Long-term follow-up of stereotactic Gamma Knife radiosurgery in epilepsy

From June 1990 to May 1995, 31 patients with epilepsy were treated by stereotactic Gamma Knife radiosurgery at the Asan Medical center. The effect of radiosurgery for epilepsy was assessed in 23 patients followed for longer than 1 year. The seizures were medically intractable in all patients: generalized in 13 cases, complex partial in 6 cases and partial in 4 cases. The duration of epilepsy ranged from 1 to 25 years, with a mean of 11.6 years. Electroencephalography and magnetic resonance imaging (MRI) were performed in all patients to identify and localize the seizure focus. The lesions on MRI were nonprogressive and less than 2.0 cm in diameter. At follow-up, 12 patients had an excellent result (class I according to Engel's classification). In 3 of these patients, antiepileptic medication was discontinued. In a further 2 patients, the seizure frequency decreased (class II and III). In the remaining 9 patients, the frequency of seizures was unchanged (class IV). Radiation-induced edema did not seem to affect the outcome with respect to seizure control. The role of radiosurgery in the treatment of epilepsy is still unclear. It is premature to draw any definite conclusions about its efficacy for intractable epilepsy in our series. However, even this small group certainly suggests the possibility of a new safe treatment method in selected patients.