Neurofilament light protein levels in cerebrospinal fluid predict long-term disability of Guillain-Barré syndrome: A pilot study

Neurofilaments as biomarkers in neurological disorders - towards clinical application

Neurofilament proteins have been validated as specific body fluid biomarkers of neuro-axonal injury. The advent of highly sensitive analytical platforms that enable reliable quantification of neurofilaments in blood samples and simplify longitudinal follow-up has paved the way for the development of neurofilaments as a biomarker in clinical practice. Potential applications include assessment of disease activity, monitoring of treatment responses, and determining prognosis in many acute and chronic neurological disorders as well as their use as an outcome measure in trials of novel therapies. Progress has now moved the measurement of neurofilaments to the doorstep of routine clinical practice for the evaluation of individuals. In this Review, we first outline current knowledge on the structure and function of neurofilaments. We then discuss analytical and statistical approaches and challenges in determining neurofilament levels in different clinical contexts and assess the implications of neurofilament light chain (NfL) levels in normal ageing and the confounding factors that need to be considered when interpreting NfL measures. In addition, we summarize the current value and potential clinical applications of neurofilaments as a biomarker of neuro-axonal damage in a range of neurological disorders, including multiple sclerosis, Alzheimer disease, frontotemporal dementia, amyotrophic lateral sclerosis, stroke and cerebrovascular disease, traumatic brain injury, and Parkinson disease. We also consider the steps needed to complete the translation of neurofilaments from the laboratory to the management of neurological diseases in clinical practice.

Dynamics and prognostic value of serum neurofilament light chain in Guillain-Barré syndrome

BACKGROUND

Neurofilament light chain (NfL) is a biomarker for axonal damage in several neurological disorders. We studied the longitudinal changes in serum NfL in patients with Guillain-Barré syndrome (GBS) in relation to disease severity, electrophysiological subtype, treatment response, and prognosis.

METHODS

We included patients with GBS who participated in a double-blind, randomised, placebo-controlled trial that evaluated the effects of a second course of intravenous immunoglobulin (IVIg) on clinical outcomes. Serum NfL levels were measured before initiation of treatment and at one, two, four, and twelve weeks using a Simoa HD-X Analyzer. Serum NfL dynamics were analysed using linear mixed-effects models. Logistic regression was employed to determine the associations of serum NfL with clinical outcome and the prognostic value of serum NfL after correcting for known prognostic markers included in the modified Erasmus GBS Outcome Score (mEGOS).

FINDINGS

NfL levels were tested in serum from 281 patients. Serum NfL dynamics were associated with disease severity and electrophysiological subtype. Strong associations were found between high levels of serum NfL at two weeks and inability to walk unaided at four weeks (OR = 1.74, 95% CI = 1.27-2.45), and high serum NfL levels at four weeks and inability to walk unaided at 26 weeks (OR = 2.79, 95% CI = 1.72-4.90). Baseline serum NfL had the most significant prognostic value for ability to walk, independent of predictors included in the mEGOS. The time to regain ability to walk unaided was significantly longer for patients with highest serum NfL levels at baseline (p = 0.0048) and week 2 (p < 0.0001). No differences in serum NfL were observed between patients that received a second IVIg course vs. IVIg and placebo.

INTERPRETATION

Serum NfL levels are associated with disease severity, axonal involvement, and poor outcome in GBS. Serum NfL potentially represents a biomarker to monitor neuronal damage in GBS and an intermediate endpoint to evaluate the effects of treatment.

FUNDING

Prinses Beatrix Spierfonds W.OR19-24.

Predicting of Mechanical Ventilation and Outcomes by Using Models and Biomarker in Guillain-Barré Syndrome

BACKGROUND

Guillain-Barré syndrome (GBS) is an acute inflammatory neuropathy. The Erasmus GBS Respiratory Insufficiency Score (EGRIS) and the modified Erasmus GBS Outcome Score (mEGOS) are prognostic models used in the prediction of mechanical ventilation and outcome. Thus far, there are only few biomarkers for the prognosis prediction of GBS patients, and albumin level is one that is promising.

