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Background A growing number of Guillain–Barré syndrome (GBS) and Miller Fisher Syndrome (MFS) cases following severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection are reported. Nevertheless, this association is still debated, and pathophysiology remains unclear. Methods Between April and December 2020, in three hospitals located in Brussels, Belgium, we examined four patients with GBS following SARS-CoV-2 infection. Results Neurological onset occurred 3 weeks after SARS-CoV-2 symptoms in all patients. Three patients presented with acute inflammatory demyelinating polyneuropathy (AIDP) and had negative anti-ganglioside testing: two suffered from a severe SARS-CoV-2 infection and had good clinical outcome after intravenous immunoglobulin (IVIG) treatment; one with mild SARS-CoV-2 infection had spontaneously favorable evolution without treatment. The fourth patient had critical SARS-CoV-2 infection and presented acute motor and sensory axonal neuropathy (AMSAN) with clinical features highly suggestive of brainstem involvement, as well as positive anti-ganglioside antibodies (anti-GD1b IgG) and had partial improvement after IVIG. Conclusions We report four cases of SARS-CoV-2-associated GBS. The interval of 3 weeks between SARS-CoV-2 symptoms and neurological onset, the clinical improvement after IVIG administration, and the presence of positive anti-ganglioside antibodies in one patient further support the hypothesis of an immune-mediated post-infectious process. Systematic extensive antibody testing might help for a better understanding of physiopathology. Supplementary Information The online version contains supplementary material available at 10.1007/s13760-021-01787-y.

Duchenne muscular dystrophy (DMD) is a progressive disease caused by the loss of function of the protein dystrophin. This protein contributes to the stabilisation of striated cells during contraction, as it anchors the cytoskeleton with components of the extracellular matrix through the dystrophin-associated protein complex (DAPC). Moreover, absence of the functional protein affects the expression and function of proteins within the DAPC, leading to molecular events responsible for myofibre damage, muscle weakening, disability and, eventually, premature death. Presently, there is no cure for DMD, but different treatments help manage some of the symptoms. Advances in genetic and exon-skipping therapies are the most promising intervention, the safety and efficiency of which are tested in animal models. In addition to in vivo functional tests, ex vivo molecular evaluation aids assess to what extent the therapy has contributed to the regenerative process. In this regard, the later advances in microscopy and image acquisition systems and the current expansion of antibodies for immunohistological evaluation together with the development of different spectrum fluorescent dyes have made histology a crucial tool. Nevertheless, the complexity of the molecular events that take place in dystrophic muscles, together with the rise of a multitude of markers for each of the phases of the process, makes the histological assessment a challenging task. Therefore, here, we summarise and explain the rationale behind different histological techniques used in the literature to assess degeneration and regeneration in the field of dystrophinopathies, focusing especially on those related to DMD.

Mutations in HNRNPA1 encoding heterogeneous nuclear ribonucleoprotein (hnRNP) A1 are a rare cause of amyotrophic lateral sclerosis (ALS) and multisystem proteinopathy (MSP). hnRNPA1 is part of the group of RNA-binding proteins (RBPs) that assemble with RNA to form RNPs. hnRNPs are concentrated in the nucleus and function in pre-mRNA splicing, mRNA stability, and the regulation of transcription and translation. During stress, hnRNPs, mRNA, and other RBPs condense in the cytoplasm to form stress granules (SGs). SGs are implicated in the pathogenesis of (neuro-)degenerative diseases, including ALS and inclusion body myopathy (IBM). Mutations in RBPs that affect SG biology, including FUS, TDP-43, hnRNPA1, hnRNPA2B1, and TIA1, underlie ALS, IBM, and other neurodegenerative diseases. Here, we characterize 4 potentially novel HNRNPA1 mutations (yielding 3 protein variants: *321Eext*6, *321Qext*6, and G304Nfs*3) and 2 known HNRNPA1 mutations (P288A and D262V), previously connected to ALS and MSP, in a broad spectrum of patients with hereditary motor neuropathy, ALS, and myopathy. We establish that the mutations can have different effects on hnRNPA1 fibrillization, liquid-liquid phase separation, and SG dynamics. P288A accelerated fibrillization and decelerated SG disassembly, whereas *321Eext*6 had no effect on fibrillization but decelerated SG disassembly. By contrast, G304Nfs*3 decelerated fibrillization and impaired liquid phase separation. Our findings suggest different underlying pathomechanisms for HNRNPA1 mutations with a possible link to clinical phenotypes.

