CSF lactate

The impact of glycolysis on ischemic stroke: from molecular mechanisms to clinical applications

Ischemic stroke (IS), a leading cause of disability and mortality worldwide, remains a significant challenge due to its complex pathogenesis. Glycolysis, a central metabolic pathway, plays a critical role in bridging the gap between metabolic dysfunction and neurological impairment. During ischemic conditions, glycolysis replaces oxidative phosphorylation as the primary energy source for brain tissue. However, in the ischemia-reperfusion state, neuronal cells show a particular reliance on aerobic glycolysis. Immune cells, such as monocytes, also contribute to atheromatous plaque formation and thrombi through increased aerobic glycolysis. Given glycolysis's involvement in various pathological stages of IS, it offers the potential for improved diagnosis, treatment, and prevention. This review comprehensively explores the role of glycolysis in different phases of IS, addresses existing controversies, and discusses its diagnostic and therapeutic applications. By elucidating the intricate relationship between glycolysis and IS, this review aims to provide novel insights for future research and clinical advancements.

Cerebrospinal fluid L-lactate as a diagnostic marker for infectious-inflammatory disorders in the central nervous system of cattle

Introduction

Bacterial infection of the central nervous system (CNS) poses a clinical challenge and is a leading cause of neurological disorders in cattle. Human studies have demonstrated an increase in cerebrospinal fluid (CSF) L-lactate levels in bacterial meningitis. The aims of this study were to establish a Reference Interval (RI) for L-lactate in bovine CSF and assess its potential as a biomarker for detecting infectious-inflammatory disorders.

Methods

CSF L-lactate was measured in the field using a commercially available lactate monitor. The RI for CSF L-lactate was calculated on healthy animals; univariate and receiver operating characteristic (ROC) analyses were performed to disclose an association between CSF L-lactate levels and interpretation of CSF in sick animals.

Results

Twenty-seven healthy cattle and 86 sick cattle with either CNS infectious-inflammatory disorders (47/86) or CNS disorders of other etiology (39/86) were included in this prospective study. The RI for CSF L-lactate was 1.1-2.4 mmol/L. The concentration was higher in the cattle with neutrophilic pleocytosis and the area under the ROC curve was 0.92 compared to other animals. Based on a cut-off of 3.15 mmol/L, CSF L-lactate had diagnostic sensitivity and specificity for neutrophilic pleocytosis of 93 and 80%, respectively.

Discussion

This is the first study to determine a RI for CSF L-lactate in cattle. Elevated CSF L-lactate levels indicated neutrophilic pleocytosis, which is often manifested in acute bacterial infection. The present findings may aid in diagnosis and correct use of antimicrobial drugs.

Cerebrospinal Fluid Lactate Levels as a Prognostic Indicator in Patients With Cryptococcal Meningitis Who Are HIV Negative: A Retrospective Cohort Study

Background

Cryptococcal meningitis (CM) is a severe central nervous system infection. In patients with HIV infections and coexisting CM, elevated baseline cerebrospinal fluid (CSF) lactate levels can predict increased mortality. However, the CSF lactate level's significance in patients with CM who are HIV negative remains unclear, necessitating further investigation to elucidate the potential distinctions and enhance patient management. This study investigated the significance of CSF lactate levels in patients with CM who were HIV negative.

Methods

This retrospective study utilized data from the clinical databases of patients who underwent lumbar punctures at a medical center in Kaohsiung City, southern Taiwan. Demographic data, CSF lactate levels, routine CSF analyses, and hematologic and neurologic findings were evaluated. The optimal CSF lactate threshold value was determined by the Youden index.

Results

This retrospective study included 70 patients with CM, among whom 44 (63%) and 26 (37%) tested negative and positive for HIV, respectively. The group without HIV exhibited higher CSF lactate levels, with an optimal CSF lactate cutoff point of 7.935 mmol/L for predicting 90-day mortality, resulting in significant predictive accuracies (area under the curve, 0.755; sensitivity, 57.1%; specificity, 100%); this value was an independent mortality predictor in patients who were HIV negative. In patients with CM who were HIV negative, CSF lactate levels ≥7.935 mmol/L correlated with higher mortality rates but without statistical significance. All patients with CM who were HIV negative and had CSF lactate levels ≥7.935 mmol/L died within 3 months of admission.