METHODS

Patients diagnosed with GBS from 2013 to 2022 at Renmin Hospital, Wuhan University, China, were included. Patients hospitalized between 2016 and 2022 underwent short- and long-term follow-ups. The correlations between EGRIS/mEGOS and mechanical ventilation and outcome were evaluated. Serum albumin level was examined the day after admission. Furthermore, we also investigated whether the level of serum albumin was useful in predicting disease severity or poor outcome.

RESULTS

In all, 145 patients were enrolled. Nineteen patients (13.1%) who required mechanical ventilation had higher Hughes GBS disability score (HGDS) at admission and discharge (P < 0.05 and P < 0.0001, respectively), shorter time from onset to admission and treatment (P < 0.01 and P < 0.001, respectively) and longer hospital stays (P < 0.001) than patients who did not require mechanical ventilation. High EGRIS scores were linked with the need for mechanical ventilation (r = 0.427, P < 0.001, AUC = 0.623). Seventy-one patients were admitted between 2016 and 2022. Of these, 65 patients had a 4-week follow-up and 61 had a 6-month follow-up. Higher mEGOS scores at admission and 7 days after admission significantly correlated with short- (P < 0.0001 and P < 0.0001) and long-term (P < 0.05 and P < 0.05) outcomes, respectively. No significant difference in outcome was found between different subtypes (4 weeks [P = 0.099] and 6 months [P = 0.172]). Patients with lower albumin level tended to have higher HGDS (at admission P < 0.05, at nadir P < 0.001, and at discharge P < 0.001) and higher properties of the need of mechanical ventilation (P < 0.05) and ICU stay (P < 0.05) than those with normal albumin levels. Those with low albumin levels were also unable to walk independently at 6 months (P < 0.01).

CONCLUSIONS

mEGOS scores predicted the outcomes of GBS patients in China, and EGRIS score predicted the need for mechanical ventilation in these patients. Albumin level at admission correlated well with disease severity and outcomes.

CYBA allelic variants are associated with severity and recovery in Guillain-Barré syndrome

BACKGROUND AND AIMS

Guillain-Barré syndrome (GBS) is a rare, acute neuropathy characterized by ascending muscle weakness. Age, axonal GBS variants, and antecedent Campylobacter jejuni infection are associated with severe GBS, but the detailed mechanisms of nerve damage are only partly explored. Pro-inflammatory myeloid cells express NADPH oxidases (NOX) that generate tissue-toxic reactive oxygen species (ROS) that are implicated in neurodegenerative diseases. This study analyzed the impact of variants of the gene encoding the functional NOX subunit CYBA (p22phox ) on acute severity, axonal damage, and recovery in adult GBS patients.

METHODS

Extracted DNA from 121 patients was genotyped for allelic variation at rs1049254 and rs4673 within CYBA using real-time quantitative polymerase chain reaction. Serum neurofilament light chain was quantified by single molecule array. Patients were followed for severity and motor function recovery for up to 13 years.

RESULTS

CYBA genotypes linked to reduced formation of ROS, i.e. rs1049254/G and rs4673/A, were significantly associated with unassisted ventilation, shorter time to normalization of serum neurofilament light chain and shorter time to regained motor function. Residual disability at follow-up was confined to patients carrying CYBA alleles associated with high formation of ROS.

INTERPRETATION

These findings implicate NOX-derived ROS in GBS pathophysiology and CYBA alleles as biomarkers of severity.

Emerging biomarkers to predict clinical outcomes in Guillain-Barré syndrome

INTRODUCTION

Guillain-Barré syndrome (GBS) is an immune-mediated poly(radiculo)neuropathy with a variable clinical outcome. Identifying patients who are at risk of suffering from long-term disabilities is a great challenge. Biomarkers are useful to confirm diagnosis, monitor disease progression, and predict outcome.

AREAS COVERED

The authors provide an overview of the diagnostic and prognostic biomarkers for GBS, which are useful for establishing early treatment strategies and follow-up care plans.

