Abstracts

Rationale: Hypothalamic hamartomas (HHs) are intrinsically epileptogenic congenital lesions typically presenting with drug resistant epilepsy with gelastic seizures. Patients affected also have progressive deficits in multiples domains of cognition. Open or endoscopic surgical procedures, although effective in controlling the seizures, are associated with significant morbidity. Previous studies on Gamma Knife surgery for HHs showed encouraging results regarding epilepsy outcome with minimal side effects. Little data is available on the neurocognitive effect of this procedure. At the Centre Hospitalier Universitaire de Sherbrooke, we have undertaken a prospective observational study of patients who underwent radiosurgery for HHs, evaluating the response rate of seizures and the impact on cognition and quality of life.Methods: Patients were included in the study if they had an HH, refractory epilepsy, and no other suspected seizure focus. After radiosurgery, seizure status was assessed every three months and reported using the Engel Classification. Neuropsychological evaluation and quality of life evaluation using a standardized questionnaire (QOLIE-89) was performed at baseline and annually thereafter. Results: Twelve patients have been included so far in the study. Age ranged from 14 to 57 years. In all cases, epilepsy began in infancy and was refractory to standard antiepileptic drugs. Nine patients had abnormal baseline neuropsychological evaluation. Using the R gis classification, nine patients had smaller hamartomas (Grade I III) and underwent treatment of the entire lesion, using a margin dose of 14 20 Gy. Among the six patients of this group with more than 12 months of follow-up, four (66%) are now seizure free (Engel Class I), and another is having only rare seizures (Engel Class II). In one patient, no improvement has occurred (Engel Class IV). Mean time to seizure freedom after treatment was eighteen months. In this group, quality of life was improved in four patients and unchanged in two others. In those patients with adequate follow up in neuropsychology, we observed marked improvement in verbal episodic memory and in attentional abilities in two patients. Three patients had larger lesions (Grade IV VI) for which a radiosurgical disconnection was attempted, with a margin dose of 15 or 16 Gy. Disconnection led to no or little improvement in epilepsy (Engel Class IV in two patients and Engel Class IIIa in 1 patient). For one patient with a grade IV lesion, radiosurgery was repeated with full lesion coverage and worthwhile improvement has occurred (Engel IIIa). More data will be available in December 2011.Conclusions: In this prospective study of patients with refractory epilepsy associated with HHs, when the entire lesion could be targeted, radiosurgery did not only improve seizures. Some encouraging effects were also observed for cognition and quality of life. Radiosurgical disconnection of large lesions was ineffective. For small HHs, radiosurgery should be a first line surgical therapy.