Skip to main content
Log in

Configuration of the circle of Willis, direction of flow, and shape of the aneurysm as risk factors for rupture of intracranial aneurysms

  • ORIGINAL COMMUNICATION
  • Published:
Journal of Neurology Aims and scope Submit manuscript

Abstract

Background

Improved knowledge on risk factors for rupture of intracranial aneurysms may lead to more tailored aneurysm management. We studied whether configuration of the circle of Willis, direction of flow towards the aneurysm, and shape of the aneurysm are risk factors for rupture.

Methods

We reviewed CT angiograms of 126 patients with 75 ruptured and 75 unruptured aneurysms, matched for site of the aneurysm, gender and age of the patient, and year of CT angiogram. For the characteristics studied, we calculated odd ratios (ORs) with corresponding 95 % confidence intervals (CIs) for risk of rupture. Configuration of the circle of Willis (incompleteness, asymmetry or dominance) was analyzed on a per site basis. Non-spherical shape was subdivided into elliptical (oval and oblong) and multilobed. In additional analyses, we adjusted for size by means of multivariable logistic regression.

Results

Flow straight into the aneurysm (OR 2.0; 95 % CI 1.0–4.1) and non-spherical shape (OR 2.8; 95 % CI 1.5–5.5) were associated with rupture. Both elliptical shape, with increasing ORs for oval (OR 1.8; 95 % CI 0.8–4.0) to oblong shape (OR 6.2; 95 % CI 1.9–21), and multilobed shape (OR 4.1; 95 % CI 1.2–14) were associated with rupture. These ORs decreased after adjustment for size. Configuration of the circle of Willis was not associated with a strong risk of rupture; moderate risk could not be excluded.

Conclusion

Direction of flow into the aneurysm and nonspherical (both elliptical and multilobed) shape may contribute to the risk of rupture, but are related to aneurysm size and may warrant more frequent follow-up.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Similar content being viewed by others

References

  1. Beck J, Rohde S, El Beltagy M, Zimmermann M, Berkefeld J, Seifert V, Raabe A (2003) Difference in configuration of ruptured and unruptured intracranial aneurysms determined by biplanar digital subtraction angiography. Acta Neurochir (Wien) 145:861–865

    Article  CAS  Google Scholar 

  2. Bromberg JEC, Rinkel GJE, Algra A, Greebe P, Beldman T, van Gijn J (1996) Validation of family history in subarachnoid hemorrhage. Stroke 27:630–632

    PubMed  CAS  Google Scholar 

  3. Foutrakis GN, Yonas H, Sclabassi RJ (1999) Saccular aneurysm formation in curved and bifurcating arteries. AJNR Am J Neuroradiol 20:1309–1317

    PubMed  CAS  Google Scholar 

  4. Hendrikse J, van Raamt AF, van der Graaf Y, Mali WP, van der Grond J (2005) Distribution of cerebral blood flow in the circle of Willis. Radiology 235:184–189

    Article  PubMed  Google Scholar 

  5. Horikoshi T, Akiyama I, Yamagata Z, Sugita M, Nukui H (2002) Magnetic resonance angiographic evidence of sex-linked variations in the circle of willis and the occurrence of cerebral aneurysms. J Neurosurg 96:697–703

    PubMed  Google Scholar 

  6. Raghavan ML, Ma B, Harbaugh RE (2005) Quantified aneurysm shape and rupture risk. J Neurosurg 102:355–362

    PubMed  Google Scholar 

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

    PubMed  CAS  Google Scholar 

  8. San Millan RD, Yilmaz H, Dehdashti AR, Alimenti A, de Tribolet N, Rufenacht DA (2006) The perianeurysmal environment: influence on saccular aneurysm shape and rupture. AJNR Am J Neuroradiol 27:504–512

    Google Scholar 

  9. Velthuis BK, van Leeuwen MS, Witkamp TD, Ramos LMP, Berkelbach van der Sprenkel JW, Rinkel GJE (2001) Surgical anatomy of the cerebral arteries in patients with subarachnoid hemorrhage: comparison of computerized tomography angiography and digital subtraction angiography. J Neurosurg 95:206–212

    Article  PubMed  CAS  Google Scholar 

  10. Wermer MJ, van der Schaaf I, Algra A, Rinkel GJ (2007) Risk of rupture of unruptured intracranial aneurysms in relation to patient and aneurysm characteristics: an updated meta-analysis. Stroke 38:1404–1410

    Article  PubMed  Google Scholar 

  11. Wermer MJ, van der Schaaf IC, Velthuis BK, Majoie CB, Albrecht KW, Rinkel GJE (2006) Yield of short-term follow-up CT/MR angiography for small aneurysms detected at screening. Stroke 37:414–418

    Article  PubMed  Google Scholar 

  12. Wiebers DO, Whisnant JP, Huston J3, Meissner I, Brown RDJ, Piepgras DG, Forbes GS, Thielen K, Nichols D, O’Fallon WM, Peacock J, Jaeger L, Kassell NF, Kongable-Beckman GL, Torner JC (2003) Unruptured intracranial aneurysms: natural history, clinical outcome, and risks of surgical and endovascular treatment. Lancet 362:103–110

    Article  PubMed  Google Scholar 

Download references

Author information

Authors and Affiliations

Authors

Corresponding author

Correspondence to Nicolien K. de Rooij MD.

Rights and permissions

Reprints and permissions

About this article

Cite this article

de Rooij, N.K., Velthuis, B.K., Algra, A. et al. Configuration of the circle of Willis, direction of flow, and shape of the aneurysm as risk factors for rupture of intracranial aneurysms. J Neurol 256, 45–50 (2009). https://doi.org/10.1007/s00415-009-0028-x

Download citation

  • Received:

  • Revised:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s00415-009-0028-x

Key words

Navigation