EXPERT OPINION

Detecting patients at risk of developing a severe outcome may improve management of disease progression and limit potential complications. Several clinical factors are associated with poor prognosis: higher age, presence of diarrhea within 4 weeks of symptom onset, rapid and severe weakness progression, dysautonomia, decreased vital capacity and facial, bulbar, and neck weakness. Biological, neurophysiological and imaging measures of unfavorable outcome include multiple anti-ganglioside antibodies elevation, increased serum and CSF neurofilaments light (NfL) and heavy chain, decreased NfL CSF/serum ratio, hypoalbuminemia, nerve conduction study with early signs of demyelination or axonal loss and enlargement of nerve cross-sectional area on ultrasound. Depicting prognostic biomarkers aims at predicting short-term mortality and need for cardio-pulmonary support, long-term patient functional outcome, guiding treatment decisions and monitoring therapeutic responses in future clinical trials.

Clinical Evaluation of Cerebrospinal Fluid p217tau and Neurofilament Light Chain Levels in Patients with Alzheimer's Disease or Other Neurological Diseases

BACKGROUND

The cerebrospinal fluid (CSF) levels of tau phosphorylated at threonine 217 (p217tau) or 181 (p181tau), and neurofilament light chain (NfL) are definite biomarkers of tauopathy and neurodegeneration in Alzheimer's disease (AD).

OBJECTIVE

To validate their utility in excluding other neurological diseases and age-related changes in clinical settings.

METHODS

We developed monoclonal antibodies against p217tau and NfL, established novel ELISAs, and analyzed 170 CSF samples from patients with AD or other neurological diseases.

RESULTS

In AD, p217tau is a more specific and abundant CSF component than p181tau. However, CSF NfL levels increase age-dependently and to a greater extent in central and peripheral nervous diseases than in AD.

CONCLUSIONS

CSF p217tau correlates better with AD neurodegeneration than other tau-related biomarkers and the major phosphorylated tau species. The clinical usage of NfL as a neurodegeneration biomarker in AD requires exclusion of various central and peripheral neurological diseases.

Systemic inflammatory markers in patients with polyneuropathies

Introduction

In patients with peripheral neuropathies (PNP), neuropathic pain is present in 50% of the cases, independent of the etiology. The pathophysiology of pain is poorly understood, and inflammatory processes have been found to be involved in neuro-degeneration, -regeneration and pain. While previous studies have found a local upregulation of inflammatory mediators in patients with PNP, there is a high variability described in the cytokines present systemically in sera and cerebrospinal fluid (CSF). We hypothesized that the development of PNP and neuropathic pain is associated with enhanced systemic inflammation.

Methods

To test our hypothesis, we performed a comprehensive analysis of the protein, lipid and gene expression of different pro- and anti-inflammatory markers in blood and CSF from patients with PNP and controls.

Results

While we found differences between PNP and controls in specific cytokines or lipids, such as CCL2 or oleoylcarnitine, PNP patients and controls did not present major differences in systemic inflammatory markers in general. IL-10 and CCL2 levels were related to measures of axonal damage and neuropathic pain. Lastly, we describe a strong interaction between inflammation and neurodegeneration at the nerve roots in a specific subgroup of PNP patients with blood-CSF barrier dysfunction.

Conclusion

In patients with PNP systemic inflammatory, markers in blood or CSF do not differ from controls in general, but specific cytokines or lipids do. Our findings further highlight the importance of CSF analysis in patients with peripheral neuropathies.

Neurofilament light chain and total tau in the differential diagnosis and prognostic evaluation of acute and chronic inflammatory polyneuropathies

Background and Purpose

To investigate the diagnostic and prognostic value of axonal injury biomarkers in patients with inflammatory polyneuropathies.

Methods

Neurofilament light chain (NfL) and total tau (T‐tau) were measured in the cerebrospinal fluid (CSF) and plasma in 41 patients with Guillain–Barré syndrome (GBS), 32 patients with chronic inflammatory demyelinating polyneuropathy (CIDP), 10 with paraproteinemia‐related demyelinating polyneuropathy (PDN), and 8 with multifocal motor neuropathy (MMN), in comparison with 39 disease‐free controls and 59 other controls. Outcome was measured with the GBS‐disability score (GBS‐ds) or Inflammatory Neuropathy Cause and Treatment (INCAT) disability score.

