Immune triggers preceding neuralgic amyotrophy.

BACKGROUND AND PURPOSE: Infections and vaccinations have been identified as potential immunological triggers of neuralgic amyotrophy (NA), but the exact type and frequency of the preceding agents is unknown. METHODS: This was a multicentre, prospective, observational, matched case-control study. NA was diagnosed by neuromuscular experts according to validated clinical criteria and electrodiagnostic studies. Clinical data and biological samples of NA patients were collected within 90 days from disease onset between June 2018 and December 2023. All NA patients were asked about prior infection and vaccination in the month before disease onset. Serological tests for hepatitis E virus, human immunodeficiency virus, severe acute respiratory syndrome coronavirus 2, Epstein-Barr virus, cytomegalovirus, parvovirus B19, varicella-zoster virus, Borrelia burgdorferi, Mycoplasma pneumoniae and Bartonella henselae were performed in a central laboratory. Each case was matched with a healthy control for age, sex, place of residence and time of blood collection. RESULTS: Fifty-seven patients and corresponding controls were included. The mean age was 45 years for both groups. NA onset was preceded by a symptomatic infectious trigger confirmed by microbiological tests in 15/57 (26.3%) patients. Coronavirus disease 2019 vaccination was considered a potential trigger in 7/57 (12.3%) subjects. An acute viral infection was associated with a bilateral involvement of the brachial plexus (p = 0.003, Cramèr's V = 0.43). CONCLUSIONS: Confirmed immune triggers (infection or vaccination) preceded disease onset in 22/57 (38.6%) NA cases. We suggest to test NA patients in the acute phase for intracellular antigens, especially in the case of concomitant bilateral involvement and hepatitis.

Characteristics and outcome of chronic inflammatory demyelinating polyradiculoneuropathy patients according to their diagnostic certainty based on the 2021 EAN/PNS criteria.

INTRODUCTION: To describe the clinical characteristics and long term outcome of CIDP patients according to 2021 EAN/PNS diagnostic certainty categories. METHODS: We reviewed clinical data, response to treatment, cerebrospinal fluid examination, and nerve conduction studies parameters of 39 adult "CIDP" and 24 "possible CIDP" patients. Data were collected at diagnosis and after one (T1), two (T2), three (T3) and five years (T5). RESULTS: At diagnosis, "possible CIDP" patients' phenotypes were more atypical (especially focal/multifocal, p < .01) and "CIDP" patients had a higher NIS and INCAT scores (p = .08 and 0.08). Compared to baseline: median NIS score decreased in "CIDP" and was stable in "possible CIDP" patients at T1 (p < .05), T2 (p < .05) and T3 (p < .01); median MRC score slightly increased in "CIDP" and was stable in "possible CIDP" patients at T2 (p < .05); and INCAT disability scale slightly decreased in "CIDP" and was stable in "possible CIDP" patients at T3 (p < .05). The proportion of moderate to severely disabled (mRS > 2) patients in "possible CIDP" group was higher than in "CIDP" group (not significant). "CIDP" patients had a better objective response to immunotherapy (59 % responders) than "possible CIDP" patients (29 % responders, p < .05), especially among typical CIDP patients (86 % of responders in "CIDP" versus 33 % of responders in "possible CIDP" patients, p < .05). CONCLUSION: "CIDP" patients had a more severe neuropathy, estimated with the NIS and INCAT scores, and "possible CIDP" patients had a more atypical phenotype at baseline. Our data suggest that long-term patient outcome and response to immunotherapy is better in "CIDP" than "possible CIDP".

Clinical, paraclinical and outcome features of 166 patients with acute anti-GQ1b antibody syndrome.