Conclusions

Patients with CM who were HIV negative had elevated CSF lactate levels that correlated with adverse outcomes, enabling early identification of high-risk individuals.

Combined Lactate Glucose Ratio as a Novel Marker for Rapid Diagnosis of Cerebrospinal Fluid Bacterial Infection in Neurosurgical Patients: Diagnostic Accuracy Study and Benchtop Analyzer Correlation

OBJECTIVE

This study aimed to assess the diagnostic accuracy of a novel marker, the combined lactate glucose ratio (CLGR), in identifying cerebrospinal fluid (CSF) bacterial infection (CBI) in neurosurgical patients. Additionally, it seeks to establish cutoff values for CLGR and evaluate the reliability of measurement using blood gas analyzer (BGA).

METHODS

CSF samples were collected from 2 neurosurgical centers in Kuala Lumpur, Malaysia, between January 2022 and October 2023. Conventional markers and CLGR were quantified using standard laboratory methods, with BGA utilized for measurement when feasible. Samples were categorized into confirmed CBI-positive (CBI+) and CBI-negative (CBI-) groups. Marker performance was compared, and receiver operating characteristic analysis conducted. Pearson correlation assessed the agreement between BGA and laboratory measurements.

RESULTS

Among the 130 CSF samples, 11 were CBI+. Both cerebrospinal fluid lactate (cLac) and CLGR were significantly elevated in the CBI + group (P < 0.001). The area under the curve for cLac and CLGR was 0.990 and 0.994, respectively. Using a cutoff of 6.0 mmol/L, cLac demonstrated sensitivity of 100%, specificity of 93.3%, positive predictive value of 57.9%, negative predictive value of 100%, and diagnostic accuracy of 93.9%. CLGR ≥20.0 showed even higher accuracy: 100.0% sensitivity, 98.6% specificity, 84.6% positive predictive value, 100% negative predictive value, and overall accuracy of 98.5%. Both markers maintained excellent performance in blood-stained CSF. BGA measurements correlated well with laboratory results (r = 0.980 and 0.999, respectively, P < 0.001).

CONCLUSIONS

CLac levels ≥6.0 mmol/L and CLGR ≥20.0 accurately identified CBI in neurosurgical patients, with CLGR exhibiting superior efficacy. The potential for instant BGA measurement suggests promise for point-of-care testing.

Astrocytic LRP1 enables mitochondria transfer to neurons and mitigates brain ischemic stroke by suppressing ARF1 lactylation

Low-density lipoprotein receptor-related protein-1 (LRP1) is an endocytic/signaling cell-surface receptor that regulates diverse cellular functions, including cell survival, differentiation, and proliferation. LRP1 has been previously implicated in the pathogenesis of neurodegenerative disorders, but there are inconsistencies in its functions. Therefore, whether and how LRP1 maintains brain homeostasis remains to be clarified. Here, we report that astrocytic LRP1 promotes astrocyte-to-neuron mitochondria transfer by reducing lactate production and ADP-ribosylation factor 1 (ARF1) lactylation. In astrocytes, LRP1 suppressed glucose uptake, glycolysis, and lactate production, leading to reduced lactylation of ARF1. Suppression of astrocytic LRP1 reduced mitochondria transfer into damaged neurons and worsened ischemia-reperfusion injury in a mouse model of ischemic stroke. Furthermore, we examined lactate levels in human patients with stroke. Cerebrospinal fluid (CSF) lactate was elevated in stroke patients and inversely correlated with astrocytic mitochondria. These findings reveal a protective role of LRP1 in brain ischemic stroke by enabling mitochondria-mediated astrocyte-neuron crosstalk.

