Trends in incidence, prevalence, and mortality of neuromuscular disease in Ontario, Canada: A population-based retrospective cohort study (2003-2014)

Background

Population trends of disease prevalence and incidence over time measure burden of disease and inform healthcare planning. Neuromuscular disorders (NMD) affect muscle and nerve function with varying degrees of severity and disease progression.

Objective

Using health administrative databases we described trends in incidence, prevalence, and mortality of adults and children with NMD. We also explored place of death and use of palliative care.

Methods

Population-based (Ontario, Canada) cohort study (2003 to 2014) of adults and children with NMD identified using International Classification of Disease and health insurance billing codes within administrative health databases.

Results

Adult disease prevalence increased on average per year by 8% (95% confidence interval (CI) 6% to 10%, P <.001), with the largest increase in adults18-39 years. Childhood disease prevalence increased by 10% (95% CI 8% to 11%, P <.0001) per year, with the largest increase in children 0 to 5 years. Prevalence increased across all diagnoses except amyotrophic lateral sclerosis and spinal muscular atrophy for adults and all diagnoses for children. Adult incidence decreased by 3% (95% CI -4% to -2%, P <.0001) but incidence remained stable in children. Death occurred in 34,336 (18.5%) adults; 21,236 (61.8%) of whom received palliative care. Death occurred in 1,009 (5.6%) children; 507 (50.2%) of whom received palliative care. Mortality decreased over time in adults (odds ratio (OR) 0.86, 95% CI 0.86–0.87, P <.0001) and children (OR 0.79, 95% CI 0.76–0.82, P <.0001). Use of palliative care over time increased for adults (OR 1.18, 95% CI 1.09 to 1.28, P <.0001) and children (OR 1.22, 95% CI 1.20 to 1.23, P <.0001).

Conclusions

In both adults and children, NMD prevalence is rising and mortality rates are declining. In adults incidence is decreasing while in children it remains stable. This confirms on a population-based level the increased survival of children and adults with NMD.

A nomenclature and classification for the congenital myasthenic syndromes: preparing for FAIR data in the genomic era

BACKGROUND

Congenital myasthenic syndromes (CMS) are a heterogeneous group of inherited neuromuscular disorders sharing the common feature of fatigable weakness due to defective neuromuscular transmission. Despite rapidly increasing knowledge about the genetic origins, specific features and potential treatments for the known CMS entities, the lack of standardized classification at the most granular level has hindered the implementation of computer-based systems for knowledge capture and reuse. Where individual clinical or genetic entities do not exist in disease coding systems, they are often invisible in clinical records and inadequately annotated in information systems, and features that apply to one disease but not another cannot be adequately differentiated.

RESULTS

We created a detailed classification of all CMS disease entities suitable for use in clinical and genetic databases and decision support systems. To avoid conflict with existing coding systems as well as with expert-defined group-level classifications, we developed a collaboration with the Orphanet nomenclature for rare diseases, creating a clinically understandable name for each entity and placing it within a logical hierarchy that paves the way towards computer-aided clinical systems and improved knowledge bases for CMS that can adequately differentiate between types and ascribe relevant expert knowledge to each.

CONCLUSIONS

We suggest that data science approaches can be used effectively in the clinical domain in a way that does not disrupt preexisting expert classification and that enhances the utility of existing coding systems. Our classification provides a comprehensive view of the individual CMS entities in a manner that supports differential diagnosis and understanding of the range and heterogeneity of the disease but that also enables robust computational coding and hierarchy for machine-readability. It can be extended as required in the light of future scientific advances, but already provides the starting point for the creation of FAIR (Findable, Accessible, Interoperable and Reusable) knowledge bases of data on the congenital myasthenic syndromes.

Multicategory classification of 11 neuromuscular diseases based on microarray data using support vector machine

We applied multicategory machine learning methods to classify 11 neuromuscular disease groups and one control group based on microarray data. To develop multicategory classification models with optimal parameters and features, we performed a systematic evaluation of three machine learning algorithms and four feature selection methods using three-fold cross validation and a grid search. This study included 114 subjects of 11 neuromuscular diseases and 31 subjects of a control group using microarray data with 22,283 probe sets from the National Center for Biotechnology Information (NCBI). We obtained an accuracy of 100%, relative classifier information (RCI) of 1.0, and a kappa index of 1.0 by applying the models of support vector machines one-versus-one (SVM-OVO), SVM one-versus-rest (OVR), and directed acyclic graph SVM (DAGSVM), using the ratio of genes between categories to within-category sums of squares (BW) feature selection method. Each of these three models selected only four features to categorize the 12 groups, resulting in a time-saving and cost-effective strategy for diagnosing neuromuscular diseases. In addition, a gene symbol, SPP1 was selected as the top-ranked gene by the BW method. We confirmed relationships between the gene (SPP1) and Duchenne muscular dystrophy (DMD) from a previous study. With our models as clinically helpful tools, neuromuscular diseases could be classified quickly using a computer, thereby giving a time-saving, cost-effective, and accurate diagnosis.

