Quantitative MRI reveals decelerated fatty infiltration in muscles of active FSHD patients

Update on Exercise in Persons With Muscle Disease

Myopathies are heterogeneous in their etiology, muscle group involvement, clinical manifestation, and progression. Deficits in myopathy may include muscle weakness, atrophy, stiffness, myalgia, and extra-muscular manifestations. Consequently, these deficits could lead to impaired musculoskeletal function, inadequate engagement in daily activities and reduced participation in social activities. Exercise has been viewed as a potentially efficacious intervention to halt the loss of muscle function and to improve secondary symptoms that result from muscle loss, such as pain and fatigue. The purpose of this review is to discuss research findings within the last 10 years that examine effects of exercise interventions in many types of myopathies in humans. In general, most studies were small scale, and they varied with respect to exercise type, intensity, and outcome measures. Despite the different pathologies, various exercise subtypes of aerobic/endurance or strength/resistance training are generally beneficial and may improve muscle strength and functional outcomes. Exercise therapies are generally safe and well tolerated. Exercise prescription should be part of routine neuromuscular care for patients with myopathy, and ideally with input from a multidisciplinary team, with a focus on providing individualized exercise regimens. Further work is needed to define the optimal intensity and type of exercise to result in the best functional outcomes for persons with myopathy, as well as the effects of combining exercise and novel disease modifying therapies.

Muscle imaging in facioscapulohumeral muscular dystrophy research: A scoping review and expert recommendations

Clinical trial readiness is an important topic in the field of facioscapulohumeral muscular dystrophy (FSHD). As FSHD is a slowly progressive and clinically heterogeneous disease, imaging biomarkers have been proposed to complement clinical outcome measures. Muscle magnetic resonance imaging (MRI), ultrasound and dual energy X-ray absorptiometry (DEXA) have been used to measure disease severity, activity and progression. We conducted a scoping review of the literature on these imaging modalities to assess gaps in knowledge and subsequently collaborated with a panel of neuromuscular imaging experts to generate recommendations on the road ahead. We systematically searched PubMed, EMBASE and Cochrane Library databases. Three-hundred and twenty-eight studies were screened and one hundred and five studies were included. MRI indices related to intramuscular fat content, STIR positivity and T2water are used as diagnostic as well as prognostic and monitoring biomarkers. Ultrasound echogenicity can be used as a diagnostic and potentially as a prognostic and monitoring biomarker. DEXA lean muscle mass may be used as an additional monitoring biomarker. Each imaging modality has its own benefits but also challenges. Based on our expert opinions, we propose a roadmap to address these challenges, ensuring the optimal use of each modality in multi-center clinical trials in FSHD.

Experiences of living with GSD5 (McArdle) disease: challenges and strategies. A qualitative study in the Netherlands

PURPOSE

Glycogen Storage Disease type 5 (GSD5 or McArdle disease) is caused by deficient glycogen phosphorylase enzyme activity in skeletal muscles. Individuals with GSD5 experience symptoms like muscle pain, fatigue, and tachycardia during exertion. Our study aimed to explore the lived experiences of individuals with GSD5, focusing on their daily challenges, the process of being diagnosed, and management strategies.

METHODS

Participants were invited to share their life experiences through in-depth, semi-structured interviews, and the collected data was analyzed using thematic analysis.

RESULTS

Using purposeful sampling, 13 individuals with GSD5 were recruited for the study. The analysis identified four key themes: "experiencing incomprehensible difficulties," "diagnosis as an explanation," "finding ways to manage daily challenges," and "listening to your body." These themes reflect diverse experiences of daily functioning, physical challenges faced, the pivotal role of diagnosis in understanding symptoms, and the adoption of management strategies like using the 'second wind' phenomenon. Participants emphasized the importance of support networks and adaptive lifestyle changes in effectively managing their condition.

CONCLUSIONS

Early diagnosis and tailored management strategies are critical for improving outcomes and quality of life in individuals with GSD5. Timely diagnosis and comprehensive multidisciplinary care are essential for effectively managing the complexities of this rare metabolic disorder.

[Arthrogryposis Multiplex Congenita in pediatric age: Correlation between Muscle MRI and functional assessment]

Arthrogryposis multiplex congenita (AMC) is a group of diseases with joint limitations at two or more distinct joint levels at birth. Joint limitations are not progressive, but the functional consequences have a lifelong impact on patients. In this article we will present the results of our study aimed at evaluating the correlation between muscle fat infiltration on MRI and activity deficiencies and limitations in children with AMC. Our study is one of the first in a pediatric population to establish the link between muscle imaging and functional aspects of AMC.

Myo-regressor Deep Informed Neural NetwOrk (Myo-DINO) for fast MR parameters mapping in neuromuscular disorders

Magnetic Resonance (MR) parameters mapping in muscle Magnetic Resonance Imaging (mMRI) is predominantly performed using pattern recognition-based algorithms, which are characterised by high computational costs and scalability issues in the context of multi-parametric mapping. Deep Learning (DL) has been demonstrated to be a robust and efficient method for rapid MR parameters mapping. However, its application in mMRI domain to investigate Neuromuscular Disorders (NMDs) has not yet been explored. In addition, data-driven DL models suffered in interpretation and explainability of the learning process. We developed a Physics Informed Neural Network called Myo-Regressor Deep Informed Neural NetwOrk (Myo-DINO) for efficient and explainable Fat Fraction (FF), water-T2 (wT2) and B1 mapping from a cohort of NMDs.A total of 2165 slices (232 subjects) from Multi-Echo Spin Echo (MESE) images were selected as the input dataset for which FF, wT2,B1 ground truth maps were computed using the MyoQMRI toolbox. This toolbox exploits the Extended Phase Graph (EPG) theory with a two-component model (water and fat signal) and slice profile to simulate the signal evolution in the MESE framework. A customized U-Net architecture was implemented as the Myo-DINO architecture. The squared L2 norm loss was complemented by two distinct physics models to define two 'Physics-Informed' loss functions: Cycling Loss 1 embedded a mono-exponential model to describe the relaxation of water protons, while Cycling Loss 2 incorporated the EPG theory with slice profile to model the magnetization dephasing under the effect of gradients and RF pulses. The Myo-DINO was trained with the hyperparameter value of the 'Physics-Informed' component held constant, i.e. λmodel = 1, while different hyperparameter values (λcnn) were applied to the squared L2 norm component in both the cycling loss. In particular, hard (λcnn=10), normal (λcnn=1) and self-supervised (λcnn=0) constraints were applied to gradually decrease the impact of the squared L2 norm component on the 'Physics Informed' term during the Myo-DINO training process. Myo-DINO achieved higher performance with Cycling Loss 2 for FF, wT2 and B1 prediction. In particular, high reconstruction similarity and quality (Structural Similarity Index > 0.92, Peak Signal to Noise ratio > 30.0 db) and small reconstruction error (Normalized Root Mean Squared Error < 0.038) to the reference maps were shown with self-supervised weighting of the Cycling Loss 2. In addition muscle-wise FF, wT2 and B1 predicted values showed good agreement with the reference values. The Myo-DINO has been demonstrated to be a robust and efficient workflow for MR parameters mapping in the context of mMRI. This provides preliminary evidence that it can be an effective alternative to the reference post-processing algorithm. In addition, our results demonstrate that Cycling Loss 2, which incorporates the Extended Phase Graph (EPG) model, provides the most robust and relevant physical constraints for Myo-DINO in this multi-parameter regression task. The use of Cycling Loss 2 with self-supervised constraint improved the explainability of the learning process because the network acquired domain knowledge solely in accordance with the assumptions of the EPG model.

Voluntary wheel running improves molecular and functional deficits in a murine model of facioscapulohumeral muscular dystrophy

Endurance exercise training is beneficial for skeletal muscle health, but it is unclear if this type of exercise can target or correct the molecular mechanisms of facioscapulohumeral muscular dystrophy (FSHD). Using the FLExDUX4 murine model of FSHD characterized by chronic, low levels of pathological double homeobox protein 4 (DUX4) gene expression, we show that 6 weeks of voluntary, free wheel running improves running performance, strength, mitochondrial function, and sarcolemmal repair capacity, while slowing/reversing skeletal muscle fibrosis. These improvements are associated with restored transcriptional activity of gene networks/pathways regulating actin cytoskeletal signaling, vascular remodeling, inflammation, fibrosis, and muscle mass toward wild-type (WT) levels. However, FLExDUX4 mice exhibit blunted increases in mitochondrial content with training and persistent transcriptional overactivation of hypoxia, inflammatory, angiogenic, and cytoskeletal pathways. These results identify exercise-responsive and non-responsive molecular pathways in FSHD, while providing support for the use of endurance-type exercise as a non-invasive treatment option.