Acute infections of the central nervous system in children and adults: diagnosis and management

Central nervous system infections are due to different microorganisms such as viruses, bacteria, mycobacteria, fungi, amoebas, and other parasites. The etiology depends on multiple risk factors, and it defines the infection location because some microorganisms prefer meninges, brain tissue, cerebellum, brain stem or spinal cord. The microorganisms induce diseases in the nervous system through direct invasion, neurotoxin production, and the triggered immune response. To determine the infection etiology, there are several diagnostic tests which may be conducted with cerebrospinal fluid, blood, respiratory and stool samples. These tests include but are not limited to direct microscopic examination of the sample, stains, cultures, antigenic tests, nucleic acid amplification tests, metagenomic next-generation sequencing, immunologic biomarker and neuroimaging, especially contrast-enhanced magnetic resonance imaging. The treatment may consist of specific antimicrobial treatment and supportive standard care. Since viruses have no specific antiviral treatment, antimicrobial treatment is mainly targeted at non-viral infections. This article will focus on diagnosis and treatment of acute acquired infections of the central nervous system beyond the neonatal period. The discussion defines the disease, provides the clinical presentation, explains the etiology and risk factors, and briefly mentions potential complications. This updated review aims to provide the reader with all the elements needed to adequately approach a patient with a central nervous system infection. Mycobacterium tuberculosis infection, Cryptococcus spp. infection and vaccines are not within the scope of this article.

Is Methylglyoxal a Potential Biomarker for the Warburg Effect Induced by the Lipopolysaccharide Neuroinflammation Model?

Methylglyoxal (MG) is considered a classical biomarker of diabetes mellitus and its comorbidities. However, a role for this compound in exacerbated immune responses, such as septicemia, is being increasingly observed and requires clarification, particularly in the context of neuroinflammatory responses. Herein, we used two different approaches (in vivo and acute hippocampal slice models) to investigate MG as a biomarker of neuroinflammation and the neuroimmunometabolic shift to glycolysis in lipopolysaccharide (LPS) inflammation models. Our data reinforce the hypothesis that LPS-induced neuroinflammation stimulates the cerebral innate immune response by increasing IL-1β, a classical pro-inflammatory cytokine, and the astrocyte reactive response, via elevating S100B secretion and GFAP levels. Acute neuroinflammation promotes an early neuroimmunometabolic shift to glycolysis by elevating glucose uptake, lactate release, PFK1, and PK activities. We observed high serum and cerebral MG levels, in association with a reduction in glyoxalase 1 detoxification activity, and a close correlation between serum and hippocampus MG levels with the systemic and neuroinflammatory responses to LPS. Findings strongly suggest a role for MG in immune responses.

Measurement of cerebrospinal fluid lactate levels in pediatric patients with suspected ventriculoperitoneal shunt infection: A retrospective cohort study

INTRODUCTION

Ventriculoperitoneal shunt (VPS) infection is a severe complication. Early diagnosis could help to decrease morbidity and treatment costs. Lactate has been used for the diagnosis of other central nervous system infections. The aim of this study is to determine the usefulness of lactate for the diagnosis of VPS infection.

METHODOLOGY

Retrospective cohort study. Lactate was measured in patients who consulted with VPS dysfunction between May 2019 and May 2022. Mean were compared according to culture results. A Receiver Operating Characteristic (ROC) curve was performed to determine the appropriate cut-off point.

RESULT

Lactate has a high negative predictive value but a low positive predictive value for the diagnosis of ventriculitis.

Cerebrospinal fluid pH regulation

The cerebrospinal fluid (CSF) fills the brain ventricles and the subarachnoid space surrounding the brain and spinal cord. The fluid compartment of the brain ventricles communicates with the interstitial fluid of the brain across the ependyma. In comparison to blood, the CSF contains very little protein to buffer acid-base challenges. Nevertheless, the CSF responds efficiently to changes in systemic pH by mechanisms that are dependent on the CO2/HCO3- buffer system. This is evident from early studies showing that the CSF secretion is sensitive to inhibitors of acid/base transporters and carbonic anhydrase. The CSF is primarily generated by the choroid plexus, which is a well-vascularized structure arising from the pial lining of the brain ventricles. The epithelial cells of the choroid plexus host a range of acid/base transporters, many of which participate in CSF secretion and most likely contribute to the transport of acid/base equivalents into the ventricles. This review describes the current understanding of the molecular mechanisms in choroid plexus acid/base regulation and the possible role in CSF pH regulation.