Early stages of building a rare disease registry, methods and 2010 data from the Belgian Neuromuscular Disease Registry (BNMDR)

The Belgian Neuromuscular Disease Registry, commissioned in 2008, aims to collect data to improve knowledge on neuromuscular diseases and enhance quality health services for neuromuscular disease patients. This paper presents a clear outline of the strategy to launch a global national registry. All patients diagnosed with one of the predefined 62 neuromuscular disease groups and living in Belgium may be included in the yearly updated Registry. Basic core data is harvested through a newly designed web application by the six accredited neuromuscular reference centres. In 2010, 3,424 patients with a neuromuscular disorder were registered. The most prevalent disease group in the Registry is Hereditary Motor and Sensory Neuropathy, as similarly stated by other studies, albeit the prevalence in Belgium is five times lower: 6.5 per 100,000 in the north of Belgium, versus 17.0-41.0 per 100,000 in other areas of Europe. Very few patients were captured in the south of the country. With the aim to collect valuable epidemiological data, the registry targets to gather high quality data, that the sample to be representative of the population and that it be complete. The past 5 years of building the registry have improved its quality, albeit the consistent gap in data from the south of the country prevails, influencing the estimated prevalence of these diseases. To this day, the true burden of neuromuscular diseases in Belgium is not known but actions have been undertaken to address these issues.

Decreased variability of the 6-minute walk test by heart rate correction in patients with neuromuscular disease

Objective

The 6-minute walk test is widely used to assess functional status in neurological disorders. However, the test is subject to great inter-test variability due to fluctuating motivation, fatigue and learning effects. We investigated whether inter-test variability of the 6MWT can be reduced by heart rate correction.

Methods

Sixteen patients with neuromuscular diseases, including Facioscapulohumeral muscular dystrophy, Limb-girdle muscular dystrophy, Charcot-Marie-Tooths, Dystrophia Myotonica and Congenital Myopathy and 12 healthy subjects were studied. Patients were excluded if they had cardiac arrhythmias, if they received drug treatment for hypertension or any other medical conditions that could interfere with the interpretation of the heart rate and walking capability. All completed three 6-minute walk tests on three different test-days. Heart rate was measured continuously.

Results

Successive standard 6-minute walk tests showed considerable learning effects between Tests 1 and 2 (4.9%; P = 0.026), and Tests 2 and 3 (4.5%; P = 0.020) in patients. The same was seen in controls between Tests 1 and 2 (8.1%; P = 0.039)). Heart rate correction abolished this learning effect.

Conclusion

A modified 6-minute walk test, by correcting walking distance with average heart rate during walking, decreases the variability among repeated 6-minute walk tests, and should be considered as an alternative outcome measure to the standard 6-minute walk test in future clinical follow-up and treatment trials.

Turkish version of the Egen Klassifikation scale version 2: validity and reliability in the Turkish population

The Egen Klassifikation Scale version 2 (EK2) is an important functional ability assessment scale for nonambulant neuromuscular patients. We investigated the validity and reliability of the EK2 scale in Turkish Duchenne muscular dystrophy (DMD) and spinal muscular atrophy (SMA) patients. Forty-one patients were included in the study. An intra/interobserver reliability study of the EK2 scale as translated into Turkish was performed. The Brooke Functional Classification Scale (BFC) for Upper and Lower Extremities, 10-item Modified Barthel's Index for Activities of Daily Living (MBI), and Pulmonary Dysfunction Index (PDI) were used to investigate the validity of the Turkish version of the EK2 scale. Cronbach's alpha was 0.81 and ICC was 0.87 with a 95% confidence interval (r=0.92, p<0.01). There were positive, moderate correlations between the EK2 sum score and the BFC upper extremity level and between the EK2 sum score and the PDI, and a negative, moderate correlation between the EK2 sum score and the MBI (p≤0.01). The Turkish version of the EK2 scale was found to be highly reliable and valid.

Clustering gene expression regulators: new approach to disease subtyping

One of the main challenges in modern medicine is to stratify different patient groups in terms of underlying disease molecular mechanisms as to develop more personalized approach to therapy. Here we propose novel method for disease subtyping based on analysis of activated expression regulators on a sample-by-sample basis. Our approach relies on Sub-Network Enrichment Analysis algorithm (SNEA) which identifies gene subnetworks with significant concordant changes in expression between two conditions. Subnetwork consists of central regulator and downstream genes connected by relations extracted from global literature-extracted regulation database. Regulators found in each patient separately are clustered together and assigned activity scores which are used for final patients grouping. We show that our approach performs well compared to other related methods and at the same time provides researchers with complementary level of understanding of pathway-level biology behind a disease by identification of significant expression regulators. We have observed the reasonable grouping of neuromuscular disorders (triggered by structural damage vs triggered by unknown mechanisms), that was not revealed using standard expression profile clustering. For another experiment we were able to suggest the clusters of regulators, responsible for colorectal carcinoma vs adenoma discrimination and identify frequently genetically changed regulators that could be of specific importance for the individual characteristics of cancer development. Proposed approach can be regarded as biologically meaningful feature selection, reducing tens of thousands of genes down to dozens of clusters of regulators. Obtained clusters of regulators make possible to generate valuable biological hypotheses about molecular mechanisms related to a clinical outcome for individual patient.

