Diagnosis Of Neuromuscular Diseases Research Articles

G.P.196 - Quantifiable diagnosis of neuromuscular diseases through network analysis

G.P.196 - Quantifiable diagnosis of neuromuscular diseases through network analysis

Expanding genotype/phenotype of neuromuscular diseases by comprehensive target capture/NGS

Objective:To establish and evaluate the effectiveness of a comprehensive next-generation sequencing (NGS) approach to simultaneously analyze all genes known to be responsible for the most clinically and genetically heterogeneous neuromuscular diseases (NMDs) involving spinal motoneurons, neuromuscular junctions, nerves, and muscles.Methods:All coding exons and at least 20 bp of flanking intronic sequences of 236 genes causing NMDs were enriched by using SeqCap EZ solution-based capture and enrichment method followed by massively parallel sequencing on Illumina HiSeq2000.Results:The target gene capture/deep sequencing provides an average coverage of ∼1,000× per nucleotide. Thirty-five unrelated NMD families (38 patients) with clinical and/or muscle pathologic diagnoses but without identified causative genetic defects were analyzed. Deleterious mutations were found in 29 families (83%). Definitive causative mutations were identified in 21 families (60%) and likely diagnoses were established in 8 families (23%). Six families were left without diagnosis due to uncertainty in phenotype/genotype correlation and/or unidentified causative genes. Using this comprehensive panel, we not only identified mutations in expected genes but also expanded phenotype/genotype among different subcategories of NMDs.Conclusions:Target gene capture/deep sequencing approach can greatly improve the genetic diagnosis of NMDs. This study demonstrated the power of NGS in confirming and expanding clinical phenotypes/genotypes of the extremely heterogeneous NMDs. Confirmed molecular diagnoses of NMDs can assist in genetic counseling and carrier detection as well as guide therapeutic options for treatable disorders.

An Overview of Laryngeal Muscle Single Fiber Electromyography.

Needle electromyography is an important tool in the diagnosis of neuromuscular diseases and has also been applied successfully in the evaluation of the vocal cord paralysis. Laryngeal electromyography, initially described by Weddell, is used to determine the cause of vocal cord paralysis and to differentiate organic from nonorganic causes of speech disorders. This test allows the diagnosis of lower motor neuron and nerve paralysis as well as myopathies. Laryngeal electromyography also helps to determine the prognosis of paralysis caused by traumatic injury of the laryngeal nerves and is used for guidance during botulinum toxin injection in spasmodic dysphonias. Single fiber electromyography is used to diagnose abnormalities of neuromuscular transmission and is applied in the study the architecture of the motor unit in muscles. This article reviews the techniques of laryngeal muscles single fiber electromyography, provides limited informative data, and discusses its potential value in the evaluation of patients with dysphonia.

Spatially distributed surface electromyography signal simulator.

Electromyographic signals are of great importance to current biomedical research society since they may be used in several ways as, for example, in the diagnosis of neuromuscular diseases, the control of active prosthetic limbs as well as the test and validation of medical equipment.

DIAGNOSTIC OPPORTUNITIES OF MUSCLE MRI IN NEUROMUSCULAR DISORDERS

Considerable clinical and genetic heterogeneity of neuromuscular disorders poses a significant challenge for their diagnosis. Unfortunately in Russia, morphologists use very limited amount of immunohistochemical techniques in analysis of muscle biopsy, and such method as quantified protein western blotting is not used at all. This situation does not facilitate provisional diagnosis, that later could be confirmed genetically. One of the modern diagnostic methods is muscle MRI. We examined 231 patients with suspicion on neuromuscular disorder using muscle MRI. Muscle MRI with following genetic examination able to establish the correct diagnosis in 125 cases (54.1%). Muscle MRI allowed to diagnose such neuromuscular diseases as Duchenne muscular dystrophy, Bethlem myopathy, Emery-Dreifuss muscular dystrophy, LGMD 2A ( с alpainopathy) and LGMD 2B (dysferinopathy). We revealed the special diagnostic pattern of skeletal muscles degeneration in lower extremities for each of above mentioned diseases. In 57 (24.7%) patients the diagnosis of neuromuscular disease was withdrawn due to complete absence of degenerative changes and in 49 (21.4%) patients we found nonspecific degenerative changes in the muscles that gave us various differential diagnostic algorithms. In conclusion, we consider MRI of thigh and calf muscles as a highly informative tool for patients with neuromuscular disorders that can be used not only for diagnostic purposes, but also for assess of progression of muscle degeneration.

