A new score combining compound muscle action potential (CMAP) amplitudes and motor score is predictive of motor outcome after AVXS-101 (Onasemnogene Abeparvovec) SMA therapy.

Spinal muscular atrophy 1 (SMA1) is a severe early genetic disease with degeneration of motor neurons. Motor development is still suboptimal after gene replacement therapy in symptomatic patients. In this study, compound muscle action potential (CMAP) amplitudes were explored as predictors of motor recovery after gene therapy. Thirteen symptomatic SMA1 patients were prospectively included at the Necker Enfants Malades Hospital, Paris, France (Cohort 1) and 12 at the other pediatric neuromuscular reference centers of the French Filnemus network (Cohort 2). In Cohort 1, median CMAP amplitudes showed the best improvement between baseline and the 12 months visit compared to the other tested nerves (ulnar, fibular and tibial). High median CMAP amplitudes at baseline was associated with unaided sitting achievement at M6 (AUC 90%). None of the patients with CHOPINTEND at M0 < 30/64 and median CMAP < 0.5 mV achieved unaided sitting at M6 and this result was confirmed on Cohort 2 used as an independent validation data. Thus, median CMAP amplitude is a valid biomarker for routine practice to predict sitting at M6. A median CMAP amplitude over 0.5 mV at baseline may predict better motor recovery.

Clinical Phenotype in an Early-Onset French Pediatric Population: Charcot-Marie-Tooth's Disease Type 2A.

Charcot-Marie-Tooth's disease type 2A (MCT2A), induced by mutation of the mitofusin 2 (MFN2) gene represents the main cause of MCT2. The aim of this study is to provide details of the clinical and electromyographic phenotype of MCT2A in a pediatric population. We conducted a French multicenter retrospective study, including all children with a genetic diagnosis of MCT2A. Thirteen MCT2A children were included with a beginning of symptoms before the age of 10 years ("early-onset group"). We report two new mutations: c.1070 A → T (p.Lys357.Met) and c.280 C → G (p.Arg94Gly). The evolution of the disease is marked by a fast worsening for three patients with loss of motor autonomy, while the evolution is relatively stable for eight patients. The group of early-onset MCT2A seems more heterogeneous than previously described, with a nonconstant severe phenotype.

Arthrogryposis in children: Etiological assessments and preparation of a protocol for etiological investigations.

INTRODUCTION: Arthrogryposis is a descriptive term defining a sign. It describes a set of joint contractures, sometimes identifiable in utero, present from birth and nonprogressive. This term includes a heterogeneous group of diseases, of neurological, neuromuscular, genetic or mechanical origin. The common physiopathological mechanism is fetal immobility syndrome. Two types of classification have been developed: a clinical one (types I, II and III) and an etiological one. The main aim of this study was to define a standardized protocol for etiological investigation based on a descriptive analysis of the various etiologies identified in a population of children followed up for arthrogryposis. Its secondary aim was to assess first the comprehensiveness and relevance of the complementary assessment and second the way in which the classifications proposed by Professor Judith Goslin Hall are applied. MATERIAL AND METHODS: Retrospective multicenter observational study. We enrolled pediatric patients with arthrogryposis being treated at a reference center for neuromuscular diseases, i.e., in three university hospital pediatric neurology units, between February 1997 and January 2017. RESULTS: Forty-two patients (25 boys and 17 girls) were enrolled. According to the clinical classification (Hall et al.), this population consisted of eight cases of type 1 arthrogryposis (19.1%), 14 type II (33.3%) and 20 type III (47.6%). The main etiology was neurological (19.1%), predominantly involving problems with gyration of a polymicrogyria type. Myopathic origin accounted for 9.5% of the population, predominantly involving genotyped distal arthrogryposis (ECEL1 gene). Additional tests produced a diagnosis of 25% type I, 43% type II and 75% type III. CONCLUSION: Arthrogryposis is a sign suggesting multiple etiologies. The main ones are neurological. Several genes have recently been identified, explaining the physiopathological mechanisms. The diagnostic process must be rigorous and coordinated within a multidisciplinary team, following a shared protocol for analysis.

[Congenital neuromuscular diseases with neonatal respiratory failure excluding myotonic dystrophy type 1 and infantile spinal muscular atrophy. Diagnosis strategy according to a 19-child series]. / Maladies neuromusculaires congénitales à expression respiratoire néonatale à l'exclusion de la dystrophie myotonique de type 1 et de l'amyotrophie spinale infantile. Stratégie d'exploration d'après une série de 19 enfants.

UNLABELLED: Apart from spinal muscular atrophy (SMA) and myotonic dystrophy type 1 (DM1), congenital neuromuscular diseases with early neonatal symptoms mean diagnostic and prognostic challenges mainly when infants require ventilatory support. OBJECTIVES: Consider a standardized strategy for infants suspected of congenital neuromuscular disease from analysis of the literature and retrospective experience with floppy and ventilatory support-dependent infants, after exclusion of well-known diseases (DM1, SMA). PATIENTS AND METHODS: Floppy infants requiring ventilatory support in their 1st month of life, but showing no evidence of DM1, SMA, Prader-Willi syndrome, or encephalopathy. The retrospective multicenter study was based on the response of regional referent neuropediatricians in the Reference Centre for Neuromuscular Diseases of Greater Southwest France to an inquiry about prenatal and perinatal history, investigations, diagnosis, and outcome of the child and family. It was conducted between 2007 and 2012. RESULTS: Among the 19 newborns studied, all had severe hypotonia. Prenatal and perinatal features were similar. Their outcome was generally severe: the median survival as measured by the Kaplan-Meier method was 6.9 months. Thirteen children died at a median age of 61 days; ten of them were treated with a palliative procedure. Five children had achieved respiratory independence but suffered from a small delay in motor development. Among the three children who continuously required ventilatory support, only one survived (follow-up period: 23 months); he was the only one undergoing tracheostomy in the cohort. Diagnostic processes were different, leading to pathological and genetic diagnosis for only six infants. There was only histological orientation for seven and no specific diagnostic orientation for the last six. These difficulties have led us to propose an exploration process based on the literature. CONCLUSION: This study highlights difficulties in obtaining a diagnosis and a precise prognosis for floppy ventilated infants. An exploration-standardized process for infants suspected of congenital neuromuscular diseases was made in order to standardize procedures. It could be used as a tool for all professionals involved.

Partial acute transverse myelitis is a predictor of multiple sclerosis in children.

BACKGROUND: Acute transverse myelitis (ATM) in children is a rare and often severe disease for which there are few known prognostic factors, particularly the subsequent risk of multiple sclerosis (MS) diagnosis. OBJECTIVES: To determine the clinical course and prognostic factors after a first episode of ATM in children. METHODS: Thirty children below 16 years of age diagnosed with a first neurological episode of ATM were included retrospectively. Clinical evaluation, treatment, laboratory, and MRI data were collected. RESULTS: Median age at onset was 11 years (range 3-15 years). Follow-up data were available for a median of 4 years (range 0.5-16.7 years). Five patients subsequently had a diagnosis of MS (17%), which was associated with acute partial transverse myelitis (odds ratio 5; 95% confidence interval 2.3-11), with a 60% probability of having a relapse at five years (p < 0.01). The 2011 Verhey criteria correctly identified MS in children with the highest specificity (96%) and sensitivity (80%). CONCLUSION: Acute partial transverse myelitis and brain MRI abnormalities at initial presentation are significantly predictive of a subsequent diagnosis of MS in children with ATM. These findings suggest that closer brain MRI monitoring after acute partial transverse myelitis might make the earlier introduction of disease-modifying therapies possible.