[Muscle biopsy in children: Usefulness in 2012]

Muscle biopsy is a mainstay diagnostic tool for investigating neuromuscular disorders in children. We report the yield of pediatric muscle biopsy in a population of 415 children by a retrospective study of 419 biopsies performed between 1/01/2000 and 31/12/2009 in a neuropediatric department, including mitochondrial respiratory chain analysis for 87 children. Two hundred and fifty-five biopsies were from boys (61%) 164 from girls (39%). Their mean age at biopsy was 6.5years; 155 (37%) biopsies were obtained before the child was 5years old. Final histopathological diagnoses were: congenital myopathy (n=193, including 15 structural congenital myopathies); progressive muscular dystrophy (n=75 [18%] including 57 dystrophinopathies); congenital muscular dystrophy (n=17, including six primary merosinopathies); dermatomyositis (n=11); spinal muscular atrophy (n=9, including six atypical spinal muscular atrophies); metabolic myopathy (n=32, including 19 mitochondrial myopathies); encephalomyopathy (n=53 [13%], including 27 with a mitochondrial respiratory chain defect). Pathological diagnosis remained undetermined in 16 cases. In 184 patients (44%), the muscle biopsy revealed specific histopathological anomalies (dystrophic process; specific ultrastructural abnormalities; perifascicular atrophy; neurogenic atrophy; metabolic anomalies) enabling a precise etiological diagnosis. For 85% of progressive muscular dystrophies, the biopsy resulted in a genetic diagnosis after identification of the protein defect. In 15% of the congenital myopathies, histopathological anomalies focused attention on one or several genes. Concerning dystrophinopathies, quantification of dystrophin deficiency on the biopsy specimen contributed to the definition of the clinical phenotype: Duchenne, or Becker. In children with a myopathy, muscle biopsy is often indispensable to establish the etiological diagnosis. Based on the results from this series, muscle biopsy can provide a precise orientation in 45% of patients, leading to a genetic hypothesis.

Neuromuscular disease classification system

Diagnosis of neuromuscular diseases is based on subjective visual assessment of biopsies from patients by the pathologist specialist. A system for objective analysis and classification of muscular dystrophies and neurogenic atrophies through muscle biopsy images of fluorescence microscopy is presented. The procedure starts with an accurate segmentation of the muscle fibers using mathematical morphology and a watershed transform. A feature extraction step is carried out in two parts: 24 features that pathologists take into account to diagnose the diseases and 58 structural features that the human eye cannot see, based on the assumption that the biopsy is considered as a graph, where the nodes are represented by each fiber, and two nodes are connected if two fibers are adjacent. A feature selection using sequential forward selection and sequential backward selection methods, a classification using a Fuzzy ARTMAP neural network, and a study of grading the severity are performed on these two sets of features. A database consisting of 91 images was used: 71 images for the training step and 20 as the test. A classification error of 0% was obtained. It is concluded that the addition of features undetectable by the human visual inspection improves the categorization of atrophic patterns.

Validation of the ICF core set for neuromuscular diseases

BACKGROUND

Understanding of the consequences of a neuromuscular disease (NMD) can improve when a valid sample of disease-specific categories based on the International Classification of Functioning, Disabilities, and Health (ICF) is available.

OBJECTIVE

To examine the content validity of the initial ICF Core Set for neuromuscular diseases (NMDs). The initial ICF Core Set was developed for three chronic neurological diseases.

DESIGN

A qualitative method.

METHODS

To examine the content validity of the initial ICF Core Set for NMD, concepts in established disease-specific health-related Quality of Life Questionnaires (HRQOL) were compared with ICF categories. Next, the selected ICF categories were linked to the ICF categories in the initial ICF Core Set.

RESULTS

All concepts in the HRQOL questionnaires, except one body function concept, were covered by the initial ICF Core Set. However, the NMD Core Set reflects a broader scope concerning health problems than the concepts in the HRQOL questionnaires do, especially concerning the "Participation" and "Environmental Factors" components.

CONCLUSION

The NMD Core Set, as well as a measurement based on this Core Set, can contribute to a better understanding of the consequences of NMDs and can also serve as a basis for clinical practice, research, social security systems, and educational programs.

CLINICAL REHABILITATION IMPACT

The newly developed NMD Core Set can be a basis for enhancing the development of rehabilitation interventions and improving overall health care for patients with a NMD.

Multiresolution MUAPs decomposition and SVM-based analysis in the classification of neuromuscular disorders

This paper describes a new method for the classification of neuromuscular disorders based on the analysis of scalograms determined by the Symlet 4 wavelet technique. The approach involves isolating single motor unit action potentials (MUAPs), computing their scalograms, taking the maximum values of the scalograms in five selected scales, and averaging across MUAPs to give a single 5-dimensional feature vector per subject. After SVM analysis, the vector is reduced to a single decision parameter, called the Wavelet Index, allowing the subject to be assigned to one of three groups: myogenic, neurogenic or normal. The software implementation of the method described above created a tool supporting electromyographic (EMG) examinations. The method is characterized by a high probability for the accurate diagnosis of muscle state. The method produced 5 misclassifications out of 800 examined cases (total error of 0.6%).

