Screening for Intracranial Aneurysms

Recommendations for Screening

The American Heart Association and American College of Cardiology recommend screening for individuals with two or more first-degree relatives with intracranial aneurysms or subarachnoid hemorrhage, particularly those with additional risk factors such as hypertension, smoking, and female sex, starting at age 20-30 years and repeating every 7 years until age 80 1, 2
Screening is also recommended for patients with autosomal dominant polycystic kidney disease, type IV Ehlers-Danlos syndrome, microcephalic osteodysplastic primordial dwarfism, and coarctation of the aorta, as well as first-degree family members of patients with these conditions 1
The American College of Radiology recommends screening for patients with two family members with intracranial aneurysms or subarachnoid hemorrhage, particularly in those with a history of hypertension, smoking, and female sex 2
More recent evidence supports screening even with a single affected first-degree relative, particularly when the relative died at a young age and when the patient has additional risk factors such as female sex 1

Risk factors for developing new aneurysms on follow-up include older age (>30 years), female sex, current or former smoking, history of hypertension, higher lipid levels, higher fasting glucose, and previous history of aneurysm 1
The incremental cost-effectiveness ratio for screening individuals with ≥2 first-degree relatives with SAH is $37,400 per QALY, and life expectancy increases from 39.44 to 39.55 years with screening 1
For individuals with only one affected first-degree relative, screening has an incremental cost-effectiveness ratio of $56,500 per QALY, and screening becomes less cost-effective if initiated after age 50 1

The first screening has a detection rate of 8-19.1% 1
Small aneurysms (<7mm) in the anterior circulation have very low rupture rates 1
Individuals with one affected first-degree relative with aneurysmal subarachnoid hemorrhage (aSAH) have an average prevalence of unruptured intracranial aneurysms (UIAs) of 4.8%, compared to 3% in the general population 2

The American College of Radiology recommends MRA head as the preferred initial screening tool, with a pooled sensitivity of 95% and specificity of 89%, and diagnostic accuracy increased at 3T scanner strength 2
CTA head is an alternative screening test if MRA is contraindicated, with a sensitivity >90% for detecting aneurysms, although it is less ideal for repeated surveillance due to radiation exposure 2
DSA (Digital Subtraction Angiography) should be used if MRA/CTA findings are positive or questionable, or when planning treatment, as recommended by the American Heart Association/American Stroke Association 1, 3

Treatment decisions should consider aneurysm size, location, patient age, and comorbidities, and the treating physician should consider both their own experience and the volume of cases at their center when making recommendations 1
Early detection allows for preventive treatment before rupture, which carries high mortality (40-50%) and morbidity rates 1
Smoking cessation and blood pressure control are recommended for all first-degree relatives, regardless of screening decision, as smoking is a major modifiable risk factor 1, 3
Regular medical follow-up and education about warning signs of aneurysm rupture are also recommended 1, 3
High-volume centers (>20 cases annually) have better outcomes for both screening interpretation and potential treatment, according to the American Heart Association/American Stroke Association guidelines 1

Both MRA and CTA have reduced sensitivity for aneurysms <3mm in size, which is a limitation of screening 2
Vessel loops and infundibular origins of vessels can lead to false-positives for aneurysm on MRA, highlighting the need for careful interpretation of results 2
Initial screening is recommended after age 30, with repeat screening every 5-7 years if initial screening is negative 1, 4