Fronto-Parietal and White Matter Haemodynamics Predict Cognitive Outcome in Children with Moyamoya Independent of Stroke

Hippocampal volume mediates the association of arterial stiffness with cognitive impairment in adult population

OBJECTIVES

To investigate the association of arterial stiffness with brain perfusion, brain tissue volume and cognitive impairment in the general adult population.

MATERIALS AND METHODS

This prospective study included 1488 adult participants (age range: 22.8-83.9 years) from the Kailuan study. All participants underwent brachial-ankle pulse wave velocity (PWV) measurement, brain MRI, and Montreal Cognitive Assessment (MoCA). The association of PWV with cerebral blood flow (CBF), brain tissue volume and MoCA score was investigated. Mediation analysis was used to determine whether CBF and brain tissue volume changes mediated the associations between PWV and MoCA score.

RESULTS

A 1 standard deviation (SD) increase in PWV was associated with lower total brain CBF [ β (95% CI) -0.67 (-1.2 to -0.14)], total gray matter CBF [β (95% CI) -0.7 [-1.27 to -0.13)], frontal lobe CBF [ β (95% CI) -0.59 (-1.17 to -0.01)], parietal lobe CBF [ β (95% CI) -0.8 (-1.43 to -0.18)], and temporal lobe CBF [ β (95% CI) -0.68 (-1.24 to -0.12)]. Negative associations were found for PWV and total brain volume [ β (95% CI) -4.8 (-7.61 to -1.99)] and hippocampus volume [ β (95% CI) -0.08 (-0.13 to -0.04)]. A 1 SD increase PWV was significantly associated with elevated odds of developing cognitive impairment [odds ratio (95% CI) 1.21 (1.01-1.45)]. Mediation analysis showed that hippocampal volume partially mediated the negative association between PWV and MoCA scores (proportion: 14.173%).

CONCLUSION

High arterial stiffness was associated with decreased total and regional CBF, brain tissue volume, and cognitive impairment. Hippocampal volume partially mediated the effects of arterial stiffness on cognitive impairment.

Assessment of MR blood-oxygen-level-dependent (BOLD) cerebrovascular reactivity under general anesthesia in children with moyamoya

BACKGROUND

Moyamoya is a progressive, non-atherosclerotic cerebral arteriopathy that may present in childhood and currently has no cure. Early diagnosis is critical to prevent a lifelong risk of neurological morbidity. Blood-oxygen-level-dependent (BOLD) MRI cerebrovascular reactivity (CVR) imaging provides a non-invasive, in vivo measure of autoregulatory capacity and cerebrovascular reserve. However, non-compliant or younger children require general anesthesia to achieve BOLD-CVR imaging.

OBJECTIVE

To determine the same-day repeatability of BOLD-CVR imaging under general anesthesia in children with moyamoya.

MATERIALS AND METHODS

Twenty-eight examination pairs were included (mean patient age = 7.3 ± 4.0 years). Positive and negatively reacting voxels were averaged over signals and counted over brain tissue and vascular territory. The intraclass correlation coefficient (ICC), Wilcoxon signed-rank test, and Bland-Altman plots were used to assess the variability between the scans.

RESULTS

There was excellent-to-good (≥ 0.59) within-day repeatability in 18 out of 28 paired studies (64.3%). Wilcoxon signed-rank tests demonstrated no significant difference in the grey and white matter CVR estimates, between repeat scans (all p-values > 0.05). Bland-Altman plots of differences in mean magnitude of positive and negative and fractional positive and negative CVR estimates illustrated a reasonable degree of agreement between repeat scans and no systematic bias.

CONCLUSION

BOLD-CVR imaging provides repeatable assessment of cerebrovascular reserve in children with moyamoya imaged under general anesthesia.

Association of blood pressure with brain perfusion and structure: A population-based prospective study

PURPOSE

To explore the association of blood pressure (BP) measurements with cerebral blood flow (CBF) and brain structure in general population.