Assessment of health-related quality of life, depression, and anxiety in slowly and rapidly progressive neuromuscular disorders

OBJECTIVES

To compare health-related quality of life (HRQoL) and psychosocial features in rapidly progressive neuromuscular disorders (RPNMD) and slowly progressive neuromuscular disorders (SPNMD) in adult ambulatory patients, to determine individual needs in 2 separate progression groups.

METHODS

Thirty-nine SPNMD patients and 46 RPNMD patients were recruited. The functional independence measurement (FIM) was employed to evaluate the functional status. For the assessment of depression, anxiety, and HRQoL, patients were requested to fill out a Beck Depression Inventory, State-Trait Anxiety Inventory, and the Nottingham Health Profile (NHP). This study was performed at the Department of Physical Therapy and Rehabilitation, Hacettepe University Faculty of Health Science, Ankara, Turkey between August and December 2009.

RESULTS

The FIM total score did not differ between the 2 groups. Only energy was significantly high (worse) among the dimensions of NHP in RPNMD patients. None of the other sub-items differed between the 2 patient groups. The SPNMD patients were more depressed than the RPNMD patients. The mean state and trait anxiety scores were significantly higher in SPNMD patients as well.

CONCLUSIONS

Significant depressive or anxious symptomatology is not associated with amyotrophic lateral sclerosis (ALS). The diagnosis of SPNMD should alert physicians in an equivalent promptness to ALS and possible depression or anxiety, and concerns of patients regarding the chronic, though slowly progressive course of the disease.

[A clinical approach in neuromuscular diseases in childhood]

The group of neuromuscular disorders includes disorders of the motor neurons in the medulla oblongata and myelon, the peripheral nerves, the neuromuscular junction, and of the muscle. Clinical manifestation varies from pre-/perinatal to adulthood. The prevalence of all neuromuscular disorders is about 1:1500. In the last years, knowledge of genetic defects in neuromuscular disorders has dramatically increased. This is due to an increase in knowledge of the underlying genetic defects. Hence the classification of the neuromuscular disorders is still changing. In clinical practice the history and the clinical examination of patients with suspected NMDs is very important in the correct selection of the necessary investigations. Many investigations are possible, but should be chosen according to the patient's symptoms. Careful interpretation of the results most often defines diagnosis. The aim of this article is to establish a work-up according to the patient's symptoms and problems in childhood.

Diagnostic value of the electromyography of the extraocular muscles

OBJECTIVE

The electromyography (EMG) of the extraocular muscles (EOM) represents a special form of electrophysiological investigation techniques which can be offered only in a few centers with special ophthalmologic and neurophysiologic expertise due to its special characteristics. The diagnostic value of the EOM-EMG is especially apparent in neuromuscular diseases which occur with predominantly ocular manifestation.

METHODS

Needle EMG examinations of EOM were performed in a cohort of 206 patients with a variety of relevant disorders mainly with a neurological focus. The results of these EMG examinations were assessed retrospectively. After local anaesthesia of the sclera and using a lid retractor to keep the eye open the EOM were identified visually by an experienced ophthalmologist and the needle was inserted. The EMG activity was registered in resting position, in mild volitional, and at maximum activation. The assessment was performed visually on a monitor by an experienced neurophysiologist.

RESULTS

In the group of neuromuscular (myopathic) diseases, the results of the EOM-EMG were compatible with the clinical diagnosis in 54 of 65 patients (83%) and in 69 of 85 patients (81%) in the group with peripheral lesions. In a "Varia" group (n=56) no diagnosis could be established despite all further investigations in 31 patients. In the remaining patients, the EOM-EMG result was compatible with the diagnosis in 22 of 25 patients (88%). Subgroup analysis revealed that particularly in myositis (30 of 33 findings in 32 patients, one patient was examined twice; 91%), muscle dystrophy (7 of 8 patients; 88%) and in isolated nerve lesions (64 of 79 patients; 81%) the diagnosis could be positively proven by the EOM-EMG. Clinically relevant complications were not observed.

CONCLUSIONS

The EOM-EMG is safe and has a high diagnostic value especially in diseases such as myositis, muscular dystrophy and isolated peripheral nerve lesions.

SIGNIFICANCE

With better knowledge of the diagnostic value of the EOM-EMG in various diseases, less relevant diagnostic investigations can be avoided in the future. Moreover, a higher degree of trust in the method should facilitate the decision to perform this special diagnostic method.

Neuromuscular complications of statins

Statins, 3-hydroxy-3-methlglutaryl coenzyme A reductase inhibitors, are commonly prescribed for patients who have hyperlipidemia. Statins were first approved in 1987. Statin therapy is well documented to reduce serum low-density lipoprotein levels, incidence of cardiovascular events, and mortality. Although statin therapy is well tolerated, serious adverse affects have been reported, including neuromuscular and hepatic complications. Myopathy is particularly concerning because of the potential for rhabdomyolysis and death. Recently, peripheral neuropathy also has been identified as a possible complication. The incidence of neuromuscular complications is expected to increase with the increased number of people using statin therapy. Clinicians should be aware of the potential neuromuscular complications. This article reviews epidemiology, possible mechanisms, risk factors, and management of statin-associated neuromuscular complications.

