Gamma Knife Surgery for Epilepsy Related to Hypothalamic Hamartomas Jean Régis, MD,* Didier Scavarda, MD, ‡ Manabu Tamura, MD,* Nathalie Villeneuve, MD, † Fabrice Bartolomei, MD, PhD, † Thierry Brue, MD, PhD, ‡,§ Isabelle Morange, MD, § David Dafonseca, MD, & and Patrick Chauvel, MD † Numerous neurosurgical approaches are available for children presenting with hypotha- lamic hamartomas (HHs) associated with severe epilepsy. A concern regarding the impair- ment of short-term memory after resective surgery is promoting the exploration of less invasive alternatives like radiosurgery. Gamma knife radiosurgery (GKS) can lead to a real reversal of the epileptic encephalopathy. Three years after radiosurgery, 60% of the children have an excellent result with complete seizure cessation in 40% and rare nondis- abling seizures in 20%, often in association with dramatic behavioral and cognitive im- provement. No permanent neurologic complications have thus far been reported. Rare transient cases of poikilothermia have been observed. GKS is clearly the safer approach for these difficult patients. Young patients with severe epilepsy and neurocognitive comorbid- ity must be treated by using a curative approach as early as possible. Topological type (according to our original classification) is the major feature for selection of the best treatment strategy. Type I HH deeply embedded in the hypothalamus is treated safely and efficiently by GKS. Type II HH can be resected by either endoscopic or transcallosal approaches or treated by GKS depending on the parent’s choice and severity of epilepsy. In small type III HH, GKS is the safer procedure because of the very close relationship to the fornix and mammillary bodies. Types V (rarely epileptic) and IV are frequently operable by disconnection. Very large type VI (or mixed type) with a large component above the floor of the third ventricle must be disconnected, and then the upper remnant is best treated by GKS using a staged technique. Overall, when the lesion is sufficiently small, GKS offers a rate of seizure control comparable to microsurgery but with much lower risk. The disad- vantage of radiosurgery is its delayed action. Longer follow-up is mandatory for a reliable evaluation of the role of GKS. Semin Pediatr Neurol 14:73-79 © 2007 Elsevier Inc. All rights reserved. KEYWORDS hypothalamic hamartoma, gamma knife surgery, resective microsurgery, discon- nective surgery, epilepsy, poikilothermia H ypothalamic hamartomas (HHs) are rare congenital het- erotopic lesions that are intrinsically epileptogenic when closely connected to the mammillary bodies. 1,2 Patients classically present with gelastic seizures during the first years of life. 3 In the more severe cases, affected patients develop an epileptic encephalopathy during the following years, 4 char- acterized by drug resistance, various types of seizures with generalisation (including drop attacks), 3 cognitive decline, 5-8 and severe psychiatric comorbidity. 9 Usually, seizure semiol- ogy suggests the involvement of temporal or frontal lobe region and suggests a phenomenon of secondary epilepto- genesis. 10-12 In 1969, Paillas and coworkers 1 first showed that the epi- lepsy associated with HH, including the signs of involvement of temporal or frontal lobe regions, can be alleviated with surgical resection of the HH lesion itself. Direct proof of the role of the HH in generating seizure activity was provided by *Department of Functional Neurosurgery, INSERM 751, Timone Hospital, Marseilles, France. ‡Department of Neurophysiology, INSERM 751, Timone Hospital, Mar- seilles, France. †Department of Pediatric Neurosurgery, Timone Hospital, Marseille, France. §Department of Endocrinology, Timone Hospital, Marseille, France. &Department of Psychiatry, Timone Hospital, Marseille, France. Address reprint requests to Jean Régis, MD, Service de Neurochirurgie Fonc- tionnelle et Stéréotaxique, C.H.U. La Timone, 264 rue Saint Pierre, 13,385 Marseille, Cedex 05. E-mail: jregis@ap-hm.fr 73 1071-9091/07/$-see front matter © 2007 Elsevier Inc. All rights reserved. doi:10.1016/j.spen.2007.03.005