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Abstract Objective The objective of this study was to summarize the available evidence regarding the clinical value and trend over time of lumbar cerebrospinal fluid (CSF) opening pressure utilization to diagnose spontaneous intracranial hypotension (SIH). Background CSF opening pressure obtained via lumbar puncture is one of the diagnostic criteria for SIH based on the International Criteria for Headache Disorders, 3rd Edition (ICHD‐3), but it has questionable utility as an initial investigation for diagnosing SIH. Methods The authors performed a systematic literature review and meta‐analysis. PubMed/MEDLINE, Scopus, and Cochrane Library were searched from inception to October 2022. Original studies and case series in English reporting three or more patients with suspected or known SIH and CSF pressure measurement were included. Meta‐analyses and meta‐regression were used to calculate pooled estimates and examine the impact of age, sex, and publication year on outcomes, including CSF pressure < 60 mm CSF, orthostatic headache, and positive findings on brain magnetic resonance imaging (MRI), spinal imaging, and radionuclide studies. Results For every 1‐year increase in the year of publication, the odds of reporting low CSF pressure decreased by 6.20% (adjusted odds ratio [aOR] = 0.94, aOR 95% confidence interval [CI] = [0.90, 0.97], p = 0.001), the odds of reporting a positive brain MRI increased by 4.67% (aOR = 1.05, aOR 95% CI = [1.01, 1.09], p = 0.026), and the odds of reporting orthostatic headache increased by 9.13% (aOR = 1.09, aOR 95% CI = [1.03, 1.15], p = 0.002). Each 1% increase in the percentage of patients with orthostatic headache was associated with a 3.13% increase in the odds of low CSF pressure (aOR = 1.03, aOR 95% CI = [1.01, 1.05], p = 0.003). Similarly, as the percentage of patients with low CSF pressure increased by 1%, there was a 2.53% increase in the odds of orthostatic headache (aOR = 1.03, aOR 95% CI = [1.01, 1.04], p = 0.005). It was estimated that 31.9% of patients with SIH had normal opening pressure (95% CI = [24.0%, 40.8%], prediction interval = [5.0%, 80.5%]). Every 1% increase in the percentage of patients with positive brain MRI was associated with a 5.25% increase in the odds of positive spinal imaging (aOR = 1.05, aOR 95% CI = [1.00, 1.11], p = 0.047). Age and positive radionuclide study did not significantly impact the outcomes measured. The corresponding I 2 for each outcome was reduced by controlling for study‐wide covariates believed to impact the prevalence of each outcome. Sensitivity analyses did not reveal discrepancies in results when studies requiring outcomes of interest were removed. Conclusion Our analysis found that recent studies indicate a reduced reliance on opening pressure for diagnosing SIH. Rather, results suggest an increasing reliance on contrast‐enhanced brain MRI, spine imaging, and clinical features for SIH diagnosis.

AbstractBackgroundCerebral small vessel disease (SVD) related vascular contributions represent a major factor contributing to cognitive decline and dementia (VCID) in older adults. However, there has not been a validated biomarker for the diagnosis and treatment monitoring of this condition. Recently, the US National Institute on Neurological Disorders and Stroke (NINDS) funded the MarkVCID Consortium to identify and validate clinical‐trial‐ready biomarkers for VCID. Cerebrovascular reactivity (CVR) MRI is one of the selected biomarkers that underwent multi‐site testing in the Consortium. The present study aimed to report the relationship between CVR and cognitive function at independent sites, based on a pre‐specified hypothesis.MethodCVR, the ability of cerebral small vessels to dilate upon stimulus, is thought to directly reflect physiological function of the brain microvasculature. Based on previous single‐site findings, the pre‐defined hypothesis was that CVR will be associated with the global cognitive function measured by Montreal Cognitive Assessment (MoCA) after adjusting for age, sex, and education, and this association will be observed in data collected and analyzed at each individual site.A total of 264 older participants from three sites were included (Table 1). Each site performed an identical CVR MRI procedure using 5% CO2 inhalation, and a standardized clinical and cognitive evaluation. Multi‐linear regression analysis was conducted on a site‐by‐site basis to examine the pre‐defined hypothesis.ResultGray‐matter CVR showed a positive association with MoCA score after adjustment for age, sex, and education, in which participants with higher CVR had higher MoCA scores. This relationship was reproduced at each site (Figure 1, p<0.05 for each), confirming our pre‐specified hypothesis.In the secondary analysis of all data together, higher gray‐matter CVR was found to be significantly associated with better executive function measure of item response theory (IRT) score (β=2.87, p=0.003).ConclusionThe present study evaluated the relationship between CVR and cognition in a multi‐center setting. CVR was found to be positively associated with global cognitive function measured by the MoCA, which was shown to be reproducible across different sites with diverse cohorts. These findings support the utility of CVR as a biomarker in future clinical trials of SVD and VCID.

