Gamma knife radiosurgery for the treatment of recurrent seizures after incomplete anterior temporal lobectomy

To evaluate the efficacy and safety of gamma knife radiosurgery (GKS) in treating temporal lobe epilepsy, GKS was performed in four adult patients with recurrent complex partial seizures who underwent incomplete anterior temporal lobectomy (ATL) but were reluctant to undergo a second resective surgery. A marginal dose of 24.5-25 Gy, corresponding to 65-70% isodose curve, was delivered to the treatment target that included the residual amygdala and the head and anterior body of the hippocampus. None of the patients had severe acute side effects but three patients had radiation-induced MRI signal changes around the target volume 13, 20, and 24 months after GKS, respectively. All four patients had significant seizure reduction during the first 6-month period and clinical efficacy persisted throughout the 2-year follow-up period. All of the patients also had improved neuropsychological profiles, including memory function and quality-of-life, compared to their pre-GKS conditions. In conclusion, the safety and clinical efficacy of GKS make it a reasonable and suitable therapeutic alternative for patients with recurrent seizures after incomplete ATL. A higher marginal dose of >25 Gy and wider coverage may be more clinically beneficial but warrant further investigation.