Duchenne muscular dystrophy is characterised by fibrofatty replacement of muscle, resulting in dilated cardiomyopathy. Hypertrophic cardiomyopathy affects 1:200–1:500 people and is characterised by asymmetric ventricular septal hypertrophy. To date, there have been two separately reported cases describing the combined pathology of these disorders. Herein, we expand upon these reports with a case series describing longitudinal findings in three patients with Duchenne muscular dystrophy who developed hypertrophic cardiomyopathy.

A major concern of rehabilitation counselors is the likelihood of work following illness and the purpose of this paper is to determine the work rate of persons with neuromuscular conditions. A review of 38 published reports indicated the capacity for employment, but this varied according to the specific neuromuscular condition. A quantitative summary of previous studies that comprised a total of 2926 participants indicated that 1266 or 43.2% were working. Higher work rates were reported for studies where (a) the focus was on specific disorders rather than neuromuscular conditions in general or (b) where the participation rate was greater than 80%.

Background: Neuromuscular disorders are a phenotypically and genotypically diverse group of diseases that can be difficult to diagnose accurately because of overlapping clinical features and nonspecific muscle pathology. Next-generation sequencing (NGS) is a high-throughput technology that can be used as a more time- and cost-effective tool for identifying molecular diagnoses for complex genetic conditions, such as neuromuscular disorders. Methods: One hundred and sixty-nine patients referred to a Canadian neuromuscular clinic for evaluation of possible muscle disease were screened with an NGS panel of muscular dystrophy–associated genes. Patients were categorized by the reason of referral (1) muscle weakness (n=135), (2) recurrent episodes of rhabdomyolysis (n=18), or (3) idiopathic hyperCKemia (n=16). Results: Pathogenic and likely pathogenic variants were identified in 36.09% of patients (61/169). The detection rate was 37.04% (50/135) in patients with muscle weakness, 33.33% (6/18) with rhabdomyolysis, and 31.25% (5/16) in those with idiopathic hyperCKemia. Conclusions: This study shows that NGS can be a useful tool in the molecular workup of patients seen in a neuromuscular clinic. Evaluating the utility of large panels of a muscle disease-specific NGS panel to investigate the genetic susceptibilities of rhabdomyolysis and/or idiopathic hyperCKemia is a relatively new field. Twenty-eight of the pathogenic and likely pathogenic variants reported here are novel and have not previously been associated with disease.

This study aimed to demonstrate proof of concept and acceptability of a brief acceptance and commitment therapy (ACT)-based guided self-help intervention for improving quality of life (QoL) and mood for people with muscle disorders (MD). A case-series with an AB design was used to assess changes in primary (QoL) and secondary (depression and anxiety) outcome variables across the period of study. Change in the psychological process targeted by ACT – psychological flexibility – was also investigated, to allow insight into possible treatment mechanisms. Post-intervention, participants also completed a brief free-text evaluation. Relative to pre-intervention scores, four (of seven) participants showed varying degrees of improvement in all primary and secondary outcome variables and were thus considered responders. However, consistent concomitant improvements in psychological flexibility were not apparent. Participants reported a mostly positive experience of the intervention; all appeared to complete the intervention, and no adverse events were reported. Nonetheless, there was evidence that those with compromised concentration or who report good initial QoL and low levels of distress may derive less benefit. Although several methodological weaknesses limit the strength of our conclusions, this ACT-based guided self-help intervention shows encouraging utility for improving QoL and mood in MD.

The present study examined ways in which progressive disability affects the pursuit of personal goals and how the uncertainty of progressive disability influences life perspectives. A total of 117 individuals with muscular dystrophy responded to two open-ended questions designed to elicit their views on the psychological and behavioural manifestations of progressive disability. Specifically, the study used a three-step phenomenological existential approach to analyse the written responses by the participants (Creswell, 2009). The results indicated that factors such as involuntary early retirement, problems establishing and maintaining romantic relationships; changing personal and career goals, fear of uncertainties, feeling undesirable and unattractive, lack of accessible transportation, and fear of passing on hereditary diseases affect an individual's psychological well-being. The need for around-the-clock care can present a burden that leads to caregiver burnout and resentment. Implications for rehabilitation professionals are provided based upon review of the literature and qualitative data analysis.

