Gamma Knife surgery for hypothalamic hamartomas causing refractory epilepsy: preliminary results from a prospective observational study

Abstract

Object Hypothalamic hamartomas (HHs) are congenital lesions typically presenting with medically refractory epilepsy. Open or endoscopic surgical procedures to remove or disconnect the hamartoma have been reported to be effective but are associated with significant morbidity. The authors of studies on Gamma Knife surgery for HHs have reported an encouraging rate of epilepsy resolution with minimal side effects. At the Centre Hospitalier Universitaire de Sherbrooke, the authors have undertaken a prospective observational study of the outcomes of patients who underwent radiosurgery for HHs. 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 3 months and reported using the Engel Classification. Quality of life evaluation was performed annually using a standardized questionnaire, and neuropsychological evaluation was performed after 2 years. Results Nine patients were included in the study. They ranged in age from 12 to 57 years. Epilepsy began in infancy in all cases and was refractory to standard antiepileptic drugs. The patients received an average of 2 antiepileptic drugs before undergoing radiosurgery. Using the Régis Classification, 6 patients had smaller hamartomas (Grade I–III) and underwent treatment of the entire lesion, using a margin dose of 14–20 Gy. Treatment volume ranged from 0.3 to 1.0 ml. Three patients had larger lesions (Grade IV–VI) for which a radiosurgical disconnection was attempted, targeting the area of attachment to the hypothalamus. For those patients, the margin dose was 15 or 16 Gy, with treatment volume ranging from 0.8 to 1.8 ml. In all patients, the radiation dose received by the optic pathways was kept below 10 Gy. Disconnection led to no improvement in epilepsy (Engel Class IV). Four patients in whom the entire lesion was treated are now seizure free (Engel Class I), with another having only rare seizures (Engel Class II). Quality of life and verbal memory were improved in those patients with more than 3 years of follow-up. No adverse event occurred after radiosurgery. Conclusions Radiosurgery safely and effectively controlled the epileptic disorder in patients with HHs when the entire lesion could be targeted. Radiosurgical disconnection is ineffective and cannot be recommended.

Safety and efficacy of Gamma Knife radiosurgery in hypothalamic hamartomas with severe epilepsies: A prospective trial in 48 patients and review of the literature

“…The evaluation of the other surgical techniques with the strict prospective methodology that we used would considerably help us to clarify the role of each technique. It is important to evaluate following this high standard the new techniques that are still investigational such as laser thermocoagulation (LITE) . However, an injury to the bilateral medial mammillary bodies (with MRI evidence) associated with severe permanent amnesic complication has been already reported with this technique.…”

Clinical characteristics and long-term outcome of surgery for hypothalamic hamartoma in children with refractory epilepsy

“…Other treatment options available for management of HH include open surgical disconnection, endoscopic resection/disconnection, stereotactic radiosurgery, radiofrequency ablation, interstitial brachytherapy, and vagal nerve stimulation. [891011121314151617181920212223242526] Ng et al ., reported the largest series of patients who have undergone endoscopic resection of HH with a seizure freedom of 49% after a minimum period of 1 year follow-up. [12] The improvement in seizures following radiosurgery with gamma knife or linear accelerator follows a temporal sequence with an early favorable response followed by transient worsening and reduction/remission of seizures thereafter.…”

“…[891011121314151617181920212223242526] Microsurgery has the highest success rate and should be the primary treatment option in an era where there is an increasing trend towards combined modalities of treatment.…”

Evaluation of the Sellar and Parasellar Regions

“…86 Radiotherapy has also been used to treat small or postoperative residual hamartoma. 87 On imaging, the hamartoma presents as either a pedunculated mass protruding into the interpeduncular cistern or a sessile/intrahypothalamic mass protruding medially into the third ventricle. A hamartoma can range from a few millimeters to centimeters in size.…”