Neurosurgery notes/Vascular/Haemorrhagic diseases/SAH/Screening for aneurysm

Screening for aneurysm

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SAH
Done with CTA or MRA
  • MRA can see thrombosed aneurysm
  • MRA better has no radiation
    • Cumulative radiation burden of CT
Advantage
  • If get negative scan can be at least more reassured for now
  • If get Positive scan can progress to get treatment
Disadvantage
  • Cost to society
  • Radiation with CTA
  • Reveal an aneurysm that is not suitable for treatment
  • Absence of aneurysms but the potential for development of new aneurysms.
  • Increased anxiety and a fear 12 of symptoms associated with subarachnoid haemorrhage, such as headache, potentially 13 increasing unnecessary primary care or emergency department attendances
Nice guidelines
  • Prevalence of intracranial aneurysms varies between studies but is estimated to range from 2% to 5% in the general population.
  • The chance of detecting an aneurysm on screening is reported to be around 10% in people with 2 first-degree relatives who have had subarachnoid haemorrhage
    • The committee also agreed that the risk of SAH is recognised to be greater in individuals with 2 first degree relatives with aSAH than those with 1 first degree relative with aSAH.
  • One cost–utility analysis found that different screening strategies (that varied by age range and frequency of screening) were cost effective compared to no screening in people with one affected first degree relative with aneurysmal subarachnoid haemorrhage.
    • Every 5 years between the age of 30 and 70 was the most cost-effective intervention
  • One cost–utility analysis found that different screening strategies (that varied by age range and frequency of screening) were cost effective compared to no screening in people with two or more first degree relatives with aneurysmal subarachnoid haemorrhage
    • Screening 2 years between the ages of 20 and 80 was the most cost-effective intervention
Mr Canty
  • Other than family members having aneurysm with no other PMHx risk factors
    • Do just one MRA
      • If neg that is it
      • If Pos then repeat scan as if incidental 1 year
  • If has PMHx risk factors
    • Do one MRA and then repeat if patient wants at 5 years
Before starting on a course of screening,
  • Patients must be carefully counselled as there is a large, cumulative, psychological burden associated with multiple scans and on identifying small aneurysms that may not require immediate intervention
Criteria
  • Strong family history (two or more first- degree relatives with intracranial aneurysms),
  • ADPKD and
  • Coarctation of the aorta
  • Screening should start at an age 10 years younger than the age of presentation of the index family member.
  • There are no clear guidelines on the frequency and mode of screening, particularly in
    • ADPKD as they have a high incidence of late de novo aneurysm formation (1.4% per patient year)
Zuurbier et al 2023
  • Predictors were
    • Female sex,
    • History of intracranial aneurysms/aSAH,
    • Older age (>50)
        • Familial screening for aneurysms in relatives of aSAH patients Follow up screening in 499 Risk score 9 Sex Previous aneurysm Older age Risk of new intracranial aneurysm after initial screening at 5 years between 2-12% at 10 years between 4-28% at 15 years between 7-40%
Wilson criteria for screening emphasise the important features of any screening program, as follows:
  • The condition should be an important health problem
  • The natural history of the condition should be understood
  • There should be a recognisable latent or early symptomatic stage
  • There should be a test that is easy to perform and interpret, acceptable, accurate, reliable, sensitive and specific
  • There should be an accepted treatment recognised for the disease
  • Treatment should be more effective if started early
  • There should be a policy on who should be treated
  • Diagnosis and treatment should be cost-effective
  • Case-finding should be a continuous process