Background Evidence suggests people with non-relapsing deteriorating (“progressive”) multiple sclerosis (pwPMS) may benefit from disease-modifying immune therapy (DMT). However, only one such treatment (ocrelizumab) has been licensed and is highly restricted to pwPMS suffering from the primary progressive phenotype. The difficulties assessing treatment outcome in pwPMS is one important reason for the lack of respective DMT. The concentration of neurofilaments in the cerebrospinal fluid (CSF) provides a biomarker of neuro-axonal damage, and both neurofilament light (NfL) and heavy chain (NfH) levels have been used as outcome indices and to guide treatment choices. Methods We report on two pwPMS, who were treated with subcutaneous cladribine undergoing CSF NfL testing, alongside MRI and clinical follow-up, before and after treatment. Results Cladribine treatment was well tolerated without any side effects. CSF NfL after treatment revealed significant reduction (by 73% and 80%, respectively) corroborating the MRI detectable drop in disease activity. Disability mildly progressed in one, and remained stable in the other pwPMS. Conclusions pwPMS with detectable disease activity (MRI, elevated NfL) should be considered for DMT. NfL appears to be a sensitive index of treatment effect in pwPMS, and may be a useful outcome in clinical trials targeting this patient group. Over and above its licensed indication (relapsing MS), cladribine may be an effective treatment option for pwPMS.

Background The mechanism of action of oral cladribine, recently licensed for relapsing multiple sclerosis, is unknown. Objective To determine whether cladribine depletes memory B cells consistent with our recent hypothesis that effective, disease-modifying treatments act by physical/functional depletion of memory B cells. Methods A cross-sectional study examined 40 people with multiple sclerosis at the end of the first cycle of alemtuzumab or injectable cladribine. The relative proportions and absolute numbers of peripheral blood B lymphocyte subsets were measured using flow cytometry. Cell-subtype expression of genes involved in cladribine metabolism was examined from data in public repositories. Results Cladribine markedly depleted class-switched and unswitched memory B cells to levels comparable with alemtuzumab, but without the associated initial lymphopenia. CD3+ T cell depletion was modest. The mRNA expression of metabolism genes varied between lymphocyte subsets. A high ratio of deoxycytidine kinase to group I cytosolic 5′ nucleotidase expression was present in B cells and was particularly high in mature, memory and notably germinal centre B cells, but not plasma cells. Conclusions Selective B cell cytotoxicity coupled with slow repopulation kinetics results in long-term, memory B cell depletion by cladribine. These may offer a new target, possibly with potential biomarker activity, for future drug development. Electronic supplementary material The online version of this article (10.1007/s00415-018-8830-y) contains supplementary material, which is available to authorized users.

Alemtuzumab is a lymphocyte-depleting antibody and one of the most effective treatments for relapsing multiple sclerosis. However, it also causes loss of immune-tolerance leading to secondary autoimmunity and marked anti-drug antibody responses. Although these anti-drug responses have been reported to be of no significance, we hypothesized that they will affect the depleting capacity and treatment response in some individuals. This was found following analysis of the regulatory submission of the pivotal phase III trials, which was obtained from the European Medicines Agency. At the population level there was lack of influence of 'ever-positive' alemtuzumab-specific antibody responses on lymphocyte depletion, clinical efficacy and adverse effects during the 2-year trial. This was not surprising as no one before the first infusion, and only 0·6% of people before the second-infusion, had pre-infusion, neutralizing antibodies (NAbs). However, at the individual level, NAbs led to poor lymphocyte depletion. Importantly, it was evident that 31% of people had NAbs and 75% had binding antibodies at the end of treatment-cycle 2, which suggests that problems may occur in people requiring additional alemtuzumab cycles. In addition, we also identified individuals, following 'post-marketing' alemtuzumab use, whose lymphocyte level was never effectively depleted after the first infusion cycle. Hence, although alemtuzumab depletes lymphocytes in most individuals, some people fail to deplete/deplete poorly, probably due to biological-response variation and NAbs, and this may lead to treatment failure. Monitoring depletion following infusion and assessment of the neutralizing response before re-infusion may help inform the decision to retreat or switch therapy to limit treatment failure.

