Long-term efficacy of gamma knife radiosurgery in mesial temporal lobe epilepsy

Abstract

Background: Gamma knife (GK) radiosurgery has been proposed as an alternative to classic microsurgery in mesial temporal lobe epilepsy (MTLE). Short-term follow-up studies have reported encouraging results, but long-term efficacy is not known. Objective: To report the efficacy and tolerance of GK radiosurgery in MTLE after a follow-up > 5 years. Methods: Patients with a follow-up > 5 years presenting with MTLE and treated with a marginal dose of 24 Gy were included in the study. Results: Fifteen patients were included. Eight were treated on the left side, and 7 were treated on the right. The mean follow-up was 8 years (range 6–10 years). At the last follow-up, 9 of 16 patients (60%) were considered seizure free (Engel Class I) (4/16 in Class IA, 5/16 in Class IB). Seizure cessation occurred with a mean delay of 12 months (± 3) after GK radiosurgery, often preceded by a period of increasing aura or seizure occurrence (6/15 patients). The mean delay of appearance of the first neuroradiologic changes was 12 months (± 4). Nine patients (60%) experienced mild headache and were placed on corticosteroid treatment for a short period. All patients who were initially seizure free experienced a relapse of isolated aura (10/15, 66%) or complex partial seizures (10/15, 66%) during antiepileptic drug tapering. Restoration of treatment resulted in good control of seizures. Conclusion: Gamma knife radiosurgery is an effective and safe treatment for mesial temporal lobe epilepsy. Results are maintained over time with no additional side effects. Long-term results compare well with those of conventional surgery.