[Persistent primitive olfactory artery: report of 5 cases].

Five cases of a persistent primitive olfactory artery are reported. The anomalous artery coursed anteromedially along the ipsilateral olfactory nerve and made a hairpin turn, supplying the circulation of the anterior cerebral artery. It was proposed that a primitive embryonic olfactory artery had remained as this artery. A cerebral aneurysm was located at the hairpin curve of the artery. Hemodynamic stress is considered to have an important role in aneurysm formation. Any aneurysm occurring at an artery should be considered for surgical treatment.