The effect of LINAC stereotactic radiosurgery on epilepsy associated with arteriovenous malformations

Reduction of seizures associated with arteriovenous malformations (AVMs) following radiosurgery has been reported. This investigation assessed the effect of LINAC radiosurgical treatment of AVMs on the associated epilepsies correlated to AVM location, size, seizure type, and postradiosurgical thrombosis. Of 100 patients with AVMs, 33 presented with seizures (11 generalized tonic-clonic seizures, 8 simple partial seizures, and 14 complex partial seizures with or without secondary generalization). Patients with AVMs >/=25.0 mm were more likely to have seizures. Patients with frontal lobe AVMs were the most likely to have associated epilepsy (72.7%). Following radiosurgery, 59% were seizure-free and 19% had marked reduction of seizure frequency. Seizure remission was most frequent for AVMs of the centrum (83.3%). Of 14 patients with 2-year follow-up angiography, 9 had complete thrombosis and 6 became seizure-free. Four of 5 patients without thrombosis also became seizure-free. We conclude that LINAC radiosurgery is effective for epilepsies associated with AVMs. Radiosurgery was most effective for generalized tonic-clonic and complex partial seizures. There was no statistically significant correlation between reduction in epilepsy and original AVM size. Four of 5 patients without thrombosis became seizure-free, suggesting that structural or biochemical alterations of epileptogenic neurons following radiosurgery may reduce epileptogenicity.