Abstract INTRODUCTION Vascular contributions to cognitive impairment and dementia (VCID) represent a major factor in cognitive decline in older adults. The present study examined the relationship between cerebrovascular reactivity (CVR) measured by magnetic resonance imaging (MRI) and cognitive function in a multi‐site study, using a predefined hypothesis. METHODS We conducted the study in a total of three analysis sites and 263 subjects. Each site performed an identical CVR MRI procedure using 5% carbon dioxide inhalation. A global cognitive measure of Montreal Cognitive Assessment (MoCA) and an executive function measure of item response theory (IRT) score were used as outcomes. RESULTS CVR and MoCA were positively associated, and this relationship was reproduced at all analysis sites. CVR was found to be positively associated with executive function. DISCUSSION The predefined hypothesis on the association between CVR and a global cognitive score was validated in three independent analysis sites, providing support for CVR as a biomarker in VCID. Highlights This study measured a novel functional index of small arteries referred to as cerebrovascular reactivity (CVR). CVR was positively associated with global cognition in older adults. This finding was observed in three independent cohorts at three sites. Our statistical analysis plan was predefined before beginning data collection.

Vascular pathology is the second leading cause of cognitive impairment and represents a major contributing factor in mixed dementia. However, biomarkers for vascular cognitive impairment and dementia (VCID) are under-developed. Here we aimed to investigate the potential role of CO2 Cerebrovascular Reactivity (CVR) measured with phase-contrast quantitative flow MRI in cognitive impairment and dementia. Forty-five (69 ± 7 years) impaired (37 mild-cognitive-impairment and 8 mild-dementia by syndromic diagnosis) and 22 cognitively-healthy-control (HC) participants were recruited and scanned on a 3 T MRI. Biomarkers of AD pathology were measured in cerebrospinal fluid. We found that CBF-CVR was lower (p = 0.027) in the impaired (mean±SE, 3.70 ± 0.15%/mmHg) relative to HC (4.28 ± 0.21%/mmHg). After adjusting for AD pathological markers (Aβ42/40, total tau, and Aβ42/p-tau181), higher CBF-CVR was associated with better cognitive performance, including Montreal Cognitive Assessment, MoCA (p = 0.001), composite cognitive score (p = 0.047), and language (p = 0.004). Higher CBF-CVR was also associated with better physical function, including gait-speed (p = 0.006) and time for five chair-stands (p = 0.049). CBF-CVR was additionally related to the Clinical-Dementia-Rating, CDR, including global CDR (p = 0.026) and CDR Sum-of-Boxes (p = 0.015). CBF-CVR was inversely associated with hemoglobin A1C level (p = 0.017). In summary, CBF-CVR measured with phase-contrast MRI shows associations with cognitive performance, physical function, and disease-severity, independent of AD pathological markers.

OBJECTIVE The management of excess CSF in patients with hydrocephalus typically requires using a shunt to divert CSF. Unfortunately, there is a high rate of shunt failure despite improvements in device components and insertion techniques. Reoperation is frequently necessary, which contributes to patient harm and increased healthcare costs. While factors affecting shunt failure are well defined in the pediatric population, information regarding adults is lacking. The authors undertook a systematic review and meta-analysis to determine how shunt failure in the adult population is reported and investigated the etiologies of shunt failure. METHODS This review is reported according to PRIMSA and utilized the MEDLINE, Embase, and Google Scholar databases. Abstracts were screened by two independent reviewers, and data were extracted in duplicate by two independent reviewers. Statistical analyses were performed using SPSS and Stata. RESULTS The pooled rates of shunt failure were 10% (95% CI 5%–15%) in studies with a mean follow-up time of less than 1 year, 12% (95% CI 8%–14%) with a follow-up time between 1 and 2 years, and 32% in studies with a follow-up time of 2 years or greater (95% CI 19%–43%). The pooled rate of failure was 17% across all studies. The most common cause of shunt failure was obstruction at 3.0% (95% CI 2%–4%), accounting for 23.2% of shunt failures. Infection was the second most common at 2.8% (95% CI 2%–3%), accounting for 22.5% of shunt failures. The most common location of shunt failure was the distal catheter, with a failure rate of 4.0% (95% CI 3%–5%), accounting for 33.4% of shunt failures. The definition of shunt failure was heterogeneous and varied depending on institutional practices. The combination of symptoms with either CT or MRI was the most frequently reported method for assessing shunt failure. CONCLUSIONS Important variation regarding how to define, investigate, and report shunt failure was identified. The overall shunt failure rate in adults is at least 32% after 2 years, which, while lower than that typically reported in the pediatric population, is significant. The most common causes of shunt failure in adults are infection and obstruction. The most common site of failure occurred at the distal catheter, highlighting the need to develop strategies to both report and mitigate distal shunt failure in adult shunt patients.