Prostatitis: Infection, neuromuscular disorder, or pain syndrome? Proper patient classification is key

Prostatitis is a broad term used to describe inflammation of the prostate that may be associated with a myriad of lower urinary tract symptoms and symptoms of sexual discomfort and dysfunction. The condition affects 5% to 10% of the male population and is the most common urologic diagnosis in men younger than 50 years. Prostatitis is classified into four categories, including acute and chronic bacterial forms, a chronic abacterial form, and an asymptomatic form. The bacterial forms are more readily recognized and treated, but symptoms in most affected men are not found to have an infectious cause. Indeed, chronic abacterial prostatitis (also known as chronic pelvic pain syndrome) is both the most prevalent form and also the least understood and the most challenging to evaluate and treat. This form of prostatitis may respond to non-prostate-centered treatment strategies such as physical therapy, myofascial trigger point release, and relaxation techniques. Because the various forms of prostatitis call for vastly different treatment approaches, appropriate evaluation, testing, and differential diagnosis are crucial to effective management.

The emerging diversity of neuromuscular junction disorders

Research advances over the last 30 years have shown that key transmembrane proteins at the neuromuscular junction are vulnerable to antibody-mediated autoimmune attack These targets are acetylcholine receptors (AChRs) and muscle specific kinase (MuSK) in myasthenia gravis, voltage-gated calcium channels (VGCCs) in the Lambert-Eaton myasthenic syndrome (LEMS), and voltage-gated potassium channels (VGKCs) in neuromyotonia. In parallel with these immunological advances, mutations identified in genes encoding pre-synaptic, synaptic and postsynaptic proteins that are crucial to neuromuscular transmission have revealed a similar diversity of congenital myasthenic syndromes (CMS). These discoveries have had a major impact on diagnosis and management.

Quantitative skeletal muscle ultrasound: diagnostic value in childhood neuromuscular disease

In this study we investigated the diagnostic value of quantitative skeletal muscle ultrasonography in 150 consecutively referred children with symptoms suspect for a neuromuscular disorder. Muscle thickness and quantitatively determined echo intensity of four muscles and the distribution of these variables within the body were examined.

RESULTS

Patients with and without a neuromuscular disorder could be discriminated with a positive predictive value of 91% and a negative predictive value of 86%. Patients with a neurogenic disorder could be distinguished from myopathies and non-neuromuscular disorders with a positive predictive value of 86% and a negative predictive of 84%, using the pattern of distribution of pathology within the body.

CONCLUSIONS

Skeletal muscle ultrasound is a good, practical and non-invasive aid in the diagnosis of neuromuscular disorders in children, that is able to discriminate between children with and without a neuromuscular disorder and between neurogenic disorders and myopathies with high predictive values.

Certification in neuromuscular medicine: A new neurologic subspecialty

Information is provided concerning the new subspecialty certificate in neuromuscular medicine of the American Board of Psychiatry and Neurology and the eligibility requirements for such certification of practicing neurologists and child neurologists. The Accreditation Council for Graduate Medical Education has approved fellowship training in the subspecialty, and it is likely that residents who wish to pursue a career in neuromuscular medicine will select this training option.

Different pattern of HSP47 expression in skeletal muscle of patients with neuromuscular diseases

Heat shock protein (HSP) 47, a collagen-specific molecular chaperone, is involved in the processing and secretion of procollagens, and its expression is increased in various fibrotic diseases. However, its involvement in muscle diseases is unknown. In this study, we analyzed HSP47 expression in muscular dystrophies and other muscle diseases. We found an overexpression of HSP47 in fibrous connective tissue and in the adjacent muscle membrane in various muscular dystrophies. However, in Ullrich congenital muscular dystrophy (UCMD), the overexpression of HSP47 was found only in the connective tissue, and not in the muscle membrane. The overexpression of HSP47 was found only in the muscle membrane in the case of active inflammatory myopathy. In particular, HSP47 was strongly expressed in the membrane of regenerating fibers. We found that HSP47 in the muscle membrane locates in the basement membrane with confocal microscopy. Our findings suggest that HSP47 may be involved in the repair or regeneration of muscle fibers in addition to the fibrotic change in the connective tissue.

RNA-MEDIATED NEUROMUSCULAR DISORDERS

Myotonic dystrophy type 1 (DM1) is caused by a CTG expansion mutation located in the 3' untranslated portion of the dystrophica myotonin protein kinase gene. The identification and characterization of RNA-binding proteins that interact with expanded CUG repeats and the discovery that a similar transcribed but untranslated CCTG expansion in an intron causes myotonic dystrophy type 2 (DM2) have uncovered a new type of mechanism in which microsatellite expansion mutations cause disease through an RNA gain-of-function mechanism. This review discusses RNA pathogenesis in DM1 and DM2 and evidence that similar mechanisms may play a role in a growing number of dominant noncoding expansion disorders, including fragile X tremor ataxia syndrome (FXTAS), spinocerebellar ataxia type 8 (SCA8), SCA10, SCA12, and Huntington's disease-like 2 (HDL2).

