Radiosurgery for drug-resistant epilepsies: State of the art, results, and perspectives

Abstract

Radiosurgery has been evaluated in our epilepsy surgery program since as early as 1992. Differential effect hypotheses based on the clinical observation of the safe antiepileptic effect of radiosurgery in AVM located in highly functional cortex have been demonstrated experimentally at the biochemical and cellular level. Memory sparing in dominant side mesial temporal lobe epilepsies (MTLE) suggests the possibility to reproduce this differential effect in clinical practice. Nowadays, with 20 years of experience in this field, numerous experimental studies and clinical prospective trials are substantiating a reasonable worldwide experience allowing us to define seriously what can be expected from radiosurgery in epilepsy. Several prospective trials have demonstrated the safety and efficacy of GKS in several kinds of epilepsies including MTLE and hypothalamic hamartomas. The role of radiosurgery in callosotomies and neocortical epilepsies is currently under evaluation. Clinical series and experimental data are suggesting that the use of radiosurgery is turning out to be beneficial only to those patients in whom strict preoperative definition of the extent of the epileptogenic zone has been achieved, and where strict rules of dose planning have been followed. As soon as these principles are not observed, the risk of treatment failure or untoward side effects increases dramatically. Long-term outcome is nowadays available for MTLE and hypothalamic hamartomas. Pure MTLE especially in patient with a high risk of verbal memory loss, or patients reluctant to a microsurgical intervention and patients with small Type I, II, and III hypothalamic hamartomas can be considered as current practice.​