Abstracts

Tuberous sclerosis (TS) is an autosomal dominant disorder of cellular differentiation, proliferation and migration. Seizures occur in 84% of patients carrying the TS mutation and they can be difficult to control with antiepileptic medications. The role of surgery and long-term postoperative outcome in these patients is not clear.
Methods: Between 1986 and 2002, 23 patients with definite and probable TS underwent epilepsy surgery at the Mayo Clinic- Rochester. Patients with possible TS were excluded, as were patients with a follow-up period of less than one year (1 patient). Patients were followed for a period ranging between 1-14 years (mean 8.9 years). Only one patient was followed for less than 1 year. Post-operative seizure control was assessed at 1 and 5 or more years using the Engel[rsquo]s classification of postoperative outcome.
Results: 14 female and 8 males with definite (20/22) and probable (2/22) TS underwent epilepsy surgery for medically intractable epilepsy. Average age at seizure onset and surgery was 31 months and 12.5 years respectively. Eight patients underwent tuberectomy, 12 lobar/multilobar resection and 2 corpus callosotomy. In general, 59% and 41% were Engel[rsquo]s class I and Engel[rsquo]s class III/IV, respectively, at 1 year. At five years, 42% and 57% of the patients were Engel class I and class III/IV, respectively. 23% of the patients in Engel[rsquo]s class I at 1 year deteriorated to Engel III/IV when followed for 5 or more years. The difference in long-term outcome at 5 or more years was not statistically significant whether the patient: underwent tuberectomy or lobar/multilobar resection; pathology showed a tuber or gliosis; preoperative EEG showed focal, multifocal or generalized epileptiform abnormalities; patient had only partial or partial with generalized seizures; patient underwent invasive intracranial monitoring; intraoperative corticography; hitory of infantile spasms; history of hypsarrhythmia, and the presence of one or multiple tubers on MRI. There was also no significant difference in the age at surgery or age at seizure onset. There was a statistically significant difference in the long-term outcome between patients who had moderate to severe developmental delay at time of surgery and those who had mild to no delay. Patients with recorded unifocal seizures on scalp EEG were more likely to do better than patients who had multifocal seizures or seizures of indeterminate onset. None of the patients had major postoperative deficits.
Conclusion: Surgery is a good option for the management of medically intractable epilepsy iassociated with TS with acceptable long-termresults. Presence of unifocal seizures and mild to no developmental delay at the time of surgery are predictive of excellent long-term outcome.