Fetal-Type Variants of the Posterior Cerebral Artery and Concurrent Infarction in the Major Arterial Territories of the Cerebral Hemisphere

Lionel A. Branch,Stephen L. Lambert,Frank J. Williams,Edward C. Mader,Zhora Z. Oganisyan

doi:10.1177/2324709616665409

Abstract

Fetal-type or fetal posterior cerebral artery (FPCA) is a variant of cerebrovascular anatomy in which the distal posterior cerebral artery (PCA) territory is perfused by a branch of the internal carotid artery (ICA). In the presence of FPCA, thromboembolism in the anterior circulation may result in paradoxical PCA territory infarction with or without concomitant infarction in the territories of the middle (MCA) or the anterior (ACA) cerebral artery. We describe 2 cases of FPCA and concurrent acute infarction in the PCA and ICA territories—right PCA and MCA in Patient 1 and left PCA, MCA, and ACA in Patient 2. Noninvasive angiography detected a left FPCA in both patients. While FPCA was clearly the mechanism of paradoxical infarction in Patient 2, it turned out to be an incidental finding in Patient 1 when evidence of a classic right PCA was uncovered from an old computed tomography scan image. Differences in anatomical details of the FPCA in each patient suggest that the 2 FPCAs are developmentally different. The FPCA of Patient 1 appeared to be an extension of the embryonic left posterior communicating artery (PcomA). Patient 2 had 2 PCAs on the left (PCA duplication), classic bilateral PCAs, and PcomAs, and absent left anterior choroidal artery (AchoA), suggesting developmental AchoA-to-FPCA transformation on the left. These 2 cases underscore the variable anatomy, clinical significance, and embryological origins of FPCA variants.

Highlights

Posterior cerebral artery (PCA) cortical branches supply blood to the occipital lobe, the inferomedial temporal lobe, and portions of the posterior inferior parietal lobe.[1]
In the definition proposed by van Raamt et al, an fetal PCA (FPCA) is called a full FPCA if the P1 segment is not visualized on computed tomography angiography (CTA), magnetic resonance angiography (MRA), or after injection of contrast into the vertebral artery; a partial FPCA if the P1 segment is smaller than the posterior communicating artery (PcomA); or an intermediate FPCA if the P1 segment is as large as the PcomA.[11]
Kolukısa et al reported a case of sequential infarction in the setting of left FPCA and extracranial internal carotid artery (ICA) stenosis; stabilization of cerebral perfusion was achieved by carotid endarterectomy.[14]

Summary

Introduction

Posterior cerebral artery (PCA) cortical branches supply blood to the occipital lobe, the inferomedial temporal lobe, and portions of the posterior inferior parietal lobe.[1]. Infarction occurred in the right MCA and PCA territories in Patient 1 and in the left ACA, MCA, and PCA territories in Patient 2 Both patients are 82-year-old right-handed women, both had a large ischemic stroke involving the anterior and posterior circulation territories of one hemisphere, and both were found to have an FPCA. Patient 2 had 3 major stroke risk factors—hypertension, hyperlipidemia, and atrial fibrillation—for which she takes warfarin Before the stroke, she lived in an assisted living facility and was able to drive a car. Brain MRA on the second hospital day showed acute infarcts in the left ACA, MCA, and PCA territories (Figure 2: DWI and ADC). Electrocardiography showed atrial fibrillation and echocardiography revealed biatrial enlargement Her mental status declined over a few days due to worsening cerebral edema. After 12 days, she was discharged to a skilled nursing facility

Discussion

Findings

Conclusion

29. Moffat DB