SUBARACHNOID HEMORRHAGE
Management of asymptomatic intracranial aneurysm
Created 31/03/2021, last revision 05/03/2023
- prevalence of unruptured (asymptomatic) intracranial aneurysms (UIA) ~ 0.5-5%
- modern and widely used imaging methods increase the rate of incidentally detected intracranial aneurysms
- multiple aneurysms are found in 20-30% of cases
- management of unruptured aneurysms is controversial
- in the process of decision making, weigh the individual risks of conservative management and intervention, consider several prognostic factors
- distinguish:
- incidental aneurysm + personal history of SAH from another aneurysm – the highest risk of bleeding (up to 10 times higher compared to true incident aneurysm)
- incidental aneurysm + positive family history of SAH
- incidental aneurysm + negative family and personal history of SAH
Risk factors
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Prognostic factors
Aneurysm characteristics
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Patient characteristics
- age, gender, and comorbidities (⇒ higher surgical risk)
- according to ISUIA mortality/morbidity in age < 45 years was 6.5%, in age 45-65 14.4%, in > 65 years 32%
- ↑ risk of rupture in decompensated hypertension
- ↑ risk for smokers (up to 4 times higher in women) [Ogilvy, 2020]
- ↑ risk in women
- race
- history of SAH from another aneurysm (~10x higher risk)
- family history of SAH (highest risk with ≥ 2 affected relatives)
Experience of a surgeon/interventional radiologist
- combined morbidity/mortality
Prognostic scores
Management
- patients should be informed about the risks and benefits of conservative treatment, clipping, and coiling (AHA/ASA 2009 IIa/B)
- procedure risks:
- post-craniotomy epilepsy
- periprocedural stroke
- aneurysm rupture
- balance the rupture risk per year versus patient life expectancy
- a randomized trial comparing surgical and conservative management of unruptured aneurysms is not available and cannot be expected soon
- there is a paradox between the fact that, according to ISUIA, the risk of bleeding is low in small aneurysms (<7 mm ⇒ 0.7% per year) and the fact that most bleeding aneurysms in routine practice are < 7-10 mm
- it is assumed that some aneurysms walk through a period of higher risk of rupture after their formation and then stabilize and move into a period of low risk of rupture – some of these aneurysms are likely to bleed shortly after their formation
- it makes sense to treat only incidental aneurysms that, for example, grow or change their shape
- long-term stable aneurysms have a low risk of bleeding
- ISUIA (International Study of Unruptured Intracranial Aneurysms) study is the largest and most widely discussed trial
- n= 4060, three groups: no surgery x clipping x coiling
- the larger the aneurysm, the greater the risk of rupture
- higher risk for aneurysms in PCoA, PCA, and basilar artery
- higher risk in patients with previous SAH from another source (approx. 10x)
- the prospective arm (1991-1998) had an overall higher incidence of bleeding than the retrospective arm (1970-1991) – 0.8% vs. 0.3%
- according to the prospective data, the risks of clipping and coiling are comparable, but coiling achieved complete obliteration in only 51% of cases
- patients with aneurysms of the anterior circulation (MCA, ACoA) had better outcomes when they were clipped rather than coiled
- the differences in the results of the retrospective and prospective arms make the generalization of the results problematic
- according to many authors, the ISUIA study underestimates the risk of bleeding, as most ruptured aneurysms are 7-10 mm in diameter
The 5-year cumulative risk of rupture | ||
anterior circulation |
posterior circulation (incl. PCoA) | |
< 7 mm | 0% | 2.5% |
7-12 mm | 2.6% | 14.5% |
13-24 mm | 14.5% | 18.4% |
≥ 25 | 40% | 50% |
A rather conservative approach
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Rather surgical/interventional procedure
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Follow-up
- first follow-up (MRA/CTA) in 6-12 months after the procedure, then every 1 or 2 years
Screening for asymptomatic aneurysms
- generally not recommended (only grade C recommendations, cost-effectiveness is unknown)
- screening is not recommended in the general population, even for smokers and alcoholics
- may be considered in female smokers 30-60 years of age [Ogilvy, 2020]
- screening is recommended in:
- patients with previous aneurysmal SAH (higher risk of new aneurysm formation)
- first-degree relatives of patients with aneurysmal SAH
- more data are needed to help identify patients who would benefit from screening