Surgical Treatment of Intractable Epilepsy Associated with Focal Cortical Dysplasia

Focal cortical dysplasias (FCDs), initially thought to be rare, are a common cause of drugrefractory epilepsy in both children and adults. Successful resection and subsequent characterization of FCDs was first described by Taylor et al. in 1971 from pathological specimens obtained in patients treated for intractable temporal lobe epilepsy (Tassi, et al.,2001; Becker, et al.,2002; Tassi, et al.,2002; Urbach, et al.,2002; Nobili, et al.,2009). The dysplasias include abnormalities of cellular proliferation, migration, and differentiation. From recent published reports, patients with cortical dysplasia constitute approximately 14% of all patients undergoing epilepsy neurosurgery. Cortical dysplasia is the most common etiology in younger surgical patients. Using the UCLA cohort as an example, cortical dysplasia was the histopathologic substrate identified in 75% of infants and children operated in the first 2 years of life. By comparison, cortical dysplasia was found in less than 10% in those having surgery who were older than age 21 years (Diaz, et al., 2008). Surgical evaluation and treatment of FCDs requires an understanding of pathological, presurgical imaging, EEG findings and intraoperative mapping of epileptogenic zone and functional areas (Sisodiya,2011).