Incidence of adult brain arteriovenous malformation hemorrhage in a prospective population-based stroke survey

Background: Brain arteriovenous malformations (AVMs) represent a potential source of intracranial hemorrhage, especially in young adults, but prospective population-based incidence data on AVM hemorrhage are lacking. We investigated the incidence of first-ever AVM hemorrhage in adults based on population data from the Northern Manhattan Stroke Study (NOMASS). Methods: NOMASS is a prospective, population-based, stroke incidence survey collecting all hospitalized and nonhospitalized cases with first-ever (incident) stroke over the age of 20 in a ZIP code-defined area. All patients undergo CT and/or MR brain imaging and clinical data are systematically collected from the medical records. For this study, data on all cases with incident intracranial hemorrhage, i.e. any intracerebral, intraventricular and/or subarachnoid hemorrhage, occurring between July 1, 1993 and June 30, 1997 were used. Patients with intracranial hemorrhage due to trauma, tumor or intracranial vascular malformations other than a previously unknown AVM were excluded from the study. Results: Of the 207 patients diagnosed with a first-ever intracranial hemorrhage, 3 cases (1.4%) with an underlying brain AVM were identified. The crude incidence rate for first-ever AVM hemorrhage in our adult population was 0.55 per 100,000 person-years (95% confidence interval 0.11-1.61). Conclusions: Our results support prior findings from retrospective surveys. Population-based studies providing a prospective design for AVM detection and diagnosis are needed to confirm the data.