Surgical treatment of intractable epilepsy accompanying cortical dysplasia

Object. Surgical treatment of cortical dysplasia (CD) together with intract able seizures is challenging because both visualization and localization of the lesion are difficult, correlation with seizure foci requires comprehen sive study, and the surgical outcomes reported thus far are unsatisfactory, The authors report their experience in the surgical treatment of CD classi fied according to a surgical point of view. Methods. The definition of CD used in this study was a dysplastic lesion vi sible on magnetic resonance (MR) images or a lesion that, although not visi ble on MR images, was diagnosed as moderate-to-severe dysplasia by using pa thological analysis. During the last 4.5 years, the authors treated 36 pati ents with intractable epilepsy accompanied by CD. They divided the 36 cases of CD into four characteristic groups: Group A, diffuse bilateral hemisphe re dysplasia: Group B, diffuse lobar dysplasia; Group C, focal dysplasia; a nd Group D, a moderate to severe degree of CD with a normal appearance on M R images. All but one patient in Group C were monitored in the epilepsy mon itoring unit by using subdural electrodes for seizure localization and func tional mapping. The incidence of CD among a cohort of 291 patients who had undergone epilep sy surgery at the authors' center during the study period was 12.4%. The me an age of the 36 patients was 21.3 years and the mean age at seizure onset was 8.5 years. The mean follow-up period was 26 months. Twenty-six patients (72.2%) belonged to Engel Class I or II (20 and six, respectively). There were five cases in Group A, nine in Group B, nine in Group C, and 13 in Gro up D. Patients in Groups A and B were significantly younger at seizure onse t and had significantly poorer surgical outcomes compared with patients in Groups C and D (p < 0.05). If outcome is compared on the basis of die exten t of removal of CD. patients in whom CD was completely removed had signific antly better outcomes than those in whom CD was only partially removed (p < 0.001). Conclusions. The authors conclude that intractable epilepsy accompanied by CD can be treated surgically using comprehensive preoperative approaches. D eliberate resective procedures aimed at complete removal of dysplastic tiss ue ensure excellent seizure control without permanent neurological deficit.