Gamma Knife Surgery in Mesial Temporal Lobe Epilepsy: A Prospective Multicenter Study

Abstract

Summary:Purpose: This article is the first prospective documentation of the efficacy and safety of gamma knife surgery (GKS) in the treatment of drug-resistant epilepsies of mesial temporal lobe origin.Methods: From July 1996 to March 2000, three European centers selected 21 patients with mesial temporal lobe epilepsy (MTLE) for a temporal lobectomy. The preoperative investigations included video-EEG with foramen ovale electrodes, magnetic resonance imaging, neuropsychological testing, and the ESI-55 quality-of-life questionnaire. In place of a cortectomy, radiosurgical treatment was performed by using the Leksell Gamma Knife (LGK) at a dose of 24 ± 1 Gy at the margin. The target included the anterior parahippocampal cortex and the basal and lateral part of the amygdala and anterior hippocampus (head and body). One patient (a heavy smoker) died of a myocardial infarction. Twenty patients were available for prospective evaluation. A minimum 2-year follow-up period included clinical, neuropsychological, and radiologic evaluations.Results: At each 6-month follow-up evaluation, the frequency of seizures was significantly smaller than that at the previous visit. The median seizure frequency of 6.16 the month before treatment was reduced to 0.33 at 2 years after treatment. At 2 years, 65% of the patients (13 of 20) were seizure free. Five patients had transient side effects, including depression, headache, nausea, vomiting, and imbalance. There was no permanent neurological deficit reported except nine visual field deficits. No neuropsychological deterioration was observed 2 years after treatment. The quality of life was significantly better than that before surgery.Conclusions: The safety and efficacy of the radiosurgical treatment of MTLEs appears good in this group of patient over short-to-middle term. Delay of the seizure cessation was the major disadvantage of GKS. A longer follow-up period is required for confirmation of these results. Key Words: EpilepsyTemporal lobe-Hippocampal sclerosis-RadiosurgeryEntorhinal cortex.Lars Leksell created the Leksell Gamma Knife (LGK) in 1968 for the purpose of functional neurosurgery, but the first attempt to use it as a minimally invasive surgical instrument for treatment of epilepsy is quite recent. Studies have shown a high rate of seizure cessation in patients with a space-occupying lesion when treated with the LGK.The first radiosurgical treatments for epilepsy surgery were performed by Talairach in the 1950s (1); he implanted yttrium in patients with mesial temporal lobe epilepsies (MTLEs) and no space-occupying lesion. The patients had a high rate of seizure control, provided that the seizure foci were confined to the mesial structures of the temporal lobe (2). Further clinical experience with the

Wednesday July 5, 2006 12:00-13:30 Hall 3D Platform Session Basic Science III: Pharmacology and Treatment

“…62.5% of patients were treated with propofol; 28.8% with thiopental and 9.6% with propofol and subsequently with thiopental. Median duration of ICU stay was 3.34 days (range [1][2][3][4][5][6][7][8][9][10][11][12]. Twenty-nine patients survived the episode of RSE; 2 patients died and 1 patient is in a persistent vegetative state due to cerebrovascular complications.…”

“…They were examined at the in-and outclinic between 1987 and 2000, and were followed-up for mean 4.5 years (range [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. The schemes of diagnostic criteria (inclusion to an epileptic syndrome and criteria of exclusion from one) were worked up according to ILAE (1989) and Proposed Diagnostic Scheme for People with Epileptic Seizures and with Epilepsy (2001), and other published data.…”

Serious Adverse Effects of Gamma Knife Radiosurgery for Mesial Temporal Lobe Epilepsy

“…3) Delay in seizure control after GKRS for MTLE has been well documented. [2][3][4]11,24) Significant reduction in seizures usually occurred at least 1 year after GKRS. Delayed treatment response makes evaluation of the treatment effectiveness difficult, because some patients might undergo open surgery before seizure control by GKRS.…”

“…GKRS for MTLE using 24 Gy resulted in seizure-free rate of 60% after 6-10 years follow-up. 3,24) Another pilot study reported that 67% of patients with MTLE were seizure-free after GKRS using 20 or 24 Gy at the 36-month followup evaluation. 2) However, some studies reported that none of the patients became seizure-free after GKRS.…”

Stereotactic radiosurgery for functional disorders

“…The same researchers then initiated a multicenter study, which was conducted at 3 European centers. 57 Twenty patients underwent radiosurgery with 24-25 Gy delivered to the mesial temporal lobe for intractable mesial temporal lobe epilepsy. After a follow-up period of 2 years, 65% of these patients were seizure free, however, it took about 12 months postsurgery for the seizure frequency to begin to drop significantly.…”