Respiratory muscle training in children and adults with neuromuscular disease

Respiratory muscle training in children and adults with neuromuscular disease

Ocorrência do SNP c.767G>T no gene DNM1responsável pelo colapso induzido pelo exercício em cães da raça Labrador Retriever no Estado de São Paulo

Resumo:O colapso induzido pelo exercício (EIC) é considerado uma síndrome autossômica recessiva que afeta principalmente cães da raça Labrador Retriever. A doença é caracterizada por fraqueza muscular e colapso após exercício intenso. Usualmente, ocorre recuperação clínica após o episódio, mas alguns animais podem vir a óbito. Os sinais clínicos são decorrentes do polimorfismo de base única (SNP) c.767G>T no gene Dynamin 1 (DNM1). O objetivo deste trabalho foi determinar a ocorrência deste SNP em 321 cães da raça Labrador Retriever do Estado de São Paulo. Primers específicos para a amplificação de todo o exon 6 do gene DNM1 foram usados nas PCRs utilizando DNA a partir de amostras de sangue ou swab bucal, a avaliação final foi realizada com sequenciamento direto dos produtos da PCR. Dentre os 321 animais estudados, 3,4 % (11/321) eram homozigotos para o SNP c.767G>T no gene DNM1 e 24,6% (79/321) eram heterozigotos. Somente um dos 11 animais homozigotos apresentavam sinais clínicos compatíveis com a EIC. Este é o primeiro estudo sobre a ocorrência deste SNP no Brasil e considerando que quase 25% dos animais estudados eram heterozigotos, a genotipagem dos animais para este SNP pode ser importante antes dos acasalamentos para cães desta raça. A EIC deve ser considerada nos diagnósticos diferenciais de enfermidades neuromusculares em cães da raça Labrador Retriever.

Novel pathogenic variants and genes for myopathies identified by whole exome sequencing.

Neuromuscular diseases (NMD) account for a significant proportion of infant and childhood mortality and devastating chronic disease. Determining the specific diagnosis of NMD is challenging due to thousands of unique or rare genetic variants that result in overlapping phenotypes. We present four unique childhood myopathy cases characterized by relatively mild muscle weakness, slowly progressing course, mildly elevated creatine phosphokinase (CPK), and contractures. We also present two additional cases characterized by severe prenatal/neonatal myopathy. Prior extensive genetic testing and histology of these cases did not reveal the genetic etiology of disease. Here, we applied whole exome sequencing (WES) and bioinformatics to identify likely causal pathogenic variants in each pedigree. In two cases, we identified novel pathogenic variants in COL6A3. In a third case, we identified novel likely pathogenic variants in COL6A6 and COL6A3. We identified a novel splice variant in EMD in a fourth case. Finally, we classify two cases as calcium channelopathies with identification of novel pathogenic variants in RYR1 and CACNA1S. These are the first cases of myopathies reported to be caused by variants in COL6A6 and CACNA1S. Our results demonstrate the utility and genetic diagnostic value of WES in the broad class of NMD phenotypes.

A practice of caution: spontaneous action potentials or artifactual spikes?

