Impairments in Brain Perfusion, Metabolites, Functional Connectivity, and Cognition in Severe Asymptomatic Carotid Stenosis Patients: An Integrated MRI Study

Abstract

Carotid artery stenosis without transient ischemic attack (TIA) or stroke is considered as “asymptomatic.” However, recent studies have demonstrated that these asymptomatic carotid artery stenosis (aCAS) patients had cognitive impairment in tests of executive function, psychomotor speed, and memory, indicating that “asymptomatic” carotid stenosis may not be truly asymptomatic. In this study, when 19 aCAS patients compared with 24 healthy controls, aCAS patients showed significantly poorer performance on global cognition, memory, and executive function. By utilizing an integrated MRI including pulsed arterial spin labeling (pASL) MRI, Proton MR Spectroscopy (MRS), and resting-state functional MRI (R-fMRI), we also found that aCAS patients suffered decreased cerebral blood flow (CBF) mainly in the Left Frontal Gyrus and had decreased NAA/Cr ratio in the left hippocampus and decreased connectivity to the posterior cingulate cortex (PCC) in the anterior part of default mode network (DMN).

Longitudinal Changes in Regional Cerebral Perfusion and Cognition After Cardiac Operation

“…Our finding that improved MCA perfusion was associated with increased processing speed is consistent with prior studies demonstrating that exercise-induced MCA perfusion is associated with improved processing speed [25,26]. In addition, poorer perfusion in brain regions supported by MCA subsidiary vasculature has been associated with lower processing speed among individuals with mild Alzheimer's disease [27] and carotid disease [28], suggesting that MCA-perfused structures (eg, posterior cingulate) may be particularly important for information processing efficiency.…”

The effect of asymptomatic carotid artery stenosis on cognitive functions

“…Karotis arter hastalıkları ile bilişsel bozuklukların ilişkisini araştıran pek çok çalışma vardır (16,17). Hem semptomatik hem de asemptomatik KAD'nın sağlıklı gönüllülerle karşılaştırıldığında kognitif testlerde kötüleşmeye yol açtığı birçok çalışma ile gösterilmiştir (9,(18)(19)(20)(21).…”

“…Wang ve arkadaşlarının yaptığı bir fonksiyonel MR çalışmasında asemptomatik KAD hastaları incelenmiş ve kontrol grubuyla kıyaslandığında global kognisyon, bellek ve işlevsellik alanında önemli ölçüde daha geride oldukları tespit edilmiştir (18). Wendell ve arkadaşları ise 60 yaş üzeri 364 hastayı 14 yıl takip etmiş ve KAD'nın demans için prospektif risk faktörü olduğunu göstermişlerdir (11).…”

Ophthalmic Artery Flow and Cognitive Performance in Patients with Carotid Artery Stenosis

“…Reversed OA flow is an indirect marker of insufficient cerebral collateral blood supply and is not necessarily suggestive of critical cerebral hypo perfusion in all patients with CAS. Indeed, compared to the direction of OA flow, regional CBF is more directly related to neuronal vitality and cognitive performance [3,34,35]. In patients with reversed OA flow, CBF is usually maintained stable by auto regulation mechanisms [12,26].…”

“…In patients with severe CAS, cerebral perfusion insufficiency not only contributes to the occurrence of ischemic stroke [1], but also insidiously leads to neural disruption and cognitive impairment [2,3]. However, the clinical outcome for patients with CAS cannot be determined by the severity of CAS alone [4] and the collateral circulation also plays a pivotal role in the pathophysiology of cerebral ischemia and cognitive impairment [5].…”