How common are incidental brain findings in the general population?

Incidental brain findings, especially asymptomatic brain infarcts, benign tumors, and aneurysms, are relatively common (> 10%) in a population of older adults. Having this information may lead to a beneficial intervention (for example, the repair of a 15-mm aneurysm) or it may worsen quality of life and increase healthcare costs (for example, by causing worry and repeat imaging for a small aneurysm or meningioma that is unlikely to become symptomatic). Longitudinal studies are needed to better delineate when we should worry and when we should reassure our patients. (LOE = 1b)

Vernooij MW, Ikram MA, Tanghe HL, et al. Incidental findings on brain MRI in the general population. N Engl J Med 2007;357(18):1821-1828.  [PMID:17978290]

Cross-sectional

Government

Population-based

As our imaging technologies improve, we are increasingly faced with the problem of what to do when a patient's test shows an incidental finding. This study provides a baseline, telling us how common various brain findings are in a cross section of the population. Since 2005 the authors have performed a brain MRI on participants in the Rotterdam Study, a prospective cohort study of dementia. Almost all participants in the Rotterdam study agreed to imaging (91%). Participants had a mean age of 63 years (range = 45 years to 96 years) and 52% were women. Incidental findings were common, including: asymptomatic lacunar (5.6%) or cortical (2.0%) infarct; benign tumors (1.6%); aneurysms (1.8%); arachnoid cysts (1.1%); Chiari malformations Type I (0.9%); major vessel stenosis (0.5%); and cavernous angioma (0.4%). Malignancy or metastasis was rare, and was seen in only 2 patients. Infarcts and meningiomas became more common with age. Although aneurysms were relatively common, 32 of 35 were smaller than 7 mm and had a very low risk of rupture.