Mitochondrial respiratory chain dysfunction in various neuromuscular diseases

The mitochondrial respiratory chain function and the occurrence of mitochondrial respiratory chain dysfunction were determined in various neuromuscular diseases. The mitochondrial complexes I-V and citrate synthase in the skeletal muscle taken from 75 orthopaedic surgical patients excluding neuromuscular diseases (control subjects) and 26 patients with various neuromuscular diseases (7 patients with Duchenne muscular dystrophy, 3 patients with spinal muscular atrophy, 6 patients with mitochondrial diseases, 7 patients with type II fibre atrophy and 3 patients with neuropathy) were assayed. Of 26 patients, results of analysis of 3 patients (1 Duchenne muscular dystrophy, 1 spinal muscular atrophy and 1 type II fibre atrophy) were excluded because the citrate synthase activities in their muscle homogenate were less than third percentile of the normal controls. As compared to the control subjects by using Student's t-test, all studied groups of patients had significantly lower activities of more than one or two mitochondrial complexes (p<0.05). However, a significantly higher activity of mitochondrial complex I was observed in patients with mitochondrial diseases (p<0.05). These findings will require further study to elucidate the pathogenesis and role of secondary mitochondrial respiratory chain dysfunction in such neuromuscular diseases.

[A motor function measurement scale for neuromuscular diseases - description and validation study]

A new scale for motor function measurement has been developed for neuromuscular diseases. After the study of a preliminary and a first version, the validation study included 303 patients, aged 6 to 62 years. Seventy-two patients had Duchenne muscular dystrophy, 32 Becker muscular dystrophy, 30 limb-girdle muscular dystrophy, 39 facio-scapulo-humeral dystrophy, 29 myotonic dystrophy, 21 congenital myopathy, 10 congenital muscular dystrophy, 35 spinal muscular atrophy and 35 hereditary neuropathy. The sensitivity for change was evaluated with 152 patients one year after. The scale comprised 32 items, in three dimensions: standing position and transfers, axial and proximal motor function, distal motor function. High correlations (>0.80) were found between the total score and other scores: Vignos and Brooke grades, Functional Independence Measure, the global severity of disability evaluated with visual analog scales by physicians and physiotherapists. This scale is reliable, does not require any special equipment and is well accepted by patients. It takes an average of 36 min (range 8-75) to complete the scale. Preliminary results of the second evaluation showed good sensitivity to change since last visit, considering rating by patient, investigator or physiotherapist. Also, significant differences in scores are obtained with the greatest deterioration observed in Duchenne patients.

Neuromuscular Disorders in Clinical Practice: Case Studies

Neuromuscular disorders represent a large group of highly varied and interesting clinical disorders, many of which have major general medical manifestations. These disorders can be diagnosed largely based on the patient's history and physical examination with a little help from modern technology. Despite the outdated belief that neurologic conditions are diagnosed but rarely treatable, all cases discussed herein represent disorders for which there are extensive options and opportunities for meaningful management. These 16 brief case overviews challenge and refresh diagnostic skills and provide the framework for selected comments regarding management options.

Muscle imaging in clinical practice: diagnostic value of muscle magnetic resonance imaging in inherited neuromuscular disorders

PURPOSE OF REVIEW

This review reports on the use of muscle magnetic resonance imaging as a clinical and research tool in inherited neuromuscular disorders.

RECENT FINDINGS

Several papers published during the past few years have reported on the value of muscle magnetic resonance imaging in detecting patterns of muscle involvement in various muscular dystrophies and other inherited myopathies. The patterns of muscle involvement observed on muscle magnetic resonance imaging are often specific for distinct genetic entities.

SUMMARY

Our review of the literature suggests that muscle magnetic resonance imaging can provide information that is useful in clinical practice and may be used as an additional tool in a diagnostic flow chart to select appropriate genetic and biochemical investigations.

Syncoilin upregulation in muscle of patients with neuromuscular disease

Syncoilin may have a role in linking the desmin-associated intermediate filament network of the muscle fiber with the dystrophin-associated protein complex (DAPC). We have evaluated syncoilin in a range of neuromuscular disorders including Duchenne and Becker muscular dystrophy, central core disease, congenital muscular dystrophies, and neurogenic disorders. Our results show that syncoilin immunolabeling is not only altered in muscle fibers with alterations in the DAPC but also in response to a variety of genetic defects, including those associated with proteins of the extracellular matrix and the intracellular Ca2+-release channel (ryanodine receptor). The pattern of syncoilin immunolabeling in these diseases appeared to reflect a rearrangement of the intermediate filament-associated cytoskeleton that characterizes both muscle fiber development and conditions in which the cytoskeletal organization of the muscle fiber is significantly affected. These observations raise the possibility that mutations in the gene encoding for syncoilin may underlie some forms of muscle disease.