Muscle MRI in Patients With Oculopharyngeal Muscular Dystrophy: A Longitudinal Study

BACKGROUND AND OBJECTIVES

Oculopharyngeal muscular dystrophy (OPMD) is a rare progressive neuromuscular disease. MRI is one of the techniques that is used in neuromuscular disorders to evaluate muscle alterations. The aim of this study was to describe the pattern of fatty infiltration of orofacial and leg muscles using quantitative muscle MRI in a large national cohort and to determine whether MRI can be used as an imaging biomarker of disease progression in OPMD.

METHODS

Patients with OPMD (18 years or older) were invited from the national neuromuscular database or by their treating physicians and were examined twice with an interval of 20 months, with quantitative MRI of orofacial and leg muscles to assess fatty infiltration which were compared with clinical measures.

RESULTS

In 43 patients with genetically confirmed OPMD, the muscles that were affected most severely were the tongue (mean fat fraction: 37.0%, SD 16.6), adductor magnus (31.9%; 27.1), and soleus (27.9%; 21.5) muscles. The rectus femoris and tibialis anterior muscles were least severely affected (mean fat fractions: 6.8%; SD 4.7, 7.5%; 5.9). Eleven of 14 significant correlations were found between fat fraction and a clinical task in the corresponding muscles (r = -0.312 to -0.769, CI = -0.874 to -0.005). At follow-up, fat fractions had increased significantly in 17 of the 26 muscles: mean 1.7% in the upper leg muscles (CI = 0.8-2.4), 1.7% (1.0-2.3) in the lower leg muscles, and 1.9% (0.6-3.3) in the orofacial muscles (p < 0.05). The largest increase was seen for the soleus (3.8%, CI = 2.5-5.1). Correlations were found between disease duration and repeat length vs increased fat fraction in 7 leg muscles (r = 0.323 to -0.412, p < 0.05).

DISCUSSION

According to quantitative muscle MRI, the tongue, adductor magnus and soleus show the largest fat infiltration levels in patients with OPMD. Fat fractions increased in several orofacial and leg muscles over 20 months, with the largest fat fraction increase seen in the soleus. This study supports that this technique is sensitive enough to show worsening in fat fractions of orofacial and leg muscles and therefore a responsive biomarker for future clinical trials.

Health-Related Quality of Life in FKRP-Related Limb-Girdle Muscular Dystrophy R9

BACKGROUND

Limb-girdle muscular dystrophy R9 (LGMDR9) is a chronic progressive hereditary muscle disease, related to the Fukutin Related Protein (FKRP) gene, that may cause major disabilities, cardiomyopathy, and ventilatory failure. Knowledge of how LGMDR9 affects health-related quality of life (HRQoL) is relevant in treatment and care.

OBJECTIVE

To investigate HRQoL in the Norwegian LGMDR9 population over 14 months and relation to fatigue and sleep quality.

METHODS

Participants (16+ years) of the Norwegian LGMDR9 cohort study completed two HRQoL measures, i.e., Individualized Neuromuscular Quality of Life questionnaire (INQoL) and the 36-item Short Form (SF-36) at baseline, 8, and 14 months and measures of fatigue and sleep quality at 9 months.

RESULTS

HRQoL response rate was 84/90 (75 c.826 C > A homozygotes and nine c.826 C > A compound heterozygotes). Compared to Norwegian normative data, all SF-36 domain scores were impaired (p≤0.006) except mental health in males (p = 0.05) and pain scores. During 14 months, perceived muscle weakness and the INQoL index (disease burden) worsened in c.826 C > A homozygotes. Compound heterozygotes reported more dysphagia and physical difficulties than homozygotes and showed a tendency towards worsening in weakness over time but some improvement on the INQoL index. Homozygous females reported generally poorer HRQoL and a higher burden than males. The INQoL index was related to perceived muscle weakness and fatigue, and fatigue to myalgia and mental distress. The prevalence of fatigue and poor sleep was 40% and 49%, respectively.

CONCLUSIONS

The 14-month follow-up period shows a worsening of perceived weakness and burden in c.826 C > A homozygotes, which can then be expected. The prevalence and impact of fatigue indicate a need for awareness and treatment of fatigue. Myalgia and mental distress are potential targets in the treatment of fatigue, which future studies need to establish. Sleep issues and gender-specific care needs also require attention in LGMDR9.

Participant experiences of guided self-help Acceptance and Commitment Therapy for improving quality of life in muscle disease: a nested qualitative study within the ACTMus randomized controlled trial

Introduction

In adults, muscle disease (MD) is typically a chronic long-term condition that can lead to a reduced quality of life (QoL). Previous research suggests that a psychological intervention, in particular Acceptance and Commitment Therapy (ACT), may help improve QoL for individuals living with chronic conditions such as MD.

Methods

This nested qualitative study was incorporated within a randomized controlled trial which evaluated a guided self-help ACT intervention for people living with MD to explore their experiences of the intervention. Semi-structured interviews (n = 20) were conducted with those who had received ACT. Data were analyzed via thematic analysis.

Results

There were four overarching themes. (1) Views on whether therapy sessions would help with a medical condition: participants' expectations regarding ACT varied. Some participants were skeptical about mindfulness. (2) I was able to look at things in a different way: participants described increased meaningful activity, greater awareness of thoughts and emotions and acceptance or adaptation to mobility problems. Some described improvement in the quality of relationships and a sense of feeling free. (3) Treating the body and the mind together: following the intervention participants noted that a holistic approach to healthcare is beneficial. (4) Intervention delivery: The remote delivery was generally seen as helpful for practical reasons and allowed participants to speak openly. Participants voiced a need for follow-up sessions.

Discussion

Overall, the intervention was experienced as acceptable. Suggested improvements included de-emphasizing the role of mindfulness and adding follow-up sessions.

New Insights into the Spread of MRS-Based Water T2 Values Observed in Highly Fatty Replaced Muscles

BACKGROUND

The reference standard for assessing water T2 (T2,H2O ) at high fat fraction (FF) is 1 H MRS. T2,H2O (T2,H2O,MRS ) dependence on FF (FFMRS ) has recently been demonstrated in muscle at high FF (i.e. ≥60%).

PURPOSE

To investigate the relationship between T2,H2O,MRS and FFMRS in the thigh/leg muscles of patients with neuromuscular diseases and to compare with quantitative MRI.

STUDY TYPE

Retrospective case-control study.

POPULATION

A total of 151 patients with neuromuscular disorders (mean age ± standard deviation = 52.5 ± 22.6 years, 54% male), 44 healthy volunteers (26.5 ± 13.0 years, 57% male).

FIELD STRENGTH/SEQUENCE

A 3-T; single-voxel stimulated echo acquisition mode (STEAM) MRS, multispin echo (MSE) imaging (for T2 mapping, T2,H2O,MRI ), three-point Dixon imaging (for FFMRI andR 2 * mapping).

ASSESSMENT

Mono-exponential and bi-exponential models were fitted to water T2 decay curves to extract T2,H2O,MRS and FFMRS . Water resonance full-width-at-half-maximum (FWHM) and B0 spread (∆B0 ) values were calculated. T2,H2O,MRI (mean), FFMRI (mean, kurtosis, and skewness), andR 2 * (mean) values were estimated in the MRS voxel.

STATISTICAL TESTS

Mann-Whitney U tests, Kruskal-Wallis tests. A P-value <0.05 was considered statistically significant.

RESULTS

Normal T2,H2O,MRS threshold was defined as the 90th percentile in healthy controls: 30.3 msec. T2,H2O,MRS was significantly higher in all patients with FFMRS  < 60% compared to healthy controls. We discovered two subgroups in patients with FFMRS  ≥ 60%: one with T2,H2O,MRS  ≥ 30.3 msec and one with T2,H2O,MRS  < 30.3 msec including abnormally low T2,H2O,MRS . The latter subgroup had significantly higher water resonance FWHM, ∆B0 , FFMRI kurtosis, and skewness values but nonsignificantly differentR 2 * (P = 1.00) and long T2,H2O,MRS component and its fraction (P > 0.11) based on the bi-exponential analysis.

DATA CONCLUSION

The findings suggest that the cause for (abnormally) T2,H2O,MRS at high FFMRS is biophysical, due to differences in susceptibility between muscle and fat (increased FWHM and ∆B0 ), rather than pathophysiological such as compartmentation changes, which would be reflected by the bi-exponential analysis.

