Reclassifications of ischemic stroke patterns due to variants of the Circle of Willis

 Reclassification does absolutely nothing for stroke survivors. We need exact protocols delivering recovery based on these differences.  Useless research.

Reclassifications of ischemic stroke patterns due to variants of the Circle of Willis

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Ida Rangus, Lennart S Milles, Ivana Galinovic, ...

First Published October 5, 2021 Research Article Find in PubMed 

https://doi.org/10.1177/17474930211048381

Article information

Abstract

Background

Variants of the Circle of Willis (vCoW) may impede correct identification of ischemic lesion patterns and stroke etiology. We assessed reclassifications of ischemic lesion patterns due to vCoW.

Methods

We analyzed vCoW in patients with acute ischemic stroke from the 1000+ study using time-of-flight magnetic resonance angiography (TOF MRA) of intracranial arteries. We assessed A1 segment agenesis or hypoplasia in the anterior circulation and fetal posterior cerebral artery in the posterior circulation. Stroke patterns were classified as one or more-than-one territory stroke pattern. We examined associations between vCoW and stroke patterns and the frequency of reclassifications of stroke patterns due to vCoW.

Results

Of 1000 patients, 991 had evaluable magnetic resonance angiography. At least one vCoW was present in 37.1%. VCoW were more common in the posterior than in the anterior circulation (33.3% vs. 6.7%). Of 238 patients initially thought to have a more-than-one territory stroke pattern, 20 (8.4%) had to be reclassified to a one territory stroke pattern after considering vCoW. All these patients had fetal posterior cerebral artery and six (30%) additionally had carotid artery disease. Of 753 patients initially presumed to have a one-territory stroke pattern, four (0.5%) were reclassified as having more-than-one territory pattern.

Conclusions

VCoW are present in about one in three stroke patients and more common in the posterior circulation. Reclassifications of stroke lesion patterns due to vCoW occurred predominantly in the posterior circulation with fetal posterior cerebral artery mimicking multiple territory stroke pattern. Considering vCoW in these cases may uncover symptomatic carotid disease.

Keywords

Circle of Willis, stroke patterns, neuroanatomy

Introduction

Identifying stroke lesion patterns and affected territories supplied by neck arteries is an essential component in determining ischemic stroke etiology. More-than-one territory stroke patterns suggest a proximal embolic source, e.g. of cardiac or aortal origin, whereas single territory stroke patterns point to large or small vessel disease.¹ Assigning stroke lesions to the corresponding arterial territories is usually carried out using pre-set brain maps due to practicality.² However, since the Circle of Willis (CoW) connects all three major cerebral territories (left anterior, right anterior, and posterior), classifying stroke lesion patterns based solely on brain maps without considering variants of the Circle of Willis (vCoW) may lead to false assignment of affected arterial territories.³ Taking vCoW into account may lead to clinically relevant reclassifications of stroke patterns.

Aims

Establishing the frequency of different vCoW could help to distinguish stroke locations that are more prone to misclassifications. Here, we analyzed the frequency of two vCoW in patients with ischemic stroke using time-of-flight magnetic resonance angiography (TOF MRA): (a) agenesis or hypoplastic A1 segment of the ACA in the anterior circulation (anterior vCoW) and (b) fetal posterior cerebral artery (fPCA) in the posterior circulation. Furthermore, we examined stroke lesion patterns (classified as one and more-than-one territory stroke pattern) in patients with complete Circle of Willis (cCoW) and vCoW. Finally, we examined the rate of reclassifications from more-than-one territory to one territory and vice versa, following reattributions of stroke lesions to the corresponding cerebral artery after identifying vCoW.