Facing the genetic heterogeneity in neuromuscular disorders: Linkage analysis as an economic diagnostic approach towards the molecular diagnosis

The identification of an ever increasing number of gene defects in patients with neuromuscular disorders has disclosed both marked phenotype and genotype variability and considerable disease overlap. In order to offer an economic strategy to characterise the molecular defect in patients with unclassified neuromuscular disorders, we designed DNA marker sets for linkage analysis of 62 distinct neuromuscular disorders gene loci, including all known muscular dystrophies, congenital myopathies, congenital myasthenic syndromes and myotonias. Genotyping of marker loci of 140 clinically well-characterised families with unclassified neuromuscular disorders reduced the number of candidates to one or two genes in 49 % of the families. Subsequent mutation analysis and genome-wide scans enabled the determination of the genetic defect in 31 % of the families including the identification of a new gene and a new mutation in an unexpected candidate gene. This highlights the effective application of this approach both for diagnostic strategies as well as for the identification of new loci and genes.

Cognitive impairment in neuromuscular disorders

Several studies have suggested the presence of central nervous system involvement manifesting as cognitive impairment in diseases traditionally confined to the peripheral nervous system. The aim of this review is to highlight the character of clinical, genetic, neurofunctional, cognitive, and psychiatric deficits in neuromuscular disorders. A high correlation between cognitive features and cerebral protein expression or function is evident in Duchenne muscular dystrophy, myotonic dystrophy (Steinert disease), and mitochondrial encephalomyopathies; direct correlation between tissue-specific protein expression and cognitive deficits is still elusive in certain neuromuscular disorders presenting with or without a cerebral abnormality, such as congenital muscular dystrophies, congenital myopathies, amyotrophic lateral sclerosis, adult polyglucosan body disease, and limb-girdle muscular dystrophies. No clear cognitive deficits have been found in spinal muscular atrophy and facioscapulohumeral dystrophy.

Camptocormia: pathogenesis, classification, and response to therapy

Originally considered a psychogenic disorder, camptocormia, an abnormal posture with marked flexion of thoracolumbar spine that abates in the recumbent position, is becoming an increasingly recognized feature of parkinsonian and dystonic disorders. Prior reports were limited by sample size, short follow-up, and paucity of data on response to therapy. The authors reviewed 16 patients evaluated in their PD Center and Movement Disorders Clinic diagnosed with camptocormia. In addition to detailed neurologic assessment all patients were videotaped. The mean age was 64.9 +/- 17.4 years, mean age at onset of neurologic symptoms was 51.5 +/- 19.9 years, duration from onset of neurologic symptoms to development of camptocormia was 6.7 +/- 7.6 years, and the mean duration of camptocormia was 4.5 +/- 3.9 years. Of the 16 patients, 11 (68.8%) had Parkinson disease (PD); others had dystonia (n = 4) and Tourette syndrome (n = 1). Twelve patients received levodopa, with minimal or no improvement in the camptocormia. Nine patients received botulinum toxin type A injections into the rectus abdominus, with notable improvement in their camptocormia in four. One patient underwent bilateral subthalamic nucleus deep brain stimulation for PD, but there was no improvement in camptocormia. Based on this series and a thorough review of the literature of camptocormia, head drop, and bent spine syndrome, the authors propose etiologic classification of camptocormia and conclude that this heterogeneous disorder has multiple etiologies and variable response to systemic and local therapies.

[Neuromuscular diseases 2: muscular dystrophies (MD)]

Traditionally, muscular dystrophies (MDs) are progressive, hereditary, and primarily degenerative myopathies. Nowadays, due to molecular biology, MDs are looked upon as clinically and genetically heterogeneous myopathies characterized by protein defects of muscle tissue resulting most often in muscle weakness. They are caused by gene mutations leading to a decrease of structural proteins or enzymes. The site of the primary defect and the protein function are different. The disorders are defined according to the underlying protein defect (dystrophinopathy, calpainopathy, and others). The gene or gene product are not yet known in all forms of MD (for example, facioscapulohumeral muscular dystrophy). Therefore, the nomenclature based on the protein defects and the term MD are used concurrently. Clinical symptoms, pathogenesis, diagnosis, therapy, prognosis, and possible prevention of the more frequent MDs are discussed: dystrophinopathies (Duchenne, Becker type), Emery-Dreifuss syndrome (3 forms), facioscapulohumeral MD, limb-girdle MD (17 forms), myotonic dystrophies (2 forms), and congenital MD (11 forms). This article highlights the significance of molecular analyses and the possible multisystemic symptoms in these myopathies.

Autoimmune muscular pathologies

The T cell-mediated mechanism responsible for Polymyositis and inclusion Body Myositis and the complement-mediated microangiopathy associated with Dermatomyositis are reviewed. The management of autoimmune myopathies with the presently available immunotherapeutic agents as well as new therapies and ongoing trials are discussed.