BACKGROUND & PURPOSE: In this retrospective study, we aimed at defining the clinical, paraclinical and outcome features of acute neurological syndromes associated with anti-GQ1b antibodies. RESULTS: We identified 166 patients with neurological symptoms appearing in less than 1 month and anti-GQ1b antibodies in serum between 2012 and 2022. Half were female (51%), mean age was 50 years (4-90), and the most frequent clinical features were areflexia (80% of patients), distal upper and lower limbs sensory symptoms (78%), ophthalmoplegia (68%), sensory ataxia (67%), limb muscle weakness (45%) and bulbar weakness (45%). Fifty-three patients (32%) presented with complete (21%) and incomplete (11%) Miller Fisher syndrome (MFS), thirty-six (22%) with Guillain-Barre syndrome (GBS), one (0.6%) with Bickerstaff encephalitis (BE), and seventy-three (44%) with mixed MFS, GBS & BE clinical features. Nerve conduction studies were normal in 46% of cases, showed demyelination in 28%, and axonal loss in 23%. Anti-GT1a antibodies were found in 56% of cases, increased cerebrospinal fluid protein content in 24%, and Campylobacter jejuni infection in 7%. Most patients (83%) were treated with intravenous immunoglobulins, and neurological recovery was complete in 69% of cases at 1 year follow-up. One patient died, and 15% of patients relapsed. Age > 70 years, initial Intensive Care Unit (ICU) admission, and absent anti-GQ1b IgG antibodies were predictors of incomplete recovery at 12 months. No predictors of relapse were identified. CONCLUSION: This study from Western Europe shows acute anti-GQ1b antibody syndrome presents with a large clinical phenotype, a good outcome in 2/3 of cases, and frequent relapses.

Immune checkpoint inhibitor-related myositis and myocarditis: diagnostic pitfalls and imaging contribution in a real-world, institutional case series.

BACKGROUND: Immune checkpoint inhibitors (ICIs) are reshaping the prognosis of many cancers, but often cause immune-related adverse events (irAEs). Among neurological irAEs, myositis is the most frequently reported. Our aim is to describe clinical and non-clinical characteristics, treatment and outcome of all irMyositis (skeletal limb-girdle and/or ocular myositis) and irMyocarditis cases in our reference center. METHODS: We retrospectively enrolled all irMyositis/irMyocarditis patients seen between 2018 and 2022. We reviewed demographics, clinical characteristics, biological, neurophysiological, imaging workup, treatment and outcome. RESULTS: We included 14 consecutive patients. The most frequent treatments were pembrolizumab (35%) or ipilimumab-nivolumab combination (35%). Limb-girdle, ocular (non-fluctuating palpebral ptosis and/or diplopia with or without ophthalmoparesis) and cardiac phenotypes were equally distributed, overlapping in 40% of cases. Ocular involvement was frequently misdiagnosed; review of brain MRIs disclosed initially missed signs of skeletal myositis in one patient and ocular myositis in 3. Seven patients had other co-existing irAEs. When performed, myography showed a myogenic pattern. CK was elevated in 8/15 patients, troponin-T in 12/12 and troponin-I in 7/9 tested patients. ICI were discontinued in all cases, with further immunosuppressive treatment in nine patients. In most cases, neurological and cardiological outcome was good at last follow-up. CONCLUSION: Myositis is a potentially severe irAE. Despite its heterogeneous presentation, some highly suggestive clinical symptoms, such as ocular involvement, or radiological signs should raise physicians' attention to avoid misdiagnosis. We thus recommend a multidisciplinary assessment (including complete neuromuscular evaluation) even in case of isolated myocarditis. Our series underlines the importance of an early diagnosis, since suspension of ICI and adequate treatment are usually associated with good functional outcome.

Neuropathies related to hepatitis E virus infection: A prospective, matched case-control study.

BACKGROUND: Acute hepatitis E virus (HEV) infection has recently emerged as a potential trigger for acute dysimmune neuropathies, but prospective controlled studies are lacking. AIMS: To compare the frequency of concomitant acute HEV infection in patients with neuralgic amyotrophy (NA), Guillain-Barré syndrome (GBS), and Bell's palsy with a matched control population. METHODS: Swiss multicenter, prospective, observational, matched case-control study over 3 years (September 2019-October 2022). Neurological cases with NA, GBS, or Bell's palsy were recruited within 1 month of disease onset. Healthy controls were matched for age, sex, geographical location, and timing of blood collection. Diagnostic criteria for acute hepatitis E were reactive serum anti-HEV IgM and IgG assays (ELISA test) and/or HEV RNA detection in serum by real-time polymerase chain reaction (RT-PCR). RT-PCR was performed on sera to confirm IgM positivity. RESULTS: We included 180 patients (59 GBS, 51 NA, 70 Bell's palsy cases) and corresponding matched controls (blood donors) with median age 51 years for both groups and equal gender distribution. Six IgM+ cases were detected in the NA, two in the GBS, and none in the Bell's palsy group. Two controls were anti-HEV IgM-positive. At disease onset, most cases with acute HEV infection had increased liver enzymes. A moderate association (p = 0.027, Fisher's exact test; Cramér's V = -0.25) was observed only between acute HEV infection and NA. CONCLUSION: This prospective observational study suggests an association between concomitant acute HEV infection and NA, but not with GBS or Bell's palsy.