EVIDENCE LEVEL

3 TECHNICAL EFFICACY: Stage 3.

Electrophysiological and Imaging Biomarkers to Evaluate Exercise Training in Patients with Neuromuscular Disease: A Systematic Review

Exercise therapy as part of the clinical management of patients with neuromuscular diseases (NMDs) is complicated by the limited insights into its efficacy. There is an urgent need for sensitive and non-invasive quantitative muscle biomarkers to monitor the effects of exercise training. Therefore, the objective of this systematic review was to critically appraise and summarize the current evidence for the sensitivity of quantitative, non-invasive biomarkers, based on imaging and electrophysiological techniques, for measuring the effects of physical exercise training. We identified a wide variety of biomarkers, including imaging techniques, i.e., magnetic resonance imaging (MRI) and ultrasound, surface electromyography (sEMG), magnetic resonance spectroscopy (MRS), and near-infrared spectroscopy (NIRS). Imaging biomarkers, such as muscle maximum area and muscle thickness, and EMG biomarkers, such as compound muscle action potential (CMAP) amplitude, detected significant changes in muscle morphology and neural adaptations following resistance training. MRS and NIRS biomarkers, such as initial phosphocreatine recovery rate (V), mitochondrial capacity (Qmax), adenosine phosphate recovery half-time (ADP t1/2), and micromolar changes in deoxygenated hemoglobin and myoglobin concentrations (Δ[deoxy(Hb + Mb)]), detected significant adaptations in oxidative metabolism after endurance training. We also identified biomarkers whose clinical relevance has not yet been assessed due to lack of sufficient study.

Frequency and satisfaction of conventional and complementary or alternative therapies for neuromuscular disorders

BACKGROUND

Causal therapies are not yet available for most neuromuscular diseases. Additionally, data on the use of complementary or alternative therapies (CAM) in patients groups with a variety of different neuromuscular diseases are rare. This retrospective cross-sectional study aims to record the frequency of use and satisfaction of conventional therapies and complementary or alternative medicine (CAM) in patients with neuromuscular disorders in order to compare them afterwards.

METHODS

Patients from the University of Leipzig (Department and Outpatient Department of Neurology), the Friedrich-Baur-Institute (Department of Neurology), the Hoher Meißner Clinic (Department of Neurology) and the German Society for Muscular Diseases (DGM e.V.) were included. The focus of this study has been on patients with chronic neuromuscular diseases. Our data are based on standardised questionnaires in analogue form from three German neuromuscular centres and in digital form from the official website of the German Society for Muscular Diseases. Therapy satisfaction was assessed with the Patient Evaluation of Global Response (PEGR) ranking scale (very satisfactory + 2 to very unsatisfactory - 2).

RESULTS

Of 192 questionnaires analysed, the most common diagnoses were spinal muscular atrophy (n = 42; 21.9%), muscular dystrophies (n = 41; 21.4%) and myotonic dystrophies (n = 38; 19.8%). More than half (n = 112; 58.3%) used both conventional and CAM treatments. Physiotherapy (n = 165) was used most frequently within all treatments with conventional manual (PEGR 1.25, p = 0.013; CI 95%) and aquatic therapy (PEGR 1.3, p = 0.038) showing significantly higher satisfaction compared to therapy on training equipment. Less-used therapies such as psychotherapy (n = 53; PEGR 1.2) were also satisfactory. Within CAM, massages (n = 96) were the most reported and meditation (PEGR 1.5) was best rated. Massage therapy was significantly more satisfactory than progressive muscle relaxation (p = 0.003) and chiropractic treatment (p = 0.036). Chiropractic treatment (PEGR - 0.1) was rated most negatively. No significant differences were found between the group of conventional therapies and CAM users regarding social and disease-dependent factors.

CONCLUSIONS

Treatment with conventional therapy (manual, aquatic therapy) and some CAM therapies can be recommended if adequately indicated.

Quantitative muscle magnetic resonance imaging depicts microstructural abnormalities but no signs of inflammation or dystrophy in post-COVID-19 condition

BACKGROUND AND PURPOSE

Post-COVID-19 condition (PCC) has high impact on quality of life, with myalgia and fatigue affecting at least 25% of PCC patients. This case-control study aims to noninvasively assess muscular alterations via quantitative muscle magnetic resonance imaging (MRI) as possible mechanisms for ongoing musculoskeletal complaints and premature exhaustion in PCC.

METHODS

Quantitative muscle MRI was performed on a 3 Tesla MRI scanner of the whole legs in PCC patients compared to age- and sex-matched healthy controls, including a Dixon sequence to determine muscle fat fraction (FF), a multi-echo spin-echo sequence for quantitative water mapping reflecting putative edema, and a diffusion-weighted spin-echo echo-planar imaging sequence to assess microstructural alterations. Clinical examination, nerve conduction studies, and serum creatine kinase were performed in all patients. Quantitative muscle MRI results were correlated to the results of the 6-min walk test and standardized questionnaires assessing quality of life, fatigue, and depression.

RESULTS

Twenty PCC patients (female: n = 15, age = 48.8 ± 10.1 years, symptoms duration = 13.4 ± 4.2 months, body mass index [BMI] = 28.8 ± 4.7 kg/m² ) were compared to 20 healthy controls (female: n = 15, age = 48.1 ± 11.1 years, BMI = 22.9 ± 2.2 kg/m² ). Neither FF nor T2 revealed signs of muscle degeneration or inflammation in either study groups. Diffusion tensor imaging (DTI) revealed reduced mean, axial, and radial diffusivity in the PCC group.

CONCLUSIONS

Quantitative muscle MRI did not depict any signs of ongoing inflammation or dystrophic process in the skeletal muscles in PCC patients. However, differences observed in muscle DTI depict microstructural abnormalities, which may reflect potentially reversible fiber hypotrophy due to deconditioning. Further longitudinal and interventional studies should prove this hypothesis.

Facioscapulohumeral muscular dystrophy: the road to targeted therapies

Advances in the molecular understanding of facioscapulohumeral muscular dystrophy (FSHD) have revealed that FSHD results from epigenetic de-repression of the DUX4 gene in skeletal muscle, which encodes a transcription factor that is active in early embryonic development but is normally silenced in almost all somatic tissues. These advances also led to the identification of targets for disease-altering therapies for FSHD, as well as an improved understanding of the molecular mechanism of the disease and factors that influence its progression. Together, these developments led the FSHD research community to shift its focus towards the development of disease-modifying treatments for FSHD. This Review presents advances in the molecular and clinical understanding of FSHD, discusses the potential targeted therapies that are currently being explored, some of which are already in clinical trials, and describes progress in the development of FSHD-specific outcome measures and assessment tools for use in future clinical trials.

Muscle quantitative MRI as a novel biomarker in hereditary transthyretin amyloidosis with polyneuropathy: a cross-sectional study

BACKGROUND

The development of reproducible and sensitive outcome measures has been challenging in hereditary transthyretin (ATTRv) amyloidosis. Recently, quantification of intramuscular fat by magnetic resonance imaging (MRI) has proven as a sensitive marker in patients with other genetic neuropathies. The aim of this study was to investigate the role of muscle quantitative MRI (qMRI) as an outcome measure in ATTRv.

METHODS

Calf- and thigh-centered multi-echo T2-weighted spin-echo and gradient-echo sequences were obtained in patients with ATTRv amyloidosis with polyneuropathy (n = 24) and healthy controls (n = 12). Water T2 (wT2) and fat fraction (FF) were calculated. Neurological assessment was performed in all ATTRv subjects. Quantitative MRI parameters were correlated with clinical and neurophysiological measures of disease severity.

RESULTS

Quantitative imaging revealed significantly higher FF in lower limb muscles in patients with ATTRv amyloidosis compared to controls. In addition, wT2 was significantly higher in ATTRv patients. There was prominent involvement of the posterior compartment of the thighs. Noticeably, FF and wT2 did not exhibit a length-dependent pattern in ATTRv patients. MRI biomarkers correlated with previously validated clinical outcome measures, Polyneuropathy Disability scoring system, Neuropathy Impairment Score (NIS) and NIS-lower limb, and neurophysiological parameters of axonal damage regardless of age, sex, treatment and TTR mutation.

CONCLUSIONS

Muscle qMRI revealed significant difference between ATTRv and healthy controls. MRI biomarkers showed high correlation with clinical and neurophysiological measures of disease severity making qMRI as a promising tool to be further investigated in longitudinal studies to assess its role at monitoring onset, progression, and therapy efficacy for future clinical trials on this treatable condition.