Characterization and diagnosis spectrum of patients with cerebrospinal fluid pleocytosis

PURPOSE

There is an overlap in the cerebrospinal fluid (CSF) characteristics of patients presenting with different etiologies of CSF pleocytosis. Here, we characterized patients with CSF pleocytosis treated in a large hospital.

METHODS

A retrospective cohort study of 1150 patients with an elevated CSF leukocyte count > 5 cells/µl treated at a university hospital in Germany from January 2015 to December 2017 was performed. Information on clinical presentation, laboratory parameters, diagnosis and outcome was collected. Clinical and laboratory features were tested for their potential to differentiate between bacterial meningitis (BM) and other causes of CSF pleocytosis.

RESULTS

The most common etiologies of CSF pleocytosis were CNS infections (34%: 20% with detected pathogen, 14% without), autoimmune (21%) and neoplastic diseases (16%). CSF cell count was higher in CNS infections with detected pathogen (median 82 cells/µl) compared to autoimmune (11 cells/µl, p = 0.001), neoplastic diseases (19 cells/µl, p = 0.01) and other causes (11 cells/µl, p < 0.001). The CHANCE score was developed to differentiate BM from other causes of CSF pleocytosis: Multivariate regression revealed that CSF cell count > 100 cells/µl, CSF protein > 100 mg/dl, CRP > 5 mg/dl, elevated white blood cell count, abnormal mental status and nuchal rigidity are important indicators. The CHANCE score identified patients with BM with high sensitivity (92.1%) and specificity (90.9%) (derivation cohort: AUC: 0.955, validation cohort: AUC: 0.956).

CONCLUSION

Overall, the most common causes for CSF pleocytosis include infectious, neoplastic or autoimmune CNS diseases in ~ 70% of patients. The CHANCE score could be of help to identify patients with high likelihood of BM and support clinical decision making.

Reliability of a point of care testing blood gas analyzer for measurement of lactate levels in cerebrospinal fluid

Analysis of cerebrospinal fluid (CSF), including lactate, is key for diagnosis of acute meningitis. Since blood gas analyzers (BGA) enable rapid and safe blood-lactate measurements, we evaluated the reliability of RAPIDPoint 500 BGA to provide a fast and accurate measure of CSF lactate. In this study, CSF lactate levels were measured by a reference assay and on RAPIDPoint 500 BGA. Comparability was evaluated through difference analysis, using Bland Altman test, and linear regression analysis, using the Passing Bablok test. Agreement rate according to CSF lactate (≥3.5 and <3.5 mmol/L) was calculated using kappa (κ) statistic. Population study included 98 CSF samples. Concerning difference analysis, according to Bland-Altman test, bias was 0.13 mmol/L (CI 95%: -0.26 to 0.52 mmol/L. In regression analysis, according to Passing-Bablok equation a systematic difference between both assays was found. In concordance analysis, the interrate realibility was very high (κ: 0.964). According to our resuls, although a systematic difference was detected when lactate levels were measured on RAPIDPoint 500 BGA, the results from Bland-Altman test and the high agreement rate support that this POCT analyzer could be useful for a early and safe detection of patients with high probability of increased CSF lactate level.

Association between Peripheral Arterial Lactate Levels and Malignant Brain Edema Following Endovascular Treatment for Ischemic Stroke

AIMS

To investigate the factors of postoperative malignant brain edema (MBE) in patients with acute ischemic stroke (AIS) treated with endovascular treatment (EVT).

BACKGROUND

MBE is a severe complication following EVT for AIS, and it is essential to identify risk factors early. Peripheral arterial lactate (PAL) levels may serve as a potential predictive marker for MBE.

OBJECTIVE

To determine whether immediate postoperative PAL levels and the highest PAL level within 24 hours of EVT are independently associated with MBE development in AIS patients.