Results

Neurofilament light chain levels in CSF and plasma were higher in GBS, CIDP, and PDN vs. disease‐free controls. Patients with MMN had higher NfL levels in plasma vs. disease‐free controls, but lower levels in CSF and plasma vs. patients with amyotrophic lateral sclerosis (ALS).

T‐tau levels in plasma were higher in GBS, CIDP, PDN, and MMN vs. all control groups.

Neurofilament light chain levels in CSF and plasma in patients with GBS correlated with GBS‐ds, as higher levels were associated with inability to run after 6 and 12 months. NfL levels in CSF and plasma in CIDP did not correlate significantly with outcome.

Conclusions

Acute and chronic inflammatory neuropathies are associated with an increase in levels of NfL in CSF and plasma, but NfL is validated as a prognostic biomarker only in GBS. NfL could be used in differentiating patients with MMN from ALS. T‐tau in plasma is a novel biomarker that could be used in a diagnostic assessment of patients with acute and chronic inflammatory polyneuropathies.

Fluid Biomarkers for Monitoring Structural Changes in Polyneuropathies: Their Use in Clinical Practice and Trials

Reliable and responsive tools for monitoring disease activity and treatment outcomes in patients with neuropathies are lacking. With the emergence of ultrasensitive blood bioassays, proteins released with nerve damage are potentially useful response biomarkers for many neurological disorders, including polyneuropathies. In this review, we provide an overview of the existing literature focusing on potential applications in polyneuropathy clinical care and trials. Whilst several promising candidates have been identified, no studies have investigated if any of these proteins can serve as response biomarkers of longitudinal disease activity, except for neurofilament light (NfL). For NfL, limited evidence exists supporting a role as a response biomarker in Guillain-Barré syndrome, vasculitic neuropathy, and chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). Most evidence exists for NfL as a response biomarker in hereditary transthyretin-related amyloidosis (hATTR). At the present time, the role of NfL is therefore limited to a supporting clinical tool or exploratory endpoint in trials. Future developments will need to focus on the discovery of additional biomarkers for anatomically specific and other forms of nerve damage using high-throughput technologies and highly sensitive analytical platforms in adequality powered studies of appropriate design. For NfL, a better understanding of cut-off values, the relation to clinical symptoms and long-term disability as well as dynamics in serum on and off treatment is needed to further expand and proceed towards implementation.

CSF Diagnostics: A Potentially Valuable Tool in Neurodegenerative and Inflammatory Disorders Involving Motor Neurons: A Review

Cerebrospinal fluid (CSF) diagnostics has emerged as a valid tool for a variety of neurological diseases. However, CSF diagnostics has been playing a subordinate role in the diagnosis of many neurological conditions. Thus, in the multitude of neuromuscular diseases in which motor neurons are affected, a CSF sample is rarely taken routinely. However, CSF diagnostics has the potential to specify the diagnosis and monitor the treatment of neuromuscular disorders. In this review, we therefore focused on a variety of neuromuscular diseases, among them amyotrophic lateral sclerosis (ALS), peripheral neuropathies, and spinal muscular atrophy (SMA), for which CSF diagnostics has emerged as a promising option for determining the disease itself and its progression. We focus on potentially valuable biomarkers among different disorders, such as neurofilaments, cytokines, other proteins, and lipids to determine their suitability, differentiating between different neurological disorders and their potential to determine early disease onset, disease progression, and treatment outcome. We further recommend novel approaches, e.g., the use of mass spectrometry as a promising alternative techniques to standard ELISA assays, potentially enhancing biomarker significance in clinical applications.

