Gamma Knife Surgery Benefits Epilepsy Patients Beyond Seizure Reduction
December 6, 2011
Neurosurgeons continue to explore minimally invasive surgery with gamma radiation (gamma knife surgery/GKS) in the treatment of brain lesions causing seizures and epilepsy. Studies of the procedure are showing it to be an effective alternative to invasive microsurgery for hypothalamic hamartomas and other lesions that lie deep within the brain. Prospective research by investigative teams in Canada and France, and presented at the American Epilepsy Society's 65th annual meeting, reveals that GKS in hypothalamic hamartomas has significant benefit in the lives of patients beyond seizure reduction.
The hypothalamus lies near the brain stem and controls a number of functions such as body temperature, circadian cycles and sleep. Hamartomas are abnormal clumps or masses of normal tissue attached to functional tissue. The lesions are present at birth and may provoke intractable seizures, including laughing seizures, and lead to precocious puberty and cognitive deficits.
Jean Regis and his team of investigators at Timone University Hospital, France, are studying the long-term results of GKS for hypothalamic hamartomas in pediatric patients as young as three years of age. Of patients treated between January 1999 and December 2007, 40 have been evaluated for at least three years post-surgery. The evaluations include seizure record review, neuropsychological tests, psychiatric evaluation, endocrinology evaluation and visual field and acuity analysis.
The number of seizures following GKS was dramatically decreased from a median of 92 seizures per month pre-operatively to 6 seizures per month after the procedure. Global Psychiatric and Cognitive co-morbidity was improved in 56% of patients, considered to be cured in 28%, remained unchanged in 8% and continued to worse in 8% of patients.
"This prospective trial is demonstrating very good safety and efficacy of gamma knife radiosurgery in the long term," says Regis. "Beyond seizure reduction, the improvement in psychiatric and cognitive domains, school performance and social integration appears to be a major benefit for children with this frequently catastrophic condition. We will continue to follow these children to observe any changes that might occur in their condition as they age."
In another study, conducted at the Centre Hospitalier Universitaire de Sherbrooke in Canada, investigators evaluated GKS for hypothalamic hamartoma in a small group of older patients 14 to 57 years of age. In this group, 66% of patients were seizure free at the time of evaluation. The mean time to seizure freedom following treatment was 18 months. Patients in whom there was little of no reduction in seizures had larger lesions than in the seizure free cohort.
"We found that when the entire lesions could be targeted, radiosurgery did more than reduce the seizures," says lead author Pascale Bourgeois. "There also were encouraging effects on cognition and quality of life. While the procedure is ineffective for large lesions, gamma knife surgery should be a first line surgical therapy for small hamartomas."