Is screening for brain aneurysm warranted for first-degree relatives of a diagnosed sibling?

Screening for Brain Aneurysms in First-Degree Relatives

Screening for brain aneurysms is warranted for first-degree relatives of a diagnosed sibling, particularly if there are additional risk factors present such as smoking or hypertension. 1

Risk Assessment for First-Degree Relatives

The risk of harboring an unruptured intracranial aneurysm (UIA) is significantly elevated in first-degree relatives of patients with aneurysms:

• First-degree relatives have a prevalence of 4-8.7% of harboring UIAs 1, 2
• Siblings have a higher likelihood of detection than children of those affected 1
• Risk increases with additional factors:
  • Age over 30 years
  • Female sex
  • Cigarette smoking
  • History of hypertension
  • Higher lipid levels
  • Higher fasting glucose 1

Screening Recommendations Based on Family History

Strongly Recommended Screening:

• Individuals with ≥2 first-degree relatives with intracranial aneurysms or subarachnoid hemorrhage (SAH) 1
• First-degree relatives who are >30 years old with additional risk factors (smoking or hypertension) 1
• First-degree relatives of patients with familial syndromes associated with aneurysms:
  • Autosomal dominant polycystic kidney disease
  • Type IV Ehlers-Danlos syndrome
  • Microcephalic osteodysplastic primordial dwarfism 1

Consider Screening:

• First-degree relatives with only one affected family member (your sister's case) 1
  • These individuals have higher relative risk than general population but lower than those with multiple affected family members

Screening Protocol

Recommended Imaging:

• MRA (Magnetic Resonance Angiography) as initial screening tool 1
  • Sensitivity rates of 69-93%
  • Particularly useful for aneurysms >3-5mm
• CTA (Computed Tomography Angiography) is an alternative 1
• DSA (Digital Subtraction Angiography) if MRA/CTA findings are positive or questionable 1

Timing and Intervals:

• Initial screening after age 30 (when risk increases significantly) 3
• If initial screening is negative:
  • Repeat screening every 5-7 years 1, 4
  • Consider more frequent intervals (3-5 years) if additional risk factors are present 4

Important Considerations

Benefits of Screening:

• Early detection allows for preventive treatment before rupture
• Rupture of aneurysms carries high mortality (40-50%) and morbidity rates 1
• Screening can identify aneurysms in 4-19.1% of first-degree relatives 1

Limitations and Risks:

• Treatment of unruptured aneurysms carries risks:
  • Surgical complications in approximately 5.1% of cases 5
  • Potential for decreased neurological function after intervention 2
• Small aneurysms (<7mm) in anterior circulation have very low rupture rates 1
• Cost-effectiveness is questionable for relatives with only one affected family member (incremental cost-effectiveness ratio of $56,500 per QALY) 1

Risk Reduction Strategies

For all first-degree relatives, regardless of screening decision:

• Smoking cessation (smoking is a major modifiable risk factor) 1
• Blood pressure control 1
• Regular medical follow-up
• Education about warning signs of aneurysm rupture

Conclusion

Given your sister's diagnosis, screening is warranted, especially if you are over 30 years old or have additional risk factors such as smoking or hypertension. The optimal approach is MRA screening with follow-up at 5-7 year intervals if initial screening is negative. This recommendation balances the increased risk you face as a first-degree relative against the potential harms of unnecessary interventions.