Stereotactic Radiosurgery May Be Effective in the Treatment of Idiopathic Epilepsy: Report on the Methods and Results in a Series of Eleven Cases

Abstract

Between 1982 and 1991, 11 patients (4 male, 7 female) ranging in age from 16 to 42 years who had been diagnosed with idiopathic focal epilepsy resistant to medication, were treated with stereotactic radiosurgery. The preoperative symptomatic period was 3–24 years. The process of localizing epileptic focus was based on chronic electrocorticography with flexible electrodes introduced into the subarachnoid space through single burr holes, and left in place during a maximum of 7 days until a clinical seizure was recorded. In most cases the procedure had to be repeated until localization was clear. This process was aided by a computer-assisted automatic analysis procedure. Final confirmation of focus location was done with depth electrode recording in most cases. Stereotactic radiosurgery was performed with a ⁶⁰Co gamma source using 10 mm collimators, except in two cases in which a betatron was used. The estimated dose was 10–20 Gy at the isocenter. Four of the 11 patients (36%) were medication-and seizure-free after a mean follow-up of 102.5 months. Five patients (45%) presented a reduction of seizures of 98, 89, 86, 75 and 75%, respectively. Two patients did not respond to treatment. Seizure reduction began after a delay period of 2–12 months except in 2 patients and in most cases seizure rate decreased progressively during several months (range: 3–48) postoperatively until stabilization. No complications related to irradiation were recorded. Doses effective for epilepsy are much lower than those for producing cerebral lesions, so the mechanism is not destruction of the focus or the pathways spreading the epileptic activity. It may be an effect upon neurotransmitters involved in epilepsy mechanisms, or an indirect effect through changes in the glial cells or by local plasticity phenomena.

Gamma Knife Surgery for Refractory Insular Cortex Epilepsy

“…One cannot exclude however the possibility of subnecrotic injury nonidentifiable on MRI. Several other studies have shown that irradiation with low-dose protocols can produce good results if sufficient time is allowed [24,38,39,40]. We acknowledge however that better outcomes could possibly have been obtained with higher doses as there is evidence that a regimen of doses around 25 Gy is superior to a 20-Gy marginal dose [11,20,21,37,41,42].…”

The Effect of LINAC Stereotactic Radiosurgery on Epilepsy Associated with Arteriovenous Malformations

“…In 1995, Regis et al [38] reported the results of a patient who had remained seizure-free for more than 16 months following the 'first' selective amygdalohippocampal radiosurgery for 'mesial temporal lobe epilepsy'. Barcia et al [39] have reported on the treatment of 11 cases of idiopathic intractable epilepsy by stereotactic radiosurgery following confirmation of the epileptogenic focus with depth electrodes. With a mean follow-up of 102.5 months, 4 of the patients (36 %) were seizure-free off anticonvulsants, and an additional 5 patients (45 %) had a reduction in seizure frequency by more than 75 %.…”

Stereotactic radiosurgery for treatment of drug-resistant epilepsy: state of the art and emerging applications

“…The study reported 11 patients who had epileptic foci treated with doses ranging from 10 to 20 Gy [21]. In the late 1990s, two papers reported seizure reduction after Gamma Knife radiosurgery of brain tumors [22][23].…”