Risk Factors for Subsequent Hemorrhage in Patients with Cerebellar Arteriovenous Malformations

ObjectiveThe aim of this study was to identify the risk factors for subsequent hemorrhage in patients with untreated cerebellar arteriovenous malformations (AVMs).MethodsWe searched our AVM database at Beijing Tiantan Hospital and identified 149 patients with cerebellar AVMs who were at least 1 month treatment free after initial diagnosis between 2000 and 2015. The patients were followed up from initial diagnosis until subsequent hemorrhage, initiation of treatment, or the end of 2015. The natural history of cerebellar AVMs was analyzed.ResultsThe overall annual rupture rate was 8.6%, with a mean follow-up period of 4.2 years (range, 1 month to 15 years). The annual rupture rate for previously ruptured AVMs was 10.8% during the whole follow-up period, 12.4% in the first 5 years (18.8% in the first year and 9.0% in the subsequent 4 years) and 6.7% in more than 5 years after initial diagnosis. The overall annual rupture rate for previously unruptured AVMs was 4.0%. Childhood at diagnosis, AVM size ≥3 cm and exclusively deep venous drainage were independent risk factors for subsequent hemorrhage. Previous AVM rupture significantly increased the hemorrhagic risk during the first 5 years but did not significantly affect subsequent hemorrhage thereafter.ConclusionsChildhood at diagnosis, large AVM size, and AVMs with exclusively deep venous drainage are independent risk factors for subsequent hemorrhage in patients with cerebellar AVMs. Previous rupture may increase the hemorrhagic risk during the first 5 years after diagnosis but may not significantly increase the risk in the following years.