In vivo assessment of the human cerebral microcirculation and its glycocalyx: A technical report

Introduction: The cerebral microcirculation and its glycocalyx, a matrix coating the luminal endothelium, are key regulators of capillary permeability and cerebral blood flow. Microvascular abnormalities are described in several neurological disorders. However, assessment of the cerebral microcirculation and glycocalyx has mainly been performed ex vivo. New method: Here, the technical feasibility of in vivo assessment of the human cerebral microcirculation and its glycocalyx using sidestream dark field (SDF) imaging is discussed. Intraoperative assessment requires the application of a sterile drape covering the camera (slipcover). First, sublingual measurements with and without slipcover were performed in a healthy control to assess the impact of this slipcover. Subsequently, using SDF imaging, the sublingual (reference), cortical, and hippocampal microcirculation and glycocalyx were evaluated in patients who underwent resective brain surgery as treatment for drug-resistant temporal lobe epilepsy. Finally, vessel density, and the perfused boundary region (PBR), a validated gauge of glycocalyx health, were calculated using GlycoCheck (c) software. Results: The addition of a slipcover affects vessel density and PBR values in a control subject. The cerebral measurements in five patients were more difficult to obtain than the sublingual ones. This was probably at least partly due to the introduction of a sterile slipcover. Results on vessel density and PBR showed similar patterns at all three measurement sites. Comparison with existing methods: This is the first report on in vivo assessment of the human cerebrovascular glycocalyx. Assessment of the glycocalyx is an additional application of in vivo imaging of the cerebral microcirculation using SDF technique. This method enables functional analysis of the microcirculation and glycocalyx, however the addition of a sterile slipcover affects the measurements. Conclusions: SDF imaging is a safe, quick, and straightforward t