BALTIMORE – Gamma Knife surgery significantly reduced the number of seizures in a subset of patients with rare congenital tumors, based on data from a prospective trial of 64 patients presented at the annual meeting of the American Epilepsy Society.

Hypothalamic hamartomas (congenital tumors that are attached to functional brain tissue) can cause a range of complications, including intractable seizures, said Dr. Jean Régis of Timone University Hospital in Marseilles, France.

Dr. Régis’s center is one of the few in the world where Gamma Knife surgery is performed on patients with hypothalamic hamartomas (HH). His ongoing study includes patients as young as age 3 years who have undergone surgery for HH. After a median of 62 months’ follow-up, the number of seizures in this group dropped from a median of 92 per month to a median of 6 per month.

But the benefits of the surgery extended beyond seizure reduction, Dr. Régis emphasized. Global psychiatric and cognitive comorbidity was considered cured in 28% of patients, improved in 56% of patients, and stable in 8% of patients at postsurgical follow-up.

Hyperkinetic behavior was identified in 34 patients at baseline. After surgery, 35% of patients were cured of hyperkinetic behavior and 30% were very much improved, Dr. Régis said. In addition, heteroaggressive behavior was noted in 56 patients at baseline, but after surgery, the behavior completely disappeared in 53% of these patients and was dramatically reduced in 32%, he added.

The specific approach for Gamma Knife surgery depends on the anatomy of the lesion, Dr. Régis noted. Most of the patients in this study had hamartomas of types I-IV, which are the smaller lesions, he said. The median marginal dose of radiation was 17 Gy and the median volume was 419 mm³.

"Longer follow-up remains mandatory due to the young age of this population," Dr. Régis said.

"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," he added.

Dr. Régis is the president of the International Stereotactic Radiosurgery Society (ISRS) and chairman of its 2011 congress. He said he has raised major congress funding from the following manufacturers of radiosurgery devices: Accuray, BrainLab, Elekta, and Radionic.