Neurochemical biomarkers to study CNS effects of COVID-19: a narrative review and synthesis

Neurological symptoms are frequently reported in patients suffering from COVID‐19. Common CNS‐related symptoms include anosmia, caused by viral interaction with either neurons or supporting cells in nasal olfactory tissues. Diffuse encephalopathy is the most common sign of CNS dysfunction, which likely results from the CNS consequences of the systemic inflammatory syndrome associated with severe COVID‐19. Additionally, microvascular injuries and thromboembolic events likely contribute to the neurologic impact of acute COVID‐19. These observations are supported by evidence of CNS immune activation in cerebrospinal fluid (CSF) and in autopsy tissue, along with the detection of microvascular injuries in both pathological and neuroimaging studies. The frequent occurrence of thromboembolic events in patients with COVID‐19 has generated different hypotheses, among which viral interaction with perivascular cells is particularly attractive, yet unproven. A distinguishing feature of CSF findings in SARS‐CoV‐2 infection is that clinical signs characteristic of neurotropic viral infections (CSF pleocytosis and blood–brain barrier injury) are mild or absent. Moreover, virus detection in CSF is rare and often of uncertain significance. In this review, we provide an overview of the neurological impact that occurs in the acute phase of COVID‐19, and the role of CSF biomarkers in the clinical management and research to better treat and understand the disease. In addition to aiding as diagnostic and prognostic tools during acute infection, the use of comprehensive and well‐characterized CSF and blood biomarkers will be vital in understanding the potential impact on the CNS in the rapidly increasing number of individuals recovering from COVID‐19.

[Correlation of cerebrospinal fluid amyloid β-protein 42 and neurofilament light protein levels with postoperative neurocognitive dysfunction in elderly patients]

OBJECTIVE

To detect cerebrospinal fluid levels of amyloid beta- protein 42 (Aβ42) and neurofilament light protein (NFL) and explore their correlation with postoperative neurocognitive dysfunction (PNCD) in elderly patients.

OBJECTIVE

A total of 90 elderly patients undergoing hip or knee replacement with joint epidural anesthesia in our Hospital between January, 2017 and December, 2018 were recruited in this study. The levels of Aβ42 and NFL in the cerebrospinal fluid were detected using ELISA. Simple cognitive status assessment scale (MMSE) was used to evaluate the cognitive status of the patients 1 day before and 7 days after the surgery. All the patients underwent neurocognitive function tests, and the z-score method was used to determine the occurrence of PNCD. Spearman rank correlation analysis was used to analyze the correlation of Aβ42 and NFL levels in the cerebrospinal fluid with MMSE scores. Receiver operating characteristic curve (ROC) was used to analyze the predictive value of cerebrospinal fluid Aβ42 and NFL levels for PNCD.

OBJECTIVE

PNCD occurred in 38 of the 90 elderly patients, with an incidence of 42.2%. The level of Aβ42 in the cerebrospinal fluid was significantly lower in PNCD group than in the nonPNCD group (1.96 vs 2.54 ng/mL; t=3.29, P < 0.05); the concentration of NFL in the cerebrospinal fluid was significantly higher in PNCD group than in non- PNCD group (4.59 vs 3.16 ng/mL; t=3.72, P < 0.05). Aβ42 level in the cerebrospinal fluid was positively correlated while NFL was negatively correlated with the MMSE score of the patients (r=-0.659, P < 0.05; r=-0.626, P < 0.05). ROC curve analysis showed that the area under the curve (AUC) of cerebrospinal fluid Aβ42 and NFL levels were 0.744 and 0.768, respectively; the AUC of their combination was 0.847 for prediction of PNCD.

OBJECTIVE

Elderly patients with PNCD have significantly higher levels of Aβ42 and NFL in the cerebrospinal fluid than those without PNCD. Both Aβ42 and NFL levels in the cerebrospinal fluid can help to predict the occurrence of POCD in elderly patients, and their combination has a higher diagnostic value.

