Abstracts

Rationale: Cortical dysplasia (CD) are frequent pathological substrates in patients with pharmacoresistant epilepsy. Previous studies showed that CD are intrinsically epileptogenic and therefore a “total” resection of the “lesion” is recommended. In cases where the CD overlap with potentially eloquent regions, it remains unclear if a subtotal, tailored resection based on careful extraoperative invasive mapping would lead to a favorable seizure outcome. We report on three patients with good surgical outcomes in whom subtotal removal of the dysplastic lesion was performed on the basis of direct cortical recordings using subdural grids.Methods: We retrospectively reviewed the Cleveland Clinic Epilepsy Center’s database for patients with pathologically confirmed CD who underwent invasive EEG evaluation for intractable epilepsy and whose EEG findings were only partially concordant to neuroimaging. Results: Three patients (36 ± 13 years) were identified with focal epilepsy arising from right perisylvian epilepsy, right frontal lobe epilepsy and left hemispheric epilepsy. These patients had extensive MRI abnormalities and one patient had bilateral perisylvian lesions. Invasive EEG recordings utilizing depth electrodes and subdural grids identified focal epileptic activity that was localized within the MRI lesion in one patient, partially within and adjacent to the lesion in another, and in a different cortical lobe (same hemisphere) in the other. A tailored resection with respect to EEG findings was thought to be more beneficial than a generous lesionectomy. All had an excellent surgical outcome, classified as Engel class I (follow up between 1.5 years and 4 years).Conclusions: Our preliminary results suggest that subtotal tailored resection, guided by invasive EEG data can result in a good surgical outcome and preservation of eloquent function in patients with extensive dysplastic lesions. These results challenge the long held belief that complete resection of the “lesion” is required for surgical success and argue for a staged approach in those patients with extensive neocortical dysplastic lesions and/or those with lesions in potentially eloquent cortex.