The anatomical variation of the circulus arteriosus cerebri in a cadaver cohort representing the population dynamics of the Western Cape.

The literature revealed a connection between the variations of the Circulus arteriosus cerebri (CAC) and cerebrovascular disease, ischemia, stroke, aneurysms and atherosclerosis. The diameters of the vessels forming the CAC have been classified into 22 types by previous authors. The aim of this study was to assess the variation of the CAC (diameter, length and anomalies) in a cadaver cohort representing the population of the Western Cape. Thirty-nine subjects (female n = 11, male n = 28) who had died of causes unrelated to brain trauma, were obtained from Stellenbosch University. Additionally, a pilot study was done on 20 specimens. The CAC were removed and fixed for three weeks in 10% buffered formaldehyde. Digital images were taken and the vessels were measured using Adobe Creative Suite 5: Extended edition (Photoshop). The normal diameter (type 1) was observed in 41% of specimens and type 4 (hypoplastic posterior communicating artery) was observed in 23.1%. One case (bilateral hypoplastic posterior communicating arteries and a hypoplastic right posterior cerebral artery) was classified as "other", since it could not be classified into the 22 types. Additional variations included duplication (17.9%) and one point fusion (15.4%) of the anterior communicating artery. Studies have shown that about half of a healthy population have a typical CAC (normal diameter and no anomalies). In the present study the prevalence of a typical CAC was only 15.4%. Studies can only be compared if the same definitions for variations are used. The knowledge of these variations is important in endarterectomy, stenting head and neck surgery and angiography.