Prognostic value of neurofilament light chain in chronic inflammatory demyelinating polyneuropathy

Chronic inflammatory demyelinating polyneuropathy is a neuroinflammatory disorder with considerable variation in clinical phenotype, disease progression and therapy response among patients. Recently, paranodal antibodies associated with poor response to intravenous immunoglobulin therapy and more aggressive disease course have been described in small subsets of patients, but reliable serum-based prognostic biomarkers are not yet available for the general population. In current retrospective longitudinal study, we utilized logistic regression models to investigate the associations of serum neurofilament light chain levels with 1-year disease progression and therapy response during follow-up in chronic inflammatory demyelinating polyneuropathy. One-year disease progression was defined as a decrease of four or more points (the minimal clinically important difference) on an 80-point Medical Research Council sum-score scale 1 year after sampling. Patients who, compared to treatment received at time of sampling, required therapy switch during follow-up due to insufficient effect were classified as non-responders. Serum neurofilament light chain was measured by electrochemiluminescence assay in clinical residual serum samples of 76 patients diagnosed with probable (13 patients) or definite (63 patients) chronic inflammatory demyelinating polyneuropathy according to European Federation of Neurological Societies/Peripheral Nerve Society diagnostic criteria. Eleven (15%) patients were female, and the mean (standard deviation) cohort age was 61.5 (11.7) years. In both univariate and multivariable (including demographics) models, elevated serum neurofilament light chain harboured increased odds for 1-year disease progression (respectively odds ratio, 1.049; 95% confidence interval, 1.022-1.084 and odds ratio, 1.097; 95% confidence interval, 1.045-1.169; both P = 0.001). Patients with levels above the median cohort neurofilament light chain level (28.3 pg/ml) had largely increased odds of 1-year disease progression (univariate: odds ratio, 5.597; 95% confidence interval, 1.590-26.457; P = 0.01; multivariable: odds ratio, 6.572; 95% confidence interval, 1.495-39.702; P = 0.02) and of insufficient treatment response (univariate: odds ratio, 4.800; 95% confidence interval, 1.622-16.442; P = 0.007; multivariable: odds ratio, 6.441; 95% confidence interval, 1.749-29.357; P = 0.009). In a combined approach analysis, patients with levels above median cohort serum neurofilament light chain level reported strongly increased odds of demonstrating 1-year disease progression and/or therapy non-response during follow-up (univariate: odds ratio, 6.337; 95% confidence interval, 2.276-19.469; P < 0.001; multivariable: odds ratio, 10.138; 95% confidence interval, 2.801-46.404; P = 0.001). These results show that in various logistic regression models, serum neurofilament light chain was associated with both 1-year disease progression and therapy response during follow-up in chronic inflammatory demyelinating polyneuropathy. Hence, our findings warrant further prospective research regarding the value of neurofilament light chain as potential prognostic biomarker in chronic inflammatory demyelinating polyneuropathy.

Serum neurofilament light chain predicts long-term prognosis in Guillain-Barré syndrome patients

OBJECTIVE

To study baseline serum neurofilament light chain (sNfL) levels as a prognostic biomarker in Guillain-Barré syndrome (GBS).

METHODS

We measured NfL in serum (98 samples) and cerebrospinal fluid (CSF) (24 samples) of patients with GBS prospectively included in the International GBS Outcome Study (IGOS) in Spain using single-molecule array (SiMoA) and compared them with 53 healthy controls (HCs). We performed multivariable regression to analyse the association between sNfL levels and functional outcome at 1 year.

RESULTS

Patients with GBS had higher NfL levels than HC in serum (55.49 pg/mL vs 9.83 pg/mL, p<0.0001) and CSF (1308.5 pg/mL vs 440.24 pg/mL, p=0.034). Patients with preceding diarrhoea had higher sNfL than patients with respiratory symptoms or no preceding infection (134.90 pg/mL vs 47.86 pg/mL vs 38.02 pg/mL, p=0.016). sNfL levels correlated with Guillain-Barré Syndrome Disability Score and Inflammatory Rasch-built Overall Disability Scale (I-RODS) at every timepoint. Patients with pure motor variant and Miller Fisher syndrome showed higher sNfL levels than patients with sensorimotor GBS (162.18 pg/mL vs 95.50 pg/mL vs 38.02 pg/mL, p=0.025). Patients with acute motor axonal neuropathy cute motor axonal neuropathy had higher sNfL levels than other variants (190.55 pg/mL vs 46.79 pg/mL, p=0.013). sNfL returned to normal levels at 1 year. High baseline sNfL levels were associated with inability to run (OR=1.65, 95% CI 1.14 to 2.40, p=0.009) and lower I-RODS (β -2.60, 95% CI -4.66 to -0.54, p=0.014) at 1 year. Cut-off points predicting clinically relevant outcomes at 1 year with high specificity were calculated: inability to walk independently (>319 pg/mL), inability to run (>248 pg/mL) and ability to run (<34 pg/mL).

