Abstracts

Rationale: Gamma knife radiosurgery (GKRS) for mesial temporal lobe epilepsy (MTLE) has been proposed as an alternative to surgical resection. We report some adverse effects of GKRS for MTLE after the follow-up of over 8 years. Methods: From October 1999 to November 2000, eleven patients (10 females, one male, 43-65 years of age) underwent GKRS. The target volume of entorhinoamygdalohippocampectomy area was 4.8-17.1 ml. Marginal dose of 20-25 Gy at the 50% isodose line was delivered. Results: Six patients became seizure free 1-4 years after GKRS and required no other surgical procedure. One of these developed mental deterioration, aphasia and right hemiparesis as a result of radiation necrosis one year after GKRS. Patient needed corticosteroid treatment for a short period. One patient was drowned to death due to convulsion 7 months after GKRS. Two patients did not show significant reduction in seizure frequency over 9 and 18 months and requested open surgery. These patients underwent anterior temporal lobectomy and showed complete remission of seizure. One patient developed severe headache, visual change and frequent simple partial seizures 5 years later. MRI and isotope studies revealed a radiation necrosis with multiple hemorrhages in the temporal lobe. This patient required urgent resection of the anterior temporal lobe and became symptoms free. One patient became seizure free 4 years later, but developed gradual mental deterioration with left hemiparesis 10 years after GKRS. MRI showed a large cyst in the right temporal region with surrounding vasogenic edema. This patient underwent temporal lobectomy and recovered fully. Conclusions: Our trials of GKRS for MTLE indicated some adverse effects with delayed seizure remission, symptomatic radiation necrosis and cyst formation. GKRS can not be considered an ideal alternative to open surgery for patients with MTLE.