Successful autologous hematopoietic stem cell transplantation in a refractory anti-Caspr1 antibody nodopathy.

AIM: Autoimmune nodopathies have specific clinicopathologic features, antibodies directed against nodal proteins (neurofascin 186) or paranodal proteins (neurofascin 155, contactin 1, contactin-associated protein 1 (Caspr1)), and usually have a poor response to first-line therapies for chronic inflammatory demyelinating polyradiculoneuropathy. Anti-Caspr1 nodopathy treated with autologous hematopoietic stem cell transplantation (AHSCT) has not been previously reported. METHODS: We report the first case of an anti-Caspr1 antibody-positive nodopathy refractory to high-intensity immunosuppressive treatment, including rituximab, that responded dramatically to AHSCT. RESULTS: A 53-year-old woman presented with a rapidly progressive generalized ataxic, painful motor, and inflammatory neuropathy supported by neurophysiologic and MRI studies. Initial tests for antibodies to nodal/paranodal proteins were negative. She was treated with multiple courses of intravenous immunoglobulin and methylprednisolone, plasma exchange, rituximab, and cyclophosphamide without significant clinical benefit. Repeated testing for antibodies to nodal/paranodal proteins yielded a positive result for anti-Caspr1/IgG4 isotype antibodies. Given the poor response to multiple high intensity treatments and the relatively young age of the patient, we decided to perform AHSCT at 30 months post-onset. Immediately after AHSCT, she stopped all immunomodulatory or immunosuppressive therapy. The Overall Neuropathy Limitation Score improved from 8/12 to 4/12 at 6 months post-AHSCT. At 3 months post-AHSCT, IgG4 against Caspr1 was negative and no reactivity against paranodes could be detected. CONCLUSION: We report a particularly severe anti-Caspr1 antibody autoimmune nodopathy that responded dramatically to AHSCT. Although the rarity of the disease limits the possibility of larger studies, AHSCT may be a valuable therapy in treatment-refractory cases.

EGR2 gene-linked hereditary neuropathies present with a bimodal age distribution at symptoms onset.

BACKGROUND: Mutations in the Early-Growth Response 2 (EGR2) gene cause various hereditary neuropathies, including demyelinating Charcot-Marie-Tooth (CMT) disease type 1D (CMT1D), congenital hypomyelinating neuropathy type 1 (CHN1), Déjerine-Sottas syndrome (DSS), and axonal CMT (CMT2). METHODS: In this study, we identified 14 patients with heterozygous EGR2 mutations diagnosed between 2000 and 2022. RESULTS: Mean age was 44 years (15-70), 10 patients were female (71%), and mean disease duration was 28 years (1-56). Disease onset was before age 15 years in nine cases (64%), after age 35 years in four cases (28%), and one patient aged 26 years was asymptomatic (7%). All symptomatic patients had pes cavus and distal lower limbs weakness (100%). Distal lower limbs sensory symptoms were observed in 86% of cases, hand atrophy in 71%, and scoliosis in 21%. Nerve conduction studies showed a predominantly demyelinating sensorimotor neuropathy in all cases (100%), and five patients needed walking assistance after a mean disease duration of 50 years (47-56) (36%). Three patients were misdiagnosed as inflammatory neuropathy and treated with immunosuppressive drugs for years before diagnosis was corrected. Two patients presented with an additional neurologic disorder, including Steinert's myotonic dystrophy and spinocerebellar ataxia (14%). Eight EGR2 gene mutations were found, including four previously undescribed. INTERPRETATION: Our findings demonstrate EGR2 gene-related hereditary neuropathies are rare and slowly progressive demyelinating neuropathies with two major clinical presentations, including a childhood-onset variant and an adult-onset variant which may mimic inflammatory neuropathy. Our study also expands the genotypic spectrum of EGR2 gene mutations.

The emerging spectrum of fetal acetylcholine receptor antibody-related disorders (FARAD).