CONCLUSION

Baseline sNfL levels are increased in patients with GBS, are associated with disease severity and axonal variants and have an independent prognostic value in patients with GBS.

Increased serum neurofilament light chain concentration indicates poor outcome in Guillain-Barré syndrome

Background

Guillain-Barré syndrome (GBS) is an autoimmune disease that results in demyelination and axonal damage. Five percent of patients die and 20% remain significantly disabled on recovery. Recovery is slow in most cases and eventual disability is difficult to predict, especially early in the disease. Blood or cerebrospinal fluid (CSF) biomarkers that could help identify patients at risk of poor outcome are required. We measured serum neurofilament light chain (sNfL) concentrations from blood taken upon admission and investigated a correlation between sNfL and clinical outcome.

Methods

Baseline sNfL levels in 27 GBS patients were compared with a control group of 22 patients with diagnoses not suggestive of any axonal damage. Clinical outcome parameters for GBS patients included (i) the Hughes Functional Score (HFS) at admission, nadir, and discharge; (ii) the number of days hospitalised; and (iii) whether intensive care was necessary.

Results

The median sNfL concentration in our GBS sample on admission was 85.5 pg/ml versus 9.1 pg/ml in controls. A twofold increase in sNfL concentration at baseline was associated with an HFS increase of 0.6 at nadir and reduced the likelihood of discharge with favourable outcome by a factor of almost three. Higher sNfL levels upon admission correlated well with hospitalisation time (r_s = 0.69, p < 0.0001), during which transfer to intensive care occurred more frequently at an odds ratio of 2.4. Patients with baseline sNfL levels below 85.5 pg/ml had a 93% chance of being discharged with an unimpaired walking ability.

Conclusions

sNfL levels measured at hospital admission correlated with clinical outcome in GBS patients. These results represent amounts of acute axonal damage and reflect mechanisms resulting in disability in GBS. Thus, sNfL may serve as a convenient blood-borne biomarker to personalise patient care by identifying those at higher risk of poor outcome.

Neurofilaments: The C-Reactive Protein of Neurology

Neurofilaments (NFs) are quickly becoming the biomarkers of choice in the field of neurology, suggesting their use as an unspecific screening marker, much like the use of elevated plasma C-reactive protein (CRP) in other fields. With sensitive techniques being readily available, evidence is growing regarding the diagnostic and prognostic value of NFs in many neurological disorders. Here, we review the latest literature on the structure and function of NFs and report the strengths and pitfalls of NFs as markers of neurodegeneration in the context of neurological diseases of the central and peripheral nervous systems.

Successful combined treatment with thymectomy, rituximab and tocilizumab for severe thymoma-associated multi autoimmune syndrome

We present a 53-year-old woman who presented simultaneously with acute inflammatory demyelinating polyneuropathy, Graves' disease, leukocytoclastic vasculitis, elevated acetylcholine antibody receptor antibodies and a mediastinal mass. Thymectomy was performed and revealed a type A thymoma and the clinical picture and paraclinical findings were consistent with a thymoma-associated multi-autoimmune syndrome (TAMA). Beside prednisolone and plasmapheresis, the patient was treated with tocilizumab and rituximab. After surgical and immunomodulatory treatment with tocilizumab and rituximab the patient's condition slowly started to improve. TAMA is associated with a spectrum of autoantibodies and immune-mediated damage to multiple organs. Even if thymectomy is crucial for long term prognosis, aggressive immunomodulation should be considered early in the disease course, especially in cases showing involvement of the peripheral and/or central nervous system.