A motor function measure scale for neuromuscular diseases. Construction and validation study

A new scale for motor function measurement has been developed for neuromuscular diseases. The validation study included 303 patients, aged 6-62 years. Seventy-two patients had Duchenne muscular dystrophy, 32 Becker muscular dystrophy, 30 limb-girdle muscular dystrophy, 39 facio-scapulo-humeral dystrophy, 29 myotonic dystrophy, 21 congenital myopathy, 10 congenital muscular dystrophy, 35 spinal muscular atrophy and 35 hereditary neuropathy. The scale comprised 32 items, in three dimensions: standing position and transfers, axial and proximal motor function, distal motor function. Agreement coefficients for inter-rater reliability were excellent (kappa=0.81-0.94) for nine items, good (kappa=0.61-0.80) for 20 items and moderate (kappa=0.51-0.60) for three items. High correlations were found between the total score and other scores: Vignos (r=0.91) and Brooke (r=0.85) grades, Functional Independence Measure (r=0.91), the global severity of disability evaluated with visual analog scales by physicians (r=0.88) and physiotherapists (r=0.91). This scale is reliable, does not require any special equipment and is well-accepted by patients. Its sensitivity to change is being assessed to permit its use in clinical trials of neuromuscular diseases.

Heat shock proteins and neuromuscular disease

The heat shock proteins are families of proteins with known activities that include chaperoning nascent peptides within the cell and cytoprotection. Most work on the nervous system has related to the role of heat shock proteins in neuroprotection from either hypoxic-ischemic or traumatic injury. The role of these proteins during normal physiological activity and injury is still under investigation. Heat shock proteins in neuromuscular disease have been investigated to some extent but were largely neglected until recently. The goal of this review is to summarize the evidence linking heat shock proteins with neuromuscular disease and to provide some insight into the roles or functions of these proteins in disease states.

[Muscular atrophy as a symptom]

Muscular atrophy is a symptom characterized by the loss of normal muscle mass. It is caused by a decline in the total number of muscle cells, or by a substantial decline in the substance of individual muscle cells. It has been associated with a preceding muscle weakness. Muscular atrophy occurs late in the course of a disease. Due to the limited ability of muscle cells to regenerate, it is frequently irreversible. Hence the aim is to detect the early stages of muscular decline and to prevent outright muscular atrophy. To achieve this it is necessary to be aware of the large number of diseases that can induce this in order to ensure timely referral to a specialist.

Neuromuscular problems of the critically ill neonate and child

This review presents insights gained over 24 years of clinical and laboratory evaluations of children, newborn to 18 years of age, who present with acute weakness in the intensive care setting. The differential diagnosis of neuromuscular disorders in these cases begins with recognition of three categories-the infant and toddler, the older child and adolescent, and the child with critical illness-within which predisposition to specific disorders may be identified. Disorders originating from anterior horn cell, peripheral nerve, neuromuscular junction, and muscle cell are discussed with emphasis on presentation and electrophysiologic findings. Nerve conduction studies, electromyography, electroencephalography, cerebrospinal fluid analysis, and magnetic resonance imaging each play important diagnostic roles in the differentiation of neuromuscular disorders in the critically ill child. Case studies suggest the wide range of presentations these disorders may make to the pediatrician or pediatric neurologist.

Perisurgical management of patients with neuromuscular disorders

Patients with neuromuscular disorders who undergo surgical procedures are particularly predisposed to complications during the perioperative period. Such complications may arise from respiratory failure, arrhythmias,or infections, and particularly MH. It is recommended that these patients be monitored for respiratory and cardiovascular complications and receive proper respiratory toilet, physio-therapy, and incentive respirometry. Proper electrolyte balance is mandatory. They should be monitored in the ICU when necessary. Excessive sedation of these patients, and drugs that could aggravate weakness or cause MH, should be avoided. Those at risk of MH should not receive drugs that may precipitate an attack.

Neuromusculoskeletal disorders in the neck and upper extremities among drivers of all-terrain vehicles--a case series

BACKGROUND

The purpose of this study was to investigate whether professional drivers of all-terrain vehicles (ATVs) with neck pain have a different array of neuromusculoskeletal disorders in the neck and upper extremities than a referent group with neck pain from the general population. It is hypothesized that exposure to shock-type vibration and unfavorable working postures in ATVs have the capacity to cause peripheral nervous lesions.

METHODS

This study was based on a case series analyzed according to a case-case comparison design. The study population consisted of 60 male subjects, including professional drivers of forest machines (n = 15), snowmobiles (n = 15), snowgroomers (n = 15) and referents from the general population (n = 15) all of whom had reported neck pain in a questionnaire and underwent an extensive physical examination of the neck and upper extremities. Based on symptom history, symptoms and signs, and in some cases chemical, electroneurographical and radiological findings, subjects were classified as having a nociceptive or neuropathic disorder or a mix of these types.

RESULTS

The occurrence of asymmetrical and focal neuropathies (peripheral nervous lesion), pure or in a mix with a nociceptive disorder was common among cases in the ATV driver groups (47%-79%). This contrasted with the referents that were less often classified as having asymmetrical and focal neuropathy (27%), but instead had more nociceptive disorders. The difference was most pronounced among drivers of snowgroomers, while drivers of forest machines were more frequently classified as having a nociceptive disorder originating in the muscles.

CONCLUSION

This study found a high prevalence of assymetrical and focal neuropathies among drivers with pain in the neck, operating various ATVs. It seems as if exposure to shock-type whole-body vibration (WBV) and appurtenant unfavorable postures in ATVs may be associated to peripheral nervous lesions.