In utero exposure to maternal antibodies targeting the fetal acetylcholine receptor isoform (fAChR) can impair fetal movement, leading to arthrogryposis multiplex congenita (AMC). Fetal AChR antibodies have also been implicated in apparently rare, milder myopathic presentations termed fetal acetylcholine receptor inactivation syndrome (FARIS). The full spectrum associated with fAChR antibodies is still poorly understood. Moreover, since some mothers have no myasthenic symptoms, the condition is likely underreported, resulting in failure to implement effective preventive strategies. Here we report clinical and immunological data from a multicentre cohort (n = 46 cases) associated with maternal fAChR antibodies, including 29 novel and 17 previously reported with novel follow-up data. Remarkably, in 50% of mothers there was no previously established myasthenia gravis (MG) diagnosis. All mothers (n = 30) had AChR antibodies and, when tested, binding to fAChR was often much greater than that to the adult AChR isoform. Offspring death occurred in 11/46 (23.9%) cases, mainly antenatally due to termination of pregnancy prompted by severe AMC (7/46, 15.2%), or during early infancy, mainly from respiratory failure (4/46, 8.7%). Weakness, contractures, bulbar and respiratory involvement were prominent early in life, but improved gradually over time. Facial (25/34; 73.5%) and variable peripheral weakness (14/32; 43.8%), velopharyngeal insufficiency (18/24; 75%) and feeding difficulties (16/36; 44.4%) were the most common sequelae in long-term survivors. Other unexpected features included hearing loss (12/32; 37.5%), diaphragmatic paresis (5/35; 14.3%), CNS involvement (7/40; 17.5%) and pyloric stenosis (3/37; 8.1%). Oral salbutamol used empirically in 16/37 (43.2%) offspring resulted in symptom improvement in 13/16 (81.3%). Combining our series with all previously published cases, we identified 21/85 mothers treated with variable combinations of immunotherapies (corticosteroids/intravenous immunoglobulin/plasmapheresis) during pregnancy either for maternal MG symptom control (12/21 cases) or for fetal protection (9/21 cases). Compared to untreated pregnancies (64/85), maternal treatment resulted in a significant reduction in offspring deaths (P < 0.05) and other complications, with treatment approaches involving intravenous immunoglobulin/ plasmapheresis administered early in pregnancy most effective. We conclude that presentations due to in utero exposure to maternal (fetal) AChR antibodies are more common than currently recognized and may mimic a wide range of neuromuscular disorders. Considering the wide clinical spectrum and likely diversity of underlying mechanisms, we propose 'fetal acetylcholine receptor antibody-related disorders' (FARAD) as the most accurate term for these presentations. FARAD is vitally important to recognize, to institute appropriate management strategies for affected offspring and to improve outcomes in future pregnancies. Oral salbutamol is a symptomatic treatment option in survivors.

Serum neurofilament light chain as a reliable biomarker of hereditary transthyretin-related amyloidosis-A Swiss reference center experience.

Hereditary transthyretin-related (hATTR) amyloidosis is a rare disease, causing a disabling and life-threatening axonal length-dependent polyneuropathy. Monitoring of disease progression and treatment response is difficult. We aimed to determine if serum neurofilament light chain (sNfL) is a reliable and early biomarker of peripheral neuropathy in hATTR amyloidosis. We prospectively included 20 hATTR patients, 14 symptomatic and 6 asymptomatic. Patients were assessed at baseline and 1 year, including a full clinical examination with disease severity and functional scores, electrochemical skin conductance measurement with Sudoscan and nerve conduction studies, and sNfL level. hATTR patient sNfL were also compared with sNfL of 4532 healthy controls of a reference database by calculating age and BMI-adjusted Z scores. At baseline, median sNfL concentration was 3.6-fold higher in symptomatic than asymptomatic hATTR patients (P = .003), and this difference was also found in our under 60-years-old patients (P = .003). There was no significant difference of sNfL concentration between asymptomatic patients and healthy controls (Z-score of -0.29), but a significant difference between symptomatic patients and healthy controls (Z-score of 2.52). We found a significant correlation between sNfL levels and most clinical and electrophysiological disease severity scores, the strongest correlation being with the NIS score. sNfL seems to be a reliable biomarker of peripheral neuropathy severity in hATTR amyloidosis and can distinguish between asymptomatic and symptomatic patients. sNfL could also become a reliable biomarker to establish disease onset and treatment response.