Cerebrospinal fluid biomarkers in patients with neurological symptoms but without neurological diseases

BACKGROUND

Elevated levels of the cerebrospinal fluid (CSF) neuronal injury markers (neurofilament light chain [NF-L] and total tau protein [t-tau]) and of the astroglial marker glial fibrillary acidic protein (GFAP) are found in etiologically different neurological disorders affecting the peripheral and the central nervous system.

AIMS

To explore the role of CSF biomarkers in the clinical management of patients admitted for alarming neurological symptoms, but in whom neurological disorders could be excluded.

METHODS

Study participants were patients seeking medical attention for neurological symptoms primarily considered to be caused by a neurological diagnosis and investigated according to clinical routine. Demographic, clinical, and CSF data were extracted retrospectively from medical records. Patients with a final neurological diagnosis were excluded.

RESULTS

Out of 990 patients, 900 with a neurological diagnosis were excluded leaving 90 patients without a final neurological diagnosis. Sixty-eight (75.6%) were females. Median (range) age at lumbar puncture was 34.7 (16.9-65.1) years. Age-adjusted CSF-NF-L, CSF-t-tau, and CSF-GFAP concentrations were normal in 89 (98.9%), 86 (95.6%), and 87 (96.7%) patients, respectively.

CONCLUSION

In patients with significant neurological symptoms but in whom a neurological diagnosis could not be made, the CSF markers NF-L, t-tau, and GFAP did not indicate signs of neuronal or astroglial cell damage close to symptom onset. Consequently, increased levels of CSF markers are not expected in this patient group and, if present, should raise suspicion of underlying neurological disorders and motivate further investigations.

Cerebrospinal Fluid (CSF) Analysis and Interpretation in Neurocritical Care for Acute Neurological Conditions

Cerebrospinal fluid (CSF) is a clear fluid circulating in the intracranial and spinal compartments. Under normal conditions, the composition of CSF remains constant. However, in various neurological disease especially in acute conditions, the composition, quantity and its pressure can be altered. By measuring the levels of various CSF components using relevant techniques, diagnosis, severity and prognostication of neurological conditions like infections, subarachnoid hemorrhage, demyelinating conditions, tumor like conditions, etc. can be done. In this review, alterations in CSF components and its relevance to the emergency care physician to help in the management of patients are enumerated.

Serum and cerebrospinal neurofilament light chain levels in patients with acquired peripheral neuropathies

Neurofilament light chain (NFL) levels reflect axonal damage in different inflammatory and neurodegenerative central nervous system conditions, in correlation with disease severity. Our aim was to determine the possible diagnostic and prognostic value of serum and cerebrospinal fluid (CSF) NFL levels in subjects with different forms of acquired peripheral neuropathies (PN). Paired serum and CSF samples of 25 patients with acquired PN were analysed for NFL using an ultrasensitive technique (Quanterix, Simoa, Lexington, MA, USA) and compared with a group of 25 age-matched healthy subjects. Demographic, clinical, CSF and neurophysiological data were reviewed. Cases with Guillain-Barré syndrome (N = 5), multifocal motor neuropathy (N = 3), chronic inflammatory demyelinating polyneuropathy (CIDP) and variants (N = 12), anti-myelin-associated glycoprotein (MAG) neuropathy (N = 3), both CIDP and anti-MAG neuropathy (N = 1), and non-systemic vasculitic neuropathy (N = 1) were studied. NFL levels were significantly (P < 0.001) increased in patients with PN and were higher in the CSF (median: 1407 pg/mL, range: 140.2-12 661) than in serum (median: 31.52 pg/mL, range: 4.33-1178). A statistically significant correlation was observed between serum and CSF levels in cases with blood-nerve-barrier damage (r = 0.71, P < 0.01), and between serum NFL levels and disease activity at sampling (r = 0.52, P < 0.01) and at last follow-up (r = 0.53, P < 0.01) in all subjects. The increase of NFL values in both serum and CSF of patients with acquired PN and the significant correlation between serum NFL levels, disease severity and final outcome support the possible role of NFL as disease activity and prognostic biomarker also in peripheral nervous system disorders.