Correlation between whole body muscle MRI and functional measures in paediatric patients with facioscapulohumeral muscular dystrophy

Symptoms and severity of facioscapulohumeral muscular dystrophy (FSHD) can vary greatly, even within the same family. Clinical trial readiness requires accurate and reliable methods of assessing disease stage and progression. MRI has not previously been assessed as a disease biomarker in paediatric FSHD. Eleven patients with FSHD1 underwent whole body muscle MRI. Pre-selected muscles were analysed by a paediatric radiologist using the semi-quantitative Mercuri/Kim method. Within each domain (oedema, fat replacement, atrophy) scores for each muscle were then summated to give each participant three cumulative domain scores. The same participants had functional measures scored: FSHD-CSS (Ricci), FSHD-CS (Lamperti), FSHD-COM, PUL2.0, MFM-32, 6MWT, myometry and manual muscle testing. Pearson coefficient was calculated to determine strength of correlation. The scores for atrophy and fat replacement showed strong correlation with functional outcome measures, particularly FSHD-CSS, FSHD-CS and FSHD-COM. In contrast, muscle oedema correlated poorly with all functional outcome measures, with no relationship seen to the 6MWT. This study of eleven children suggests that semi-quantitative visual Mercuri score utilising fat replacement or atrophy on whole body muscle MRI correlates strongly with disease-specific functional measures and may be a useful measure of disease severity in paediatric FSHD.

Radiomics and machine learning applied to STIR sequence for prediction of quantitative parameters in facioscapulohumeral disease

Purpose

Quantitative Muscle MRI (qMRI) is a valuable and non-invasive tool to assess disease involvement and progression in neuromuscular disorders being able to detect even subtle changes in muscle pathology. The aim of this study is to evaluate the feasibility of using a conventional short-tau inversion recovery (STIR) sequence to predict fat fraction (FF) and water T2 (wT2) in skeletal muscle introducing a radiomic workflow with standardized feature extraction combined with machine learning algorithms.

Methods

Twenty-five patients with facioscapulohumeral muscular dystrophy (FSHD) were scanned at calf level using conventional STIR sequence and qMRI techniques. We applied and compared three different radiomics workflows (WF1, WF2, WF3), combined with seven Machine Learning regression algorithms (linear, ridge and lasso regression, tree, random forest, k-nearest neighbor and support vector machine), on conventional STIR images to predict FF and wT2 for six calf muscles.

Results

The combination of WF3 and K-nearest neighbor resulted to be the best predictor model of qMRI parameters with a mean absolute error about ± 5 pp for FF and ± 1.8 ms for wT2.

Conclusion

This pilot study demonstrated the possibility to predict qMRI parameters in a cohort of FSHD subjects starting from conventional STIR sequence.

Facioscapulohumeral Muscular Dystrophy

PURPOSE OF REVIEW

This article reviews the current knowledge on the clinical characteristics and disease mechanism of facioscapulohumeral muscular dystrophy (FSHD), as well as advances in targeted therapy development.

RECENT FINDINGS

FSHD has a wide range of severity, yet a distinct phenotype characterized by weakness of the facial, shoulder, and upper arm muscles, followed by weakness of the trunk and leg muscles. It can be caused by two genetic mechanisms that share a common downstream pathway, namely, the epigenetic derepression and subsequent misexpression of the myotoxic DUX4 transcription factor. Treatment is currently supportive and outlined in evidence-based guidelines. Advances in the understanding of the pathogenic mechanism of FSHD are paving the way for targeted therapy development. Approaches for targeted therapies to reduce DUX4 expression that are currently being explored include small molecules, antisense oligonucleotides, vector-based RNA interference, and gene therapy. In anticipation of more clinical trials, "clinical trial preparedness," including the development of sensitive biomarkers and clinical outcome measures, are needed.

SUMMARY

The cornerstones of the diagnosis of FSHD are clinical observation and genetic testing. Management is currently supportive, but progress in the understanding of the disease mechanism has shifted the field of FSHD toward targeted therapy development.

Exercise in myositis: What is important, the prescription or the person?

Our aim for this narrative review was to undertake a search of studies into exercise for people living with Idiopathic Inflammatory myopathies (IIM). We explored the strength of existing evidence with a particular consideration for the implications for people living with IIM and what is important to them. The search strategy from the 2021 Cochrane Physical Activity review in neuromuscular disease was used, and we selected articles that included people with IIM, including Dermatomyositis (DM), Inclusion Body Myositis (IBM), Immune Mediated Necrotising Myopathy (IMNM) [also known as necrotizing autoimmune myopathy (NAM)], and Polymyositis (PM). 2967 records were screened and 16 were included in this review. Safety of exercise was demonstrated in nine articles, using a range of measures of disease activity, serum creatine kinase, indicators of inflammation, pain, or fatigue. Two studies that took muscle biopsies showed no evidence of increased inflammation. Aerobic exercise protocols were used in 8 studies across conditions and demonstrated improvements in cardiorespiratory fitness or exercise capacity. Six studies of strength training observed improvements in muscle function, with two studies reporting muscle biopsy results of amplified immune response and up regulation of genes related to recycling of damaged proteins. Nine of 13 studies that measures functional outcomes showed significant improvements, and evidence for behaviour change was observed in a study of a self-management intervention. The evidence of safety and effect of training is reassuring and welcome, and we now need to explore how we support people to incorporate exercise and physical activity longer term into active lifestyles.

Dynamic magnetic resonance imaging of muscle contraction in facioscapulohumeral muscular dystrophy

Quantitative muscle MRI (water-T2 and fat mapping) is being increasingly used to assess disease involvement in muscle disorders, while imaging techniques for assessment of the dynamic and elastic muscle properties have not yet been translated into clinics. In this exploratory study, we quantitatively characterized muscle deformation (strain) in patients affected by facioscapulohumeral muscular dystrophy (FSHD), a prevalent muscular dystrophy, by applying dynamic MRI synchronized with neuromuscular electrical stimulation (NMES). We evaluated the quadriceps muscles in 34 ambulatory patients and 13 healthy controls, at 6-to 12-month time intervals. While a subgroup of patients behaved similarly to controls, for another subgroup the median strain decreased over time (approximately 57% over 1.5 years). Dynamic MRI parameters did not correlate with quantitative MRI. Our results suggest that the evaluation of muscle contraction by NMES-MRI is feasible and could potentially be used to explore the elastic properties and monitor muscle involvement in FSHD and other neuromuscular disorders.

The relationship between quantitative magnetic resonance imaging of the ankle plantar flexors, muscle function during walking and maximal strength in people with neuromuscular diseases

BACKGROUND

Progression of plantar flexor weakness in neuromuscular diseases is usually monitored by muscle strength measurements, although they poorly relate to muscle function during walking. Pathophysiological changes such as intramuscular adipose tissue affect dynamic muscle function independent from isometric strength. Diffusion tensor imaging and T2 imaging are quantitative MRI measures reflecting muscular pathophysiological changes, and are therefore potential biomarkers to monitor plantar flexor functioning during walking in people with neuromuscular diseases.

METHODS

In fourteen individuals with plantar flexor weakness diffusion tensor imaging and T2 scans of the plantar flexors were obtained, and the diffusion indices fractional anisotropy and mean diffusivity calculated. With a dynamometer, maximal isometric plantar flexor strength was measured. 3D gait analysis was used to assess maximal ankle moment and power during walking.

FINDINGS

Fractional anisotropy, mean diffusivity and T2 relaxation time all moderately correlated with maximal plantar flexor strength (r > 0.512). Fractional anisotropy and mean diffusivity were not related with ankle moment or power (r < 0.288). T2 relaxation time was strongly related to ankle moment (r = -0.789) and ankle power (r = -0.798), and moderately related to maximal plantar flexor strength (r < 0.600).

INTERPRETATION

In conclusion, T2 relaxation time, indicative of multiple pathophysiological changes, was strongly related to plantar flexor function during walking, while fractional anisotropy and mean diffusivity, indicative of fiber size, only related to maximal plantar flexor strength. This indicates that these measures may be suitable to monitor muscle function and gain insights into the pathophysiological changes underlying a poor plantar flexor functioning during gait in people with neuromuscular diseases.

Bildgebung der Muskulatur bei Neuromuskulären Erkrankungen – von der Initialdiagnostik bis zur Verlaufsbeurteilung

Die bildgebende Diagnostik hat sich zu einem integralen Element der Betreuung von PatientInnen mit neuromuskulären Erkrankungen entwickelt. Als wesentliches Diagnostikum ist hierbei die Magnetresonanztomografie als breit verfügbares und vergleichsweise standardisiertes Untersuchungsverfahren etabliert, wobei die Sonografie der Muskulatur bei hinreichend erfahrenem Untersucher ebenfalls geeignet ist, wertvolle diagnostische Informationen zu liefern. Das CT hingegen spielt eine untergeordnete Rolle und sollte nur bei Kontraindikationen für eine MRT in Erwägung gezogen werden. Zunächst wurde die Bildgebung bei Muskelerkrankungen primär in der Initialdiagnostik unter vielfältigen Fragestellungen eingesetzt. Das Aufkommen innovativer Therapiekonzepte bei verschiedenen neuromuskulären Erkrankungen machen neben einer möglichst frühzeitigen Diagnosestellung insbesondere auch eine multimodale Verlaufsbeurteilung zur Evaluation des Therapieansprechens notwendig. Auch hier wird die Bildgebung der Muskulatur als objektiver Parameter des Therapieerfolges intensiv diskutiert und in Forschung wie Praxis zunehmend verwendet.

