The glycocalyx is a gel-like layer lining the luminal surface of the endothelium. The glycocalyx exerts an important barrier role because it prevents exposure of plasma components to the endothelial surface. Disruption of the glycocalyx by local inflammation or ischemia results in decreased glycocalyx thickness which is associated with a number of vascular diseases. The cerebrovascular glycocalyx has sparsely been studied, but is of great interest because of its potential role in cerebrovascular disease. In this review, we describe all existing techniques to visualize the glycocalyx and designate techniques that may be suitable for studying the cerebrovascular glycocalyx. A total of seven imaging techniques are discussed thoroughly, including transmission electron microscopy, intravital microscopy, micro-particle image velocimetry, confocal laser scanning microscopy, two-photon laser scanning microscopy, orthogonal polarization spectral imaging and sidestream dark field/oblique imaging. Measurement of serum concentrations of glycocalyx-specific constituents is another method for glycocalyx analysis. Also, we have reviewed the methods of glycocalyx analysis by using these imaging techniques. So far, the cerebrovascular glycocalyx has only been studied in vitro. However, other cerebral microcirculatory properties have been studied in vivo. This suggests that the cerebrovascular glycocalyx can be studied in vivo by using some of the described techniques, when specific software is subjoined to the analysis. In conclusion, we have summarized techniques available for glycocalyx assessment, and explained the significance and technical possibilities regarding cerebrovascular glycocalyx visualization. Cerebrovascular glycocalyx assessment would add valuable information to our understanding of the pathophysiology of cerebrovascular disease. Moreover, as a part of the blood-brain barrier, more knowledge on the cerebrovascular glycocalyx may lead to better understanding of neurodegenerative conditions that are caused by a compromised blood-brain barrier including Alzheimer's disease, vascular dementia, multiple sclerosis and epilepsy.

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. 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© software. 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. 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. SDF imaging is a safe, quick, and straightforward technique to evaluate the functional cerebral microcirculation and glycocalyx. Because of their eminent role in cerebral homeostasis, this method may significantly add to research on the role of vascular pathophysiology underling various neurological disorders.

Purpose: Surgical resection of intracranial meningiomas in patients that are 80 years old and older, i.e. very old patients, is increasingly considered. Meningiomas with a largest diameter of at least 5 cm—‘giant meningiomas’—form a distinct entity, and their surgical resection is considered more difficult and prone to complications. Here, we evaluated functional outcome, morbidity and mortality, and the prognostic value of tumor size in very old patients who underwent resection of giant supratentorial meningiomas. Methods: We retrospectively reviewed clinical and radiological data, functional performance (Karnofsky Performance Score), histopathological diagnosis and complications of very old patients who underwent surgery of a supratentorial meningioma at the Helsinki University Hospital between 2010 and 2018. Results: We identified 76 very old patients, including 28 with a giant meningioma. Patients with a giant meningioma suffered from major complications more commonly than those with a non-giant meningioma (36% vs. 17%, p = 0.06), particularly from postoperative intracranial hemorrhages (ICH). At the 1-year follow-up, functional performance and mortality rate were comparable between patients with giant meningiomas and those with non-giant meningiomas. An exceptionally high rate of giant meningiomas were diagnosed as atypical meningiomas (WHO II) at an (11 out of 28 cases). Conclusions: Giant meningioma surgery entails a high complication rate in frail, very old patients. The prevention of postoperative ICH in this specific patient group is of utmost importance. An atypical histopathology was notably frequent among very old patients with a giant meningioma, which should be taken into account when planning the surgical strategy.

Introduction: Adequate functioning of the blood–brain barrier (BBB) is important for brain homoeostasis and normal neuronal function. Disruption of the BBB has been described in several neurological diseases. Recent reports suggest that an increased permeability of the BBB also contributes to increased seizure susceptibility in patients with epilepsy. The endothelial glycocalyx is coating the luminal side of the endothelium and can be considered as the first barrier of the BBB. We hypothesise that an altered glycocalyx thickness plays a role in the aetiology of temporal lobe epilepsy (TLE), the most common type of epilepsy. Here, we propose a protocol that allows intraoperative assessment of the cerebrovascular glycocalyx thickness in patients with TLE and assess whether its thickness is decreased in patients with TLE when compared with controls. Methods and analysis: This protocol is designed as a prospective observational case–control study in patients who undergo resective brain surgery as treatment for TLE. Control subjects are patients without a history of epileptic seizures, who undergo a craniotomy or burr hole surgery for other indications. Intraoperative glycocalyx thickness measurements of sublingual, cortical and hippocampal microcirculation are performed by video microscopy using sidestream dark-field imaging. Demographic details, seizure characteristics, epilepsy risk factors, intraoperative haemodynamic parameters and histopathological evaluation are additionally recorded. Ethics and dissemination: This protocol has been ethically approved by the local medical ethical committee (ID: NL51594.068.14) and complies with the Declaration of Helsinki and principles of Good Clinical Practice. Informed consent is obtained before study enrolment and only coded data will be stored in a secured database, enabling an audit trail. Results will be submitted to international peer-reviewed journals and presented at international conferences. Trial registration number: NTR5568 .

Background: The 'CPPopt-Guided Therapy: Assessment of Target Effectiveness' (COGiTATE) randomised controlled trial demonstrated the feasibility and safety of targeting an automated cerebral perfusion pressure (CPP) tailored to optimize cerebrovascular autoregulation (CPPopt) in patients with traumatic brain injury (TBI) requiring intracranial pressure management. The average values of the autoregulation index known as the pressure reactivity index (PRx) were not different between the intervention (CPP target = CPPopt) and control (CPP target = 60–70 mmHg) groups of the trial. This secondary analysis was performed to investigate whether: (1) in the intervention group, PRx was closer to PRxopt (PRx at CPPopt) values, indicating a more preserved reactivity, as opposed to in the control group; (2) in the intervention group, patients experienced lower hourly PRx when CPP was close to the CPPopt-based target. Methods: We analyzed data from the 28 and 32 patients randomized to the control and intervention groups of the COGiTATE study, respectively. We compared hourly averaged ΔPRx (PRx minus PRxopt, where PRxopt is PRx at CPPopt) between the two groups, focusing on periods of globally preserved/homogeneous autoregulation (negative PRxopt). For each patient in the intervention group, PRx values in periods when ΔCPP (CPP minus CPPopt target) was between −5 and + 5 mm Hg were compared to values in periods when ΔCPP was outside this range. Results: The median ΔPRx was significantly lower in the intervention group for negative PRxopt (Mann–Whitney U-test, p < 0.001). For each patient in this group, the median PRx was lower in periods when CPP was close to the CPPopt-based target (Wilcoxon test, p < 0.001). Conclusions: Despite no statistically significant difference in the grand mean PRx, our results suggest that targeting CPPopt does provide a way of improving cerebrovascular reactivity in patients with TBI, offering a rational intervention for trials that address this issue. We also bring insight into aspects of the PRx/CPP relationship that should be considered for autoregulation-guided management for future clinical protocols and trials design.