What preventive measures should be taken for individuals with a family history of brain aneurysm?

Preventive Measures for Individuals with a Family History of Brain Aneurysm

Individuals with a family history of brain aneurysm should undergo screening with MRA or CTA, particularly those with two or more affected first-degree relatives, and should aggressively manage modifiable risk factors including smoking cessation and blood pressure control. 1

Risk Assessment

• Family history significantly increases the risk of harboring an unruptured intracranial aneurysm, with prevalence ratios indicating an increased risk between 1.9% and 5.9% compared to the general population 2
• The risk is particularly elevated in individuals with multiple affected family members - having three or more affected relatives triples the risk of subarachnoid hemorrhage 2
• First-degree relatives of those with familial intracranial aneurysm syndrome have approximately 8% risk of harboring an unruptured aneurysm with a relative risk of 4.2 2

Screening Recommendations

Who Should Be Screened:

• Strong recommendation for screening in individuals with two or more first-degree relatives with history of aneurysmal subarachnoid hemorrhage (aSAH) or unruptured intracranial aneurysm (Class I; Level of Evidence B) 1
• For individuals with one first-degree relative with history of brain aneurysm, screening should be considered, especially with additional risk factors 1
• Screening is particularly important for those with additional risk factors that increase likelihood of aneurysm detection: 2, 1
  • Female sex (odds ratio 2.46)
  • History of cigarette smoking (odds ratio 3.24 for 20 pack-years compared to never smokers)
  • History of hypertension (odds ratio 1.26 for 10 years of hypertension)
  • Higher lipid levels
  • Higher fasting glucose

Screening Methods:

• MRA without contrast is the preferred initial screening method with sensitivity rates of 69-93% for aneurysms >3-5mm 1
• CT angiography is an acceptable alternative with sensitivities of 77-97% for aneurysms as small as 2-3mm 1

Screening Intervals:

• Long-term serial screening is recommended, as the yield remains substantial even after more than 10 years of follow-up and two initial negative screens 3
• Screening should be repeated approximately every 5 years, though some evidence suggests shorter intervals may be beneficial 4, 3
• In a long-term study, aneurysms were identified in 11% of individuals at first screening, 8% at second screening, 5% at third screening, and 5% at fourth screening 3
• Even after two negative screens, 3% of individuals developed de-novo aneurysms in follow-up screening 3

Risk Factor Modification

• Smoking cessation is critical as smoking is one of the strongest modifiable risk factors for aneurysm formation and rupture 1, 5
• Blood pressure control is essential, as hypertension is a major risk factor for hemorrhagic stroke 2
  • Antihypertensive medication reducing diastolic blood pressure by an average of 6 mm Hg has been shown to produce a 42% reduction in stroke incidence 2
• Avoid sympathomimetic drugs including cocaine and phenylpropanolamine, which have been implicated as causes of subarachnoid hemorrhage 2
• Limit alcohol consumption, as heavy alcohol use is an independent risk factor for subarachnoid hemorrhage 2

Special Considerations

• Individuals who have been previously treated for aneurysms require particularly vigilant follow-up, as they have a higher risk (relative risk 5.5) of developing new aneurysms 6
• The annual rate of new aneurysm formation in patients previously treated for a ruptured aneurysm is 1-2% per year 2
• Patients with multiple intracranial aneurysms may be particularly susceptible to new aneurysm formation 2
• Women have a higher incidence of aneurysmal subarachnoid hemorrhage compared to men (1.24 times higher) 2
• Screening should begin at age 16-18 years and continue until age 65-70 years 3
• Aneurysms have been identified in 5% of individuals who were screened before age 30 years 3

Genetic Considerations

• Certain genetic syndromes are associated with increased risk of aneurysm formation and should prompt more aggressive screening: 2
  • Autosomal dominant polycystic kidney disease
  • Type IV Ehlers-Danlos syndrome
  • Marfan syndrome
  • Coarctation of the aorta
  • Bicuspid aortic valve
  • Other rare conditions including neurofibromatosis type 1, tuberous sclerosis, and Noonan syndrome 2

By implementing these preventive measures, individuals with a family history of brain aneurysm can significantly reduce their risk of aneurysmal subarachnoid hemorrhage, which carries high morbidity and mortality rates.