Over the last decade, innate immune system receptors and sensors called inflammasomes have been identified to play key pathological roles in the development and progression of numerous diseases. Among them, the nucleotide-binding oligomerization domain (NOD-), leucine-rich repeat (LRR-) and pyrin domain-containing protein 3 (NLRP3) inflammasome is probably the best characterized. To date, NLRP3 has been extensively studied in the heart, where its effects and actions have been broadly documented in numerous cardiovascular diseases. However, little is still known about NLRP3 implications in muscle disorders affecting non-cardiac muscles. In this review, we summarize and present the current knowledge regarding the function of NLRP3 in diseased skeletal muscle, and discuss the potential therapeutic options targeting the NLRP3 inflammasome in muscle disorders. French Association against Myopathies H121203009 Fund for Scientific Research-FNRS PDR/T.0026.21

Introduction Cramp-fasciculation syndrome is a peripheral nerve hyperexcitability disorder, which could be caused by inflammatory neuropathy. Case report We describe a 51-year-old woman who presented with a 4- to 5-year history of fasciculations and painful cramping of the right thenar eminence. Results Electrophysiological studies showed motor conduction block in the right median nerve between the axilla and the elbow with fasciculation potentials and cramp discharges on electromyography in the right abductor pollicis brevis muscle. High titers of serum anti-GM1 immunoglobulin M antibodies were detected. Conclusions Monofocal motor neuropathy of the right median nerve was diagnosed. Intravenous immunoglobulin treatment led to significant improvement of symptoms and signs. Although fasciculations and cramps have been reported in multifocal motor neuropathy and are considered supporting criteria for the diagnosis, the occurrence of cramp-fasciculation syndrome as the presenting feature and predominant manifestation in monofocal motor neuropathy, a variant of multifocal motor neuropathy, is unique. Muscle Nerve 56: 828-832, 2017.

Background Little is known about what leads to recovery between relapses in multiple sclerosis (MS), particularly following treatment. In the past, it has been demonstrated that soluble neural cell adhesion molecule (sNCAM), a putative biomarker of neuroplasticity, increased following steroid treatment in the Cerebrospinal fluid (CSF) of MS subjects undergoing acute relapses. Taking this a step further, we have evaluated the effect of disease-modifying treatment (DMTs) on CSF sNCAM levels in various subtypes of MS. Methods We measured CSF sNCAM levels at baseline and after 12-24 months of DMT in 69 patients, 49 relapsing-remitting MS (RRMS), 20 progressive MS(PMS), and 24 healthy controls (HC) using an in-house ELISA. Of this, 31 patients had received natalizumab, 17 mitoxantrone, and 21 fingolimod. Changes in disability were measured using EDSS and disease severity by MSSS. In conjunction, CSF NfL levels were also measured. Results At baseline, the mean sNCAM level was 268.7 ng/mL (SD: 109 ng/mL) in MS patients compared with 340.6 ng/ml (SD: 139 ng/mL) in HC, and PMS had significantly lower sNCAM (239.2 ng/mL, SD: 123.0, P = 0.019) compared to RRMS (269.4, SD: 127.4, P = 0.043). After natalizumab and mitoxantrone treatments, we observed an increase in mean sNCAM. However, in the fingolimod-treated group, mean sNCAM decreased. There was no correlation found with EDSS or MSSS, or NfL levels as a whole. Conclusions Cerebrospinal fluid sNCAM levels were found to be lower in MS than in HC and the lowest sNCAM levels were found in PMS. Following natalizumab and mitoxantrone treatments, we observed an elevation in sNCAM levels, an effect that was not observed following fingolimod treatment. These changes, however, did not appear to correlate with disability in the short-term or NfL levels.

