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.