Abstracts

Rationale: Tuberous sclerosis complex (TSC) often causes intractable epilepsy. Epilepsy surgery is an option to control of intractable epilepsy secondary to multiple cortical tubers. Magnetoencephalography (MEG) has been applied for presurgical evaluations. We analyzed characteristics of MEG spike source (MEGSS) comparing with surgical resection and seizure outcome in TSC patients. Methods: We retrospectively analyzed MRI, scalp video EEG (SVEEG), MEG, intracranial video EEG (IVEEG) and surgical outcome of 14 TSC patients. We used single moving dipole analysis to localize MEGSSs at an earliest phase of epileptiform discharges (10-70Hz). We divided the patients into Group A (seizure free) and B (residual seizures). We analyzed number, lateralization, and removal ratio of MEGSSs. Results: Age at surgery ranged from 2.2 to 18.1 years old (mean 8.2). MRI revealed multiple cortical tubers bilaterally in 12 patients and unilaterally in 2. SVEEG revealed hemispheric laterality of interictal discharges in all patients and laterality of ictal onsets in 12 patients. IVEEG revealed seizure onset zones in the grid areas (hemispheric in one, 3 lobes in 8, 2 in 3, one in 2 patients). Eight and 6 patients were in Group A and B, respectively, with follow-up period (3-72 months, mean 42). MEGSSs ranged 28-107 (63) in Group A and 19-82 (54) in Group B. The lateralized MEGSSs over the resection side ranged 64-100% (82) in Group A and 66-99% (84) in Group B. The removal ratio ranged 10-92% (63) in Group A and 0-77% (30) in Group B (p=0.013). Conclusions: The removal ratio of MEGSSs in Group A was significantly higher than that in Group B. The maximum removal of MEGSSs provided the good seizure outcome in TSC patients with even lateralized MEGSSs and multiple tubers.