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

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.

To report the efficacy and tolerance of GK radiosurgery in MTLE after a follow-up > 5 years.

Patients with a follow-up > 5 years presenting with MTLE and treated with a marginal dose of 24 Gy were included in the study.

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.

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.