Quantitative assessment of sitting time in ambulant adults with Muscular Dystrophy

BACKGROUND

Current investigations into physical behaviour in Muscular Dystrophy (MD) have focussed largely on physical activity (PA). Negative health behaviours such as sedentary behaviour (Physical Behaviour) and sitting time (Posture Classification) are widely recognised to negatively influence health, but by contrast are poorly reported, yet could be easier behaviours to modify.

METHODS

14 ambulant men with MD and 12 healthy controls (CTRL) subjects completed 7-days of free-living with wrist-worn accelerometry, assessing physical behaviour (SB or PA) and Posture Classification (Sitting or Standing), presented at absolute (minutes) or relative (% Waking Hours). Participant body composition (Fat Mass and Fat Free Mass) were assessed by Bioelectrical Impedance, while functional status was assessed by 10 m walk test and a functional scale (Swinyard Scale).

RESULTS

Absolute Sedentary Behaviour (2.2 Hours, p = 0.025) and Sitting Time (1.9 Hours, p = 0.030 was greater in adults with MD compared to CTRL and Absolute Physical Activity (3.4 Hours, p < 0.001) and Standing Time (3.2 Hours, p < 0.001) was lower in adults with MD compared to CTRL. Absolute hours of SB was associated with Fat Mass (Kg) (R = 0.643, p < 0.05) in ambulatory adults with MD.

DISCUSSION

This study has demonstrated increased Sedentary Behaviour (2.2 hours) and Sitting time (1.9 Hours) in adults with MD compared to healthy controls. Extended waking hours in sitting and SB raises concerns with regards to progression of potential cardio-metabolic diseases and co-morbidities in MD.

Reproducibility of manual segmentation in muscle imaging

Purpose

To assess the reproducibility of a manual muscle MRI segmentation method that follows a specific set of recommendations developed in our center.

Materials and methods

Nine healthy volunteers underwent a muscle MRI examination that included a TSE T2 sequence of the thighs. Muscle segmentation was performed by three operators: an expert operator (OP1) with 3 years of experience and two radiology residents (OP2 and 3) who were both given basic segmentation instructions, whereas only OP2 underwent additional supervised training from OP1. Intra- and inter-operator Dice similarity coefficient (DSC) was calculated.

Results

OP1 showed the highest average intra-operator DSC values (0.885), whereas OP2 had higher average DSC (0.856) compared to OP3 (0.818). The highest inter-operator agreement was observed between Operators 1 and 2 (0.814) and the lowest between OP2 and OP3 (0.702). Confidence interval (CI) analysis showed that the most experienced operator also had the least variability in drawing the ROIs, whereas OP2 showed both higher intra-operator reproducibility compared to OP3 and higher inter-operator agreement with OP1. The muscles that showed the least reproducibility were the semimembranosus and the short head of the biceps femoris.

Discussion

Following specific recommendations such as these ones derived from our single-center experience leads to an overall high reproducibility of manual muscle segmentation and is helpful in improving both intra-operator and inter-operator reproducibility in less experienced operators.

Interventions for promoting physical activity in people with neuromuscular disease

BACKGROUND

The World Health Organization (WHO) recommends that people of all ages take regular and adequate physical activity. If unable to meet the recommendations due to health conditions, international guidance advises being as physically active as possible. Evidence from community interventions of physical activity indicate that people living with medical conditions are sometimes excluded from participation in studies. In this review, we considered the effects of activity-promoting interventions on physical activity and well-being in studies, as well as any adverse events experienced by participants living with inherited or acquired neuromuscular diseases (NMDs).  OBJECTIVES: To assess the effects of interventions designed to promote physical activity in people with NMD compared with no intervention or alternative interventions.

SEARCH METHODS

On 30 April 2020, we searched Cochrane Neuromuscular Specialised Register, CENTRAL, Embase, MEDLINE, and ClinicalTrials.Gov. WHO ICTRP was not accessible at the time.

SELECTION CRITERIA

We considered randomised or quasi-randomised trials, including cross-over trials, of interventions designed to promote physical activity in people with NMD compared to no intervention or alternative interventions. We specifically included studies that reported physical activity as an outcome measure. Our main focus was studies in which promoting physical activity was a stated aim but we also included studies in which physical activity was assessed as a secondary or exploratory outcome.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane procedures.

MAIN RESULTS

The review included 13 studies (795 randomised participants from 12 studies; number of participants unclear in one study) of different interventions to promote physical activity. Most studies randomised a minority of invited participants. No study involved children or adolescents and nine studies reported minimal entry criteria for walking. Participants had one of nine inherited or acquired NMDs. Types of intervention included structured physical activity support, exercise support (as a specific form of physical activity), and behaviour change support that included physical activity or exercise. Only one included study clearly reported that the aim of intervention was to increase physical activity. Other studies reported or planned to analyse the effects of intervention on physical activity as a secondary or exploratory outcome measure. Six studies did not report results for physical activity outcomes, or the data were not usable. We judged 10 of the 13 included studies at high or unclear risk of bias from incomplete physical activity outcome reporting. We did not perform a meta-analysis for any comparison because of differences in interventions and in usual care. We also found considerable variation in how studies reported physical activity as an outcome measure. The studies that reported physical activity measurement did not always clearly report intention-to-treat (ITT) analysis or whether final assessments occurred during or after intervention. Based on prespecified measures, we included three comparisons in our summary of findings. A physical activity programme (weight-bearing) compared to no physical activity programme One study involved adults with diabetic peripheral neuropathy (DPN) and reported weekly duration of walking during and at the end of a one-year intervention using a StepWatch ankle accelerometer. Based on the point estimate and low-certainty evidence, intervention may have led to an important increase in physical activity per week; however, the 95% confidence interval (CI) included the possibility of no difference or an effect in either direction at three months (mean difference (MD) 34 minutes per week, 95% CI -92.19 to 160.19; 69 participants), six months (MD 68 minutes per week, 95% CI -55.35 to 191.35; 74 participants), and 12 months (MD 49 minutes per week, 95% CI -75.73 to 173.73; 70 participants). Study-reported effect estimates for foot lesions and full-thickness ulcers also included the possibility of no difference, a higher, or lower risk with intervention. A sensor-based, interactive exercise programme compared to no sensor-based, interactive exercise programme One study involved adults with DPN and reported duration of walking over 48 hours at the end of four weeks' intervention using a t-shirt embedded PAMSys sensor. It was not possible to draw conclusions about the effectiveness of the intervention from the very low-certainty evidence (MD -0.64 hours per 48 hours, 95% CI -2.42 to 1.13; 25 participants). We were also unable to draw conclusions about impact on the Physical Component Score (PCS) for quality of life (MD 0.24 points, 95% CI -5.98 to 6.46; 35 participants; very low-certainty evidence), although intervention may have made little or no difference to the Mental Component Score (MCS) for quality of life (MD 5.10 points, 95% CI -0.58 to 10.78; 35 participants; low-certainty evidence). A functional exercise programme compared to a stretching exercise programme One study involved adults with spinal and bulbar muscular atrophy and reported a daily physical activity count at the end of 12 weeks' intervention using an Actical accelerometer. It was not possible to draw conclusions about the effectiveness of either intervention (requiring compliance) due to low-certainty evidence and unconfirmed measurement units (MD -8701, 95% CI -38,293.30 to 20,891.30; 43 participants). Functional exercise may have made little or no difference to quality of life compared to stretching (PCS: MD -1.10 points, 95% CI -5.22 to 3.02; MCS: MD -1.10 points, 95% CI -6.79 to 4.59; 49 participants; low-certainty evidence). Although studies reported adverse events incompletely, we found no evidence of supported activity increasing the risk of serious adverse events.

AUTHORS' CONCLUSIONS

We found a lack of evidence relating to children, adolescents, and non-ambulant people of any age. Many people living with NMD did not meet randomised controlled trial eligibility criteria. There was variation in the components of supported activity intervention and usual care, such as physical therapy provision. We identified variation among studies in how physical activity was monitored, analysed, and reported. We remain uncertain of the effectiveness of promotional intervention for physical activity and its impact on quality of life and adverse events. More information is needed on the ITT population, as well as more complete reporting of outcomes. While there may be no single objective measure of physical activity, the study of qualitative and dichotomous change in self-reported overall physical activity might offer a pragmatic approach to capturing important change at an individual and population level.