BackgroundHigh density surface electromyogram (EMG) techniques with electrode arrays have been used to record spontaneous muscle activity, which is important, both for supporting the diagnosis of neuromuscular diseases and for laboratory based neurophysiological investigations. This short report addresses a practical issue we have experienced during recording of spontaneous muscle activity using electrode arrays from subjects with major neuromuscular disorders.FindingsWe show that recording artifacts can appear similar to spontaneous action potential spikes. Moreover, a causal filter may induce asymmetric distortions of an artifact and thus confuse it with a real action potential spike. As a consequence, for a single channel surface EMG recording, it might be difficult to judge whether a voltage transient is a real action potential or an artifact. Further investigation of the signal distributions among other channels of the array can be used to reach a more confident judgment.ConclusionsDuring examination of spontaneous muscle activity using electrode arrays, caution is required for differentiation of physiological signals from artifactual spikes, which is important for accurate extraction of diagnostic or investigatory information.

A comprehensive genomic approach for neuromuscular diseases gives a high diagnostic yield.

Neuromuscular diseases (NMDs) are a group of >200 highly genetically as well as clinically heterogeneous inherited genetic disorders that affect the peripheral nervous and muscular systems, resulting in gross motor disability. The clinical and genetic heterogeneities of NMDs make disease diagnosis complicated and expensive, often involving multiple tests. To expedite the molecular diagnosis of NMDs, we designed and validated several next generation sequencing (NGS)-based comprehensive gene panel tests that include complementary deletion and duplication testing through comparative genomic hybridization arrays. Our validation established the targeted gene panel test to have 100% sensitivity and specificity for single nucleotide variant detection. To compare the clinical diagnostic yields of single gene (NMD-associated) tests with the various NMD NGS panel tests, we analyzed data from all clinical tests performed at the Emory Genetics Laboratory from October 2009 through May 2014. We further compared the clinical utility of the targeted NGS panel test with that of exome sequencing (ES). We found that NMD comprehensive panel testing has a 3-fold greater diagnostic yield (46%) than single gene testing (15-19%). Sanger fill-in of low-coverage exons, copy number variation analysis, and thorough in-house validation of the assay all complement panel testing and allow the detection of all types of causative pathogenic variants, some of which (about 18%) may be missed by ES. Our results strongly indicate that for molecular diagnosis of heterogeneous disorders such as NMDs, targeted panel testing has the highest clinical yield and should therefore be the preferred first-tier approach.

Ultrasound texture-based CAD system for detecting neuromuscular diseases.

Diagnosis of neuromuscular diseases in ultrasonography is a challenging task since experts are often unable to discriminate between healthy and pathological cases. A computer-aided diagnosis (CAD) system for skeletal muscle ultrasonography was developed and tested for myositis detection in ultrasound images of biceps brachii. Several types of features were extracted from rectangular and polygonal image regions-of-interest (ROIs), including first-order statistics, wavelet-based features, and Haralick's features. Features were chosen that are sensitive to the change in contrast and structure for pathological ultrasound images of neuromuscular diseases. The number of features was reduced by applying different sequential feature selection strategies followed by a supervised principal component analysis. For classification, two linear approaches were investigated: Fisher's classifier and the linear support vector machine (SVM) as well as the nonlinear [Formula: see text]-nearest neighbor approach. The CAD system was benchmarked on datasets of 18 subjects, seven of which were healthy, while 11 were affected by myositis. Three expert radiologists provided pre-classification and testing interpretations. Leave-one-out cross-validation on the training data revealed that the linear SVM was best suited for discriminating healthy and pathological muscle tissue, achieving 85/87 % accuracy, 90 % sensitivity, and 83/85 % specificity, depending on the radiologist. A muscle ultrasonography CAD system was developed, allowing a classification of an ultrasound image by one-click positioning of rectangular ROIs with minimal user effort. The applicability of the system was demonstrated with the challenging example of myositis detection, showing highly accurate results that were robust to imprecise user input.

