We present the outcomes obtained at one institution in patients who have undergone Gamma Knife (GK) Stereotactic Radiosurgery as part of the multi-modality treatment of refractory epilepsy caused by hypothalamic hamartomas (HH).

     Between 2004 and 2009, 13 patients with HH underwent GK. Five patients were excluded for followup time less than 1 year. Eight remaining patients (mean age 15.5 years, range 5.7 – 29.3 years) had mean followup of 35 months (range 13 – 69 mos). Five patients had prior surgery: one transcallosal resection of HH, 2 endoscopic transventricular resections of HH, two temporal lobectomies, and one arachnoid cyst evacuation.

     In an IRB approved study, postoperative complications and long-term outcome measures were monitored prospectively with the use of a proprietary database.

      There were six patients with Delalande type II HH; the remainder were type III or IV. Seizure frequency ranged from 1 – 2 monthly to 20 or more daily. The mean lesion volume was 735 cubic millimeters (range 169 – 3000, median 265 mm3). The mean dose to the 50% isodose line was 17.9 Gray (range 16 – 20 Gy). The mean maximum point dose to the optic chiasm was 7.5 Gy (range 5.2 – 10 Gy). Three patients underwent additional surgical resection at 15, 21, and 32 months after Gamma Knife therapy. Of the eight total patients included, four patients are seizure free (two after additional surgery), one patient has 50 – 90 % reduction in seizure frequency, one patient has reduction in seizures of 35%, and two are unchanged in this respect (one had additional surgery). Overall quality of life based on telephone/survey followup was improved in 6 patients accounting for improvement in seizure control (n=7), improvement in short term memory loss (n=2) and improved aggressive behavior (n=4); in one patient, quality of life remains minimally affected. Morbidity included transient poikilothermia, increased depression but with improvement in anger, and persistent fear of the dark after GK.

     This is a retrospective study.

      Of the 140 patients at our institution who have undergone treatment for HH, we reserve Gamma Knife therapy for small HH’s, distal from radiosensitive structures in patients with higher cognitive function and a stable clinical picture that will allow time for the effects of radiosurgery to occur without further deterioration.

     The lack of significant morbidity and clinical outcomes demonstrated show a low risk of GK therapy for HH and results comparable to those from the Marseilles group.