Monitoring of cerebral blood flow (CBF) and autoregulation are essential components of neurocritical care, but continuous noninvasive methods for CBF monitoring are lacking. Diffuse correlation spectroscopy (DCS) is a noninvasive diffuse optical modality that measures a CBF index (CBF_i) in the cortex microvasculature by monitoring the rapid fluctuations of near-infrared light diffusing through moving red blood cells. We tested the feasibility of monitoring CBF_i with DCS in at-risk patients in the Neurosciences Intensive Care Unit. DCS data were acquired continuously for up to 20 h in six patients with aneurysmal subarachnoid hemorrhage, as permitted by clinical care. Mean arterial blood pressure was recorded synchronously, allowing us to derive autoregulation curves and to compute an autoregulation index. The autoregulation curves suggest disrupted cerebral autoregulation in most patients, with the severity of disruption and the limits of preserved autoregulation varying between subjects. Our findings suggest the potential of the DCS modality for noninvasive, long-term monitoring of cerebral perfusion, and autoregulation.

Investigating the cerebral physiology of healthy term newborns’ brains is important for better understanding perinatal brain injuries, of which the most common etiologies are hypoxia and ischemia. Hence, cerebral blood flow and cerebral oxygenation are important biomarkers of brain health. In this study, we employed a hybrid diffuse optical system consisting of diffuse correlation spectroscopy (DCS) and frequency-domain near infrared spectroscopy (FDNIRS) to measure hemoglobin concentration, oxygen saturation, and indices of cerebral blood flow and metabolism. We measured 30 term infants to assess the optical and physiological characteristics of the healthy neonatal brain in the frontal, temporal, and parietal lobes. We observed higher metabolism in the right hemisphere compared to the left and a positive correlation between gestational age and the level of cerebral hemoglobin concentration, blood volume, and oxygen saturation. Moreover, we observed higher cerebral blood flow and lower oxygen saturation in females compared to males. The delayed maturation in males and the sexual dimorphism in cerebral hemodynamics may explain why males are more vulnerable to perinatal brain injuries than females.

Background: Cognitive impairment associated with childhood malnutrition and stunting is generally considered irreversible.Objective: The aim was to t

In addition to generating functional limb movement via electrical stimulation, other research proposed lower intensity stimulation for stroke patients from proprioceptive and neuro-biofeedback aspects. This study investigates the effects of different intensity levels of electrical stimulation during passive cycling on cortical activation using multichannel near infrared spectroscopy (NIRS) covering premotor cortex (PMC), supplementary motor area (SMA), sensorimotor cortex (SMC), and secondary sensory cortex (S2) regions. Sixteen subjects, including nine stroke patients and seven normal subjects, were instructed to perform passive cycling driven by an ergometer at a pace of 50 rpm under conditions without (NES) and with low-intensity electrical stimulation (LES) at 10 mA and high-intensity electrical stimulation (HES) at 30 mA. Changes in oxyhemoglobin in different brain regions and the derived interhemispheric correlation coefficient (IHCC) representing the symmetry in response of two hemispheres were evaluated to observe cortical activation and cerebral autoregulation. Our results showed that cortical activation of normal subjects exhibited overall deactivations in HES compared with that under LES and NES. In stroke patients, bilateral S2 activated significantly greater under LES compared with those under NES and HES. The IHCC of the normal group displayed a significant higher value in SMC compared to that of the stroke group. Our study utilized noninvasive NIRS to observe hemodynamic changes and bilateral autoregulation symmetry from IHCC suggesting that passive cycling with low-intensity electrical stimulation could better facilitate cortical activation compared with that obtained with no or high-intensity electrical stimulation. The results of this study could provide general guidelines to simplify the settings of electrical stimulation-assisted-passive cycling in clinical use.