Abstracts

Rationale: This study is to examine the value of CT scan in children with medically refractory epilepsy (MRE) caused by focal cortical dysplasia (FCD) with regard to seizure outcome and types of FCD. Methods: Seven patients with MRE caused by FCD and focal hyperintensity in CT scans who were consecutively treated with focal resection of epileptogenic region (ER) between 2004 and 2008 were reviewed retrospectively. All patients had extraoperative intracranial EEG monitoring prior to surgery. The patients with hemimegalencephaly and tuberous sclerosis were excluded. Results: Age at seizure onset ranged from 1 day to 53 months (median 7 months, mean 14 months). Two patients had seizures in utero (excessive fetal movement and hiccup). Four patients had prenatal risks including viral infection in 1, congestive heart failure in 1, and prematurity (24 and 28 weeks GA) in 2. All patients had pathologic handedness, left in 4 and right in 1 patient. All had developmental delay (DD) with 4 patients had mildly and 3 had moderately DD. Locations of FCD were multilobar in one, frontal in two, fronto-parietal in two, parietal in one and lateral temporal in one patient. All patients had abnormal MRIs which were concordant with the CT scans. Five patients had focal transmantle dysplasia. SPECT and PET scans were done in 4 patients and all were concordant with the CT scans. Interictal EEG showed focal epileptiform activity in 5 and regional epileptiform activity in 2 patients. Ictal EEG showed focal onset in 4, regional onset in 1, and lateralized onset in 2 patients. Age at surgery varied from 1 to 138 months (median 31 months, mean 55 months). All patients had complete resection of ER. Five had mild hemiparesis and 2 had no neurologic deficit. Pathology showed severe FCD in all with FCD 2A in 2 and 2B (balloon cell-typed) in 5 patients. Pathology showed calcifications in 6 patients. All patients have been seizure free. Follow up ranged from 23 months to 6 years (median 53 months; mean 49 months). Conclusions: Focal hyperintensity in the CT scans of patients with MRE caused by FCD is valuable in presurgical evaluation and associated with the followings; 1) severe FCD type, most commonly balloon cell-typed FCD with calcification; 2) abnormal MRI scan especially with focal transmantle dysplasia in extratemporal region; 3) high prenatal risks; 4) focal abnormalities in the EEG; 5) excellent seizure outcome after the surgery; 6) low risk of surgical complications despite the location in eloquent cortex, probably due to plasticity; 7) high risk of DD despite successful epilepsy surgery. The major limitations of this study are retrospective design, small numbers of patients, and selective bias because CT scan is not a routine evaluation tool for epilepsy surgery.