METHODS

We retrospectively analyzed patients with AIS who underwent EVT from October 2019 to October 2022. Arterial blood was collected every 8 h after EVT to measure PAL, and record the immediate postoperative PAL and the highest PAL level within 24 h. Brain edema was evaluated using brain computed tomography scans within 7 days of EVT.

RESULTS

The study included 227 patients with a median age of 71 years, of whom 59.5% were male and MBE developed in 25.6% of patients (58/227). Multivariate logistic regression analysis showed that the immediate postoperative PAL (odds ratio, 1.809 [95% confidence interval (CI), 1.215-2.693]; p = 0.004) and the highest PAL level within 24 h of EVT (odds ratio, 2.259 [95% CI, 1.407-3.629]; p = 0.001) were independently associated with MBE. The area under the curve for predicting MBE based on the highest PAL level within 24 hours of EVT was 0.780 (95% CI, 0.711-0.849).

CONCLUSION

Early increase in PAL levels is an independent predictor of MBE after EVT in AIS patients.

A preliminary study investigating the clinical potential of measuring cerebrospinal-fluid lactate levels in patients with narcolepsy type 1 and 2

STUDY OBJECTIVES

Besides the quantification of orexin-A/hypocretin-1 cerebrospinal fluid (CSF) levels in narcolepsy for diagnostic purposes, several other CSF biomarkers have been evaluated, although with controversial results. Since CSF lactate concentrations fluctuate according to the sleep-wake cycle with higher levels during wakefulness and lower levels during sleep, as documented in animal model studies, the present study aimed at quantifying the CSF lactate levels in patients with narcolepsy type 1 (NT1) and 2 (NT2), which are two sleep disorders featured by excessive daytime sleepiness (EDS).

METHODS

Patients with NT1 and NT2 were enrolled in this study and compared to a control group of similar age and sex. All the subjects included in the study underwent a polysomnographic study followed by lumbar puncture for the quantification of CSF lactate levels at awakening.

RESULTS

23 NT1 (43.5 % male; 36.43 ± 11.89 years) and 15 NT2 patients (46.7 % male; 37.8 ± 14.1 years) were compared to 17 controls (58.8 % male; 32.3 ± 8.4 years). CSF lactate concentrations were reduced in patients with NT1 and NT2 compared to controls but no differences were found between the two groups of patients. ROC curves analysis showed that CSF lactate ≤1.3 mmol/l had a sensitivity of 96.49 and a specificity of 82.35 % for discriminating patients with narcolepsy from controls.

CONCLUSIONS

The present study showed a decrease in CSF lactate levels in patients with narcolepsy. Notably, the reduction of lactate levels was present in both NT1 and NT2 patients, independently of CSF orexin levels. Narcolepsy patients present EDS with daytime napping and REM-related episodes, possibly substantiating the CSF lactate levels reduction related to the impaired daytime wakefulness which was demonstrated in animal studies. Moreover, CSF lactate levels present a good sensitivity and adequate specificity for differentiating narcolepsy from controls. Further studies are needed to understand the role of CSF lactate and its usefulness for monitoring daytime vigilance in patients with narcolepsy.

Differences in Cerebral Metabolism between Moderate- and High-Severity Groups of Patients with Out-of-Hospital Cardiac Arrest Undergoing Target Temperature Management

The aim of this study was to investigate the differences in cerebral metabolism and the prognostic value of cerebrospinal fluid (CSF) lactate 24 h after the return of spontaneous circulation (ROSC) in patients with out-of-hospital cardiac arrest (OHCA). CSF lactate and pyruvate levels were measured immediately and every 2 h for 24 h after the ROSC. The distribution of cerebral mitochondrial dysfunction (MD) and cerebral ischemia was also evaluated. In the moderate-severity group, the absence of cerebral MD or ischemia was observed in six patients (40.0%) immediately after ROSC and in nine patients (60.0%) 24 h after the ROSC. In the high-severity group, the absence of cerebral MD or ischemia was observed in four patients (30.8%) immediately after ROSC and in three patients (23.1%) 24 h after the ROSC. The distribution of cerebral metabolism over time varied depending on the severity of the OHCA. The predictive value of CSF lactate levels for a poor neurological prognosis was better for patients in the moderate-severity group than for the overall patient cohort. Therefore, the severity in the patients with OHCA should be considered when studying cerebral metabolism or using CSF lactate as a prognostic tool.

