Distribution of variations in anatomy of the circle of Willis: results of a cadaveric study of the Malawian population and review of literature

Nyasa, Charles; Mwakikunga, Anthony; Tembo, Lackson; Dzamalala, Charles P.; Ihunwo, Amadi O.

doi:10.11604/pamj.2021.38.11.27126

Cited by 6 publications

(5 citation statements)

References 15 publications

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“…For instance, PCA hypoplasia has been reported across populations at different prevalence rates. Nyasa and co-authors reported an incident rate as high as 13% in the Malawi population 3 compared to 5% reported in a USA study 39 . Others have reported an even lower rate of less than 5%, including samples from the South African population 14 , 40 , 41 .…”

Section: Discussionmentioning

confidence: 83%

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Exploring the anatomical configurations of the cerebral arteries in a cohort of South African patients

Sibiya,

Omotoso,

Harrichandparsad

et al. 2024

Sci Rep

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The cerebral arteries, specifically the anterior cerebral artery (ACA) and posterior cerebral artery (PCA), work together with the smaller calibre arteries to provide effective communication between the anterior and posterior circuits of the brain via the circle of Willis (CoW). Morphologic variations of the cerebral arteries and the CoW may alter blood flow to the brain, resulting in intracranial vascular disorders associated with stroke, and aneurysms. This study aimed to document the morphology of the cerebral arteries and the CoW in the South African population. Two hundred and thirty-nine computed tomography angiography scans were assessed. Cerebral arteries and CoW normal morphology and variations were classified as complete, absent, or hypoplastic. The ACA A1 was absent in 4.91%, hypoplastic in 30.40%, fenestrated in 1.06%, and typical in 63.6%. The ACA A2 was absent in 0.42%, hypoplastic in 26.28%, and typical in 69.44%. We found triple ACA A2 in 2.98%, azygos in 1.28% and fenestrated in 1.28%. The middle cerebral artery (MCA) was hypoplastic in 7.35% and typical in 92.64%. The PCA was hypoplastic in 28.74% and typical in 71.25%. Knowledge of the configuration of the CoW plays a significant role in guiding therapeutic decision-making in treating various neurovascular pathologies.

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Section: Discussionmentioning

confidence: 83%

“…The internal carotid artery also participates in the construction of the CoW. This configuration allows collateral blood flow and pressure equalization 3 . The AComA and PComA are important components of the CoW as they act as collateral channels to stabilize blood flow between the two hemispheres 1 .…”

Section: Introductionmentioning

confidence: 99%

Exploring the anatomical configurations of the cerebral arteries in a cohort of South African patients

Sibiya,

Omotoso,

Harrichandparsad

et al. 2024

Sci Rep

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“…Prediction 4 : Functional cerebral asymmetry may be related to anatomical differences in the circle of Willis ( Kızılgöz et al, 2022 ; Nyasa et al, 2021 ; Payne, 2017 ).…”

Section: Discussionmentioning

confidence: 99%

Approaches to Measuring Language Lateralisation: An Exploratory Study Comparing Two fMRI Methods and Functional Transcranial Doppler Ultrasound

Bishop,

Woodhead,

Watkins

2024

Neurobiology of Language

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In this exploratory study we compare and contrast two methods for deriving a laterality index (LI) from functional magnetic resonance imaging (fMRI) data: the weighted bootstrapped mean from the Laterality Toolbox (toolbox method), and a novel method that uses subtraction of activations from homologous regions in left and right hemispheres to give an array of difference scores (mirror method). Data came from 31 individuals who had been selected to include a high proportion of people with atypical laterality when tested with functional transcranial Doppler ultrasound (fTCD). On two tasks, word generation and semantic matching, the mirror method generally gave better agreement with fTCD laterality than the toolbox method, both for individual regions of interest, and for a large region corresponding to the middle cerebral artery. LI estimates from this method had much smaller confidence intervals (CIs) than those from the toolbox method; with the mirror method, most participants were reliably lateralised to left or right, whereas with the toolbox method, a higher proportion were categorised as bilateral (i.e. the CI for the LI spanned zero). Reasons for discrepancies between fMRI methods are discussed: one issue is that the toolbox method averages the LI across a wide range of thresholds. Furthermore, examination of task-related t-statistic maps from the two hemispheres showed that language lateralisation is evident in regions characterised by deactivation, and so key information may be lost by ignoring voxel activations below zero, as is done with conventional estimates of the LI.

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“…A study based on experimental animals showed that the occlusion of the internal carotid artery (ICA) leads to the dilatation of the leptomeningeal collaterals in only 12 s, thus demonstrating the fast recruiting response of vasoconstricted arteries [15]. The most common vascular variants, according to postmortem and imaging studies in humans, were the agenesis or hypoplasia of the ACA, the unilateral fetal type of the PCA, and the complete CoW, which only occurs in a minority of patients [16][17][18][19].…”

Section: Introductionmentioning

confidence: 99%

The Presence of Communicating Arteries in the Circle of Willis Is Associated with Higher Rate of Functional Recovery after Anterior Circulation Ischemic Stroke

Sablić,

Dolić,

Kraljević

et al. 2023

Biomedicines

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Acute ischemic stroke (AIS) is the world’s second leading cause of mortality. An established method for treating stroke patients in acute settings is endovascular therapy (EVT). However, the correlation of the successful endovascular treatment of AIS with the presence of communicating arteries in the circle of Willis needs to be proven. Our study examined clinical and radiological data of 158 consecutive patients treated with mechanical thrombectomy (MT) at our comprehensive stroke center. We analyzed their CT angiograms and digital subtraction angiography (DSA) to assess anatomical variants of Willis’ circle and formed two groups—collateral-negative and collateral-positive group. The first group included patients with aplasia of both anterior (ACoA) and posterior communicating Artery (PCoA). The second group included patients that have at least one communicating artery (either anterior or posterior). We evaluated their reperfusion outcomes and functional recovery three months later. Our results showed that patients with communicating arteries had smaller areas of infarction on post-interventional CT and higher rates of functional recovery (Modified Rankin Score). The ACoA had a higher impact on early and late outcomes, confirmed by lower control CT scores and more favorable functional recovery. Therefore, anatomic variants of Willis’ circle should be considered as a significant prognostic factor in AIS.

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Distribution of variations in anatomy of the circle of Willis: results of a cadaveric study of the Malawian population and review of literature

Cited by 6 publications

References 15 publications

Exploring the anatomical configurations of the cerebral arteries in a cohort of South African patients

Exploring the anatomical configurations of the cerebral arteries in a cohort of South African patients

Approaches to Measuring Language Lateralisation: An Exploratory Study Comparing Two fMRI Methods and Functional Transcranial Doppler Ultrasound

The Presence of Communicating Arteries in the Circle of Willis Is Associated with Higher Rate of Functional Recovery after Anterior Circulation Ischemic Stroke

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