Assessing low-frequency oscillations in cerebrovascular diseases and related conditions with near-infrared spectroscopy: a plausible method for evaluating cerebral autoregulation?

Abstract

Background: Cerebral autoregulation (CA) is the brain's ability to always maintain an adequate and relatively constant blood supply, which is often impaired in cerebrovascular diseases. Near-infrared spectroscopy (NIRS) examines oxygenated hemoglobin (OxyHb) in the cerebral cortex. Low-and very low-frequency oscillations (LFOs ≈ 0.1 Hz and VLFOs ≈ 0.05 to 0.01 Hz) in OxyHb have been proposed to reflect CA. Aim: To systematically review published results on OxyHb LFOs and VLFOs in cerebrovascular diseases and related conditions measured with NIRS. Approach: A systematic search was performed in the MEDLINE database, which generated 36 studies relevant for inclusion. Results: Healthy people have relatively stable LFOs. LFO amplitude seems to reflect myogenic CA being decreased by vasomotor paralysis in stroke, by smooth muscle damage or as compensatory action in other conditions but can also be influenced by the sympathetic tone. VLFO amplitude is believed to reflect neurogenic and metabolic CA and is lower in stroke, atherosclerosis, and with aging. Both LFO and VLFO synchronizations appear disturbed in stroke, while the former is also altered in internal carotid stenosis and hypertension. Conclusion: We conclude that amplitudes of LFOs and VLFOs are relatively robust measures for evaluating mechanisms of CA and synchronization analyses can show temporal disruption of CA. Further research and more coherent methodologies are needed.

Functional Near-Infrared Spectroscopy and Its Clinical Application in the Field of Neuroscience: Advances and Future Directions

“…Frequency-domain fNIRS is another emerging tool for assessing CA in stroke patients. Low (LFO) and very-low frequency oscillation (VLFO) of oxyhemoglobin are found to be robust parameter for evaluating CA (Andersen et al, 2018;Su et al, 2018). Based on the cerebral oscillation theory, LFO and VLFO are associated with cerebral sympathetic activity.…”

“…Furthermore, LFO reflects the myogenic component of CA; whereas VLFO reflects neurogenic (larger vasculature) and metabolic (microcirculation). Analysis of amplitudes and the interhemispheric synchronization of LFO and VLFO is a well-established method to assess the CA (see review ( Andersen et al, 2018 )). In patients with acute ischemic stroke (<5 days), the decrease in amplitudes of LFOs in the ischemic hemisphere and interhemispheric desynchronization were seen ( Phillip et al, 2014 ).…”

Diffuse optical assessment of cerebral‐autoregulation in older adults stratified by cerebrovascular risk

“…CA is a physiological mechanism maintaining stable cerebral blood flow (CBF) within a certain range of blood pressure variations [9,10] . The main regulatory mechanisms of CA are the metabolic, endothelial, myogenic and neurogenic functions that regulate blood flow and tissue oxygenation [11,12], as well as carbon dioxide partial pressure, hypocapnia and hypercapnia [12]. Disturbances in any one of these components would impact CA, as has been shown in diabetic patients [13,14].…”

Differences in Net Information Flow and Dynamic Connectivity Metrics Between Physically Active and Inactive Subjects Measured by Functional Near-Infrared Spectroscopy (fNIRS) During a Fatiguing Handgrip Task

“…The hemodynamic oscillations at these frequency bands can be measured using functional brain mapping using functional magnetic resonance image (fMRI) (Zhang et al, 2015), or functional near-infrared spectroscopy (fNIRS) (Li et al, 2012;Bosch et al, 2017;Andersen et al, 2018;Cao et al, 2018b). FNIRS measures non-invasively the change of oxyhemoglobin ( HbO) and deoxyhemoglobin ( Hb) concentrations resulting from neurovascular coupling secondary to neuronal activation by utilizing light at near-infrared wavelengths (650-1000 nm).…”