Clinical, Neurophysiological and Histopatological correlations in Pure Neural Leprosy

Although neuropathy remains one of the most problematic issues faced by leprosy patients, the evolving process of its findings continues a challenge particularly in pure neural leprosy (PNL). We evaluated neurological examination, nerve conduction studies and histhopathological data of patients with PNL and ulnar neuropathy. Patients with longer duration of symptoms had reduction in the motor conduction velocities and patients with fibrosis in the biopsy had axonal damage in the nerve conduction studies. This suggests that focal demyelination may be present in leprosy patients at the moment of the diagnosis and be related to the duration of the neuropathy.

Neurological symptoms and axonal damage in COVID-19 survivors: are there sequelae?

The persistence of neurological symptoms after SARS-CoV-2 infection, as well as the presence of late axonal damage, is still unknown. We performed extensive systemic and neurological follow-up evaluations in 107 out of 193 consecutive patients admitted to the COVID-19 medical unit, University Hospital of Verona, Italy between March and June 2020. We analysed serum neurofilament light chain (NfL) levels in all cases including a subgroup (n = 29) of patients with available onset samples. Comparisons between clinical and biomarker data were then performed. Neurological symptoms were still present in a significant number (n = 49) of patients over the follow-up. The most common reported symptoms were hyposmia (n = 11), fatigue (n = 28), myalgia (n = 14), and impaired memory (n = 11) and were more common in cases with severe acute COVID-19. Follow-up serum NfL values (15.2 pg/mL, range 2.4–62.4) were within normal range in all except 5 patients and did not differentiate patients with vs without persistent neurological symptoms. In patients with available onset and follow-up samples, a significant (p < 0.001) decrease of NfL levels was observed and was more evident in patients with a severe acute disease. Despite the common persistence of neurological symptoms, COVID-19 survivors do not show active axonal damage, which seems a peculiar feature of acute SARS-CoV-2 infection.

Decreased Neurofilament L Chain Levels in Cerebrospinal Fluid and Tolerogenic Plasmacytoid Dendritic Cells in Natalizumab-Treated Multiple Sclerosis Patients – Brief Research Report

BackgroundNeurofilament Light (NfL) chain levels in both cerebrospinal fluid (CSF) and serum have been correlated with the reduction of axonal damage in multiple sclerosis (MS) patients treated with Natalizumab (NTZ). However, little is known about the function of plasmacytoid cells in NTZ-treated MS patients.ObjectiveTo evaluate CSF NfL, serum levels of soluble-HLA-G (sHLA-G), and eventual tolerogenic behavior of plasmacytoid dendritic cells (pDCs) in MS patients during NTZ treatment.MethodsCSF NfL and serum sHLA-G levels were measured using an ELISA assay, while pDCs (BDCA-2+) were accessed through flow cytometry analyses.ResultsCSF levels of NfL were significantly reduced during NTZ treatment, while the serum levels of sHLA-G were increased. Moreover, NTZ treatment enhanced tolerogenic (HLA-G+, CD274+, and HLA-DR+) molecules and migratory (CCR7+) functions of pDCs in the peripheral blood.ConclusionThese findings suggest that NTZ stimulates the production of molecules with immunoregulatory function such as HLA-G and CD274 programmed death-ligand 1 (PD-L1) which may contribute to the reduction of axonal damage represented by the decrease of NfL levels in patients with MS.

CSF and Circulating NFL as Biomarkers for the Discrimination of Parkinson Disease From Atypical Parkinsonian Syndromes: Meta-analysis

Purposeof review: To evaluate whether CSF and circulating neurofilament light chain (NFL), a marker of axonal damage, could discriminate Parkinson’s disease (PD) from atypical parkinsonian syndromes (APS).Recent findings:MEDLINE and SCOPUS were systematically searched, and fifteen studies were included (1035 PD patients,930 APS patients). CSF and circulating NFL levels were 1.26 and 1.53 standard deviations higher in APS compared to PD patients respectively [g=1.26 (95% CI 0.99-1.53);12 studies, 880 PD patients, 847 APS patients, g=1.53 (1.15-1.91);4 studies, 307 PD patients, 197 APS patients. Pooled areas under the curve were 0.941 (0.916-0.965) and 0.874 (0.802-0.946) for CSF and circulating NFL, corresponding to average sensitivities of 86% (79-90%) and 91% (86-95%), and specificity of 88% (82-92%) and 76% (62-85%), respectively.Summary:These results strongly support the high diagnostic accuracy of both CSF and circulating NFL in differentiating PD from APS, highlighting their usefulness as promising biomarkers.

Chronic White Matter Inflammation and Serum Neurofilament Levels in Multiple Sclerosis