Colapso induzido pelo exercício em um Labrador Retriever

The exercise-induced collapse (EIC) is a hereditary disease characterized by muscle weakness, impaired locomotion and collapse after intense exercise. This autossomic recessive disorder affects mainly Labrador Retriever presenting the mutation c.767G>T in the dynamin 1 (DNM1) gene. The objective of this study is to report the first case of exercise-induced collapse in Labrador Retriever in Brazil. The molecular test detected the specific genetic mutation and confirmed the clinical diagnosis in a Labrador Retriever with clinical history of weakness and collapse after exercise. It is important to include this disease as part of the differential diagnosis of neuromuscular diseases in Labrador Retriever and use the molecular test to guide matings.

Autosomal recessive limb-girdle muscular dystrophies in the Czech Republic.

BackgroundAutosomal recessive limb-girdle muscular dystrophies (LGMD2) include a number of disorders with heterogeneous etiology that cause predominantly weakness and wasting of the shoulder and pelvic girdle muscles. In this study, we determined the frequency of LGMD subtypes within a cohort of Czech LGMD2 patients using mutational analysis of the CAPN3, FKRP, SGCA, and ANO5 genes.MethodsPCR-sequencing analysis; sequence capture and targeted resequencing.ResultsMutations of the CAPN3 gene are the most common cause of LGMD2, and mutations in this gene were identified in 71 patients in a set of 218 Czech probands with a suspicion of LGMD2. Totally, we detected 37 different mutations of which 12 have been described only in Czech LGMD2A patients. The mutation c.550delA is the most frequent among our LGMD2A probands and was detected in 47.1% of CAPN3 mutant alleles. The frequency of particular forms of LGMD2 was 32.6% for LGMD2A (71 probands), 4.1% for LGMD2I (9 probands), 2.8% for LGMD2D (6 probands), and 1.4% for LGMD2L (3 probands).Further, we present the first results of a new approach established in the Czech Republic for diagnosis of neuromuscular diseases: sequence capture and targeted resequencing. Using this approach, we identified patients with mutations in the DYSF and SGCB genes.ConclusionsWe characterised a cohort of Czech LGMD2 patients on the basis of mutation analysis of genes associated with the most common forms of LGMD2 in the European population and subsequently compared the occurrence of particular forms of LGMD2 among countries on the basis of our results and published studies.

Assessing fractal dimension methods as feature extractors for EMG signal classification

The study of electromyographic (EMG) signals has gained increased attention in the last decades since the proper analysis and processing of these signals can be instrumental for the diagnosis of neuromuscular diseases and the adaptive control of prosthetic devices. As a consequence, various pattern recognition approaches, consisting of different modules for feature extraction and classification of EMG signals, have been proposed. In this paper, we conduct a systematic empirical study on the use of Fractal Dimension (FD) estimation methods as feature extractors from EMG signals. The usage of FD as feature extraction mechanism is justified by the fact that EMG signals usually show traces of self-similarity and by the ability of FD to characterize and measure the complexity inherent to different types of muscle contraction. In total, eight different methods for calculating the FD of an EMG waveform are considered here, and their performance as feature extractors is comparatively assessed taking into account nine well-known classifiers of different types and complexities. Results of experiments conducted on a dataset involving seven distinct types of limb motions are reported whereby we could observe that the normalized version of the Katz׳s estimation method and the Hurst exponent significantly outperform the others according to a class separability measure and five well-known accuracy measures calculated over the induced classifiers.

Evaluation of simultaneous muscle and nerve biopsies for the diagnosis of neuromuscular diseases.

