What are the screening recommendations for individuals with a family history of cerebral aneurysm?

Screening Recommendations for Individuals with Family History of Cerebral Aneurysm

Screening is strongly recommended 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. 1

Who Should Be Screened

Definite Screening Recommendations:

• Individuals with ≥2 first-degree relatives with intracranial aneurysm (IA) or subarachnoid hemorrhage (SAH) 1, 2
• Patients with autosomal dominant polycystic kidney disease, especially those with family history of IA/hemorrhagic stroke 1
• First-degree family members of patients with type IV Ehlers-Danlos syndrome 1
• Patients with microcephalic osteodysplastic primordial dwarfism 1
• Patients with coarctation of the aorta 1

Consider Screening For:

• Individuals with one first-degree relative with aneurysmal SAH, especially if:
  • The relative died at a young age
  • Additional risk factors are present (female sex, smoking, hypertension) 2

Screening Methods and Timing

Initial Screening:

• MRA is the preferred initial screening tool (sensitivity 95%, specificity 89%) 2
• CTA is an alternative if MRA is contraindicated 2
• DSA (Digital Subtraction Angiography) should be used if MRA/CTA findings are positive or questionable 2

Screening Schedule:

• Begin screening at age 20-30 years 1, 2
• For individuals with ≥2 first-degree relatives with IA/SAH:
  • Repeat screening every 7 years until age 80 1
  • More recent evidence suggests every 5 years may be appropriate 3
• Continue long-term serial screening even after two initial negative screens, as de-novo aneurysms can develop 3

Risk Factors Increasing Likelihood of Aneurysm Detection

• Older age (>30 years)
• Female sex
• Current or former smoking
• History of hypertension
• Higher lipid levels
• Higher fasting glucose
• Previous history of aneurysm (strongest risk factor for finding new aneurysms on follow-up) 1, 3

Cost-Effectiveness and Outcomes

• Screening individuals with ≥2 first-degree relatives with SAH is cost-effective with an incremental cost-effectiveness ratio of $37,400 per QALY 1
• 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 1
• Screening becomes less cost-effective if initiated after age 50 1

Yield of Screening

• First screening: 8-19.1% detection rate 1, 3, 4
• Second screening: 8% detection rate 3
• Third screening: 5% detection rate 3
• Fourth screening: 5% detection rate 3
• Even after two negative screens, 3% of individuals may develop de-novo aneurysms 3

Important Caveats

1. Risk of rupture between screenings: SAH can occur within the recommended 5-7 year screening intervals 5, 3

2. Size and location matter: Small aneurysms (<7mm) in the anterior circulation have very low rupture rates 1

3. Limitations of imaging: Both MRA and CTA have reduced sensitivity for aneurysms <3mm 2

4. False positives: Vessel loops and infundibular origins can be misinterpreted as aneurysms on imaging 2

5. Risk modification: All individuals with family history should be counseled on smoking cessation and blood pressure control, regardless of screening decision 2

The evidence strongly supports long-term serial screening for individuals with familial risk of cerebral aneurysms, as the yield remains substantial even after multiple negative screenings. This approach can significantly reduce morbidity and mortality from aneurysmal subarachnoid hemorrhage in high-risk populations.