EMG de fibre unique Bouhour, F.
Neurophysiologie clinique,
June 2019, 2019-06-00, 20190601, Letnik:
49, Številka:
3
Journal Article
Recenzirano
L’électromyographie de fibre unique (EMG-FU) a la réputation d’être une technique difficile, consommatrice de temps et d’interprétation délicate mais elle constitue cependant le test ...électrophysiologique le plus sensible pour les pathologies de la jonction neuromusculaire (JNM). Elle permet également l’étude de la densité et de la morphologie des unités motrices utiles dans diverses pathologies neuromusculaires.
Son principe repose sur le recueil par une électrode-aiguille concentrique des potentiels synchrones de 2 fibres musculaires appartenant à la même unité motrice. L’ EMG-FU est effectuée soit lors d’une contraction modérée soit par stimulation axonale dans le muscle frontal ou orbiculaire de l’œil, ou dans l’extenseur des doigts. Le jitter est la variabilité de survenue des potentiels, au niveau de la surface de recueil de l’électrode, d’une décharge à l’autre. L’augmentation du jitter est souvent d’origine jonctionnelle (pathologie de la JNM, jonctions immatures lors des processus de réinnervation) mais peut aussi témoigner d’une conduction instable dans les nerfs moteurs et les fibres musculaires.
L’EMG de FU a un intérêt diagnostique dans les atteintes de la JNM avec une sensibilité de 80 % dans la myasthénie. Le syndrome de Lambert Eaton se caractérise par une variation du jitter en fonction de la fréquence de stimulation lors d’un EMG-FU stimulé. L’étude du jitter a un intérêt pronostique car semble corrélé à la sévérité de la myasthénie. L’EMG de FU est aussi pathologique dans le syndrome de Miller Fisher (lié à une origine jonctionnelle du déficit moteur ?) et dans l’ophtalmoplégie externe progressive d’origine mitochondriale.
Myasthenia gravis and pregnancy Roche, P.; Bouhour, F.
Revue neurologique,
March 2021, 2021-Mar, 2021-03-00, Letnik:
177, Številka:
3
Journal Article
Recenzirano
Myasthenia gravis is an autoimmune disease characterised by fluctuating muscle weakness, which worsens during activity. It affects particularly scapular and pelvic girdles, axial and bulbar muscles. ...Myasthenia gravis is twice more frequent in women and symptoms often appear in the second and third decade of life. Thus, a growing number of women affected by this condition become pregnant. To minimise the effects of myasthenia gravis on pregnancy and the newborn, and to avoid myasthenia crisis in the post-partum, the pregnancy must be planned as far as possible. During pregnancy, treatment must be reviewed due to the threat of teratogenic effects (mycophenolate mofetil, rituximab), and the follow-up must be multidisciplinary.
Background and purpose
Hypertrophy/signal hyperintensity and/or gadolinium enhancement of plexus structures on magnetic resonance imaging (MRI) are observed in two‐thirds of cases of typical chronic ...inflammatory demyelinating polyneuropathy (CIDP). The objective of our study was to determine the additional benefit of plexus MRI in patients referred to tertiary centers with baseline clinical and electrophysiological characteristics suggestive of typical or atypical CIDP.
Methods
A total of 28 consecutive patients with initial suspicion of CIDP were recruited in nine centers and followed for 2 years. Plexus MRI data from the initial assessment were reviewed centrally. Physicians blinded to the plexus MRI findings established the final diagnosis (CIDP or neuropathy of another cause). The proportion of patients with abnormal MRI was analyzed in each group.
Results
Chronic inflammatory demyelinating polyneuropathy was confirmed in 14 patients (50%), as were sensorimotor CIDP (n = 6), chronic immune sensory polyradiculoneuropathy (n = 2), motor CIDP (n = 1) and multifocal acquired demyelinating sensory and motor neuropathy (n = 5). A total of 37 plexus MRIs were performed (17 brachial, 19 lumbosacral and 8 in both localizations). MRI was abnormal in 5/37 patients (14%), all of whom were subsequently diagnosed with CIDP 5/14(36%), after an atypical baseline presentation. With plexus MRI results masked, non‐invasive procedures confirmed the diagnosis of CIDP in all but one patient 1/14 (7%). Knowledge of the abnormal MRI findings in the latter could have prevented nerve biopsy being performed.
Conclusion
Systematic plexus MRI in patients with initially suspected CIDP provides little additional benefit in confirming the diagnosis of CIDP.
Un split hand index (SHI) (APB×FDI/ADM) inférieur à 5,2 été proposé récemment comme paramètre électrophysiologique simple permettant de différencier la SLA de populations contrôles.
Valider ce seuil ...pathologique dans une cohorte de patients SLA suivis au centre de Lyon en le comparant à une population contrôle. Évaluer si une asymétrie entre le SHI droit et le SHI gauche (aSHI) pourrait précéder la diminution du SHI en dessous du seuil pathologique retenu.
