The Effect of LINAC Stereotactic Radiosurgery on Epilepsy Associated with Arteriovenous Malformations

Abstract

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.

Seizure outcomes following radiosurgery for cerebral arteriovenous malformations

“…16,21,43,73 In this systematic review, we observed an overall seizure incidence of 28% in studies that included AVM patients treated with SRS. Risk factors While defining factors for seizure development in patients with AVMs may be important for risk stratification, analyzing seizure outcome following AVM treatment will help direct future therapy.…”

“…22,37,39,57 Relationships between seizure characteristics and seizure outcomes following SRS were also inconsistent; complex partial seizures with or without secondary generalization, generalized tonic-clonic seizures, infrequent and shortduration seizures, and seizure frequency have been associated with improved seizure control. 16,33,39,57,71 In contrast, other studies have also found no significant relationship between seizure outcome and seizure type, duration, frequency, and pattern or age at seizure onset. 16,37,39,57,71 The influence of hemorrhage on seizure outcome was also controversial.…”

“…16,33,39,57,71 In contrast, other studies have also found no significant relationship between seizure outcome and seizure type, duration, frequency, and pattern or age at seizure onset. 16,37,39,57,71 The influence of hemorrhage on seizure outcome was also controversial. Two of the 3 studies that evaluated radiosurgery margin and/or maximum dose showed no significant association between these radiosurgical parameters and seizure outcome.…”

“…For the final quantitative analysis, we identified 19 series comprising 1104 patients with AVMs and seizures who underwent SRS. 2,13,16,20,22,33,34,37,39,41,43,48,57,58,63,64,69,71,73 Figure 1 shows a flow chart of the review process.…”

“…22,28,41 At nonnecrotizing radiation doses, seizure suppression may be attributable to neuromodulatory effects. 10,16,53,54 Inhibition of protein synthesis has been hypothesized as a downstream effect of irradiation, curtailing sustained spontaneous neuronal discharges, along with inducing differential effects on the inhibitory g-aminobutyric acid and excitatory amino acid systems. 10,53,54 Stereotactic radiosurgery may also achieve seizure control through a radiosurgically induced gliotic capsule around the nidus.…”