Early detection of ICU-acquired weakness in septic shock patients ventilated longer than 72 h.

PURPOSE: ICU-acquired weakness, comprising Critical Illness Polyneuropathy (CIP) and Myopathy (CIM) is associated with immobilization and prolonged mechanical ventilation. This study aims to assess feasibility of early detection of CIP and CIM by peroneal nerve test (PENT) and sensory sural nerve action potential (SNAP) screening in patients with septic shock and invasively ventilated for more than 72 h. METHODS: We performed repetitive PENT screening from 72 h after intubation until detecting a pathological response. We tested SNAPs in pathological PENT to differentiate CIP from CIM. We performed muscle strength examination in awake patients and recorded time from intubation to first in-bed and out-of-bed mobilization. RESULTS: Eighteen patients were screened with PENT and 88.9% had abnormal responses. Mean time between intubation and first screening was 94.38 (± 22.41) hours. Seven patients (38.9%) had CIP, two (11.1%) had CIM, one (5.6%) had CIP and CIM, six (33.3%) had a pathological response on PENT associated with ICU-acquired weakness (but no SNAP could be performed to differentiate between CIP and CIM) and two patients had (11.1%) had no peripheral deficit. In patients where it could be performed, muscle strength testing concorded with electrophysiological findings. Twelve patients (66.7%) had out-of-bed mobilization 10.8 (± 7.4) days after admission. CONCLUSION: CIP and CIM are frequent in septic shock patients and can be detected before becoming symptomatic with simple bedside tools. Early detection of CIP and CIM opens new possibilities for their timely management through preventive measures such as passive and active mobilization.

Anti-disialosyl-immunoglobulin M chronic autoimmune neuropathies: a nationwide multicenter retrospective study.

BACKGROUND AND PURPOSE: In this retrospective study involving 14 university hospitals from France and Switzerland, the aim was to define the clinicopathological features of chronic neuropathies with anti-disialosyl ganglioside immunoglobulin M (IgM) antibodies (CNDA). RESULTS: Fifty-five patients with a polyneuropathy evolving for more than 2 months and with at least one anti-disialosyl ganglioside IgM antibody, that is, anti-GD1b, -GT1b, -GQ1b, -GT1a, -GD2 and -GD3, were identified. Seventy-eight percent of patients were male, mean age at disease onset was 55 years (30-76) and disease onset was progressive (82%) or acute (18%). Patients presented with limb sensory symptoms (94% of cases), sensory ataxia (85%), oculomotor weakness (36%), limb motor symptoms (31%) and bulbar muscle weakness (18%). Sixty-five percent of patients had a demyelinating polyradiculoneuropathy electrodiagnostic profile and 24% a sensory neuronopathy profile. Anti-GD1b antibodies were found in 78% of cases, whilst other anti-disialosyl antibodies were each observed in less than 51% of patients. Other features included nerve biopsy demyelination (100% of cases), increased cerebrospinal fluid protein content (75%), IgM paraprotein (50%) and malignant hemopathy (8%). Eighty-six percent of CNDA patients were intravenous immunoglobulins-responsive, and rituximab was successfully used as second-line treatment in 50% of cases. Fifteen percent of patients had mild symptoms and were not treated. CNDA course was progressive (55%) or relapsing (45%), and 93% of patients still walked after a mean disease duration of 11 years. CONCLUSION: Chronic neuropathies with anti-disialosyl ganglioside IgM antibodies have a recognizable phenotype, are mostly intravenous immunoglobulins-responsive and present with a good outcome in a majority of cases.

Early-onset leukoencephalomyelopathy due to a biallelic NDUFV1 variant in a mid-forties patient.

We present a patient who developed, after an early-onset, a stable course of spastic paraplegia and ataxia for 4 decades and eventually succumbed to two episodes of postinfectious lactic acidosis. Diagnostic workup including muscle biopsy and postmortem analysis, oxymetric analysis, spectrophotometric enzyme analysis, and MitoExome sequencing revealed a necrotizing leukoencephalomyelopathy due to the so far unreported biallelic variant of the NDUFV1 gene (p.(Pro122Leu)). This case extends our understanding of NDUFV1 variants with a 14-fold longer lifetime than so far reported cases, and will foster sensitivity toward respiratory chain disease also in adult patients with sudden deteriorating neurological deficits.