Adiponectin (ApN) is a hormone abundantly secreted by adipocytes and it is known to be tightly linked to the metabolic syndrome. It promotes insulin-sensitizing, fat-burning, and anti-atherosclerotic actions, thereby effectively counteracting several metabolic disorders, including type 2 diabetes, obesity, and cardiovascular diseases. ApN is also known today to possess powerful anti-inflammatory/oxidative and pro-myogenic effects on skeletal muscles exposed to acute or chronic inflammation and injury, mainly through AdipoR1 (ApN specific muscle receptor) and AMP-activated protein kinase (AMPK) pathway, but also via T-cadherin. In this review, we will report all the beneficial and protective properties that ApN can exert, specifically on the skeletal muscle as a target tissue. We will highlight its effects and mechanisms of action, first in healthy skeletal muscle including exercised muscle, and second in diseased muscle from a variety of pathological conditions. In the end, we will go over some of AdipoRs agonists that can be easily produced and administered, and which can greatly mimic ApN. These interesting and newly identified molecules could pave the way towards future therapeutic approaches to potentially prevent or combat not only skeletal muscle disorders but also a plethora of other diseases with sterile inflammation or metabolic dysfunction.

Neurodegeneration plays a key role in multiple sclerosis (MS) contributing to long-term disability in patients. The prognosis is, however, unpredictable coloured by complex disease mechanisms which can only be clearly appreciated using biomarkers specific to pathobiology of the underlying process. Here, we describe six promising neurodegenerative biomarkers in MS (neurofilament proteins, neurofilament antibodies, tau, N-acetylaspartate, chitinase and chitinase-like proteins and osteopontin), critically evaluating the evidence using a modified Bradford Hill criteria.

Background In multiple sclerosis (MS) upper limb neurological impairments, are an important driver of disability and handicap. The gold standard for assessing upper limb function is the 9-hole peg test (9HPT). One disadvantage of the current plastic version is its price, which prevents its widespread adoption by the MS community. Objective To develop and validate an affordable 9HPT for patients to self-monitor upper limb function. Methods We enrolled 177 volunteers, 68 healthy controls and 109 people with MS (pwMS) at varying stages of their disease. Volunteers performed two trials of the 9HPT with their dominant hand and two with their non-dominant hand using both plastic 9HPT and cardboard 9HPT. The primary comparison parameter was the time needed to perform the task. Results The mean score for the cardboard 9HPT was 24.58 (SEM 1.54 s) seconds compared to 26.03 (SEM 1.44 s) seconds for the plastic 9HPT (p=0.007). However, the two versions of the tests correlated very strongly, r=0.96 (p Conclusion This study demonstrates that the cardboard version is at least equivalent to the plastic version of the test with arguably better design attributes making it the preferred option for self-monitoring.

Background Alemtuzumab is an effective disease modifying treatment (DMT) for people with relapsing multiple sclerosis (pwRMS). Its mechanism of action includes profound lymphocyte depletion. Objective To analyse the pattern of lymphocyte depletion and associated infections after alemtuzumab administration in a cohort of pwRMS treated at our centre. Methods pwRMS treated with alemtuzumab were identified on our clinical record system (Cerner Millennium). Baseline blood results, total lymphocyte counts (TLC) and infections post-treatment were studied. Results 84 pwMS on alemtuzumab were followed up for a mean of 8.7 months. One month after the first treatment cycle, TLC was 13% of baseline (from 2.2 to 0.28 × 109/l). TLC recovered to >0.6 by month 3 and to >1 by month 9, however remained below baseline in all pwRMS. After the 2nd treatment cycle, TLC reconstitution was more rapid, to >1×109/l within six months. 19 (23%) pwRMS had infections within four months of treatment cycles. Infections affected the respiratory tract in 7 (8%) pwRMS, and the urinary tract in 9 (11%). All but one infection occurred with TLC Conclusion Infections are common in pwRMS treated with alemtuzumab. To reduce their incidence prophylactic antibiotics should be considered in pwRMS with TLC of

We report a case of Takotsubo syndrome after epilepsy, and review the literature. We identified 59 cases of Takotsubo syndrome after focal or generalised epilepsy. As in Takotsubo syndrome in general, the patients were mostly female (84%), with a mean age of 63 years, and the evolution was generally favourable. There was one death and one stroke, and 4 cases were of relapsing Takotsubo after a new seizure. Takotsubo syndrome may induce cardiac arrhythmias. A near-SUDEP (sudden unexplained death in epilepsy) was reported in one patient. Animal models of SUDEP have shown similar cardiac lesions to those seen in Takotsubo syndrome, and strengthen the hypothesis of a link between these conditions. Takotsubo syndrome after epilepsy may be relatively common; we suggest measurement of serum troponin levels in high-risk patients and cardiac follow-up. © 2011 British Epilepsy Association. Published by Elsevier Ltd. All rights reserved.