Skeletal muscle and peripheral nerve are occasionally simultaneously biopsied with the goal of increasing diagnostic yield in patients with an uncertain clinical diagnosis or in cases where the pathology is known to be focal or multifocal (eg, vasculitis or amyloidosis). The purpose of the present study is to evaluate the diagnostic utility of performing simultaneous muscle and nerve biopsies. A surgical pathology database was searched from 1993 to 2011 to identify patients who had concomitant skeletal muscle and peripheral nerve biopsies. Demographic and pathologic findings were recorded for all cases. Two hundred eighty-seven patients were included for study. There were 161 (56%) males and 126 (44%) females with a mean age at the time of biopsy of 51 years. The most commonly sampled sites were gastrocnemius muscle (n=186, 65%) and sural nerve (n=264, 92%). Most cases (n=166, 58%) were found to have a definitive diagnosis in either muscle or nerve. Of the cases with definitive diagnoses, 44 (27%) were based off the muscle only, 100 (60%) off the nerve only, and 22 (13%) had a definitive diagnosis in both the muscle and nerve. The most common diagnoses made on muscle biopsy alone were denervation atrophy (n=34) and inflammatory myopathy (n=7). The most common diagnosis made on nerve biopsy alone was a moderate or greater degree of axonal loss (n=82). Vasculitis was found in muscle in 2 cases, in the nerve in 14 cases, and both muscle and nerve in 4 cases. Amyloidosis was exclusive to muscle in no cases, was seen in nerve only in 1 case, and was found in both muscle and nerve in 4 cases. Performing simultaneous muscle and nerve biopsies can improve diagnostic yield (from 8% to 58% in the current study).

P440: Determining new features for diagnosis of neuromuscular diseases

P440: Determining new features for diagnosis of neuromuscular diseases

Diagnosis of neuromuscular diseases using a novel questionnaire and data mining applications. Science or fiction?

Diagnosis of neuromuscular diseases using a novel questionnaire and data mining applications. Science or fiction?

Sonographic Evaluation of the Peripheral Nerves in Hereditary Neuropathy With Liability to Pressure Palsies: A Case Report

Hereditary neuropathy with liability to pressure palsies (HNPP) is an autosomal dominantly inherited disorder that affects peripheral nerves by repeated focal pressure. HNPP can be diagnosed by clinical findings, electrodiagnostic studies, histopathological features, and genetic analysis. Ultrasonography is increasingly used for the diagnosis of neuromuscular diseases; however, sonographic features of HNPP have not been clearly defined. We report the sonographic findings and comparative electrodiagnostic data in a 73-year-old woman with HNPP, confirmed by genetic analysis. The cross-sectional areas of peripheral nerves were enlarged at typical nerve entrapment sites, but enlargement at non-entrapment sites was uncommon. These sonographic features may be helpful for diagnosis of HNPP when electrodiagnostic studies are suspicious of HNPP and/or gene study is not compatible.

The Challenge of Next Generation Sequencing in the Context of Neuromuscular Diseases

New genomic technologies, such as exome, whole-genome and transcriptome sequencing, are transforming the genetic diagnosis of neuromuscular diseases and dramatically accelerating the discovery of new disease-associated genes. The increasingly widespread availability of these technologies creates both opportunities and challenges for neuromuscular disease researchers. Here we survey the current literature on the application of new genomic technologies to the diagnosis of severe muscle diseases, with a focus on assessment of the approaches used for data processing, analysis and interpretation. We also highlight several key areas requiring improvement.

An intelligent model for two level diagnoses of neuromuscular diseases

In this paper, we have developed a intelligent model that performs two level diagnosis of neuromuscular diseases (NMDs) by using muscular, cognitive, psychological, internal lingual and EMG parameters. At first level, the NMDs are: muscular dystrophy, polymyositis, endocrine myopathy, metabolic myopathy, neuropathy, poliomyelitis and myasthenia gravis. These diseases are further classified in more specific diseases at second level. Data mining methods are used to obtain the important parameters/symptoms. A hierarchal rule base model is integrated with case base reasoning for calculating cumulative confidence factor (CCF) and confidence index. In addition to this a Bayesian network (BN) model is also developed for calculating the probability of occurrence of diseases and to make a comparative view of the results obtained by CCF and BN approaches.