Time-domain near-infrared spectroscopy in subjects with asymptomatic cerebral small vessel disease

Biomarkers of microcirculation dysfunction may help in the study of cerebral small vessel disease (CSVD). Time-Domain Near-Infrared spectroscopy (TD-NIRS), estimating the oxygenation of microcirculation of cerebral outer layers, might indirectly correlate with CSVD. We retrospectively evaluated TD-NIRS data from healthy subjects with age ≥ 55 years; no history of brain disease; normal neurological examination; absence of stenosis > 50% of extra/intra-cranial arteries; incidental finding of asymptomatic CSVD at brain magnetic resonance imaging (MRI). According to Fazekas scale, subjects were classified by presence of white matter hyperintensities in periventricular region (pvWMHs), deep white matter region (dWMHs), or both (d+pvWMHs). We compared the concentration of hemoglobin species and tissue oxygen saturation (StO2) among these groups. The study included 20 subjects, median age 67.5 (IQR 61–78) years old (6 without WMHs, 5 with pvWMHs, 9 with d+pvWMHs). Subjects with d+pvWMHs had significantly lower StO2 compared to subjects without WMHs (p = 0.022) or with pvWMHs (p = 0.004). StO2 < 56.7% indicated the presence of d+pvWMHs with 91% sensitivity and 67% specificity [AUC 91% (CI 95% 78–100%)]. In this prelimi-nary study, cerebral TD-NIRS detected significantly lower StO2 in subjects with radiological signs of asymptomatic CSVD. Further studies are needed to evaluate if StO2 might represent a marker of asymptomatic CSVD.