A dissection and angiographic study of morphological variations in the anterior communicating artery complex in a South African sample

Background: The anterior communicating artery complex (ACAC), which includes the A1 and A2 segments of the anterior cerebral artery (ACA) and the anterior communicating artery (ACoA), is a common site for anatomical variation and aneurysm formation. While cerebral arterial variations have been linked to aneurysm development, limited data exists on these variations in the South African population. Methods: This study assessed ACAC morphology through two components: dissection of 68 formalin-fixed adult brains (35 female, 33 male) and analysis of 200 adult magnetic resonance angiogram (MRA) scans (145 female, 55 male). Anatomical variations in the ACAC were recorded and evaluated for their prevalence and potential association with cerebral aneurysms. Results: Variations in the ACAC were prevalent in 67.6 % of dissection specimens and 43.5 % of angiographic images. The most frequent variations of the ACoA observed in both dissection and angiographic samples were X-shaped formations and hypoplasia. In dissections, the A1 segment frequently displayed hypoplasia, duplication, and fenestration, while the A2 segment typically presented the 'anastomosed' variation. In angiographic scans, the A2 segment often exhibited a triple ACA configuration. A history of ACAC aneurysms was present in 23.9 % of MRA scans. However, no significant correlation was observed between ACAC variations and aneurysm presence. Conclusion: This study demonstrates significant morphological diversity within the ACAC, including newly described variations, and highlights inconsistencies with existing literature regarding aneurysm association. These findings underscore the need for region-specific anatomical data to inform surgical planning and risk assessment in cerebrovascular interventions.