[Neurological shoulder pain and weakness : practical attitudes]. / Douleurs et faiblesse de l'épaule neurologique : attitudes pratiques.

Shoulder pain or paresis should be assessed carefully, as there are many possible causes, which can be osteoarticular, degenerative, inflammatory, or neurological. Weakness or pain can be related to cervicobrachialgia, plexitis, or focal mononeuropathy. The clinical picture should identify any muscular or mechanical origin of paresis responsible for pseudo-paretic functional limitation. Neurogenic scapulalgia with functional deficit implies the compression or entrapment of a nerve trunk including the axillary, long thoracic, accessory, suprascapular, or dorsal scapular nerves. Nerve conduction study and myography together with medical imaging help to identify the relevant etiology. Treatment mostly includes pain relief and physiotherapy, but surgery is rarely necessary.

L'épaule douloureuse ou parétique est d'appréhension délicate et de causes variées : ostéoarticulaire, dégénérative, inflammatoire ou neurologique. La faiblesse ou la douleur peuvent être liées à une cervicobrachialgie, une plexite ou une mononeuropathie focale. Le tableau clinique doit distinguer une parésie d'origine musculaire ou mécanique responsable alors d'une limitation fonctionnelle pseudo-parétique. Une scapulalgie déficitaire neurogène implique la recherche d'une mononeuropathie d'enclavement ou compressive d'un tronc nerveux, axillaire, long thoracique, accessoire du XIe nerf crânien, suprascapulaire ou dorsal de la scapula. Au besoin l'ENMG (électroneuromyogramme)et l'imagerie débrouilleront les multiples étiologies. Le traitement requiert le plus souvent une antalgie et une rééducation, rarement une chirurgie.

A multicenter cross-sectional French study of the impact of COVID-19 on neuromuscular diseases.

BACKGROUND: Due to their health condition, patients with neuromuscular diseases (NMD) are at greater risk of developing serious complications with COVID-19. The objective of this study was to analyze the prevalence of COVID-19 among NMD patients and the risk factors for its impact and severity during the first wave of the pandemic. Clinical data were collected from NMD-COVID-19 patients, between March 25, 2020 and May 11, 2020 in an anonymous survey carried out by expert physicians from the French Health Care Network Filnemus. RESULTS: Physicians reported 84 patients, including: 34 with myasthenia gravis, 27 with myopathy and 23 with neuropathy. COVID-19 had no effect on NMD for 48 (58%) patients and 48 (58%) patients developed low COVID-19 severity. COVID-19 caused the death of 9 (11%) NMD patients. Diabetic patients were at greater risk of dying. Patients with diabetes, hypertension or severe forms of NMD had a higher risk of developing a moderate or severe form of COVID-19. In our cohort, corticosteroids and other immunosuppressants were not significantly associated with higher COVID-19 severity for acquired NMD. CONCLUSION: During this period, a small percentage of French NMD patients was affected by COVID-19 compared to the general French population and COVID-19 had a limited short-term effect on them. Diabetes, hypertension and a severe degree of NMD were identified as risk factors of unfavorable outcome following COVID-19. Conversely, in our cohort of patients with acquired NMD, corticosteroids or other immunosuppressants did not appear to be risk factors for more severe COVID-19.

Implication of folate deficiency in CYP2U1 loss of function.

Hereditary spastic paraplegias are heterogeneous neurodegenerative disorders. Understanding of their pathogenic mechanisms remains sparse, and therapeutic options are lacking. We characterized a mouse model lacking the Cyp2u1 gene, loss of which is known to be involved in a complex form of these diseases in humans. We showed that this model partially recapitulated the clinical and biochemical phenotypes of patients. Using electron microscopy, lipidomic, and proteomic studies, we identified vitamin B2 as a substrate of the CYP2U1 enzyme, as well as coenzyme Q, neopterin, and IFN-α levels as putative biomarkers in mice and fluids obtained from the largest series of CYP2U1-mutated patients reported so far. We also confirmed brain calcifications as a potential biomarker in patients. Our results suggest that CYP2U1 deficiency disrupts mitochondrial function and impacts proper neurodevelopment, which could be prevented by folate supplementation in our mouse model, followed by a neurodegenerative process altering multiple neuronal and extraneuronal tissues.

Guillain-Barré syndrome after SARS-CoV-2 infection in an international prospective cohort study.

