in pediatric epilepsy surgery.
Abstract:
Twenty-five percent of children with epilepsy continue to seize despite the best medical management and may be defined as medically refractory. Many children with medically refractory localization-related epilepsy, i.e. seizures which originate in a particular area of the brain and secondarily spread to involve other brain regions, may benefit from a variety of surgical treatments including hemispherectomy, corpus callosotomy, focal cortical resection of the temporal lobe, focal cortical resection of extratemporal regions of the brain, and multiple subpial resections. A successful outcome from epilepsy surgery is generally defined as a seizure-free state with no imposition of neurologic deficit. In order to achieve these twin goals two criteria must be fulfilled. First, precise localization of the epileptogenic zone in the brain is necessary. The epileptogenic zone may be defined as the region of epileptogenic cerebral cortex whose removal will result in a seizure-free state. Second, one must determine the anatomic localization of eloquent 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 ascertain the earliest symptom in the clinical progression of the seizure (semiology) is imperative as is ictal and interictal scalp EEG, neuropsychological testing, magnetic resonance imaging, positron emission tomography, single photon emission computerized tomography, and interictal magnetoencephalography. In the typical child undergoing evaluation for epilepsy surgery, if the clinical, neuropsychological, EEG, and radiological data are all concordant and point to the same area of epileptogenicity in the brain, cortical excision of the suspected epileptogenic zone is undertaken. However, if the data are discordant, and/or the epileptogenic zone resides wholly or in part within eloquent cortex, invasive intracranial monitoring from depth and/or subdural electrodes during a seizure is required to map out the areas of epileptogenicity in the brain. The assessment of potential risks and benefits for this type of epilepsy surgery in children involves complex age-related issues, including the possible impact of uncontrolled seizures, medication, or surgery on learning and development.