Quantitative Muscle-MRI Correlates with Histopathology in Skeletal Muscle Biopsies

BACKGROUND

Skeletal muscle biopsy is one of the gold standards in the diagnostic workup of muscle disorders. By histopathologic analysis, characteristic features like inflammatory cellular infiltrations, fat and collagen replacement of muscle tissue or structural defects of the myofibers can be detected. In the past years, novel quantitative MRI (qMRI) techniques have been developed to quantify tissue parameters, thus providing a non-invasive diagnostic tool in several myopathies.

OBJECTIVE

This proof-of-principle study was performed to validate the qMRI-techniques to skeletal muscle biopsy results.

METHODS

Ten patients who underwent skeletal muscle biopsy for diagnostic purposes were examined by qMRI. Fat fraction, water T2-time and diffusion parameters were measured in the muscle from which the biopsy was taken. The proportion of fat tissue, the severity of degenerative and inflammatory parameters and the amount of type 1- and type 2- muscle fibers were determined in all biopsy samples. The qMRI-data were then correlated to the histopathological findings.

RESULTS

The amount of fat tissue in skeletal muscle biopsy correlated significantly with the fat fraction derived from the Dixon sequence. The water T2-time, a parameter for tissue edema, correlated with the amount of vacuolar changes of myofibers and endomysial macrophages in the histopathologic analysis. No significant correlations were found for diffusion parameters.

CONCLUSION

In this proof-of-principle study, qMRI techniques were related to characteristic histopathologic features in neuromuscular disorders. The study provides the basis for further development of qMRI methods in the follow-up of patients with neuromuscular disorders, especially in the context of emerging treatment strategies.

Overview of MR Image Segmentation Strategies in Neuromuscular Disorders

Neuromuscular disorders are rare diseases for which few therapeutic strategies currently exist. Assessment of therapeutic strategies efficiency is limited by the lack of biomarkers sensitive to the slow progression of neuromuscular diseases (NMD). Magnetic resonance imaging (MRI) has emerged as a tool of choice for the development of qualitative scores for the study of NMD. The recent emergence of quantitative MRI has enabled to provide quantitative biomarkers more sensitive to the evaluation of pathological changes in muscle tissue. However, in order to extract these biomarkers from specific regions of interest, muscle segmentation is mandatory. The time-consuming aspect of manual segmentation has limited the evaluation of these biomarkers on large cohorts. In recent years, several methods have been proposed to make the segmentation step automatic or semi-automatic. The purpose of this study was to review these methods and discuss their reliability, reproducibility, and limitations in the context of NMD. A particular attention has been paid to recent deep learning methods, as they have emerged as an effective method of image segmentation in many other clinical contexts.

Texture analysis and machine learning to predict water T2 and fat fraction from non-quantitative MRI of thigh muscles in Facioscapulohumeral muscular dystrophy

PURPOSE

Quantitative MRI (qMRI) plays a crucial role for assessing disease progression and treatment response in neuromuscular disorders, but the required MRI sequences are not routinely available in every center. The aim of this study was to predict qMRI values of water T2 (wT2) and fat fraction (FF) from conventional MRI, using texture analysis and machine learning.

METHOD

Fourteen patients affected by Facioscapulohumeral muscular dystrophy were imaged at both thighs using conventional and quantitative MR sequences. Muscle FF and wT2 were calculated for each muscle of the thighs. Forty-seven texture features were extracted for each muscle on the images obtained with conventional MRI. Multiple machine learning regressors were trained to predict qMRI values from the texture analysis dataset.

RESULTS

Eight machine learning methods (linear, ridge and lasso regression, tree, random forest (RF), generalized additive model (GAM), k-nearest-neighbor (kNN) and support vector machine (SVM) provided mean absolute errors ranging from 0.110 to 0.133 for FF and 0.068 to 0.115 for wT2. The most accurate methods were RF, SVM and kNN to predict FF, and tree, RF and kNN to predict wT2.

CONCLUSION

This study demonstrates that it is possible to estimate with good accuracy qMRI parameters starting from texture analysis of conventional MRI.

MRI in Neuromuscular Diseases: An Emerging Diagnostic Tool and Biomarker for Prognosis and Efficacy

There is an unmet need to identify biomarkers sensitive to change in rare, slowly progressive neuromuscular diseases. Quantitative magnetic resonance imaging (MRI) of muscle may offer this opportunity, as it is noninvasive and can be carried out almost independent of patient cooperation and disease severity. Muscle fat content correlates with muscle function in neuromuscular diseases, and changes in fat content precede changes in function, which suggests that muscle MRI is a strong biomarker candidate to predict prognosis and treatment efficacy. In this paper, we review the evidence suggesting that muscle MRI may be an important biomarker for diagnosis and to monitor change in disease severity. ANN NEUROL 2020;88:669-681.

12-Month changes of muscle strength, body composition and physical activity in adults with dystrophinopathies

PURPOSE

Muscular dystrophy (MD) is an umbrella term for muscle wasting conditions, for which longitudinal changes in function and body composition are well established in children with Duchenne (DMD), however, changes in adults with DMD and Beckers (BMD), respectively, remain poorly reported. This study aims to assess 12-month changes in lower-limb strength, muscle size, body composition and physical activity in adults with Muscular Dystrophy (MD).

METHODS

Adult males with Duchenne MD (DMD; N = 15) and Beckers MD (BMD; N = 12) were assessed at baseline and 12-months for body composition (Body fat and lean body mass (LBM)), Isometric maximal voluntary contraction (Knee-Extension (KEMVC) and Plantar-Flexion (PFMVC)) and physical activity (tri-axial accelerometry).

RESULTS

12-Month change in strength was found as -19% (PFMVC) and -14% (KEMVC) in DMD. 12-Month change in strength in BMD, although non-significant, was explained by physical activity (R²=0.532-0.585). Changes in LBM (DMD) and body fat (BMD) were both masked by non-significant changes in body mass.

DISCUSSION

12-Month changes in adults with DMD appear consistent with paediatric populations. Physical activity appears important for muscle function maintenance. Specific monitoring of body composition, and potential co-morbidities, within adults with MD is highlighted.Implications for rehabilitationQuantitative muscle strength assessment shows progressive muscle weakness in adults with Duchenne Muscular Dystrophy is comparable to paediatric reports (-14 to -19%).Physical activity should be encouraged in adults with Beckers Muscular Dystrophy, anything appears better than nothing.Body composition, rather than body mass, should be monitored closely to identify any increase in body fat.

Quantitative Muscle MRI Depicts Increased Muscle Mass after a Behavioral Change in Myotonic Dystrophy Type 1

Background Patients with myotonic dystrophy type 1 (DM1) increased their physical activity and exercise capacity following a behavioral intervention. However, it is unknown what is altered in muscles of patients with DM1 as a result of this intervention. The increased exercise capacity suggests that decelerated fat infiltration or increased muscle cross-sectional area (CSA) could be involved. Purpose To assess the effect of this activity-stimulating behavioral intervention on the lower extremity muscles of patients with DM1 with longitudinal quantitative muscle MRI. Materials and Methods In this prospective trial, participants with DM1 were randomized to a behavioral intervention (n = 14) or continued regular care (standard care; n = 13); no age-matched pairing was performed. Participants underwent MRI of the lower extremities at baseline and 10-month follow-up (January 2015 to March 2016). Fat fraction (FF), muscle CSA, and muscle water T2 (T2_water) as markers for fat infiltration, muscle mass, and alteration in tissue water distribution (edema), respectively, were assessed with a chemical shift-encoded Dixon sequence and multiecho spin-echo sequence. Longitudinal within-group and between-group changes were assessed with paired-samples t tests and multivariable regression models. Results A total of 27 patients with DM1 (15 men) were evaluated. Patient age was comparable between groups (intervention, 45 years ± 13 [standard deviation]; standard care, 5 years ± 12; P = .96). Muscle CSA increased 5.9 cm² ± 7.8 in the intervention group during the 10-month follow-up (P = .03) and decreased 3.6 cm² ± 7.2 in the standard care group (P = .13). After 10 months, the mean difference between the groups was 9.5 cm² (P = .01). This effect was stronger in muscles with baseline FF below the mean ± standard deviation of unaffected volunteers (-0.4 cm² ± 0.15; P < .001). FF increased 0.9% ± 1.0 in the intervention group (P = .02) and 1.2% ± 1.2 for standard care (P = .02), with no between-group difference (P = .56). T2_water did not change significantly in either group (intervention, P = .08; standard care, P = .88). Conclusion A behavioral intervention targeting physical activity increased lower extremity muscle cross-sectional area in patients with myotonic dystrophy, preferentially in healthy-appearing muscle. © RSNA, 2020 Online supplemental material is available for this article.

