Abstracts

Rationale: To compare the risk of epileptic seizure(s) in adults having conservative management or interventional treatment for a brain arteriovenous malformation (AVM).Methods: We used annual general practitioner follow-up, patient questionnaires and medical records surveillance to quantify the 5-year risk of seizure(s) and the chances of achieving two-year seizure freedom for patients undergoing AVM treatment compared to patients managed conservatively in a prospective population-based study of newly diagnosed AVMs in adults in Scotland in 1999-2003.Results: We identified 229 adults with a new diagnosis of an AVM, of whom two-thirds received interventional treatment (154/229; 67%) during 1,862 person-years of follow-up (median completeness of follow-up 97%). There was no significant difference in the time to first or recurrent seizure over 5 years following AVM treatment, compared to the first 5 years following clinical presentation in conservatively managed adults, in analyses stratified by mode of presentation (intracerebral haemorrhage [ICH], 35% vs. 26%, p=0.5; seizure, 67% vs. 72%, p=0.6; incidental, 21% vs. 10%, p=0.4). Only haematoma volume significantly influenced the five-year risk of a first-ever seizure in adults presenting with ICH (hazard ratio [HR] = 1.02 [95%CI 1.01 to 1.04]; p<0.001); there was a trend towards an increased seizure risk after the occurrence of a symptomatic seizure at ICH onset (HR = 2.4 [95%CI 0.9 to 6.2]; p=0.07) while receipt of AVM treatment (HR = 3.0 [95% CI 0.4 to 24]; p=0.3) did not independently influence the risk. For patients with epilepsy, the chances of achieving two-year seizure-freedom during 5-year follow-up were similar following AVM treatment (n=39; 52%, 95%CI 36% to 68%) or conservative management (n=21; 57%, 95%CI 35% to 79%; p=0.7), though more patients undergoing AVM treatment were on anti-epileptic therapy at the start of follow-up (82% versus 21%).Conclusions: Interventional treatment does not seem to influence the five-year risk of seizures in adults with an AVM, and further confirmation of these findings is awaited from an ongoing randomised controlled trial.