Abstracts

Tuberous sclerosis complex (TSC) is characterized by multiple cortical tubers and intractable epilepsy. Epilepsy surgery is considered if seizures originate from a single lesion in a non-eloquent area of the brain. However, patients with TSC are not optimal candidates for surgery because of multiple cortical tubers and multifocal epileptogenic foci. Recent development of multi-modality functional neuroimaging (i.e. interictal [¹¹C]AMT PET, FLAIR MRI) have been reported to improve localization of epileptogenic tuber(s), and thus the outcome of surgery in TSC. We studied correlation between intracranial EEG recording and subtraction ictal SPECT co-registered to magnetic resonance images (SISCOM) in this group. Eight children with TSC and drug resistant epilepsy, ages 14 months to 18 years (mean 6.2 years) were identified out of 154 children who underwent resective surgery since 1992 in Medical College of Georgia. Six out of 8 patients had SISCOM due to unlocalizing scalp-video EEG. All 8 patients underwent chronic implanted subdural EEG recording. Ictal SPECT was not performed in two children who had localized ictal scalp EEG. Bilateral multiple tubers by MRI were present in all eight children. The SISCOM findings successfully guided the placement of intracranial electrode implantation in all 6 patients. All but one patient was required multilobar cortical resection based upon intracranial ictal EEG findings. SISCOM localizations were concordant with intracranial EEG localization in five out of six and included in cortical resection. Five children have had more than12 months of postoperative follow-up. Seizure-free outcome was achieved in 5 (12-33 months). While the SISCOM lesion provided excellent guidance in terms of intracranial electrode placement, epileptic zones were often multiple including the SISCOM lesion. Our data suggest that more extensive subdural grid or strip coverage is required in children with TSC and intractable epilepsy not to miss the presence of multiple epileptic foci.