Prevalence of ACA variations: A systematic review and meta‑analysis

Abstract

The anterior cerebral artery (ACA) and its divisions enclose symptomatically critical and supplementary differentiations. Anatomical variations of the distal ACA that are irregularly detected can be separated into three major groups, namely, azygos, bihemispheric and median ACA variations. The present study performed a systematic review and meta-analysis. The PICOS criteria and electronic databases, namely the Cochrane Library, PubMed (until December, 2023), Embase (until December, 2023) and MEDLINE (until December, 2023) were used to identify 48 articles to fulfill the eligible criteria. As a limited number of studies exist on the prevalence of ACA anatomical variations, the present meta-analysis aimed to determine the precise incidence of these variants. In addition, with the comparative description between cadaveric (autopsy) and imaging cases, more accurate results were extract from the prevalence presentation of the distal ACA variants. On the whole, no statistically significant differences were found between autopsy and imaging studies.

Keywords: anatomy A1; anatomy A2; anterior cerebral artery; anterior cerebral artery anomalies; anterior cerebral artery variations.

Figure 1

Flowchart of the study selection process.

Figure 2

(A) Forest plot for azygos ACA. The results demonstrated that the prevalence of azygos ACA was 1.5% (mean) (95% CI, 0.01-0.02, P<0.01). (B) Funnel plot, testing the sensitivity with funnel plot for azygos ACA; significant publication bias was found (P<0.01) and the heterogeneity was extensive (I²=83%). ACA, anterior cerebral artery; I², the percentage of total variation across studies that is due to heterogeneity rather than chance; CI, confidence interval.

Figure 3

(A) Forest plot for bihemispheric ACA. The results demonstrated that the prevalence of bihemishperic ACA was 7.5% (mean) (95% CI, 0.03-0.12). (B) Funnel plot for bihemispheric ACA; significant publication bias was found (P<0.01) and the heterogeneity was significant (I²=89%). ACA, anterior cerebral artery; I², the percentage of total variation across studies that is due to heterogeneity rather than chance; CI, confidence interval.

Figure 4

(A) Forest plot for median ACA. The results demonstrated that the prevalence of median ACA was 5.5% (mean) (95% CI, 0.04-0.07, P<0.01). (B) Funnel plot testing the sensitivity with funnel plot for median ACA; significant publication bias was found (P<0.01) and the heterogeneity was considerable (I²=85%). No considerable differences were found between the prevalence determined in autopsy (6%) and imaging (5%) studies. ACA, anterior cerebral artery; I², the percentage of total variation across studies that is due to heterogeneity rather than chance; CI, confidence interval.

Figure 5

The anatomical variations of the distal ACA. (A) Normal pattern, (B) azygos, (C) median, and (D) bihemispheric ACA variations. ACA, anterior cerebral artery. This image was generated using the ChatGPT artificial intelligence tool.