Anatomical Science International

, Volume 91, Issue 4, pp 325–333 | Cite as

A multitude of variations in the configuration of the circle of Willis: an autopsy study

  • Wiesława Klimek-Piotrowska
  • Monika Rybicka
  • Aleksandra Wojnarska
  • Agnieszka Wójtowicz
  • Mateusz Koziej
  • Mateusz K. Hołda
Original Article


The circle of Willis (CW) is an anastomotic system of arteries located at the base of the brain. The aim of the study was to evaluate the anatomic configuration of the CW in the Polish population and to compare results with previously conducted research. Brains were obtained from 100 recently deceased human adults, and the diameters of cerebral vessels were measured using a slide caliper. Cerebral vessels were observed, paying attention to their origin, diameter, typical configuration and variations. Twenty-seven percent of cases presented the typical literature pattern. The remaining 73 % of all cases were atypical; in 16 % the CW was incomplete and in 57 % complete. Atypical findings involved the posterior communicating artery (PcomA), 62 %; anterior communicating artery (AcomA), 22 %; anterior cerebral artery (ACA), 14 %; posterior cerebral artery (PCA), 8 %. The most common variations were bilateral hypoplastic PcomAs (27 % of cases) and unilateral hypoplastic PcomAs (19 % of cases). Only 9 of the 22 types of CW variations classified previously in the literature were observed, and 26 variations (36 cases) in our study were labeled as ‘other’ type. Mean diameter values for typical CW patterns were internal carotid artery = 3.6 mm, ACA = 2.3 mm, AcomA = 1.9 mm, PCA = 2.2 mm and PcomA = 1.4 mm. Circle of Willis variations have a large impact on clinical practice. This study shows many rare variations that should be taken into consideration to avoid any unexpected complications during surgical procedures involving cerebral vessels.


Circle of Willis Anterior communicating artery Anterior cerebral artery Posterior communicating artery Posterior cerebral artery Internal carotid artery 



Circle of Willis


Anterior communicating artery


Anterior cerebral artery


Internal carotid artery


Posterior cerebral artery


Posterior communicating artery


Computed tomography angiography


Unilateral selective cerebral perfusion


Compliance with ethical standards

Conflict of interest

The authors have no conflicts of interest to disclose.

Financial disclosure

The authors have no financial relationships relevant to this article to disclose.


