Quantification of the Tissue Oxygenation Delay Induced by Breath-Holding in Patients with Carotid Atherosclerosis

Abstract

Carotid artery stenosis (CAS) is a common vascular disease with long-term consequences for the brain. Although CAS is strongly associated with impaired cerebral hemodynamics and neurodegeneration, the mechanisms underlying hemodynamic impairment in the microvasculature remain unknown. In this work, we employed functional near-infrared spectroscopy (fNIRS) to introduce a methodological approach for quantifying the temporal delay of the evoked hemodynamic response. The method was validated during a vasodilatory task (breath-holding) in 50 CAS patients and 20 controls. Our results suggest that the hemodynamic response to breath-holding can be delayed by up to 6 s in the most severe patients, a significant increase from the median 4 s measured for the control group (p = 0.01). In addition, the fraction of brain regions that responded to the task decreased as the CAS severity increased, from a median of 90% in controls to 73% in the most severe CAS group (p = 0.04). The presence of collateral circulation increases the response to breath-holding and decreases the average time delays across the brain, although the number of communicating arteries alone cannot predict these fNIRS-based hemodynamic variables (p > 0.09). Overall, this work proposes a method to quantitatively assess impaired cerebral hemodynamics in CAS patients.

Assessing the consistency and sensitivity of the neural correlates of narrative stimuli using functional near-infrared spectroscopy

“…By shining and detecting near-infrared light on the surface of the scalp, fNIRS estimates oxy-(HbO) and deoxy-hemoglobin (HbR) from the cortex, relying on neurovascular coupling to infer brain activity (Boas et al, 2014;Ferrari & Quaresima, 2012;Huppert, 2006;Jöbsis, 1977;Scholkmann et al, 2014;Steinbrink et al, 2006). Despite this increased interest in the use of fNIRS in clinical settings (Abdalmalak et al, 2017;Amyot et al, 2019;Kazazian et al, 2021;Kempny et al, 2016;Quiroga et al, 2022;Rupawala et al, 2018), reproducibility and sensitivity of fNIRS to detect neural activation at the individual level is understudied (Novi et al, 2020a).…”