title: Serious adverse effects of gamma knife radiosurgery for mesial temporal lobe epilepsy.
abstract: Gamma knife radiosurgery (GKRS) for mesial temporal lobe epilepsy (MTLE) has been proposed as an alternative to surgical resection. We report serious adverse effects of the treatment after follow-up periods over 9 years in 11 patients treated with GKRS between 1997 and 2000. The target volume of the entorhinoamygdalohippocampectomy area was 4.8-17.1 ml. Marginal dose of 20-25 Gy to the 50% isodose was delivered. One patient was drowned after suffering seizure 7 months after GKRS. Two patients did not show any reduction in seizure frequency over 9 and 18 months. Both patients requested open surgery and became seizure-free postoperatively. Four of the other eight patients were classified as Engel's class I within 4 years after GKRS. One of the four patients experienced symptomatic radiation-induced cerebral edema transiently, one developed radiation necrosis and required surgery 5 years after GKRS, and one developed cognitive impairment with hemiparesis 10 years after GKRS. Magnetic resonance (MR) imaging showed a large cyst in the irradiated temporal lobe. This patient recovered fully after the cyst excision. Only one patient became seizure-free and antiepileptic drug-free without symptomatic radiation-induced complications. However, MR imaging revealed abnormal enhancement, cyst formation, and diffuse white matter change in the irradiated temporal lobe 9 years after GKRS. GKRS for MTLE causes adverse effects of delayed seizure remission and symptomatic radiation-induced complications. Therefore, GKRS cannot be considered as an ideal alternative to surgery for MTLE. Long-term follow-up studies including MR imaging with contrast medium are required for the patients even after successful control of seizures.
authors.affiliation: Department of Neurosurgery, Asanogawa General Hospital, Kanazawa, Ishikawa. te03@asanogawa-gh.or.jp
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Kawamura
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Onishi
authors.forename: Yukihiko
authors.initials: Y
authors.lastname: Kohda
authors.forename: Genjiro
authors.initials: G
authors.lastname: Hirose
mesh_terms: D000328:Adult; D000368:Aged; D038481:Anterior Temporal Lobectomy / Q000009:adverse effects*; D001925:Brain Damage, Chronic / Q000175:diagnosis / Q000601:surgery; D004833:Epilepsy, Temporal Lobe / Q000175:diagnosis / Q000601:surgery*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000175:diagnosis / Q000601:surgery; D016634:Radiosurgery / Q000009:adverse effects*; D012008:Recurrence; D012086:Reoperation