Calcul du SHI et de l’aSHI (ΔSHI/SHImax×100) aux membres supérieurs chez 21 patients atteints de SLA et 30 témoins.
Le SHI est significativement plus petit chez les patients SLA (3 vs 14, p<0,05). Pour un seuil à 5,2, la sensibilité du SHI pour le diagnostic de SLA était de 80 % et la spécificité de 100 %. Le aSHI moyen était plus élevé (36 % chez les patients SLA vs 20 % chez les témoins, p<0,05). Un seuil de 50 % présente une sensibilité de 42 % et une spécificité de 96 % pour le diagnostic de SLA. Ce seuil retenu permet de reclasser comme pathologique 1 patient SLA sur 21 ayant un SHI>5,2 aux 2 membres supérieurs. La combinaison des deux seuils permet d’augmenter la sensibilité à 85 %.
Confirmation qu’un SHI inférieur à 5,2 présente une sensibilité et une spécificité satisfaisante pour différencier la SLA de contrôles. L’aSHI pourrait être une mesure complémentaire utile au début de la maladie nécessitant d’être validée en comparaison à des diagnostics différentiels de la SLA.
Mutations in one of the five eukaryotic initiation factor 2B genes (EIF2B1-5) were first described in childhood ataxia with cerebral hypomyelination—vanishing white matter syndrome. The syndrome is ...characterized by (i) cerebellar and pyramidal signs in children aged 2–5 years; (ii) extensive cavitating leucoencephalopathy; and (iii) episodes of rapid deterioration following stress. Since then a broad clinical spectrum from congenital to adult-onset forms has been reported, leading to the concept of eIF2B-related disorders. Our aim was to describe clinical and brain magnetic resonance imaging characteristics, genetic findings and natural history of patients with adult-onset eIF2B-related disorders (after age 16). The inclusion criteria were based on the presence of eIF2B mutations and a disease onset after the age of 16 years. One patient with an asymptomatic diagnosis (age 16 years) was also included. Clinical and magnetic resonance findings were retrospectively recorded in all patients. All patients were examined to assess clinical evolution, using functional, pyramidal, cerebellar and cognitive scales. This multi-centric study included 16 patients from 14 families. A sex ratio imbalance was noted (male/female = 3/13). The mean age of onset was 31.1 years (range 16–62). Initial symptoms were neurologic (n = 11), psychiatric (n = 2) and ovarian failure (n = 2). Onset of the symptoms was linked to a precipitating factor in 13% of cases that included minor head trauma and delivery. During follow-up (mean: 11.2 years, range 2–22 years) 12.5% of the patients died. Of the 14 survivors, 62% showed a decline in their cognitive functions, and 79% were severely handicapped or bedridden. One case remained asymptomatic. Stress worsened clinical symptoms in 38% of the patients. Magnetic resonance imaging findings consist of constant cerebral atrophy, extensive cystic leucoencephalopathy (81%), corpus callosum (69%) and cerebellar (38%) T2-weighted hyperintensities. All families except one showed mutations in the EIF2B5 gene. The recurrent p.Arg113His-eIF2Bɛ mutation was found in 79% of the 14 eIF2B-mutated families, mainly at a homozygous state. The family with a mutation in EIF2B2 had the relatively prevalent p.Glu213Gly mutation. eIF2B-related disorder is probably underestimated as an adult-onset inherited leucoencephalopathy. In this late-onset form, presentation ranges from neurologic symptoms to psychiatric manifestations or primary ovarian failure. Cerebral atrophy is constant, whereas the typical vanishing of the white matter can be absent. Functional and/or cognitive prognosis remains severe. Molecular diagnosis is facilitated for these forms by the screening of the two recurrent p.Arg113His-eIF2Bɛ and p.Glu213Gly-eIF2Bβ mutations, positive in 86% of cases.
•Recurrent Ig shortages require a responsible use.•Disability and impairment scales should be used regularly to assess Ig efficacy.•Treatment dependence should be evaluated throughout treatment.•The ...minimum effective dose should be adjusted throughout the disease course.
Treatment strategies in chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) must be adapted on a case-to-case basis. Validated and reproducible tools for monitoring treatment response are required at diagnosis, when initiating treatment and throughout follow-up. A task force of French neurologists, experts in neuromuscular disease reference centers, was assembled to provide expert advice on the management of typical CIDP with intravenous immunoglobulins (Ig), and to harmonize treatment practices in public and private hospitals. The task force also referred to the practical experience of treating CIDP with Ig at the diagnostic, induction and follow-up stages, including the assessment and management of Ig dependence, and following the recommendations of the French health agency.
