Primitive Persistent Olfactory Artery: a case report.

Clinical History

A 53 y.o. man was referred to our neurological department for right lid ptosis and lateral gaze diplopia. All neurological and systemic investigations were negative. A brain MRI supported by angioMR study disclosed the occasional evidence of a persistent primitive olfactory artery.

Imaging Findings

Familial and remote histories were negative. The neurological examination confirmed the occasional occurrence of ptosis. Hess- Lancaster test was negative, EMG and SFEMG were negative for neuromuscolar junction pathologies or myopathy. Blood examninations (anti thyroid Ab, anti ENA, C3, C4, Waaler-Rose, cryoglobulins, anti cardiolipins, anti phospholipids, anti beta 2, glycoproteins, anti prothrombins, anti Ach receptors) were all within normal limits. A brain MRI was performed to exclude possible intracranial pathologies. Axial, T2 and PD, sagittal T1 in Turbo spin Echo technique, Coronal FLAIR images were obtained. The suspicion of a possible vascular malformation was directly raised by the scout view. This presumptive finding was confirmed by an Angio MR performed in 3D Time of Flight technique with reconstruction in Maximum Intensity Projection that precisely depicted the presence of a Primitive Persistent Olfactory Artery (PPOA).

Discussion

There was no correlation betwen patient symptoms and radiological findings. The improvement of patient symptoms after anticholinesterase drug led to a clinical diagnosis of probable myathenia ocularis. PPOA is a known rare variant of the anterior portion of the circle of Willis. It originates from the terminal segment of the internal carotid artery and shows a rather typical course, running along the olfactory bulb, then abruptly turning around it and becoming the anterior cerebral artery. The olfactory branch of this vessel begins to disappear from 7th month of pregnancy to term. Usually, PPOA regresses and remains as the recurrent artery of Heubner. The presence of PPOA carries the lack of the anterior communicating artery. As for others anomalies of the circle of Willis, it may be associated with aneurysms. We believe that the recognition of this anatomic variant is important in order to differentiate it from other vascular pathologies (anterior fossa dural arteriovenous malformations, for one). PPOA has a typical course, easily recognizable on the axial DP images. Confirmation of this diagnosis requires AngioMR, that is also beneficial in excluding aneurysms.

Differential Diagnosis List

Final Diagnosis

Probable myasthenia ocularis. Primitive Persistent Olfactory Artery.

URL:	https://www.eurorad.org/case/4518
DOI:	10.1594/EURORAD/CASE.4518
ISSN:	1563-4086