Lancet Neurol March 2008 Sajedha Mahmood

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