Mutations in one of the 3 genes encoding collagen VI (COLVI) are responsible for a group of heterogeneous phenotypes of which Bethlem myopathy (BM) represents the milder end of the spectrum. ...Genotype-phenotype correlations and long-term follow-up description in BM remain scarce.
We retrospectively evaluated the long-term clinical evolution, and genotype-phenotype correlations in 35 genetically identified BM patients (23 index cases).
Nineteen patients showed a typical clinical picture with contractures, proximal weakness and slow disease progression while 11 presented a more severe evolution. Five patients showed an atypical presentation, namely a limb girdle muscle weakness in 2 and a congenital myopathy pattern with either no contractures, or only limited to ankles, in 3 of them. Pathogenic COL6A1-3 mutations were mostly missense or in frame exon-skipping resulting in substitutions or deletions. Twenty one different mutations were identified including 12 novel ones. The mode of inheritance was, autosomal dominant in 83% of the index patients (including 17% (N=4) with a de novo mutation), recessive in 13%, and undetermined in one patient. Skipping of exon 14 of COL6A1 was found in 35% of index cases and was mostly associated with a severe clinical evolution. Missense mutations were detected in 39% of index cases and associated with milder forms of the disease.
Long-term follow-up identified important phenotypic variability in this cohort of 35 BM patients. However, worsening of the functional disability appeared typically after the age of 40 in 47% of our patients, and was frequently associated with COL6A1 exon 14 skipping.
Pompe disease is a rare autosomal recessive muscle lysosomal glycogenosis, characterised by limb-girdle muscle weakness and frequent respiratory involvement. The French Pompe registry was created in ...2004 with the initial aim of studying the natural history of French patients with adult Pompe disease. Since the marketing in 2006 of enzyme replacement therapy (alglucosidase alfa, Myozyme®), the French Pompe registry has also been used to prospectively gather the biological and clinical follow-up data of all adult patients currently treated in France. This report describes the main clinical and molecular features, at the time of inclusion in the French registry, of 126 patients followed up in 21 hospital-based neuromuscular or metabolic centres. Sixty-five men and 61 women have been included in the registry. Median age at inclusion was 49 years, and the median age at onset of progressive limb weakness was 35 years. Fifty-five percent of the patients were walking without assistance, 24% were using a stick or a walking frame, and 21% were using a wheelchair. Forty-six percent of the patients needed ventilatory assistance, which was non-invasive in 35% of the cases. When performed, muscle biopsies showed specific features of Pompe disease in less than two-thirds of the cases, confirming the importance of acid alpha-glucosidase enzymatic assessment to establish the diagnosis. Molecular analysis detected the common c.-32-13T>G mutation, in at least one allele, in 90% of patients. The French Pompe registry is so far the largest country-based prospective study of patients with Pompe disease, and further analysis will be performed to study the impact of enzyme replacement therapy on the progression of the disease.
La maladie de Pompe est une glycogénose musculaire rare, de transmission autosomique récessive, caractérisée par une faiblesse des ceintures, fréquemment associée à une insuffisance respiratoire. Le registre français de la maladie de Pompe a été créé en 2004, avec pour objectif initial d’étudier l’histoire naturelle des patients atteints de la forme adulte de la maladie de Pompe. Depuis la commercialisation de l’enzymothérapie substitutive par alglucosidase alfa (Myozyme®) en 2006, le registre français de la maladie de Pompe a aussi permis le recueil de données cliniques et biologiques pour l’ensemble des patients adultes actuellement traités en France. Ce travail décrit les principales caractéristiques cliniques et moléculaires des 126 patients adultes, qui sont suivis dans 21 centres de référence de maladies neuromusculaires ou métaboliques. Soixante-cinq hommes et 61 femmes ont été inclus dans le registre. L’âge médian à l’inclusion était de 49ans ; l’âge médian du début de la faiblesse musculaire évolutive des ceintures était de 35ans. Soixante-cinq pour cent des patients pouvaient marcher sans aide, 24 % avaient recours à l’aide d’une canne ou d’un déambulateur, et 21 % avaient recours au fauteuil roulant. Quarante-six pour cent des patients avaient recours à une ventilation assistée, avec une ventilation non invasive dans 35 % des cas. La biopsie musculaire montrait des anomalies caractéristiques de la maladie de Pompe dans moins de deux tiers des cas, lorsqu’elle avait été pratiquée, confirmant ainsi l’importance du dosage enzymatique de l’activité alpha-glucosidase acide pour établir le diagnostic. Les analyses moléculaires ont permis de détecter la présence de la mutation commune c.-32-13T>G sur au moins un des deux allèles chez 90 % des patients. Le registre français de la maladie de Pompe a permis de constituer la plus grande cohorte de patients adultes atteints de cette maladie, et suivis de façon prospective, à l’échelle d’un pays. Des analyses complémentaires sont en cours afin d’étudier les effets de l’enzymothérapie substitutive sur l’évolution de la maladie.
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