Persistent Primitive Olfactory Artery as Novel Collateral Channel to the Anterior Cerebral Artery in Moyamoya Disease

Background: There are a variety of collateral routes to compensate persistent cerebral ischemia in moyamoya disease. However, there is no report presenting the persistent primitive olfactory artery (POA) as a spontaneous collateral route to the anterior cerebral artery (ACA) in moyamoya disease. Methods: We precisely examined cerebral angiography in 84 patients with moyamoya disease to identify the collateral channel through the persistent POA. Its anatomy was evaluated on pre- and postoperative angiography. Results: Of 84 patients, four (4.8%) had spontaneous collateral channel through the persistent POA. All of these four hemispheres were categorized into Stage 5. In all four patients, the collateral blood flow arose from the ophthalmic artery and run to the persistent POA through the ethmoidal moyamoya. The persistent POA provided collateral blood flow from the ophthalmic artery to the ACA in all four patients. Superficial temporal artery to middle cerebral artery anastomosis and encephalo-duro-myo-arterio-pericranial synangiosis was performed in three of four patients. After surgery, the collateral channel through the persistent POA completely disappeared or markedly regressed, suggesting a significant improvement of cerebral hemodynamics in the territory of not only the MCA but also the ACA. Conclusion: The persistent POA can potentially provide collateral blood flow to the ACA in about 5% of patients with moyamoya disease, and should be recognized as a novel collateral channel in moyamoya disease. The persistent POA may be useful to evaluate therapeutic effects of surgical revascularization on the ACA territory.