In the wake of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic, an increasing number of patients with neurological disorders, including Guillain-Barré syndrome (GBS), have been reported following this infection. It remains unclear, however, if these cases are coincidental or not, as most publications were case reports or small regional retrospective cohort studies. The International GBS Outcome Study is an ongoing prospective observational cohort study enrolling patients with GBS within 2 weeks from onset of weakness. Data from patients included in this study, between 30 January 2020 and 30 May 2020, were used to investigate clinical and laboratory signs of a preceding or concurrent SARS-CoV-2 infection and to describe the associated clinical phenotype and disease course. Patients were classified according to the SARS-CoV-2 case definitions of the European Centre for Disease Prevention and Control and laboratory recommendations of the World Health Organization. Forty-nine patients with GBS were included, of whom eight (16%) had a confirmed and three (6%) a probable SARS-CoV-2 infection. Nine of these 11 patients had no serological evidence of other recent preceding infections associated with GBS, whereas two had serological evidence of a recent Campylobacter jejuni infection. Patients with a confirmed or probable SARS-CoV-2 infection frequently had a sensorimotor variant 8/11 (73%) and facial palsy 7/11 (64%). The eight patients who underwent electrophysiological examination all had a demyelinating subtype, which was more prevalent than the other patients included in the same time window [14/30 (47%), P = 0.012] as well as historical region and age-matched control subjects included in the International GBS Outcome Study before the pandemic [23/44 (52%), P = 0.016]. The median time from the onset of infection to neurological symptoms was 16 days (interquartile range 12-22). Patients with SARS-CoV-2 infection shared uniform neurological features, similar to those previously described in other post-viral GBS patients. The frequency (22%) of a preceding SARS-CoV-2 infection in our study population was higher than estimates of the contemporaneous background prevalence of SARS-CoV-2, which may be a result of recruitment bias during the pandemic, but could also indicate that GBS may rarely follow a recent SARS-CoV-2 infection. Consistent with previous studies, we found no increase in patient recruitment during the pandemic for our ongoing International GBS Outcome Study compared to previous years, making a strong relationship of GBS with SARS-CoV-2 unlikely. A case-control study is required to determine if there is a causative link or not.

Iatrogenic immune-mediated neuropathies: diagnostic, epidemiological and mechanistic uncertainties for causality and implications for clinical practice.

Acute and chronic immune-mediated neuropathies have been widely reported with medical intervention. Although causal relationship may be uncertain in many cases, a variety of drugs, several vaccination types, surgical procedures and bone marrow transplants have been reported as possible cause or trigger of a putative immune-mediated response resulting in acute and chronic neuropathies. We conducted a systematic review of the literature from 1966 to 2020 on reported cases of possible iatrogenic immune-mediated neuropathies. We determined in each case the likelihood of causality based on frequency of the association, focusing primarily on clinical presentation and disease course as well as available ancillary investigations (electrophysiology, blood and cerebrospinal fluid and neuropathology). The response to immunotherapy and issue of re-exposure were also evaluated. We also considered hypothesised mechanisms of onset of immune-mediated neuropathy in the specific iatrogenic context. We believe that a likely causal relationship exists for only few drugs, mainly antitumour necrosis factor alpha agents and immune checkpoint inhibitors, but remains largely unsubstantiated for most other suggested iatrogenic causes. Unfortunately, given the lack of an accurate diagnostic biomarker for most immune-mediated neuropathies, clinical assessment will often override ancillary investigations, resulting in lower levels of certainty that may continue to cast serious doubts on reliability of their diagnosis. Consequently, future reports of suspected cases should collect and exhaustively assess all relevant data. At the current time, besides lack of evidence for causality, the practical implications on management of suspected cases is extremely limited and therapeutic decisions appear likely no different to those made in non-iatrogenic cases.

NGS-Based Diagnosis of Treatable Neurogenetic Disorders in Adults: Opportunities and Challenges.

