Revised: April 15, 2013
Accepted: May 8, 2013
Published online: June 28, 2013
Processing time: 112 Days and 7 Hours
Variations of the anterior cerebral artery (ACA)-anterior communicating artery (ACoA) complex are commonly observed when associated with a symptomatic intracranial aneurysm. We report an asymptomatic ACoA aneurysm associated with duplicated hypoplastic A1 segment of the right ACA, observed in a 70-year-old female cadaver. Furthermore, the aneurysm, practically substituting the ACoA, caused a remarkable depression on the internal surface of the right frontal lobe, anterior to the optic chiasm. Aneurysms and other anomalies of the ACA and ACoA are common and their microvascular surgical management requires sound knowledge of the normal and variant vascular anatomy. Persistence of some embryonic vessels that normally disappear, disappearance of vessels that would normally persist or sprouting of new vessels due to hemodynamic and genetic factors are the usual causes for such anomalies. The high incidence of coexisting vascular anomalies and aneurysm suggests that such abnormalities predispose to aneurysm formation due to changes in the regional blood flow. A1 segment duplication has been reported to occur in 4% of subjects in cadaveric studies and in up to 0.5%-9.7% of cases of ACoA aneurysm surgery. Angiographic hypoplasias and aplasias of the A1 segment have been also correlated with ACoA aneurysm patients.
Core tip: Variations of the anterior cerebral artery (ACA)-anterior communicating artery (ACoA) complex are commonly observed when associated with a symptomatic intracranial aneurysm. We report an asymptomatic ACoA aneurysm associated with duplicated hypoplastic A1 segment of the right ACA, observed in a 70-year-old female. Furthermore, the aneurysm, practically substituting the ACoA, caused a remarkable depression on the internal surface of the right frontal lobe, antero-inferior to the anterior commissure and anterior to the optic chiasm. A literature review of similar cases and underlying mechanisms of such anomalies is presented.