Abstracts

Rationale: Epilepsy affects approximately 80% of patients with Tuberous Sclerosis Complex (TSC). Many are pharmacologically refractory. Successful epilepsy surgeries have been achieved in patients with TSC and medically intractable epilepsy, with remission rates estimated at 57%. In the past this was done simply by correlating surface EEG recordings with an identifiable lesion on CT or MRI. More sophisticated techniques have been developed, including EEG combined MRI and ictal SPECT, allowing for better identification of epileptogenic tubers. Methods: We present two illustrative cases from patients with TSC cared for at the University of Colorado Epilepsy Center. We chose one case with clear localization of seizure onset and one without clear localization on Phase II invasive monitoring. Their case histories, examination findings, and presurgical evaluation results are compared for potential predictors of surgical feasibility. These clinical features are then compared to the published literature for further understanding of the complexities of epilepsy surgery in this highly variable disorder. Results: Our case series contrasts the presurgical evaluation of two well-matched, adult patients with TSC, BH and NL. Both men have a history of medically-intractable epilepsy since infancy. Both men are high-functioning intellectually. Both patients have numerous cortical hamartomas on CT and MRI. Patient BH presented with a distinct semiology which correlated well with findings on surface EEG recordings. Patient NL's seizure description was more bland. Phase I monitoring failed to localize seizures. BH did not have SPECT as part of his preoperative evaluation. NL's SPECT reiterated this diagnostic uncertainty. BH's intracranial EEG recordings clearly demonstrated a single primary epileptogenic tuber, thus making him an ideal candidate for surgical resection (see Image 1). In contrast, NL's intracranial EEG monitoring revealed multifocal and nonlocalizable areas of seizure onset. He was not a resective candidate, but went forward with vagal nerve stimulator placement. BH had no post operative complications. At one year follow up BH reports 4 identical complex partial seizures. He is now able to work, whereas he was disabled by his seizures prior to the surgery. Conclusions: Our cases demonstrate the diagnostic challenges epileptogists face when confronted with presurgical evaluation of patients with TSC and medically-intractable epilepsy. Advances in functional neuroimaging and neurosurgical techniques have expanded epilepsy surgery to a group of patients previously thought to be poor surgical candidates. These advancements have shown to improve behavior, cognition, and quality of life in pediatric cohorts. However, long-term surgical outcomes data is necessary in adult populations. Future prospective studies may help determine which clinical and neurodiagnostic features predict surgical feasibility and outcomes in adult patients.