The study of the underlying mechanisms by which cells respond to mechanical stimuli, i.e. the link between the mechanical stimulus and gene expression, represents a new and important area in the morphological sciences. Several cell types (‘mechanocytes’), e.g. osteoblasts and fibroblasts as well as smooth, cardiac and skeletal muscle cells are activated by mechanical strain and there is now mounting evidence that this involves the cytoskeleton. Muscle offers one of the best opportunities for studying this type of mechanotransduction as the mechanical activity generated by and imposed upon muscle tissue can be accurately controlled and measured in both in vitro and in vivo systems. Muscle is highly responsive to changes in functional demands. Overload leads to hypertrophy, whilst decreased load force generation and immobilisation with the muscle in the shortened position leads to atrophy. For instance it has been shown that stretch is an important mechanical signal for the production of more actin and myosin filaments and the addition of new sarcomeres in series and in parallel. This is preceded by upregulation of transcription of the appropriate genes some of which such as the myosin isoforms markedly change the muscle phenotype. Indeed, the switch in the expression induced by mechanical activity of myosin heavy chain genes which encode different molecular motors is a means via which the tissue adapts to a given type of physical activity. As far as increase in mass is concerned, our group have cloned the cDNA of a splice variant of IGF that is produced by active muscle that appears to be the factor that controls local tissue repair, maintenance and remodelling. From its sequence it can be seen that it is derived from the IGF gene by alternative splicing but it has different exons to the liver isoforms. It has a 52 base insert in the E domain which alters the reading frame of the 3′ end. Therefore, this splice variant of IGF-1 is likely to bind to a different binding protein which exists in the interstitial tissue spaces of muscle, neuronal tissue and bone. This would be expected to localise its action as it would be unstable in the unbound form which is important as its production would not disturb the glucose homeostasis unduly. This new growth factor has been called mechano growth factor (MGF) to distinguish it from the liver IGFs which have a systemic mode of action. Although the liver is usually thought of as the source of circulating IGF, it has recently been shown that during exercise skeletal muscle not only produces much of the circulating IGF but active musculature also utilises most of the IGF produced. We have cloned both an autocrine and endocrine IGF-1, both of which are upregulated in cardiac as well as skeletal muscle when subjected to overload. It has been shown that, in contrast to normal muscle, MGF is not detectable in dystrophic mdx muscles even when subjected to stretch and stretch combined with electrical stimulation. This is true for muscular dystrophies that are due to the lack of dystrophin (X-linked) and due to a laminin deficiency (autosomal), thus indicating that the dystrophin cytoskeletal complex may be involved in the mechanotransduction mechanism. When this complex is defective the necessary systemic as well as autocrine IGF-1 growth factors required for local repair are not produced and the ensuing cell death results in progressive loss of muscle mass. The discovery of the locally produced IGF-1 appears to provide the link between the mechanical stimulus and the activation of gene expression.

In mdx mice, a model for Duchenne muscular dystrophy, the timing between the replication of myoblasts and their incorporation into myotubes was determined autoradiographically. Thirty-eight mdx mice aged 23 d were injected with tritiated thymidine to label myoblasts replicating early in the dystrophic process. At intervals from 8 h to 30 d after injection the tibialis anterior muscles were removed, processed for autoradiography and analysed for labelled central myonuclei (derived from the progeny of myoblasts which had been labelled at 23 d). At 8 h after injection there were no labelled central myonuclei, showing that the labelled myoblasts had not fused within this time. At 1 d, 2% of central myonuclei were labelled, at 2 d, up to 32% were labelled, at 3 d ∼60% were labelled, and at 4 d the labelling peaked at 74%. In the 27 mice sampled from 5–30 d after injection, the levels of central myonuclear labelling varied enormously: from 1–63%. However, there was a consistent decrease in the numbers of labelled central myonuclei with time. This may have been due to dilution of the relative numbers of labelled myonuclei due to other, nonlabelled, myoblasts replicating after the availability of tritiated thymidine, and fusing. It was also possible that labelled myofibres underwent subsequent necrosis and were eliminated from the muscle. The proposal that a regenerated myofibre can undergo a subsequent cycle of necrosis and regeneration was supported by evidence of some necrotic myofibres with labelled and unlabelled central nuclei. These results have implications for understanding the cellular biology and pathology of dystrophic muscle, particularly in relation to myoblast transfer therapy as a potential treatment of Duchenne muscular dystrophy.