METHOD

This prospective study included 902 participants from Kailuan community. All participants underwent brain MRI and BP measurements. The association of BP indicators with CBF, brain tissue volume and white matter hyperintensity (WMH) volume were investigated. In addition, mediation analysis was used to determine whether significantly changed brain tissue volume explained associations between BP and CBF.

RESULTS

Elevated diastolic BP (DBP), but not systolic BP (SBP), was associated with lower CBF in the total brain (β [95 % CI]: -0.62 [-1.14, -0.10]), total gray matter (β [95 % CI]: -0.71 [-1.27, -0.14]), hippocampus (β [95 % CI]: -0.59 [-1.13, -0.05]), frontal (β [95 % CI]: -0.72 [-1.31, -0.13]), parietal (β [95 % CI]: -0.92 [-1.54, -0.3]), temporal (β [95 % CI]: -0.63 [-1.18, -0.08]), and occipital lobe (β [95 % CI]: -0.69 [-1.37, -0.01]). Higher SBP and DBP were associated with reduced total and regional brain tissue volume (all p < 0.05). Increased SBP and PP were associated with higher total and periventricular WMH volume (all p < 0.05). In addition, mediation analysis identified that significantly decreased brain volume did not mediate the associations of BP measurements and lower CBF in corresponding region (all p > 0.05).

CONCLUSIONS

Elevated BP level was associated with decreased total and regional CBF and brain tissue volume and increased WMH burden.

Characterization of Neuropsychological Outcomes in a Cohort of Pediatric Patients with Moyamoya Arteriopathy

INTRODUCTION

Moyamoya arteriopathy is a severe, progressive cerebral arteriopathy that places affected children at high risk for stroke. Moyamoya has been associated with a range of neuropsychological deficits in adults, but data on many cognitive domains remain limited in the pediatric population and little is known about the neuropsychological profile of children with syndromic moyamoya.

METHODS

This is a single-center, retrospective cohort study of children with moyamoya arteriopathy followed at our center who underwent neuropsychological testing between 2003 and 2021. Test scores were extracted from neuropsychological reports. Medical records were reviewed with attention to individual neuropsychological test results, medical comorbidities, presence of infarct(s) on neuroimaging, and history of clinical ischemic stroke.

RESULTS

Of the 83 children with moyamoya followed at our center between 2003 and 2021, 13 had completed neuropsychological testing across multiple cognitive domains. Compared to age-based normative data, children in this sample had lower scores in overall intelligence (p = 0.003), global executive functioning (p = 0.005), and overall adaptive functioning (p = 0.015). There was no significant difference in overall intelligence between children with (n = 6) versus without (n = 7) a history of clinical stroke (p = 0.368), though children with any radiographic infarct scored lower in this domain (p = 0.032).

CONCLUSION

In our cohort, children with moyamoya demonstrated impaired intelligence and executive functioning, even in the absence of clinical stroke. Neuropsychological evaluation should be considered standard of care for all children with moyamoya, even those without a history of clinical stroke.

Pediatric Moyamoya Biomarkers: Narrowing the Knowledge Gap

Moyamoya is a progressive cerebrovascular disorder that leads to stenosis of the arteries in the distal internal carotid, proximal middle cerebral and proximal anterior cerebral arteries of the circle of Willis. Typically a network of collaterals form to bypass the stenosis and maintain cerebral blood flow. As moyamoya progresses it affects the anterior circulation more commonly than posterior circulation, and cerebral blood flow becomes increasingly reliant on external carotid supply. Children with moyamoya are at increased risk for ischemic symptoms including stroke and transient ischemic attacks (TIA). In addition, cognitive decline may occur over time, even in the absence of clinical stroke. Standard of care for stroke prevention in children with symptomatic moyamoya is revascularization surgery. Treatment of children with asymptomatic moyamoya with revascularization surgery however remains more controversial. Therefore, biomarkers are needed to assist with not only diagnosis but also with determining ischemic risk and identifying best surgical candidates. In this review we will discuss the current knowledge as well as gaps in research in relation to pediatric moyamoya biomarkers including neurologic presentation, cognitive, neuroimaging, genetic and biologic biomarkers of disease severity and ischemic risk.