Publications by authors named "Ludivine Kouton"

4 Publications

  • Page 1 of 1

Motor unit number index as an individual biomarker: Reference limits of intra-individual variability over time in healthy subjects.

Clin Neurophysiol 2020 Sep 9;131(9):2209-2215. Epub 2020 Jul 9.

Referral Centre for Neuromuscular Diseases and ALS, La Timone Hospital, Marseille, France.

Objective: Motor unit number index (MUNIX) is proposed to monitor neuromuscular disorders. Our objective is to determine the intra-individual variability over time of the MUNIX.

Methods: In 11 different hospital centres, MUNIX was assessed twice, at least 3 months apart (range 90-360 days), in tibialis anterior (TA), abductor pollicis brevis (APB), abductor digiti minimi (ADM) and deltoid muscles in 118 healthy subjects. MUNIX sum score 2, 3 and 4 were respectively the sum of the MUNIX of the TA and ADM, of the TA, APB and ADM and of the TA, APB, ADM and deltoid muscles.

Results: The repeatability of the MUNIX was better for sum scores than for single muscle recordings. The variability of the MUNIX was independent of sex, age, interval between measurements and was lower for experienced than non-experienced operators. The 95th percentile of the coefficient of variability of the MUNIX sum score 2, 3 and 4 were respectively 22%, 18% and 15% for experienced operators.

Conclusions: The MUNIX technique must be performed by experienced operators on several muscles to reduce its variability and improve its reliability.

Significance: A variation of the MUNIX sum score ≥20% can be interpreted as a significant change of muscle innervation.
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September 2020

Antibodies against the node of Ranvier: a real-life evaluation of incidence, clinical features and response to treatment based on a prospective analysis of 1500 sera.

J Neurol 2020 Dec 16;267(12):3664-3672. Epub 2020 Jul 16.

Timone Neuroscience Institute, UMR CNRS 7289, Aix-Marseille University, 13005, Marseille, France.

Introduction: IgG4 antibodies against neurofascin (Nfasc155 and Nfasc140/186), contactin (CNTN1) and contactin-associated protein (Caspr1) are described in specific subtypes of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). Our objective was to assess, in a real-life practice, the incidence, the clinical features and the response to treatment of these forms of CIDP.

Methods: 1500 sera of patients suspected of having CIDP from France, Belgium and Switzerland were prospectively tested using a flow cytometry technique. The characteristics of patients with antibodies against the node of Ranvier were compared to 100 seronegative CIDP from our department.

Results: IgG4 antibodies against Nfasc155, CNTN1, and Caspr1 were, respectively, detected in 15 (prevalence 1%), 10 (0.7%) and 2 (0.2%) sera. Antibodies specific of the Nfasc140/186 were not detected. All subjects with antibodies against the node of Ranvier fulfilled diagnostic criteria for CIDP. CIDP with anti-Nfasc155 were younger, had more sensory ataxia and postural tremor than seronegative CIDP. CIDP with anti-CNTN1 had more frequent subacute onset and facial paralysis, commoner renal involvement with membranous glomerulonephritis and greater disability, than seronegative CIDP. CIDP with anti-Caspr1 had more frequent respiratory failure and cranial nerve involvement but not more neuropathic pain than seronegative CIDP. Intravenous immunoglobulins were ineffective in most seropositive patients. Rituximab produced dramatic improvement in disability and decreased antibodies titres in 13 seropositive patients (8 with anti-Nfasc155 and 5 with anti-CNTN1 antibodies).

Conclusions: Although rare, anti-paranodal antibodies are clinically valuable, because they are associated with specific phenotypes and therapeutic response.
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December 2020

Electrophysiological features of chronic inflammatory demyelinating polyradiculoneuropathy associated with IgG4 antibodies targeting neurofascin 155 or contactin 1 glycoproteins.

Clin Neurophysiol 2020 04 6;131(4):921-927. Epub 2020 Feb 6.

Referral Centre for Neuromuscular Diseases and ALS, La Timone hospital, Marseille, France; Aix-Marseille University, Timone Neuroscience Institute, UMR CNRS 7289, 13005 Marseille, France. Electronic address:

Objective: Chronic inflammatory demyelinating polyradiculoneuropathies (CIDP) with antibodies against neurofascin 155 (Nfasc155) or contactin-1 (CNTN1) have distinctive clinical features. Knowledge on their electrophysiological characteristics is still scarce. In this study, we are investigating whether these patients have specific electrophysiological characteristics.

Methods: The electrophysiological data from 13 patients with anti-Nfasc155 IgG4 antibodies, 9 with anti-CNTN1 IgG4 antibodies were compared with those of 40 consecutive CIDP patients without antibodies.

Results: All the patients with antibodies against Nfasc155 or CNTN1 fulfilled the EFNS/PNS electrodiagnostic criteria for definite CIDP. There was no electrophysiological difference between patients with anti-CNTN1 and anti-Nfasc155 antibodies. Nerve conduction abnormalities were heterogeneously distributed along nerves trunks and roots. They were more pronounced than in CIDP without antibodies. Motor conduction velocity on median nerve <24 m/s or motor velocity on ulnar nerve <26 m/s or motor distal latency on ulnar nerve >7.4 ms were predictive of positive antibodies against the node of Ranvier with a sensitivity of 59% and a specificity of 93%.

Conclusions: Marked conduction abnormalities may suggest the presence of positive antibodies against the node of Ranvier.

Significance: Anti-Nfasc155 and anti-CNTN1 antibodies target the the paranodal axo-glial domain but are associated with nerve conduction abnormalities mimicking a "demyelinating" neuropathy.
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April 2020

Antibodies to neurofascin, contactin-1, and contactin-associated protein 1 in CIDP: Clinical relevance of IgG isotype.