The identification of neurological disorders by next-generation sequencing (NGS)-based gene panels has helped clinicians understand the underlying physiopathology, resulting in personalized treatment for some rare diseases. While the phenotype of distinct neurogenetic disorders is generally well-known in childhood, in adulthood, the phenotype can be unspecific and make the standard diagnostic approach more complex. Here we present three unrelated adults with various neurological manifestations who were successfully diagnosed using NGS, allowing for the initiation of potentially life-changing treatments. A 63-year-old woman with progressive cognitive decline, pyramidal signs, and bilateral cataract was treated by chenodeoxycholic acid following the diagnosis of cerebrotendinous xanthomatosis due to a homozygous variant in CYP27A1. A 32-year-old man with adult-onset spastic paraplegia, in whom a variant in ABCD1 confirmed an X-linked adrenoleukodystrophy, was treated with corticoids for adrenal insufficiency. The third patient, a 28-year-old woman with early-onset developmental delay, epilepsy, and movement disorders was treated with a ketogenic diet following the identification of a variant in SLC2A1, confirming a glucose transporter type 1 deficiency syndrome. This case study illustrates the challenges in the timely diagnosis of medically actionable neurogenetic conditions, but also the considerable potential for improving patient health through modern sequencing technologies.

Charcot-Marie-Tooth disease misdiagnosed as chronic inflammatory demyelinating polyradiculoneuropathy: An international multicentric retrospective study.

BACKGROUND AND PURPOSE: Charcot-Marie-Tooth (CMT) disease, an untreatable hereditary polyneuropathy, may mimic chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), a treatable neuropathy. METHODS: In this retrospective study, we analyzed the characteristics of CMT patients misdiagnosed as CIDP at 16 university hospitals in three countries, compared these patients with a reference group of CIDP patients, and estimated the cost of misdiagnosis. RESULTS: Among 1104 CIDP cases, we identified 35 CMT patients misdiagnosed as CIDP (3.2%). All were initially diagnosed with definite or probable CIDP (European Federation of Neurological Societies/Peripheral Nerve Society criteria), and mutations in PMP22, MPZ, and 10 other CMT genes were found in 34%, 31%, and 35% of cases, respectively. In comparison with a reference group of 35 CIDP patients, CMT patients were younger (median age at disease onset = 39 vs. 56 years) and more frequently had motor weakness at disease onset (80% vs. 29%), hearing loss (14% vs. 0%), normal brachial plexus imaging (70% vs. 40%), lower cerebrospinal fluid protein content (median = 0.5 vs. 0.8 g/L), and lower treatment response (20% vs. 69%). Treatment cost in these 35 misdiagnosed patients was estimated at 4.6 million euros (M€), whereas the cost of CMT genetic analysis in 1104 patients was estimated at 2.7 M€. CONCLUSIONS: In this study, 35 of 1104 (3.2%) patients initially diagnosed with CIDP had CMT. Importantly, the cost of treating these 35 misdiagnosed patients was significantly higher than the cost of performing CMT genetic analysis in 1104 patients (4.6 M€ vs. 2.7 M€), suggesting that CMT genetic investigations should be more widely used before diagnosing CIDP.

[Acute severe neuropathies in the context of SARS-CoV-2 infection]. / Neuropathies aiguës sévères induites par l'infection à SARS-CoV-2.

Various neuromuscular complications have been described in SARS-CoV-2 infection, especially Guillain-Barré syndrome (GBS) and Critical Illness neuromyopathy (CI-NM). Two representative cases are discussed below. It appears that GBS shares most of the characteristics of classical post-infectious GBS, but SARS-CoV-2 may contribute to the increased incidence of CI-NM. Other rare complications have been described, including Tapia Syndrome and Kawasaki-like multiple system inflammatory syndrome. The question of vaccination and the risk of immune-mediated neuropathies remains open, but the lack of reported cases is reassuring as these complications usually occur within 6 weeks after vaccination.

Différentes complications neuromusculaires ont été décrites suite à l'infection à SARS-CoV-2, notamment le syndrome de Guillain-Barré (SGB) et la neuromyopathie des soins intensifs (NMSI). Deux cas représentatifs sont discutés ici. Il apparaît que le SGB partage la plupart des caractéristiques du SGB postinfectieux classique, mais le SARS-CoV-2 pourrait participer à la majoration de l'incidence de la NMSI. D'autres complications rares ont été décrites, notamment le syndrome de Tapia et le syndrome inflammatoire multisystémique de type Kawasaki. La question de la vaccination et du risque de neuropathie à médiation immunitaire reste ouverte, mais l'absence de réaction rapportée est rassurante dans la mesure où ces complications surviennent habituellement dans les 6 semaines après la vaccination.