Ten-Year Detection Rate of Brain Arteriovenous Malformations in a Large, Multiethnic, Defined Population

Abstract

Background and Purpose-To evaluate whether increased neuroimaging use is associated with increased brain arteriovenous malformation (BAVM) detection, we examined detection rates in the Kaiser Permanente Medical Care Program of northern California between 1995 and 2004. Methods-We reviewed medical records, radiology reports, and administrative databases to identify BAVMs, intracranial aneurysms (IAs: subarachnoid hemorrhage [SAH] and unruptured aneurysms), and other vascular malformations (OVMs: dural fistulas, cavernous malformations, Vein of Galen malformations, and venous malformations). Poisson regression (with robust standard errors) was used to test for trend. Random-effects meta-analysis generated a pooled measure of BAVM detection rate from 6 studies. Results-We identified 401 BAVMs (197 ruptured, 204 unruptured), 570 OVMs, and 2892 IAs (2079 SAHs and 813 unruptured IAs). Detection rates per 100 000 person-years were 1.4 (95% CI, 1.3 to 1.6) for BAVMs, 2.0 (95% CI, 1.8 to 2.3) for OVMs, and 10.3 (95% CI, 9.9 to 10.7) for IAs. Neuroimaging utilization increased 12% per year during the time period (PϽ0.001). Overall, rates increased for IAs (PϽ0.001), remained stable for OVMs (Pϭ0.858), and decreased for BAVMs (Pϭ0.001). Detection rates increased 15% per year for unruptured IAs (PϽ0.001), with no change in SAHs (Pϭ0.903). However, rates decreased 7% per year for unruptured BAVMs (Pϭ0.016) and 3% per year for ruptured BAVMs (Pϭ0.005). Meta-analysis yielded a pooled BAVM detection rate of 1.3 (95% CI, 1.2 to 1.4) per 100 000 person-years, without heterogeneity between studies (Pϭ0.25). Key Words: brain AVM Ⅲ cerebral aneurysm Ⅲ vascular malformation Ⅲ incidence Ⅲ MRI B rain arteriovenous malformations (BAVMs) are lesions of the cerebral vasculature in which arterial blood flow is shunted directly into the venous system without passing through a capillary system, resulting in high-flow lesions prone to rupture. The estimated detection rate of BAVMs has been reported to be Ϸ1 per 100 000 person-years, accounting for 1% to 2% of all strokes. 1 In order of decreasing frequency, the clinical presentations of BAVMs include hemorrhage, seizures, headaches, and neurologic deficits. 2 The primary management aspect of BAVMs is prevention of rupture and the resulting intracranial hemorrhagic event. 3 The annual risk of intracranial hemorrhage after diagnosis of BAVMs is Ϸ2% to 4% per year; the rate is higher for those with initially ruptured and lower for those with unruptured presentations. 1,4,5 BAVMs that do not bleed can cause seizures, headaches, or neurologic deficits due to a mass effect and involvement of neighboring eloquent brain regions. 3,6 Initial discovery of BAVMs in patients usually follows clinical presentation, most commonly hemorrhage from a ruptured lesion. Advances in neuroimaging techniques, including magnetic resonance imaging (MRI), computed tomography (CT), and cerebral angiography, have provided improved resolution for detecting and evaluating BAVMs. [7][8][9] With the ability to detect ...

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