Unruptured intracranial aneurysm (UIA)
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
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 3).
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 4).
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 5)
Rupture risk
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.