Anterior Cerebral Artery Fusiform Aneurysm Attributable to Bilateral Persistent Primitive Olfactory Artery: Case Report

Persistent primitive olfactory arteries (PPOAs) are a rare variant of the anterior cerebral artery (ACA). Cerebral aneurysms may arise in the PPOA; most are saccular and on the unilateral PPOA. We report a 66-year-old male with bilateral PPOAs and a fusiform aneurysm on the left side detected at a health check-up. A brain magnetic resonance imaging (MRI) scan revealed a fusiform dilation in the proximal portion of the left ACA on a brain MRI. Good surgical results were obtained by combining trapping-and bonnet bypass surgery. Brain MRI and cerebral angiograms showed bilateral PPOAs and a fusiform aneurysm with the pearl-and-string sign in the proximal portion of the left PPOA. The aneurysm was trapped and a bonnet bypass using a radial artery (RA) graft was placed between the left superficial temporal artery and the distal portion of the left PPOA. The postoperative course was uneventful and 30 months after surgery he had no neurological symptoms; MRA showed no recurrence. In this patient, aneurysmal trapping and an A3-A3 bypass were an option, however, it would have placed an additional load on the right PPOA. Our decision to trap the aneurysm and perform bonnet bypass surgery using an RA graft led to success.