Treatment of Ventriculitis and Meningitis After Neurosurgery Caused by Carbapenem-Resistant Enterobacteriaceae (CRE): A Challenging Topic

Post-neurosurgical infection is a common complication of neurosurgery, and serious infection can threaten the life of patients. In recent years, the increase in multidrug-resistant bacteria, especially carbapenem-resistant Enterobacteriaceae (CRE), has proved fatal to patients. Although there are a few cases of CRE meningitis and few clinical trials have been carried out, it has attracted increasing attention with the increasing probability of its occurrence, especially considering that there are few successful cases. An increasing number of studies are also looking for the risk factors and clinical symptoms of CRE intracranial infection. In terms of treatment, some new antibiotics are gradually being used in the clinic, but due to the complicated drug-resistant mechanism of CRE and the obstruction of the blood‒brain barrier (BBB), the therapeutic effect is still very poor. In addition, obstructive hydrocephalus and brain abscess caused by CRE meningitis are still important causes of patient death and are also difficult to treat.

The Diagnostic Value of Cerebrospinal Fluid Lactate for Detection of Sepsis in Community-Acquired Bacterial Meningitis

Community-acquired bacterial meningitis conveys significant morbidity and mortality due to intracranial and systemic complications, and sepsis is a major contributor to the latter. While cerebrospinal fluid (CSF) analysis is essential in the diagnosis of bacterial meningitis, its predictive utility for detection of sepsis is unknown. We investigated the diagnostic performance of CSF parameters for sepsis defined by the Sepsis-3 criteria in a retrospective cohort of patients with community-acquired bacterial meningitis. Among 103 patients, 69.5% developed sepsis. CSF lactate was associated with sepsis with an odds ratio of 1.11 (p = 0.022), while CSF cell counts, glucose and protein levels were not (all p > 0.4). Employing the optimal cutoff of 8.2 mmol/L, elevated CSF lactate resulted in a sensitivity of 81.5% and specificity of 61.5% for sepsis. In exploratory analyses, CSF lactate was also associated with in-hospital mortality with an odds ratio of 1.21 (p = 0.011). Elevated CSF lactate might contribute to early diagnosis of sepsis as well as prognostication in patients with community-acquired bacterial meningitis.

Role of cerebrospinal fluid lactate in diagnosing meningitis in critically ill patients

BACKGROUND

Meningitis is a life-threatening clinical condition associated with high mortality and morbidity. Early diagnosis and specific treatment may improve outcomes. Lack of specific clinical signs or tests make the diagnosis challenging.

AIM

To assess the efficacy of cerebrospinal fluid (CSF) lactate in diagnosing meningitis in critically ill patients.

METHODS

A prospective, observational cohort study was carried out in a neuro-medical intensive care unit (ICU) over a 22 mo period. Adult patients, with suspected meningitis admitted in ICU, were serially recruited. Patients who refused consent, those with peripheral sensorineural deficit, or with any contraindication to lumber puncture were excluded. CSF cytology, bio-chemistry, lactates, culture and polymerase chain reaction based meningo-encephalitis panel were evaluated. Patients were divided in two groups based on clinical diagnosis of meningitis. The efficacy of CSF lactate in diagnosing meningitis was evaluated and compared with other tests.

RESULTS

Seventy-one patients were included and 23 were diagnosed with meningitis. The mean values of CSF total leucocyte count (TLC), proteins and lactates were significantly higher in meningitis group. There was a significant correlation of CSF lactate levels with CSF cultures and meningo-encephalitis panel. CSF lactate (> 2.72 mmol/L) showed good accuracy in diagnosing meningitis with an area under the curve of 0.81 (95% confidence interval: 0.69-0.93), sensitivity of 82.6%, and specificity 72.9%. These values were comparable to those of CSF TLC and protein. Twelve patients with bacterial meningitis had significantly higher CSF lactate (8.9 ± 4.7 mmol/L) than those with non-bacterial meningitis (4.2 ± 3.8 mmol/L), P = 0.006.

