Aneurysms: CNS


Intracranial aneurysms are a source of clinical concern because their rupture can cause subarachnoid haemorrhage, which is associated with high risk of death and disability. The prevalence of intracranial aneurysms has been difficult to assess but is estimated to be roughly 2% of the general population in North America. The size of an intracranial aneurysm is the greatest predictor of rupture. Other predictors of rupture include a prior history of subarachnoid haemorrhage and the location of the aneurysm. The majority of intracranial aneurysms discovered incidentally in the general population are smaller than 10 mm in diameter and pose little risk of rupture. Aneurysms requiring treatment can be treated with surgical clipping or endovascular coil embolisation. A large randomised study has shown that the functional outcome at 1 year is better after endovascular coiling than with surgical clipping in patients suitable for either therapy.

Key concepts:

  • Intracranial aneurysms occur in an estimated 2% of the North American general population.

  • Rupture of an intracranial aneurysm leads to a devastating type of stroke called subarachnoid haemorrhage.

  • Size of an intracranial aneurysm is the greatest predictor of rupture.

  • More than 90% of unruptured aneurysms are less than 10 mm in diameter and have a low yearly risk of rupture.

  • Intracranial aneurysms at risk for rupture can be treated with surgical clipping or endovascular embolisation.

  • Ruptured aneurysms require prompt treatment to prevent a catastrophic recurrent haemorrhage.

Keywords: intracranial; aneurysm; subarachnoid haemorrhage; stroke; atherosclerosis; angiography; computed tomography; magnetic resonance imaging; neurosurgery

Figure 1.

Above: graphical representation of endovascular coiling of an intracranial aneurysm. Below: graphical representation of surgical clipping across the neck of an intracranial aneurysm. By permission of Mayo Foundation for Medical Education and Research. All rights reserved.


Further Reading

Bederson JB, Connolly ES Jr, Batjer HH et al. (2009) Guidelines for the management of aneurysmal subarachnoid hemorrhage: a statement for healthcare professionals from a special writing group of the Stroke Council, American Heart Association. Stroke 40(3): 994–1025 Epub 22 January.

Brisman JL, Song JK, Newell DW et al. (2006) Cerebral aneurysms. New England Journal of Medicine 355: 928–939.

International Study of Unruptured Intracranial Aneurysms Investigators (2003) Unruptured intracranial aneurysms: natural history, clinical outcome, and risks of surgical and endovascular treatment. Lancet 362: 103–110.

Rinkel GJ, Djibuti M, Algra A and van Gijn J (1998) Prevalence and risk of rupture of intracranial aneurysms: a systematic review. Stroke 29: 251–256.

Schievink W (1997) Intracranial aneurysms. New England Journal of Medicine 336: 1267‐a.

Wiebers DO, Piepgras DG, Meyer FB et al. (2004) Pathogenesis, natural history, and treatment of unruptured intracranial aneurysms. Mayo Clinic Proceedings 79(12): 1572–1583.

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How to Cite close
Rubin, Mark N, Lanzino, Giuseppe, and Rabinstein, Alejandro(Apr 2010) Aneurysms: CNS. In: eLS. John Wiley & Sons Ltd, Chichester. [doi: 10.1002/9780470015902.a0022324]