Short-term follow-up of stereotactic Gamma Knife radiosurgery in epilepsy.

The efficacy of stereotactic Gamma Knife radiosurgery (STGKRS) for epilepsy was assessed in 9 patients followed up for more than 1 year. The mean duration of seizures was 9 years (range 1-22 years). In all 9 patients the epilepsy was classified as medically intractable. MRI showed nonprogressive focal cerebral lesions of less than 2.0 cm in size with or without calcification. After STGKRS, 8 patients had an excellent result (seizure free, single seizure episode, or auras only). In 2 of these patients antiepileptic drug therapy could be discontinued. One patient had no worthwhile improvement. Neither the anatomic distribution of the lesion on neuroimaging study nor extracranial EEG-recorded epileptiform activity appeared to be significant determinants of outcome. Radiation-induced edema did not seem to affect the outcome of seizure control. This preliminary report indicates that, in selected patients with medically intractable seizures associated with a focal cerebral lesion, STGKRS may be effective in controlling or greatly reducing the seizures.