Intro

• Prevalence by imaging and autopsy is 0.4 to 6%

• The best guess is about 2% have asymptomatic aneurysms

• Of those, 20 to 30% have multiple aneurysms

• Rupture occurs at about 6 to 16 per 100k = about 1 in 10,000

• The risk of rupture relates to size means smaller = less likely

Screening

• Consider in first-degree relatives of patients with known aneurysms when 2 or 3 family members affected

Risk

• Large study from Scotland shows 10-year risk of having aneurysm and rupture leading to subarachnoid haemorrhage (SAH) =

• 1 x second degree relative = 0.3%

• 1 x first degree relative = 0.8%

• 2 x first degree relatives = 7.1%

• The background risk of general population = 0.1%

Two or more affected first-degree relatives

• Screening recommended

• One study showed 37 out of 400 = 9% had aneurysms

• One strategy is to screen relatives yearly with MRA for 3 years and then expand the screening interval to every 5 years for those who had no aneurysms detected

One affected first-degree relative

• Lifetime risk is 1 to 5% at age 70 of rupture and SAH

• One study showed aneurysm is 4% = twice prevalence of the general population

• Screening generally not recommended