Abstracts

RATIONALE:_Radiosurgery is often used to treat arteriovenous malformations (AVMs) located in deep brain locations. Most such procedures are successful in not only obliteration of the AVM but also decreasing associated seizures. Whereas radiosurgery is occasionally associated with development of easy-to-control seizures immediately post-operatively, there are no reports of intractable epilepsy developing after radiosurgery. METHODS: A case is presented in which a patient received gamma knife radiosurgery for an AVM and gradually developed intractable epilepsy thereafter. RESULTS: A 37 year old right handed female underwent radiosurgery for a right mesial parieto-temporo-occiptal AVM. One year later, the AVM had reduced in size, but the patient started having complex partial seizures (CPS). These initially occurred at a frequency of one per month, but six months later were occurring every other week. She also started having secondarily generalized tonic-clonic seizures (GTCS) once a month. Over the next year her seizure frequency gradually increased to several CPS per day and 2-3 GTCS per week despite treatment with various combinations of antiepileptic drugs. By this time her AVM had decreased to one-third the original size. Video-EEG monitoring demonstrated both CPS and GTCS to be arising from the right posterior quadrant. MRI revealed not only presence of the right sided AVM but also right hippocampal atrophy with increased T2 signal. She underwent surgical resection of the AVM and right temporal lobectomy. Three months post surgery she is seizure free. CONCLUSIONS: Radiosurgery has the potential of inducing intractable epilepsy.