[An aneurysm of the distal anterior cerebral artery with a remarkably anomalous configuration].

A case of aneurysm on the distal anterior cerebral artery with a remarkably anomalous configuration was reported. In the present case, the left anterior cerebral artery showed hairpin-like angulation, at the top of which a small saccular aneurysm was noticed. This anomalous anterior cerebral artery seemed to feed the territories of the fronto-orbital artery and the pericallosal artery. Although the incidence of distal anterior cerebral artery aneurysm is low, they are very interesting due to several characteristics. According to the reported cases of distal anterior cerebral artery aneurysms, acute angulation of the parent vessel, at the top of which saccular aneurysm is often noticed, and the hemodynamic stress has been considered to play important roles in aneurysm formation. The findings of the cerebral angiograms and the operation of the present case were demonstrated.