Spontaneous Slow Hemodynamic Oscillations are Impaired in Cerebral Microangiopathy

Abstract

Small-vessel disease or cerebral microangiopathy (CMA) is a common finding in elderly people. It is related to a variety of vascular risk factors and may finally lead to subcortical ischemic vascular dementia. Because vessel stiffness is increased, we hypothesized that slow spontaneous oscillations are reduced in cerebral hemodynamics. Accordingly, we examined spontaneous oscillations in the visual cortex of 13 patients suffering from CMA, and compared them with 14 agematched controls. As an imaging method we applied functional near-infrared spectroscopy, because it is particularly sensitive to the microvasculature. Spontaneous low-frequency oscillations (LFOs) (0.07 to 0.12 Hz) were specifically impaired in CMA in contrast to spontaneous very-lowfrequency oscillations (0.01 to 0.05 Hz), which remained unaltered. Vascular reagibility was reduced during visual stimulation. Interestingly, changes were tightly related to neuropsychological deficits, namely executive dysfunction. Vascular alterations had to be attributed mainly to the vascular risk factor arterial hypertension. Further, results suggest that the impairments might be, at least partly, reversed by medical treatment such as angiotensin-converting enzyme inhibitors/angiotensin II receptor blockers. Results indicate that functional near-infrared spectroscopy may detect changes in the microvasculature due to CMA, namely an impairment of spontaneous LFOs, and of vascular reagibility. Hence, CMA accelerates microvascular changes due to aging, leading to impairments of autoregulation.

Continuous Assessment of Cerebral Autoregulation With Near-Infrared Spectroscopy in Adults After Subarachnoid Hemorrhage

“…A similar result was demonstrated in cohort of patients with sepsis taking ABP instead of CPP for calculation. 18 This good agreement of TCD-and NIRS-based CA assessment is a direct consequence of the finding that NIRS-based cerebral oximetry is able to detect intracranial slow fluctuations in its modalities, 15,16 which are highly coherent with slow waves recorded in MCA blood flow velocity ( Figure 1A). 18 In the past, it has been criticized that the NIRS measurements are also affected by skin and bone oxygenation changes, but the underlying mathematical models of a new generation of monitors and in particular of NIRO 200 are able to exclude the extracranial component efficiently.…”

Oscillations in Cerebral Haemodynamics in Patients with Falciparum Malaria

“…NIRS provides valuable information not only through the magnitudes of the measured parameters but also as a trend measurement. Such measurements in healthy adults have revealed slow oscillations in cerebral NIRS recordings [4], which are known to be impaired by pathological conditions like Alzheimer’s disease [5], cerebral microangiopathy [6] and cerebral infarction [7]. Their frequencies are distinctly below the heart rate and respiration frequencies, they are spontaneous and their origin is controversial [4].…”

Investigating the post-stimulus undershoot of the BOLD signal—a simultaneous fMRI and fNIRS study

“…This analysis covered un-averaged data and was independent of functional stimulation that may bias results. Correlation during rest is presumably based on spontaneous vascular oscillations related to vasomotion, such as low and very low frequency oscillations and on oscillations related to respiration (Colantuoni et al, 1994;Obrig et al, 2000a;Schroeter et al, 2004bSchroeter et al, , 2005. With an effective sampling rate of 1 Hz, oscillations due to heart pulsations did not influence our measurements.…”