Deep phenotyping of facioscapulohumeral muscular dystrophy type 2 by magnetic resonance imaging

BACKGROUND AND PURPOSE

The aim was to define the radiological picture of facioscapulohumeral muscular dystrophy 2 (FSHD2) in comparison with FSHD1 and to explore correlations between imaging and clinical/molecular data.

METHODS

Upper girdle and/or lower limb muscle magnetic resonance imaging scans of 34 molecularly confirmed FSHD2 patients from nine European neuromuscular centres were analysed. T1-weighted and short-tau inversion recovery (STIR) sequences were used to evaluate the global pattern and to assess the extent of fatty replacement and muscle oedema.

RESULTS

The most frequently affected muscles were obliquus and transversus abdominis, semimembranosus, soleus and gluteus minimus in the lower limbs; trapezius, serratus anterior, latissimus dorsi and pectoralis major in the upper girdle. Iliopsoas, popliteus, obturator internus and tibialis posterior in the lower limbs and subscapularis, spinati, sternocleidomastoid and levator scapulae in the upper girdle were the most spared. Asymmetry and STIR hyperintensities were consistent features. The pattern of muscle involvement was similar to that of FSHD1, and the combined involvement of trapezius, abdominal and hamstring muscles, together with complete sparing of iliopsoas and subscapularis, was detected in 91% of patients. Peculiar differences were identified in a rostro-caudal gradient, a predominant involvement of lower limb muscles compared to the upper girdle, and in the higher percentage of STIR hyperintensities in FSHD2.

CONCLUSION

This multicentre study defines the pattern of muscle involvement in FSHD2, providing useful information for diagnostics and clinical trial design. Both similarities and differences between FSHD1 and FSHD2 were detected, which is also relevant to better understand the pathogenic mechanisms underlying the FSHD-related disease spectrum.

Age-related degeneration of the lumbar paravertebral muscles: Systematic review and three-level meta-regression

BACKGROUND

Morphological changes of the lumbar spine muscles are not well characterised with ageing. To further the understanding of age-related degeneration of the lumbar spine musculature, normative morphological changes that occur within the paravertebral muscles must first be established.

METHODS

A systematic review and meta-regressions were conducted adhering to PRISMA guidelines. Searches for published and unpublished data were completed in June 2019.

RESULTS

Searches returned 4781 articles. 34 articles were included in the quantitative analysis. Three-level meta-analyses showed age-related atrophy (r = -0.26; 95% CI: -0.33, -0.17) and fat infiltration (r = 0.39; 95% CI: 0.28, 0.50) in the lumbar paravertebral muscles. Degenerative changes were muscle-specific and men (r = -0.32; 95% CI: -0.61, 0.01) exhibited significantly greater muscle atrophy than women (r = -0.24; 95% CI: -0.47, 0.03). Imaging modality, specifically ultrasound, also influenced age-related muscle atrophy. Measurements taken across all lumbar levels revealed the greatest fat infiltration with ageing (r = 0.58, 95% CI: 0.35, 0.74). Moderators explained a large proportion of between-study variance in true effects for muscle atrophy (72.6%) and fat infiltration (79.8%) models.

CONCLUSIONS

Lumbar paravertebral muscles undergo age-related degeneration in healthy adults with muscle, lumbar level and sex-specific responses. Future studies should use high-resolution imaging modalities to quantify muscle atrophy and fat infiltration.

Phenotypic correlations in a large single-center cohort of patients with BSCL2 nerve disorders: a clinical, neurophysiological and muscle magnetic resonance imaging study

BACKGROUND AND PURPOSE

BSCL2 heterozygote mutations are a common cause of distal hereditary motor neuropathies (dHMNs). A series of BSCL2 patients is presented and clinical, neurophysiological and muscle magnetic resonance imaging (MRI) findings are correlated.

METHODS

Twenty-six patients from five families carrying the p.N88S mutation were identified. Age of onset, clinical phenotype (dHMN, Charcot-Marie-Tooth, spastic paraplegia), physical examination, disability measured as a modified Rankin Scale score and neurophysiological findings were collected. A whole body muscle MRI had been performed in 18 patients. The pattern of muscle involvement on T1-weighted and short time inversion recovery sequences was analysed. Hierarchical analysis using heatmaps and an MRI Composite Score were generated. Statistical analysis was carried out with STATA SE v.15 (TX, USA).

RESULTS

The mean age was 51.54 ± 19.94 years and 14 patients were men. dHMN was the most common phenotype (50%) and five patients (19.23%) showed no findings on examination. Disease onset was commonly in childhood and disability was low (modified Rankin Scale score 1.34 ± 1.13) although median time since onset of disease was 32 years (range 10-47). Charcot-Marie-Tooth-like patients were more disabled and disability correlated with age. On muscle MRI, thenar eminence, soleus and tibialis anterior were most frequently involved, irrespective of clinical phenotype. MRI Composite Score was strongly correlated with disability.

CONCLUSION

Patients with the p.N88S BSCL2 gene mutation are phenotypically variable, although dHMN is most frequent and generally slowly progressive. Muscle MRI pattern is consistent regardless of phenotype and correlates with disease severity, probably serving as a reliable outcome measure for future clinical trials.

Facioscapulohumeral Muscular Dystrophies

PURPOSE OF REVIEW

Facioscapulohumeral muscular dystrophy (FSHD) is a common muscular dystrophy affecting both pediatric and adult patients. This article reviews the phenotype and pathophysiology of the disease as well as the recent efforts in clinical outcome measures and clinical trials.

RECENT FINDINGS

As the name implies, FSHD involves weakness of facial muscles, muscles that fix the scapula, and muscles overlying the humerus (biceps and triceps). The distinctive phenotype of FSHD occurs secondary to two different genetic mechanisms. FSHD type 1 (FSHD1) is due to a deletion on chromosome 4q, leading to hypomethylation and derepression of DUX4. FSHD type 2 (FSHD2) is due to mutations in SMCHD1 with resulting hypomethylation of the same subtelomeric region of chromosome 4q and derepression of DUX4. Understanding the central role of DUX4 has opened up the possibility of disease-modifying treatments. In preparation for clinical trials of novel agents, researchers are in the process of validating a number of clinical trial outcome measures including MRI, the 6-minute walk test, the FSHD Composite Outcome Measure, reachable workspace, electrical impedance myography, and the FSHD Health Index.

SUMMARY

The treatment of FSHD is currently supportive only. While past clinical trials in FSHD have been largely disappointing, novel agents in development, including antisense oligonucleotides, gene therapy, and small molecules, hold promise for future meaningful therapies.

Strength training and aerobic exercise training for muscle disease

BACKGROUND

Strength training or aerobic exercise programmes, or both, might optimise muscle and cardiorespiratory function and prevent additional disuse atrophy and deconditioning in people with a muscle disease. This is an update of a review first published in 2004 and last updated in 2013. We undertook an update to incorporate new evidence in this active area of research.

OBJECTIVES

To assess the effects (benefits and harms) of strength training and aerobic exercise training in people with a muscle disease.

SEARCH METHODS

We searched Cochrane Neuromuscular's Specialised Register, CENTRAL, MEDLINE, Embase, and CINAHL in November 2018 and clinical trials registries in December 2018.

SELECTION CRITERIA

Randomised controlled trials (RCTs), quasi-RCTs or cross-over RCTs comparing strength or aerobic exercise training, or both lasting at least six weeks, to no training in people with a well-described muscle disease diagnosis.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane.

