Abstracts

RATIONALE: Focal cortical dysplasia (FCD) is increasingly recognized as a cause of medically intractable epilepsy and often becomes symptomatic early in life. We conducted a retrospective study to compare seizure outcome after epilepsy surgery in patients with FCD operated on within 3 years of seizure onset versus patients operated on after 3 years of seizure onset to address the hypothesis that outcome following surgical intervention in FCD is related to duration of epilepsy before surgical intervention occurs.
METHODS: Pediatric patients were identified from a neuropathology database and included if they had cortical resection for intractable epilepsy at Children[scquote]s Hospital Boston between January 1990 and June 2000, with at least 1-year post-operative follow-up. Adult patients were identified from the epilepsy surgery database of Brigham and Women[scquote]s Hospital (January 1990-June 2000) and included in the series if they had neuropathologically proven FCD and a 1-year minimum follow-up. FCD was characterized by loss of usual laminar architecture with large pyramidal neurons scattered through all layers. On the basis of the presence or absence of ballooned cells, we differentiated FCD type I (lack of balloon cells) from FCD type II. Outcomes with respect to epileptic seizures were classified according to the system proposed by Engel and collaborators (1993).
RESULTS: Thirty patients were divided into two groups based on the duration of epilepsy before surgery; 11 patients suffered intractable seizures for less than 3 years (range, 9 [ndash] 29 months; mean, 15 months) and 19 patients had a history of intractable epilepsy longer than 3 years (range, 38 [ndash] 4 years; mean, 19 years). Four patients were excluded because of insufficient follow-up data. Age at onset of epilepsy was slightly lower in patients with FCD type II (median, 2 years 8 months; mean, 4 years 5 months) compared with patients with FCD type I (median, 3 years; mean: 6 years). Localization of dysplastic lesion was temporal in 11 out of 26 patients (42%), frontal in 7 out of 26 (27%), multilobar/frontal (including central region) in 4 out of 26 (15%), posterior multilobar in 2 patients (8%), parietal in one patient (4%) and occipital in one patient (4%).
Patients who had early surgical intervention (group 1) had a frequency of class IA of 88% (8/9) at 1 year and 77% (7/9) at the last visit. Patients who were referred for epilepsy surgery late in their course (group 2) were seizure free in 47% (8/17) of cases at 1 year after surgery and in 41% (7/17) of cases at the last visit. The two groups did not differ significantly in type of FCD. In group 1, FCD type I was diagnosed in 6 out of 9 (66.6%) and FCD type II in 3 out of 9 patients (33.3%), where among the 17 patients of group II, 12 (70.5%) had FCD type I and 5 (29.5%) had FCD type II.
CONCLUSIONS: We demonstrated that surgery resulted in good seizure control in 14 of 26 (54%) of patients with intractable epilepsy due to FCD. Outcome was most favorable in patients with surgical resection of the FCD within three year of onset of seizures. Our data support the strategy of performing early surgery in children with intractable epilepsy secondary to FCD. Delaying surgery reduces the likelihood of eliminating disabling seizures.
[Supported by: A grant from the National EpiFellows Foundation to MRC, the Lombroso Foundation for Epilepsy Research, and a grant from the NINDS (NS27984) to GLH.]