The detection and management of unruptured intracranial aneurysms

• Published in: Brain (London, England : 1878) Vol. 123; no. 2; pp. 205 - 221
• Main Authors: Wardlaw, J. M., White, P. M.
• Format: Journal Article
• Language: English
• Published: Oxford Oxford University Press 01.02.2000; Oxford Publishing Limited (England)
• Subjects: ADPKD = adult polycystic kidney disease; Adult; Age of Onset; Aged; Biological and medical sciences; Cerebral Angiography; CI = confidence interval; Cost-Benefit Analysis; CT angiography; CTA = computed tomographic angiography; Diagnosis, Differential; Female; GDC = Guglielmi detachable coils; Humans; IADSA = intra-arterial digital subtraction angiography; Incidence; Intracranial Aneurysm - diagnosis; Intracranial Aneurysm - epidemiology; Intracranial Aneurysm - surgery; ISUIA = International Study of Unruptured Intracranial Aneurysms; magnetic resonance angiography; Magnetic Resonance Imaging; Male; Mass Screening - economics; Medical sciences; Middle Aged; MRA = magnetic resonance angiography; Neurology; NSAID = non-steroid anti-inflammatory drug; Patient Care Planning; Pedigree; Prognosis; Risk Assessment; RR = relative risk; SAH = subarachnoid haemorrhage; screening; Sensitivity and Specificity; TCD = transcranial Doppler; Tomography, X-Ray Computed; transcranial ultrasound; Ultrasonography; unruptured intracranial aneurysm; Vascular diseases and vascular malformations of the nervous system; Sonography; Doppler ultrasound study; Human; Intracranial; Nervous system diseases; Radiodiagnosis; Aneurysm; Cardiovascular disease; Medical screening; Nuclear magnetic resonance imaging; Epidemiology; Cerebral disorder; Vascular disease; Transcranial route; Clinical management; Treatment; Central nervous system disease; Risk factor; Medical imagery; Computerized axial tomography; Diagnosis; NMR angiography; Cerebrovascular disease
• ISSN: 0006-8950; 1460-2156
• DOI: 10.1093/brain/123.2.205

The incidence of subarachnoid haemorrhage (SAH) is 6–8 per 100 000 person years, peaking in the sixth decade. SAH, mostly due to rupture of an intracranial aneurysm, accounts for a quarter of cerebrovascular deaths. Aneurysms increase in frequency with age beyond the third decade, are 1.6 times more common in women and are associated with a number of genetic conditions. Prospective autopsy and angiographic studies indicate that between 3.6 and 6% of the population harbour an intracranial aneurysm. Studies have found an increased rate of SAH in first degree relatives of SAH patients (relative risk 3.7–6.6). In affected families, the most frequent relationship between sufferers is sibling to sibling. The rupture rate of asymptomatic aneurysms was thought to be 1–2% per annum, but the recent International Study of Unruptured Intracranial Aneurysms found that the rupture rate of small aneurysms was only 0.05% per annum in patients with no prior SAH, and 0.5% per annum for large (>10 mm diameter) aneurysms and for all aneurysms in patients with previous SAH. Non-invasive tests such as magnetic resonance angiography (MRA), computed tomographic angiography (CTA) and transcranial Doppler (TCD) have been advocated as alternatives to intra-arterial digital subtraction angiography to screen for aneurysms. Although all are promising techniques, the quality of data testing their accuracy is limited. Overall reported sensitivity for CTA and MRA (TCD is poorer) was 76–98% and specificity was 85–100%, but many subjects had an aneurysm or recent SAH, which could overestimate accuracy. CTA and MRA are much poorer methods for the detection of aneurysms <5 mm diameter, which account for up to one-third of unruptured aneurysms. Elective surgical clipping of asymptomatic aneurysms has a morbidity of 10.9% and mortality of 3.8%. Treatment of aneurysms by Guglielmi coils, for which there is less long-term follow-up available, has a 4% morbidity and 1% mortality, but only achieves complete aneurysm occlusion in 52–78% of cases. There has been interest in screening for aneurysms, but the indication for, and cost effectiveness of screening are unclear because aneurysm prevalence varies, rupture rate is low, non-invasive imaging tests are not yet accurate enough to exclude small aneurysms and the morbidity and mortality for elective surgical treatment of unruptured aneurysms is high. There may be a limited role for investigation of high risk subgroups. Ideally, screening in such subgroups should be tested in a randomized trial. The avoidance of risk factors for aneurysms such as smoking, hypertension and hypercholesterolaemia should be part of the management of at-risk subjects.