Related Experiment Video
Updated: May 23, 2026
Anteromesial Temporal Lobectomy for Medically Intractable Temporal Lobe Epilepsy: An Operative Study
Published on: August 15, 2025
Delayed complication after Gamma Knife surgery for mesial temporal lobe epilepsy
Kenichi Usami1, Kensuke Kawai, Tomoyuki Koga
1Department of Neurosurgery, The University of Tokyo Hospital, Tokyo, Japan. usaken-tky@umin.ac.jp
Object:
Despite the controversy over the clinical significance of Gamma Knife surgery (GKS) for refractory mesial temporal lobe epilepsy (MTLE), the modality has attracted attention because it is less invasive than resection. The authors report long-term outcomes for 7 patients, focusing in particular on the long-term complications.
Methods:
Between 1996 and 1999, 7 patients with MTLE underwent GKS. The 50% marginal dose covering the medial temporal structures was 18 Gy in 2 patients and 25 Gy in the remaining 5 patients.
Results:
High-dose treatment abolished the seizures in 2 patients and significantly reduced them in 2 others. One patient in this group was lost to follow-up. However, 2 patients presented with symptomatic radiation necrosis (SRN) necessitating resection after 5 and 10 years. One patient who did not need necrotomy continued to show radiation necrosis on MRI after 10 years. One patient died of drowning while swimming in the sea 1 year after GKS, before seizures had disappeared completely.
Conclusions:
High-dose treatment resulted in sufficient seizure control but carried a significant risk of SRN after several years. Excessive target volume was considered as a reason for delayed necrosis. Drawbacks such as a delay in seizure control and the risk of SRN should be considered when the clinical significance of this treatment is evaluated.
Insights
Gamma Knife surgery (GKS) for refractory mesial temporal lobe epilepsy (MTLE) can control seizures but carries a significant risk of symptomatic radiation necrosis (SRN) years later. Careful evaluation of risks versus benefits is crucial.
Area of Science:
- Neurosurgery
- Radiation Oncology
- Epilepsy Treatment
Background:
- Gamma Knife surgery (GKS) is a less invasive alternative to resection for refractory mesial temporal lobe epilepsy (MTLE).
- The long-term clinical significance and complications of GKS for MTLE remain debated.
Purpose of the Study:
- To report long-term outcomes and complications of GKS in patients with refractory MTLE.
- To evaluate the risk of symptomatic radiation necrosis (SRN) following GKS for MTLE.
Main Methods:
- Seven patients with MTLE underwent GKS between 1996 and 1999.
- Dose prescription varied, with 18 Gy or 25 Gy (50% marginal dose) delivered to medial temporal structures.
Main Results:
- High-dose GKS (25 Gy) achieved seizure abolition in 2 patients and significant reduction in 2 others.
- Two patients developed symptomatic radiation necrosis (SRN) requiring resection 5 and 10 years post-treatment.
- One patient showed MRI evidence of radiation necrosis without symptoms 10 years after GKS.
Conclusions:
- High-dose GKS can provide sufficient seizure control for refractory MTLE.
- Delayed SRN is a significant complication, potentially linked to excessive target volume.
- The clinical utility of GKS for MTLE must weigh seizure control against the risks of delayed complications like SRN.
