1. Outcome after interventional or conservative management of unruptured brain arteriovenous malformations: a prospective, population-based cohort study Lancet Neurol March 2008 Sajedha Mahmood

2. Background AVMs are leading cause of ICH in young adults, but ICH is presenting symptom in only half of AVM diagnoses Increased detection of incidental, asymptomatic AVMs due to improved imaging Unruptured AVMs can be treated by intervention to avoid future rupture Risk of complications vs risk of conservative treatment Columbia AVM Databank analysis shows that outcome after intervention for unruptured AVM worse than conservative management Currently ARRUBA (randomised trial of unruptured brain AVMs) ongoing This study compares functional outcome of adults with unruptured AVM following intervention vs observation Prospective, population-based cohort study

3. Methods Scottish Intracranial Vascular Malformation Study (SIVMS) Register of patients > 16 years when first diagnosed with any unruptured intracranial vascular malformation Data from 1999 - 2003 Follow-up data accrued until analysis date 1 October 2007 Demographic data: age, sex, socioeconomic status Clinical data: type of presentation, comorbidities, smoking status, Oxford Handicap scale at presentation Neuroradiological data: first diagnostic imaging assessed by 2 neuroradiologists AVM size, venous drainage pattern, function of adjacent brain area, Spetzler-Martin grade, deep brain location, AVM-associated aneurysms Intervention defined as any type of intervention on AVM or associated aneurysm AVM nidus obliteration confirmed by DSA or MRA

4. Methods Follow-up: annual OHS ratings provided by GP Annual survey of medical records for occurrence of ICH, infarction or focal neurological deficit ICH: defined as symptomatic clinical event with signs of ICH on imaging, in CSF or post mortem Independent investigator assessed death, infarction, FNDs on basis of medical records, imaging and pathology Unaware of prognostic features

5. Analysis Comparison of demographic, clinical, radiological characteristics Survival analysis: OHS scores 0-1 vs 2-6 (2= some restrictions to lifestyle, but able to look after themselves) Time from presentation onwards for conservative management group Time from first intervention for treatment group

7. Results 229 adults with AVMs 114 presented with unruptured aneurysm 63 of 114 (55%) - interventional treatment - type of treatment decided by local clinician 51 (45%) - observation 7 patients treated had ICH/infarct/FND between presentation and intervention Treatment began a median of 1 year after presentation AVM nidus completely obliterated in 42 (67%), partially in 19 (30%), no data available for 2 (3%) 2 deaths within 3 years after treatment: one partially obliterated AVM post embolisation, other after radiosurgery with obliterated AVM on imaging few weeks prior to ICH 4 deaths in untreated group: one SAH, others unrelated causes

10. Progression to first ICH, infarction, FND

11. Progression to sustained poor outcome

12. Progression to poor functional outcome

13. Conclusions Intervention and AVM size are predictors of progression to poor outcome (OHS 2-6) in first 3 years No difference in progression to OHS 2-6 that is sustained until end of year 3 in both arms No difference in overall spectrum of dependence

14. Discussion Thorough case evaluation Prospective annual follow-up Blinded assessment of outcomes Comparison between treated vs untreated OHS as outcome measurement Prospective cohort study Baseline imbalance between both groups DSA data not available for all patients Short-term follow-up Follow-up by GPs rather than neurologist/neurosurgeon