Abstract A quadrupole time‐of‐flight mass spectrometer coupled with a trapped ion mobility spectrometry (timsTOF) operated in parallel accumulation‐serial fragmentation (PASEF) mode has recently emerged as a platform capable of providing four‐dimensional (4D) features comprising of elution time, collision cross section (CCS), mass‐to‐charge ratio, and intensity of peptides. The PASEF mode provides ∼100% ion sampling efficiency both in data‐dependent acquisition (DDA) and data‐independent acquisition (DIA) modes without sacrificing sensitivity. In addition, targeted measurements using PASEF integrated parallel reaction monitoring (PRM) mode have also been described. However, only limited number of studies have used timsTOF for analysis of clinical samples. Although Orbitrap mass spectrometers have been used for biomarker discovery from cerebrospinal fluid (CSF) in a variety of neurological diseases, these Orbitrap‐derived datasets cannot readily be applied for driving experiments on timsTOF mass spectrometers. We generated a catalog of peptides and proteins in human CSF in DDA mode on a timsTOF mass spectrometer and used these data to build a spectral library. This strategy allowed us to use elution times and ion mobility values from the spectral library to design PRM experiments for quantifying previously discovered biomarkers from CSF samples in Alzheimer's disease. When the same samples were analyzed using a DIA approach combined with a spectral library search, a higher number of proteins were identified than in a library‐free approach. Overall, we have established a spectral library of CSF as a resource and demonstrated its utility for PRM and DIA studies, which should facilitate studies of neurological disorders.

The Clinical Proteomic Tumor Analysis Consortium (CPTAC) has provided some of the most in-depth analyses of the phenotypes of human tumors ever constructed. Today, the majority of proteomic data analysis is still performed using software housed on desktop computers which limits the number of sequence variants and post-translational modifications that can be considered. The original CPTAC studies limited the search for PTMs to only samples that were chemically enriched for those modified peptides. Similarly, the only sequence variants considered were those with strong evidence at the exon or transcript level. In this multi-institutional collaborative reanalysis, we utilized unbiased protein databases containing millions of human sequence variants in conjunction with hundreds of common post-translational modifications. Using these tools, we identified tens of thousands of high-confidence PTMs and sequence variants. We identified 4132 phosphorylated peptides in nonenriched samples, 93% of which were confirmed in the samples which were chemically enriched for phosphopeptides. In addition, our results also cover 90% of the high-confidence variants reported by the original proteogenomics study, without the need for sample specific next-generation sequencing. Finally, we report fivefold more somatic and germline variants that have an independent evidence at the peptide level, including mutations in ERRB2 and BCAS1. In this reanalysis of CPTAC proteomic data with cloud computing, we present an openly available and searchable web resource of the highest-coverage proteomic profiling of human tumors described to date.

Background While venous congestion in the peripheral vasculature has been described and accepted, intracranial venous congestion remains poorly understood. The characteristics, pathophysiology, and management of cerebral venous stasis, venous hypertension and venous congestion remain controversial, and a unifying conceptual schema is absent. The cerebral venous and lymphatic systems are part of a complex and dynamic interaction between the intracranial compartments, with interplay between the parenchyma, veins, arteries, cerebrospinal fluid, and recently characterized lymphatic-like systems in the brain. Each component contributes towards intracranial pressure, occupying space within the fixed calvarial volume. This article proposes a framework to consider conditions resulting in brain and neck venous congestion, and seeks to expedite further study of cerebral venous diagnoses, mechanisms, symptomatology, and treatments. Methods A multi-institution retrospective review was performed to identify unique patient cases, complemented with a published case series to assess a spectrum of disease states with components of venous congestion affecting the brain. These diseases were organized according to anatomical location and purported mechanisms. Outcomes of treatments were also analyzed. Illustrative cases were identified in the venous treatment databases of the authors. Conclusion This framework is the first clinically structured description of venous pathologies resulting in intracranial venous and cerebrospinal fluid hypertension. Our proposed system highlights unique clinical symptoms and features critical for appropriate diagnostic work-up and potential treatment. This novel schema allows clinicians effectively to approach cases of intracranial hypertension secondary to venous etiologies, and furthermore provides a framework by which researchers can better understand this developing area of cerebrovascular disease.

Abstract Alzheimer's disease (AD) is the most common cause of dementia and is associated with serious neurologic sequelae resulting from neurodegenerative changes. Identification of markers of early-stage AD could be important for designing strategies to arrest the progression of the disease. The brain is rich in lipids because they are crucial for signal transduction and anchoring of membrane proteins. Cerebrospinal fluid (CSF) is an excellent specimen for studying the metabolism of lipids in AD because it can reflect changes occurring in the brain. We aimed to identify CSF lipidomic alterations associated with AD, using untargeted lipidomics, carried out in positive and negative ion modes. We found CSF lipids that were significantly altered in AD cases. In addition, comparison of CSF lipid profiles between persons with mild cognitive impairment (MCI) and AD showed a strong positive correlation between the lipidomes of the MCI and AD groups. The novel lipid biomarkers identified in this study are excellent candidates for validation in a larger set of patient samples and as predictive biomarkers of AD through future longitudinal studies. Once validated, the lipid biomarkers could lead to early detection, disease monitoring and the ability to measure the efficacy of potential therapeutic interventions in AD.