Blood flow velocity in the arteries of the anterior cerebral artery complex in patients with an azygos anterior cerebral artery aneurysm: a transcranial color-coded sonography study

Objective

It is presumed that increased blood flow through the single azygos anterior cerebral artery (Az) may contribute to the formation of an Az aneurysm. The aim of this study was to assess the blood flow velocities in the arteries of the anterior cerebral artery (ACA) complex in patients with the Az aneurysm.

Patients and methods

A series of three patients (2 men, aged: 65, 52 and 41) with an aneurysm (unruptured in two cases) of the distal Az was examined. Blood flow velocities in the Az and the A1 segment of the ACA were measured by means of a transcranial color-coded duplex sonography (TCCS) and the Az to A1 segment (Az/A1) velocity ratio was calculated. The control group consisted of 22 healthy subjects (mean age: 44 years).

Results

There was a trend toward decreased (p = 0.06) mean blood flow velocity in the Az compared to the A2 segment of the ACA of the control group. Blood velocity in the A1 segment did not differ between the study and control groups. Pulsatility and resistance indices in the Az were similar to those in the A2 segment of the control group. There were no differences between the Az/A1 ratio in the study group and the A2/A1 velocity ratio in the control group.

Conclusion

Our results suggest that Az aneurysms are not associated with increased blood flow velocity in the Az. Possibly, a hemodynamic stress related to the Az bifurcation geometry, together with a bent course of this artery around the genu of the corpus callosum, predispose to aneurysm formation.