Unruptured intracranial aneurysm (UIA)
see also International Study of Unruptured Intracranial Aneurysms.
Epidemiology
Around 3% of the adult global population has unruptured intracranial aneurysms (UIAs) 1)
It is clear that more incidental intracranial aneurysms will be encountered in the future and advancing technology can be expected to demonstrate them with increasing regularity.
The prevalence of Unruptured intracranial aneurysm (UIAs) in first-degree relatives of patients with aSAH in the Hong Kong Chinese population was lower than that in Caucasians. At the same time, most of the UIAs detected in a study were small (85.7% were < 5 mm, vs 66% in a meta-analysis). With a similar incidence of aSAH in Hong Kong (7.5 per 100,000 person-years) as compared with data cited in the literature, the hypothesis that UIA rupture risk size threshold is different in Chinese patients should be further investigated 2).
Natural history
Although the diagnosis of unruptured intracranial aneurysm (IA) has become more frequent, its natural history and management still remain controversial 3).
A better comprehension of its evolution could optimize our therapeutic strategies.
It has been shown that even small aneurysms may enlarge and bleed unpredictably with the passage of time.
Many factors are involved in management of patients with unruptured intracranial aneurysms. Site, size, and group specific risks of the natural history should be compared with site, size, and age-specific risks of repair for each patient 4).
Pooled multivariable analyses of individual data are needed to identify independent risk factors and to provide more reliable risk estimates for individual patients 5).
Studies on natural history of unruptured intracranial aneurysms suggest 10 year cumulative bleeding-related mortality and severe morbidity of no less than 7.5%. In the study of Krisht et al., surgical clipping resulted in an 0.8% rate of mortality and 3.4% permanent morbidity. This suggests that surgical clipping has the potential of a superior outcome to the natural history of patients who have an estimated life expectancy of no less than 10 years 6).
Prevalence
Higher in patients with autosomal dominant polycystic kidney disease (ADPKD) or a positive family history of intracranial aneurysm or subarachnoid haemorrhage than in people without comorbidity.
In Finland and Japan, the higher incidence of subarachnoid haemorrhage is not explained by a higher prevalence of UIAs, implicating higher risks of rupture 7).
During 1995 to 2004, a period of increasing neuroimaging utilization, Gabriel et al., did not observe an increased rate of detection of unruptured brain arteriovenous malformation (BAVM), despite increased detection of unruptured intracranial aneurysm (IA)s 8).
Etiology
A analysis identified differentially expressed genes and miRNAs in unruptured human cerebral aneurysms, suggesting the possibility of a role for miRNAs in aneurysm formation 9)
Rupture risk
see Unruptured intracranial aneurysm rupture risk
Screening
see Unruptured intracranial aneurysm screening.
Clinical features
Most unruptured intracranial aneurysms don’t have symptoms. “Most of these patients are found incidentally, when they get an MRI scan or computed tomography angiography scan for something unrelated.
Diagnosis
see Unruptured intracranial aneurysm diagnosis.
Treatment
see Unruptured intracranial aneurysm treatment.
Outcome
Unruptured intracranial aneurysm Outcome.
Case series
see Unruptured intracranial aneurysm case series.
Case reports
Unruptured intracranial aneurysm case reports.