ObjectiveTo assess whether chronic white matter inflammation in multiple sclerosis (MS) patients - as detected in-vivo by paramagnetic rim MRI lesions (PRL) - is associated with higher serum neurofilament light chain (sNfL) levels, a marker of neuro-axonal damage.MethodsIn 118 MS patients with no gadolinium-enhancing lesions or recent relapses, we analyzed 3D-submillimeter phase MRI and sNfL levels. Histopathological evaluation was performed in 25 MS lesions from 20 additional autopsy MS patients.ResultsIn univariable analyses, participants with ≥2 PRL (“PRL ≥2”, n=43) compared to those with ≤1 PRL (“PRL 0–1,” n=75) had higher age-adjusted sNfL percentiles (median, 91 and 68; p<0.001) and higher MS disease severity scale (MSSS median, 4.3 and 2.4; p=0.003). In multivariable analyses, sNfL percentile levels were higher in PRL ≥2 cases (βadd: 16.3; 95% CI: 4.6–28.0; p<0.01), whereas disease-modifying treatment (DMT), EDSS, and T2 lesion load did not affect sNfL. In a similar model, sNfL percentile levels were highest in cases with ≥4 PRL (n=30; βadd: 30.4; 95% CI, 15.6–45.2; p<0.01). Subsequent multivariable analysis revealed that PRL ≥2 cases had also higher MSSS (βadd: 1.1; 95% CI, 0.3–1.9; p<0.01), whereas MSSS was not affected by DMT or T2 lesion load. On histopathology, both chronic active and smoldering lesions exhibited more severe acute axonal damage at the lesion edge than in the lesion center (edge vs center: p=0.004 and p=0.0002, respectively).InterpretationChronic white matter inflammation was associated with increased levels of sNfL and disease severity in non-acute MS patients, suggesting that PRL contribute to clinically relevant, inflammation-driven neurodegeneration.

Kynurenines and Neurofilament Light Chain in Multiple Sclerosis

Multiple sclerosis is an autoimmune, demyelinating, and neurodegenerative disease of the central nervous system. In recent years, it has been proven that the kynurenine system plays a significant role in the development of several nervous system disorders, including multiple sclerosis. Kynurenine pathway metabolites have both neurotoxic and neuroprotective effects. Moreover, the enzymes of the kynurenine pathway play an important role in immunomodulation processes, among others, as well as interacting with neuronal energy balance and various redox reactions. Dysregulation of many of the enzymatic steps in kynurenine pathway and upregulated levels of these metabolites locally in the central nervous system, contribute to the progression of multiple sclerosis pathology. This process can initiate a pathogenic cascade, including microglia activation, glutamate excitotoxicity, chronic oxidative stress or accumulated mitochondrial damage in the axons, that finally disrupt the homeostasis of neurons, leads to destabilization of neuronal cell cytoskeleton, contributes to neuro-axonal damage and neurodegeneration. Neurofilaments are good biomarkers of the neuro-axonal damage and their level reliably indicates the severity of multiple sclerosis and the treatment response. There is increasing evidence that connections exist between the molecules generated in the kynurenine metabolic pathway and the change in neurofilament concentrations. Thus the alterations in the kynurenine pathway may be an important biomarker of the course of multiple sclerosis. In our present review, we report the possible relationship and connection between neurofilaments and the kynurenine system in multiple sclerosis based on the available evidences.

A neurologist’s perspective on serum neurofilament light in the memory clinic: a prospective implementation study

Background Neurofilament light in serum (sNfL) is a biomarker for axonal damage with elevated levels in many neurological disorders, including neurodegenerative dementias. Since within-group variation of sNfL is large and concentrations increase with aging, sNfL’s clinical use in memory clinic practice remains to be established. The objective of the current study was to evaluate the clinical use of serum neurofilament light (sNfL), a cross-disease biomarker for axonal damage, in a tertiary memory clinic cohort. Methods Six neurologists completed questionnaires regarding the usefulness of sNfL (n = 5–42 questionnaires/neurologist). Patients that visited the Alzheimer Center Amsterdam for the first time between May and October 2019 (n = 109) were prospectively included in this single-center implementation study. SNfL levels were analyzed on Simoa and reported together with normal values in relation to age, as part of routine diagnostic work-up and in addition to cerebrospinal fluid (CSF) biomarker analysis. Results SNfL was perceived as useful in 53% (n = 58) of the cases. SNfL was more often perceived as useful in patients < 62 years (29/48, 60%, p = 0.05) and males (41/65, 63%, p < 0.01). Availability of CSF biomarker results at time of result discussion had no influence. We observed non-significant trends for increased perceived usefulness of sNfL for patients with the diagnosis subjective cognitive decline (64%), psychiatric disorder (71%), or uncertain diagnosis (67%). SNfL was mostly helpful to neurologists in confirming or excluding neurodegeneration. Whether sNfL was regarded as useful strongly depended on which neurologist filled out the questionnaire (ranging from 0 to 73% of useful cases/neurologist). Discussion Regardless of the availability of CSF biomarker results, sNfL was perceived as a useful tool in more than half of the evaluated cases in a tertiary memory clinic practice. Based on our results, we recommend the analysis of the biomarker sNfL to confirm or exclude neurodegeneration in patients below 62 years old and in males.

Numerical Investigation of Axonal Damage for Regular and Irregular Axonal Distributions

Recently, various researches have revealed the importance of the investigations performed for evaluating mechanical properties and damages of the brain tissues while dealing with the production of surgical ligaments and helmets. Therefore, it is vital to study the structure of the brain both experimentally and numerically. By experimental tests, despite being costly, it is almost impossible to establish stress distribution in micro scale, which causes injury. Micromechanical predictions are effective ways to assess brain behavior. They can be applied to compensate for some experimental test limitations. In this work, a numerical study of the axonal injury in different heterogeneous porcine brain parts with different axon distributions under quasi-static loading is provided. In order to produce a heterogeneous structure, axons are distributed in regular, semi-regular, and irregular patterns inside the representative volume element. To accurately examine the brain tissue time-dependent behavior, a visco-hyperelastic constitutive model is developed. Also, axonal damage is studied under different conditions by applying different levels of load and rate. Because of geometrical complexities, a self-consistent method was applied to study the damage in higher volume fractions of the axon. The results reveal that the regions of the brain enjoying a regular axon distribution would have higher strength. In addition, among the two influential load and loading rate parameters, the brain tissue in all regions shows more sensitivity toward the applying load.