Neurol Neuroimmunol Neuroinflamm 2020 01 21;7(1). Epub 2019 Nov 21.

From the Department of Brain and Behavioral Sciences (A.C., I.C., G.C., R.C., E.V.), University of Pavia, Pavia, Italy; Department of Neuromuscular Disease (A.C.), UCL Queen Square Institute of Neurology, London, United Kingdom; Neuroalgology Unit (R.L., P.D., L.P., G.L.), IRCCS Fondazione Istituto Neurologico "Carlo Besta," Milan, Italy; Department of Neurosciences (C.B., M.R., A.S.), University of Padova, Padova, Italy; IRCCS Mondino Foundation (I.C., G.C., E.Z., R.C., M.G., E.V., E.A., A.B., D.F.), Pavia, Italy; Department of Neuroscience (L.B., C.D.M., A.S.), Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health (DiNOGMI), University of Genova, Genova, Italy; IRCCS Ospedale Policlinico San Martino (L.B., C.D.M., A.S.), Genova, Italy; Department of Neurosciences (F.M., E.S., A.T.), Odontostomatological and Reproductive Sciences, University of Naples "Federico II," Naples, Italy; Fondazione Policlinico Universitario Agostino Gemelli-IRCCS. UOC Neurologia (M.L., A.R., M.S.), Rome, Italy; Università Cattolica del Sacro Cuore (M.L., A.R., M.S.), Rome, Italy; Section of Neurology (S.F., S.M.), Department of Neuroscience, Biomedicine and Movement Sciences, University of Verona, Verona, Italy; Department of Neurology and Stroke Unit (A.M.C.), Ospedale di Circolo/Fondazione Macchi, Varese, Italy; Department of Systems Medicine (G.A.M., G.M.), University of Rome Tor Vergata, Rome, Italy; Neurological Department (A.R.), ASST Lecco; Ospedale Treviglio ASST Bergamo Ovest (M.C.), Italy; Department of Neurology (R.F., F.C.), San Raffaele Scientific Institute, Milan, Italy; Department of Neurorehabilitation Sciences (M.C.), Casa Cura Policlinico (CCP), Milan, Italy; Department of Clinical and Experimental Medicine (A.M.), University of Messina, Messina, Italy; Department of Medicine, Surgery and Neurosciences (F.G.), University of Siena, Italy; Referral Center for Neuromuscular Diseases and ALS (L.K., E.M.), AP-HM, Timone University Hospital, Marseille, France; Université de Bordeaux (C.M.), Interdisciplinary Institute for Neuroscience, Bordeaux, France; Humanitas Clinical and Research Center (C.G., P.D., E.N.-O.), Milan University, Milan, Italy; IRCCS Centro Neurolesi "Bonino Pulejo" (C.S.), Messina, Italy; Department of Biomedical and Clinical Sciences "Luigi Sacco" (G.B., G.L.), University of Milan, Milan, Italy; and Institute for Neurosciences of Montpellier (J.D.), INSERM U1051, Montpellier University, Hopital Saint Eloi, Montpellier, France.

Objective: To assess the prevalence and isotypes of anti-nodal/paranodal antibodies to nodal/paranodal proteins in a large chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) cohort, compare clinical features in seronegative vs seropositive patients, and gather evidence of their isotype-specific pathogenic role.

Methods: Antibodies to neurofascin-155 (Nfasc155), neurofascin-140/186 (Nfasc140/186), contactin-1 (CNTN1), and contactin-associated protein 1 (Caspr1) were detected with ELISA and/or cell-based assay. Antibody pathogenicity was tested by immunohistochemistry on skin biopsy, intraneural injection, and cell aggregation assay.

Results: Of 342 patients with CIDP, 19 (5.5%) had antibodies against Nfasc155 (n = 9), Nfasc140/186 and Nfasc155 (n = 1), CNTN1 (n = 3), and Caspr1 (n = 6). Antibodies were absent from healthy and disease controls, including neuropathies of different causes, and were mostly detected in patients with European Federation of Neurological Societies/Peripheral Nerve Society (EFNS/PNS) definite CIDP (n = 18). Predominant antibody isotypes were immunoglobulin G (IgG)4 (n = 13), IgG3 (n = 2), IgG1 (n = 2), or undetectable (n = 2). IgG4 antibody-associated phenotypes included onset before 30 years, severe neuropathy, subacute onset, tremor, sensory ataxia, and poor response to intravenous immunoglobulin (IVIG). Immunosuppressive treatments, including rituximab, cyclophosphamide, and methotrexate, proved effective if started early in IVIG-resistant IgG4-seropositive cases. Five patients with an IgG1, IgG3, or undetectable isotype showed clinical features indistinguishable from seronegative patients, including good response to IVIG. IgG4 autoantibodies were associated with morphological changes at paranodes in patients' skin biopsies. We also provided preliminary evidence from a single patient about the pathogenicity of anti-Caspr1 IgG4, showing their ability to penetrate paranodal regions and disrupt the integrity of the Nfasc155/CNTN1/Caspr1 complex.

Conclusions: Our findings confirm previous data on the tight clinico-serological correlation between antibodies to nodal/paranodal proteins and CIDP. Despite the low prevalence, testing for their presence and isotype could ultimately be part of the diagnostic workup in suspected inflammatory demyelinating neuropathy to improve diagnostic accuracy and guide treatment.

Classification Of Evidence: This study provides Class III evidence that antibodies to nodal/paranodal proteins identify patients with CIDP (sensitivity 6%, specificity 100%).
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January 2020