Abstracts

Rationale: Epilepsies associated to Hypothalamic Hamartomas are frequently drug-resistant with a severe psychiatric and cognitive comorbidity. We have organized a prospective trial in order to evaluate the safety and efficacy of radiosurgery using the Gamma Knife (GK).Methods: Between January 1999 and December 2007 64 patients were investigated, included and treated by GK in Timone University Hospital. The median age was 20 years (min 3 max 50. Preoperative work-up and 3 years evaluation included: seizure diary, neuropsychological testing, psychiatric evaluation, endocrinological evaluation, visual field and acuity. Till now, follow up of more than 3 years is available for 40 patients. The hamartomas were of topological Type I (Regis et al 2004) in 8 patients, Type II in 14 patients, Type III in 12 patients, Type IV in 1 patients, Type V in 1 patients and mixed Type in 3 patients. The median of the marginal dose was 17 Gy (Mean: 17,8+- 1,6 ; min=14; max= 20). The median of the volume was 419 mm3 (Mean 556,7 +- 394; min=31 ; max=1600). The median number of isocenters was 8 (Mean 9,4 +- 5,5; min=1 ; max= 31). 25 patients (62,5%) have been treated twice due to partial result.Results: The median follow up was 62 months (36-107). At last follow up the rate of Engel I was 47,5 %, Engel II 17,5% (I+II 65%) & Engel III (20%). Median Preoperative number of seizures in a month was 92 [Mean, 427 +- 1009; min 3,3; max 6000]. Median number of seizures in a month at last follow has dramatically decreased to 6 [Mean 34,6 +- 78; min= 0; max=425]. Global Psychiatric and Cognitive comorbidity was considered cured in 28%, improved 56%, stable 8% and have continued to worsen in 8%. No permanent neurological (specially no mnesic nor visual deficit) side effect is reported. A non-disabling transient poikilothermia was observed in 3 patients (7,5%). A transient increase of seizure frequency is reported in 7 patients (17,5%). Microsurgery was proposed due to insufficient efficacy of GKS in 5 patients (Type II, Type III, type IV in one patient each, mixed type in 2 patients). The postoperative outcome (after microsurgery) was Engel I (17%), Engel III (33%) and Engel IV (50%).Conclusions: This prospective trial is demonstrating the very good safety efficacy of Gamma Knife radiosurgery in the long term. Beyond seizure reduction, the improvement of the psychiatric, cognitive condition and school and social insertion is turning out to be the major benefit of GKS in this frequently catastrophic epilepsy group. In case of failure the limitation of the epileptogenic zone to the HH itself must be questioned. Longer follow up remains mandatory due to the young age of this population.