  1. Alpers BJ, Berry RG (1963) Circle of Willis in cerebral vascular disorders. The anatomical structure. Arch Neurol 8:398–402CrossRefPubMedGoogle Scholar
  2. Beck J, Rohde S, Berkefeld J, Seifert V, Raabe A (2006) Size and location of ruptured and unruptured intracranial aneurysms measured by 3-dimensional rotational angiography. Surg Neurol 65(1):18–25 (discussion 25-7) CrossRefPubMedGoogle Scholar
  3. Bor AS, Velthuis BK, Majoie CB, Rinkel GJ (2008) Configuration of intracranial arteries and development of aneurysms: a follow-up study. Neurology 70(9):700–705CrossRefPubMedGoogle Scholar
  4. De Silva KR, Silva R, Amaratunga D, Gunasekera WS, Jayesekera RW (2011) Types of the cerebral arterial circle (circle of Willis) in a Sri Lankan population. BMC Neurol 11:5CrossRefPubMedPubMedCentralGoogle Scholar
  5. Dimmick SJ, Faulder KC (2009) Normal variants of the cerebral circulation at multidetector CT angiography. Radiographics 29(4):1027–1043CrossRefPubMedGoogle Scholar
  6. Eftekhar B, Dadmehr M, Ansari S, Ghodsi M, Nazparvar B, Ketabchi E (2006) Are the distributions of variations of circle of Willis different in different populations? Results of an anatomical study and review of literature. BMC Neurol 6:22CrossRefPubMedPubMedCentralGoogle Scholar
  7. El Khamlichi A, Azouzi M, Bellakhdar F, Ouhcein A, Lahlaidi A (1985) Anatomic configuration of the circle of Willis in the adult studied by injection technics. Apropos of 100 brains. Neurochirurgie 31(4):287–293PubMedGoogle Scholar
  8. Fisher CM (1965) The circle of Willis: anatomical variations. Vasc Dis 2:99–105Google Scholar
  9. Han A, Yoon DY, Chang SK, Lim KJ, Cho BM, Shin YC, Kim SS, Kim KH (2011) Accuracy of CT angiography in the assessment of the circle of Willis: comparison of volume-rendered images and digital subtraction angiography. Acta Radiol 52(8):889–893CrossRefPubMedGoogle Scholar
  10. Henderson RD, Eliasziw M, Fox AJ, Rothwell PM, Barnett HJ (2000) Angiographically defined collateral circulation and risk of stroke in patients with severe carotid artery stenosis. North American Symptomatic Carotid Endarterectomy Trial (NASCET) Group. Stroke 31(1):128–132CrossRefPubMedGoogle Scholar
  11. Hoksbergen AW, Majoie CB, Hulsmans FJ, Legemate DA (2003) Assessment of the collateral function of the circle of Willis: three-dimensional time-of-flight MR angiography compared with transcranial color-coded duplex sonography. AJNR Am J Neuroradiol 24(3):456–462PubMedGoogle Scholar
  12. Kapoor K, Singh B, Dewan LI (2008) Variations in the configuration of the circle of Willis. Anat Sci Int 83(2):96–106CrossRefPubMedGoogle Scholar
  13. Klimek-Piotrowska W, Kopeć M, Kochana M, Krzyżewski RM, Tomaszewski KA, Brzegowy P, Walocha J (2013) Configurations of the circle of Willis: a computed tomography angiography based study on a Polish population. Folia Morphol (Warsz) 72(4):293–299CrossRefGoogle Scholar
  14. Lasjaunias P, Berenstein AI, Ter Brugge KG (2001) Surgical neuroangiography, 2nd edn, vol 1. Springer, Berlin, pp 105–179Google Scholar
  15. Lavieille J, Choux M, Sedan R (1966) Étude anatomo-radiologique de l’artère communicante postérieure. Neurochirurgie 12:717–731PubMedGoogle Scholar
  16. Lazorthes G, Gouaze A, Santini JJ, Salamon G (1979) The arterial circle of the brain (circulus arteriosus cerebri). Anat Clin 1:241–257CrossRefGoogle Scholar
  17. Papantchev V, Stoinova V, Aleksandrov A, Todorova-Papantcheva D, Hristov S, Petkov D, Nachev G, Ovtscharoff W (2013) The role of Willis circle variations during unilateral selective cerebral perfusion: a study of 500 circles. Eur J Cardiothorac Surg 44(4):743–753CrossRefPubMedGoogle Scholar
  18. Puchades-Orts A, Nombela-Gomez M, Ortuño-Pacheco G (1976) Variation in form of circle of Willis: some anatomical and embryological considerations. Anat Rec 185(1):119–123CrossRefPubMedGoogle Scholar
  19. Rhoton AL (2002) The supratentorial arteries. Neurosurgery 51(4 Suppl):S53–S120PubMedGoogle Scholar
  20. Riggs HE, Rupp C (1963) Variation in form of circle of Willis. The relation of the variations to collateral circulation: anatomic analysis. Arch Neurol 8:8–14CrossRefPubMedGoogle Scholar
  21. Siddiqi H, Tahir M, Lone KP (2013) Variations in cerebral arterial circle of Willis in adult Pakistani population. J Coll Physician Surg Pak 23(9):615–619Google Scholar
  22. Stehbens WE (1963) Aneurysms and anatomical variation of cerebral arteries. Arch Pathol 75:45–64PubMedGoogle Scholar
  23. Tanaka H, Fujita N, Enoki T, Matsumoto K, Watanabe Y, Murase K, Nakamura H (2006) Relationship between variations in the circle of Willis and flow rates in internal carotid and basilar arteries determined by means of magnetic resonance imaging with semiautomated lumen segmentation: reference data from 125 healthy volunteers. AJNR Am J Neuroradiol 27(8):1770–1775PubMedGoogle Scholar
  24. Willis T (1971) The anatomy of the brain: the 1681 edition, reset, and reprinted, with the original illustrations by Sir Christoper Wren. Usv Pharmaceutical Corp, TuchahoeGoogle Scholar
  25. Zhang C, Wang L, Li X, Li S, Pu F, Fan Y, Li D (2014) Modeling the circle of Willis to assess the effect of anatomical variations on the development of unilateral internal carotid artery stenosis. Biomed Mater Eng 24(1):491–499PubMedGoogle Scholar

Copyright information

© Japanese Association of Anatomists 2015

Authors and Affiliations

  • Wiesława Klimek-Piotrowska
    • 1
  • Monika Rybicka
    • 1
  • Aleksandra Wojnarska
    • 1
  • Agnieszka Wójtowicz
    • 1
  • Mateusz Koziej
    • 1
  • Mateusz K. Hołda
    • 1
  1. 1.Department of AnatomyJagiellonian University Medical CollegeKrakowPoland

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