Fetal-type posterior cerebral artery

A fetal (origin of the) posterior cerebral artery is a common variant in the posterior cerebral circulation, estimated to occur in 20-30% of individuals

The posterior communicating artery (PCOM) is larger than the P1 segment of the posterior cerebral artery (PCA) and supplies the bulk of the blood to the PCA. If bilateral, the basilar artery is significantly smaller than normal.

The term is typically used to refer to the situation where the PCOM is larger than the P1. However, variation in usage abounds.

The P1 can be small (hypoplastic) or absent. The significance is in the stroke pattern, as the PCA is therefore part of the anterior circulation. Additionally a larger PCOM (with P1 present) allows for collateral circulation.

In cases of non-fetal PCA, the PCOM lies superomedial to the oculomotor nerve, whereas in cases of fetal PCA, it lies superior or superolateral to the oculomotor nerve.

A fetal variant posterior cerebral artery (fetal PCA) is an embryological remnant in which the PCA is primarily supplied via the anterior cerebral circulation.

It is a very common variant in the posterior cerebral circulation, estimated to occur in up to 30% of individuals.

The posterior communicating artery (PCOM) is larger than the P1 segment of the posterior cerebral artery (PCA) and supplies the bulk of the blood to the PCA. If bilateral, the basilar artery is significantly smaller than normal.

The term is typically used to refer to the situation where the PCOM is larger than the P1. However, variation in usage abounds.

The P1 can be small (hypoplastic) or absent. The significance is in the stroke pattern, as the PCA is therefore part of the anterior circulation. Additionally a larger PCOM (with P1 present) allows for collateral circulation.

In cases of non-fetal PCA, the PCOM lies superomedial to the oculomotor nerve, whereas in cases of fetal PCA, it lies superior or superolateral to the oculomotor nerve.

http://depts.washington.edu/bbsoft/carotid_collaterals/images/Fetal_PCA_lat.jpg

A fetal posterior communicating artery variant is defined as a posterior communicating artery (PCOM), which has the same caliber as the P2 segment of the posterior cerebral artery (PCA) and is associated with an atrophic P1 segment. Because fetal PCOM arteries are the primary supply to the PCA, care must be taken not to compromise flow to this artery during clipping or coiling of posterior communicating artery aneurysms (PCOM). The incidence of the fetal PCOM variant is 4-29% of patients and bilateral fetal PCOM variants occur in 1-9% of patients ¹⁾.

A fetal PCOM or fetal origin of the posterior cerebral artery is a very common variant in the posterior cerebral circulation. It is estimated to occur in up to 30% individuals. The posterior communicating artery (PCOM) is larger than the P1 segment of the posterior cerebral artery (PCA) and supplies the bulk of the blood to the PCA. If bilateral, the basilar artery is significantly smaller than normal.

The term is typically used to refer to the situation where the PCOM is larger than the P1. However, variation in usage abounds.

The P1 can be small (hypoplastic) or absent. The significance is in the stroke pattern, as the PCA is therefore part of the anterior circulation. Additionally a larger PCOM (with P1 present) allows for collateral circulation.

In case of non fetal PCA, the PCOM lies superomedial to the occulomotor nerve, whereas in case of fetal PCA, it lies superior or superolateral to the occulomotor nerve.

Posterior communicating artery aneurysms, were associated with a higher prevalence of ipsilateral Fetal-type posterior cerebral artery. This variant was associated with larger sizes of the aneurysm necks but was not associated with the sizes of the aneurysm domes or with their rupture statuses ²⁾.

Results demonstrated that fetal-type posterior cerebral artery may be an independent risk factor for the recurrence of posterior communicating artery aneurysms. Therefore, fetal-type posterior cerebral artery can be considered as an important risk factor for posterior communicating artery aneurysm recurrences, along with other known risk factors such as size, ruptured status, endovascular treatment, and incomplete occlusion ³⁾.

A 51-years-old male patient presented with a headache and mild right hemiparesis. He had a Giant serpentine aneurysm (GSA) arising from the left fetal-type posterior cerebral artery (fPCA) that was out of follow-up for six years. Radiological images revealed midline shifting and mesencephalon compression. They performed endovascular parent artery occlusion with coil. The symptoms of the patient improved at the first-month follow-up. Even if there is a mass effect in GSAs, deconstructive EVT is a safe and feasible method for managing these lesions ⁴⁾.