CONCLUSION

CSF lactate may be used to aid in our diagnosis of meningitis in ICU patients. CSF lactate (> 2.72 mmol/L) showed good accuracy, sensitivity, and specificity in diagnosing meningitis and may also help to differentiate between bacterial and non-bacterial meningitis.

Characteristics of patients with meningitis after lumbar epidural steroid injection

To investigate the clinical, laboratory, and radiological features of meningitis after lumbar epidural steroid injection (M-ESI) without accompanying spinal infection, data of patients with meningitis admitted between January 2014 and December 2021 in a single center were retrospectively reviewed. Among them, patients with a recent history of lumbar ESI were identified, and their medical records were collected. Patients with concomitant infections other than meningitis, including spinal epidural abscess, were excluded. Seven patients with M-ESI were identified. All patients presented with headache and fever without focal neurological deficits, and headache developed shortly after a procedure (median, 4 hours). Cerebrospinal fluid (CSF) analysis showed neutrophilic pleocytosis (median, 6729/μL), elevated protein level (median, 379.1 mg/dL), decreased ratio of CSF glucose to serum glucose (median, 0.29), and elevated lactate level (median, 8.64 mmol/L). Serum level of C-reactive protein was elevated in 6, but serum procalcitonin level was within normal range. No causative pathogen was identified in the microbiological studies. The most frequent radiologic feature was sulcal hyperintensity on fluid-attenuated inversion recovery images (57%), followed by pneumocephalus (43%). Symptoms subsided in a short period (median, 1 day) after initiating treatment with antibiotics and adjuvant intravenous corticosteroids. None of the patients experienced neurological sequelae. Though the cardinal symptoms and CSF findings of M-ESI were comparable to those of bacterial meningitis, M-ESI seems to have distinctive characteristics regarding the clinical course, laboratory parameters, and pneumocephalus.

Quantitation of Lactate in Cerebrospinal Fluid Using Liquid Chromatography-Electrospray-Tandem Mass Spectrometry

We describe a simple stable isotope dilution method for accurate and precise measurement of cerebrospinal fluid (CSF) lactate as a clinical diagnostic test. Lactate is produced from cellular metabolism, primarily in muscle cells, and provides a source of energy especially during instances of low oxygen levels. Measurement of lactate in CSF provides diagnostic information regarding the body's oxidative metabolism including diagnosis of lactate acidosis, aiding in the diagnosis of blood-brain barrier glucose transporter defect and differentiation between bacterial and viral meningitis. Determination of lactate in CSF (20 μL) was performed utilizing high-performance liquid chromatography coupled with electrospray positive ionization tandem mass spectrometry (HPLC-ESI-MS/MS). Lactate in CSF is determined by a 1:10 dilution with internal standard (sodium lacate-d3) and injected directly onto the HPLC-ESI-MS/MS system. Each assay is quantified using a six-point standard curve (0.625-20 mM) and has an analytical measurement range of 0.3-20 mM.

Diagnostic utility of cerebrospinal fluid (CSF) findings in seizures and epilepsy with and without autoimmune-associated disease

Patients with seizures and epilepsy routinely undergo multiple diagnostic tests, which may include cerebrospinal fluid (CSF) analysis. This review aims to outline different CSF parameters and their alterations in seizures or epilepsy. We then discuss the utility of CSF analysis in seizure patients in different clinical settings in depth. Some routine CSF parameters are frequently altered after seizures, but are not specific such as CSF protein and lactate. Pleocytosis and CSF specific oligoclonal bands are rare and should be considered as signs of infectious or immune mediated seizures and epilepsy. Markers of neuronal damage show conflicting results, and are as yet not established in clinical practice. Parameters of neuronal degeneration and more specific immune parameters are less well studied, and are areas of further research. CSF analysis in new-onset seizures or status epilepticus serves well in the differential diagnosis of seizure etiology. Here, considerations should include autoimmune-associated seizures. CSF findings in these disorders are a special focus of this review and are summarized in a comprehensive overview. Until now, CSF analysis has not yielded clinically helpful biomarkers for refractory epilepsy or for assessment of neuronal damage which is a subject of further studies.

