The clinical use of radiosurgery instead of conventional resective surgery for the treatment of medically resistant epilepsy was derived from observations of the beneficial effects of radiation therapy, brachytherapy, and radiosurgery on the symptomatic seizures produced by lesions of several pathologies (mainly tumors or arteriovenous malformations) even in children, and even before there was an effect on the primary lesion. It has been postulated that epileptic neurons are more sensitive to irradiation compared with normal cerebral tissue and hence the effect without primary radiation damage. While its use primarily in children still remains in question, multiple trials are being initiated to define the efficacy of this tool since it has been shown in one European study to be safe and efficient for improvement in seizure outcome in adults.
One concern with radiosurgery is that the focus localization may be too imprecise in the children with pathologies that are not MTS. In those instances, anatomic localization and electrophysiologic confirmation may not be adequate to define the extent of the epileptogenic zone. Contrary to what happens with resective surgery, anatomic and functional localization is confirmed prior to the initiation and at the end of the resection. Focus localization with radiosurgery is performed preoperatively, the source located stereotactically within a very small volume, without in situ confirmation, with possible collateral damage from the radiation. With improvements in the technology, indeed, the potential for minimally invasive excisions of the seizure focus is optimal with minimal morbidity. In the future, radiosurgery may be both a promising primary procedure and a complement to conventional resective surgery for intractable epilepsy when better methods for focus imaging and localization are achieved.
[Also, see information on the Gamma Knife.]