An incomplete Circle of Willis is not a risk factor for white matter hyperintensities: The Tromsø Study

Lars B Hindenes,Asta K Håberg,Ellisiv B Mathiesen,Torgil R Vangberg

doi:10.1016/j.jns.2020.117268

Abstract

ObjectiveThe Circle of Willis (CoW) is often underdeveloped or incomplete, leading to suboptimal blood supply to the brain. As hypoperfusion is thought to play a role in the aetiology of white matter hyperintensities (WMH), the objective of this study was to assess whether incomplete CoW variants were associated with increased WMH volumes compared to the complete CoW. MethodsIn a cross-sectional population sample of 1751 people (age 40–84 years, 46.4% men), we used an automated method to segment WMH using T1-weighted and T2-weighted fluid-attenuated inversion recovery image obtained at 3T. CoW variants were classified from time-of-flight scans, also at 3T. WMH risk factors, including age, sex, smoking and blood pressure, were obtained from questionnaires and clinical examinations. We used linear regression to examine whether people with incomplete CoW variants had greater volumes of deep WMH (DWMH) and periventricular WMH (PWMH) compared to people with the complete CoW, correcting for WMH risk factors. ResultsParticipants with incomplete CoW variants did not have significantly higher DWMH or PWMH volumes than those with complete CoW when accounting for risk factors. Age, pack-years smoking, and systolic blood pressure were risk factors for increased DWMH and PWMH volume. Diabetes was a unique risk factor for increased PWMH volume. ConclusionIncomplete CoW variants do not appear to be risk factors for WMH in the general population.

Highlights

White matter hyperintensities (WMH) are seen as a marker of cere bral small vessel disease [51]
The R2 for the regression model was 0.458, and considerably higher than for the deep WMH (DWMH) model. This indicates that the same set of vascular risk factors and incomplete Circle of Willis (CoW) variants in the regression models explained periventricular WMH (PWMH) volume better than DWMH volume. In this population-based study, we examined whether participants with incomplete CoW variants had increased WMH volumes compared to those with the complete CoW
The main findings were that neither PWMH or DWMH volumes were significantly increased in participants with incomplete CoW variants relative to participants with a complete CoW when correcting for age, gender and WMH risk factors

Summary

Introduction

White matter hyperintensities (WMH) are seen as a marker of cere bral small vessel disease [51]. They are common in older adults, and their prevalence rapidly increases with age [5]. It is very common that at least one of the Abbreviations: CoW, Circle of Willis; WMH, white matter hyperintensities; DWMH, deep white matter hyperintensities; PWMH, periventricular white matter hyperintensities; MPRAGE, magnetisation prepared rapid acquisition gradient-echo; GRAPPA, Generalized Autocalibrating Partially Parallel Acquisition; FLASH, fast low angle shot; TOF, time-of-flight; FLAIR, fluid-attenuated inversion recovery; T1w, T1-weighted; SVD, small vessel disease; MNI, Montreal Neurological Institute; ANTs, Advanced Normalization Tools

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Results

Conclusion