Brain energy metabolism and neurodegeneration: hints from CSF lactate levels in dementias

Mitochondrial dysfunction is pivotal in the development of neurodegenerative dementias, causing cellular death alongside disease-specific pathogenic cascades. Holding cerebrospinal fluid (CSF) lactates as an indirect measure of brain metabolic activity, we first compared CSF lactate levels from patients with Alzheimer's disease (AD)-stratified according to the ATN system and epsilon genotype-frontotemporal dementia (FTD) and dementia with Lewy body (DLB) to findings from healthy controls. With respect to controls, we detected lower CSF lactates in patients with AD and FTD but comparable levels in patients with DLB. Second, a correlation analysis between CSF lactates and biomarkers of neurodegeneration identified an inverse correlation between lactates and levels of t-tau and p-tau only in the Alzheimer's continuum. The reduction of CSF lactate correlates to the advent of tauopathy and cellular death in AD, implying that Aβ pathology alone is not sufficient to induce neuronal metabolic impairment. The metabolic impairment in FTD patients has a similar explanation, as it is likely due to fast neuronal degeneration in the disease. The absence of CSF lactate reduction in patients with DLB may be related to the prevalent subcortical localization of the pathology.

Point-of-care detection of lactate in cerebrospinal fluid

Purpose

Measurements of cerebrospinal fluid (CSF) lactate can aid in detecting infections of the central nervous system and surrounding structures. Neurosurgical patients with temporary lumbar or ventricular CSF drainage harbor an increased risk for developing infections of the central nervous system, which require immediate therapeutic responses. Since blood gas analyzers enable rapid blood-lactate measurements, we were interested in finding out if we can reliably measure CSF-lactate by this point-of-care technique.

Methods

Neurosurgical patients on our intensive care unit (ICU) with either lumbar or external ventricular drainage due to a variety of reasons were included in this prospective observational study. Standard of care included measurements of leucocyte counts, total protein and lactate measurements in CSF by the neurochemical laboratory of our University Medical Center twice a week. With respect to this study, we additionally performed nearly daily measurements of cerebrospinal fluid by blood gas analyzers to determine the reliability of CSF-lactate measured by blood gas analyzers as compared to the standard measurements with a certified device.

Results

62 patients were included in this study. We performed 514 CSF-lactate measurements with blood gas analyzers and compared 180 of these to the in-house standard CSF-lactate measurements. Both techniques correlated highly significantly (Pearson correlation index 0.94) even though lacking full concordance in a Bland–Altman plotting. Of particular importance, regular measurements enabled immediate detection of central infection in three patients who had developed meningitis during the course of their treatment.

Conclusion

Blood gas analyzers measure CSF-lactate with sufficient reliability and can help in the timely detection of a developing meningitis. In addition to and triggering established CSF diagnostics, CSF-lactate measurements by blood gas analyzers may improve surveillance of patients with CSF drainage.

This study was retrospectively registered on April 20th 2020 in the German trial register. The trial registration number is DRKS00021466.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40635-021-00385-9.

How Comorbidity Reflects on Cerebrospinal Fluid Biomarkers of Neurodegeneration in Aging

Systemic comorbidity precipitates the risk for dementia. To comprehend the underlying mechanisms into a therapeutic perspective, we analyzed how comorbidity affects neurodegeneration-related cerebrospinal fluid (CSF) biomarkers of 55 cognitively intact subjects. The Charson Comorbidity Index (CCI) was correlated with CSF amyloid-β42 (Aβ42), amyloid-β40, total-tau, 181-phosphorylated-tau (p-tau), the Aβ42/p-tau ratio, neurogranin, and lactate. The age-related brain lesions at imaging were also considered. CCI had a raw association with Aβ42/p-tau and p-tau, and a stronger, age-independent correlation with lactate. These preliminary findings suggested that, in normal subjects, systemic comorbidity might increase CNS oxidative stress and, together with aging, contribute to develop an Alzheimer's disease-like biochemical profile.