MAIN RESULTS

We included 14 trials of aerobic exercise, strength training, or both, with an exercise duration of eight to 52 weeks, which included 428 participants with facioscapulohumeral muscular dystrophy (FSHD), dermatomyositis, polymyositis, mitochondrial myopathy, Duchenne muscular dystrophy (DMD), or myotonic dystrophy. Risk of bias was variable, as blinding of participants was not possible, some trials did not blind outcome assessors, and some did not use an intention-to-treat analysis. Strength training compared to no training (3 trials) For participants with FSHD (35 participants), there was low-certainty evidence of little or no effect on dynamic strength of elbow flexors (MD 1.2 kgF, 95% CI -0.2 to 2.6), on isometric strength of elbow flexors (MD 0.5 kgF, 95% CI -0.7 to 1.8), and ankle dorsiflexors (MD 0.4 kgF, 95% CI -2.4 to 3.2), and on dynamic strength of ankle dorsiflexors (MD -0.4 kgF, 95% CI -2.3 to 1.4). For participants with myotonic dystrophy type 1 (35 participants), there was very low-certainty evidence of a slight improvement in isometric wrist extensor strength (MD 8.0 N, 95% CI 0.7 to 15.3) and of little or no effect on hand grip force (MD 6.0 N, 95% CI -6.7 to 18.7), pinch grip force (MD 1.0 N, 95% CI -3.3 to 5.3) and isometric wrist flexor force (MD 7.0 N, 95% CI -3.4 to 17.4). Aerobic exercise training compared to no training (5 trials) For participants with DMD there was very low-certainty evidence regarding the number of leg revolutions (MD 14.0, 95% CI -89.0 to 117.0; 23 participants) or arm revolutions (MD 34.8, 95% CI -68.2 to 137.8; 23 participants), during an assisted six-minute cycle test, and very low-certainty evidence regarding muscle strength (MD 1.7, 95% CI -1.9 to 5.3; 15 participants). For participants with FSHD, there was low-certainty evidence of improvement in aerobic capacity (MD 1.1 L/min, 95% CI 0.4 to 1.8, 38 participants) and of little or no effect on knee extension strength (MD 0.1 kg, 95% CI -0.7 to 0.9, 52 participants). For participants with dermatomyositis and polymyositis (14 participants), there was very low-certainty evidence regarding aerobic capacity (MD 14.6, 95% CI -1.0 to 30.2). Combined aerobic exercise and strength training compared to no training (6 trials) For participants with juvenile dermatomyositis (26 participants) there was low-certainty evidence of an improvement in knee extensor strength on the right (MD 36.0 N, 95% CI 25.0 to 47.1) and left (MD 17 N 95% CI 0.5 to 33.5), but low-certainty evidence of little or no effect on maximum force of hip flexors on the right (MD -9.0 N, 95% CI -22.4 to 4.4) or left (MD 6.0 N, 95% CI -6.6 to 18.6). This trial also provided low-certainty evidence of a slight decrease of aerobic capacity (MD -1.2 min, 95% CI -1.6 to 0.9). For participants with dermatomyositis and polymyositis (21 participants), we found very low-certainty evidence for slight increases in muscle strength as measured by dynamic strength of knee extensors on the right (MD 2.5 kg, 95% CI 1.8 to 3.3) and on the left (MD 2.7 kg, 95% CI 2.0 to 3.4) and no clear effect in isometric muscle strength of eight different muscles (MD 1.0, 95% CI -1.1 to 3.1). There was very low-certainty evidence that there may be an increase in aerobic capacity, as measured with time to exhaustion in an incremental cycle test (17.5 min, 95% CI 8.0 to 27.0) and power performed at VO2 max (maximal oxygen uptake) (18 W, 95% CI 15.0 to 21.0). For participants with mitochondrial myopathy (18 participants), we found very low-certainty evidence regarding shoulder muscle (MD -5.0 kg, 95% CI -14.7 to 4.7), pectoralis major muscle (MD 6.4 kg, 95% CI -2.9 to 15.7), and anterior arm muscle strength (MD 7.3 kg, 95% CI -2.9 to 17.5). We found very low-certainty evidence regarding aerobic capacity, as measured with mean time cycled (MD 23.7 min, 95% CI 2.6 to 44.8) and mean distance cycled until exhaustion (MD 9.7 km, 95% CI 1.5 to 17.9). One trial in myotonic dystrophy type 1 (35 participants) did not provide data on muscle strength or aerobic capacity following combined training. In this trial, muscle strength deteriorated in one person and one person had worse daytime sleepiness (very low-certainty evidence). For participants with FSHD (16 participants), we found very low-certainty evidence regarding muscle strength, aerobic capacity and VO2 peak; the results were very imprecise. Most trials reported no adverse events other than muscle soreness or joint complaints (low- to very low-certainty evidence).

AUTHORS' CONCLUSIONS

The evidence regarding strength training and aerobic exercise interventions remains uncertain. Evidence suggests that strength training alone may have little or no effect, and that aerobic exercise training alone may lead to a possible improvement in aerobic capacity, but only for participants with FSHD. For combined aerobic exercise and strength training, there may be slight increases in muscle strength and aerobic capacity for people with dermatomyositis and polymyositis, and a slight decrease in aerobic capacity and increase in muscle strength for people with juvenile dermatomyositis. More research with robust methodology and greater numbers of participants is still required.

Lower extremity muscle pathology in myotonic dystrophy type 1 assessed by quantitative MRI

Objective

To determine the value of quantitative MRI in providing imaging biomarkers for disease in 20 different upper and lower leg muscles of patients with myotonic dystrophy type 1 (DM1).

Methods

We acquired images covering these muscles in 33 genetically and clinically well-characterized patients with DM1 and 10 unaffected controls. MRIs were recorded with a Dixon method to determine muscle fat fraction, muscle volume, and contractile muscle volume, and a multi-echo spin-echo sequence was used to determine T2 water relaxation time (T2_water), reflecting putative edema.

Results

Muscles in patients with DM1 had higher fat fractions than muscles of controls (15.6 ± 11.1% vs 3.7 ± 1.5%). In addition, patients had smaller muscle volumes (902 ± 232 vs 1,097 ± 251 cm³), smaller contractile muscle volumes (779 ± 247 vs 1,054 ± 246 cm³), and increased T2_water (33.4 ± 1.0 vs 31.9 ± 0.6 milliseconds), indicating atrophy and edema, respectively. Lower leg muscles were affected most frequently, especially the gastrocnemius medialis and soleus. Distribution of fat content per muscle indicated gradual fat infiltration in DM1. Between-patient variation in fat fraction was explained by age (≈45%), and another ≈14% was explained by estimated progenitor CTG repeat length (r² = 0.485) and somatic instability (r² = 0.590). Fat fraction correlated with the 6-minute walk test (r = −0.553) and muscular impairment rating scale (r = 0.537) and revealed subclinical muscle involvement.

Conclusion

This cross-sectional quantitative MRI study of 20 different lower extremity muscles in patients with DM1 revealed abnormal values for muscle fat fraction, volume, and T2_water, which therefore may serve as objective biomarkers to assess disease state of skeletal muscles in these patients.

ClinicalTrials.gov identifier

NCT02118779.

Advances in Quantitative Imaging of Genetic and Acquired Myopathies: Clinical Applications and Perspectives

In the last years, magnetic resonance imaging (MRI) has become fundamental for the diagnosis and monitoring of myopathies given its ability to show the severity and distribution of pathology, to identify specific patterns of damage distribution and to properly interpret a number of genetic variants. The advances in MR techniques and post-processing software solutions have greatly expanded the potential to assess pathological changes in muscle diseases, and more specifically of myopathies; a number of features can be studied and quantified, ranging from composition, architecture, mechanical properties, perfusion, and function, leading to what is known as quantitative MRI (qMRI). Such techniques can effectively provide a variety of information beyond what can be seen and assessed by conventional MR imaging; their development and application in clinical practice can play an important role in the diagnostic process and in assessing disease course and treatment response. In this review, we briefly discuss the current role of muscle MRI in diagnosing muscle diseases and describe in detail the potential and perspectives of the application of advanced qMRI techniques in this field.

Phenotype-genotype relations in facioscapulohumeral muscular dystrophy type 1

To determine how much of the clinical variability in facioscapulohumeral muscular dystrophy type 1 (FSHD1) can be explained by the D4Z4 repeat array size, D4Z4 methylation and familial factors, we included 152 carriers of an FSHD1 allele (23 single cases, 129 familial cases from 37 families) and performed state-of-the-art genetic testing, extensive clinical evaluation and quantitative muscle MRI. Familial factors accounted for 50% of the variance in disease severity (FSHD clinical score). The explained variance by the D4Z4 repeat array size for disease severity was limited (approximately 10%), and varied per body region (facial muscles, upper and lower extremities approximately 30%, 15% and 3%, respectively). Unaffected gene carriers had longer repeat array sizes compared to symptomatic individuals (7.3 vs 6.0 units, P = 0.000) and slightly higher Delta1 methylation levels (D4Z4 methylation corrected for repeat size, 0.96 vs -2.46, P = 0.048). The D4Z4 repeat array size and D4Z4 methylation contribute to variability in disease severity and penetrance, but other disease modifying factors must be involved as well. The larger effect of the D4Z4 repeat array on facial muscle involvement suggests that these muscles are more sensitive to the influence of the FSHD1 locus itself, whereas leg muscle involvement seems highly dependent on modifying factors.

Quantitative muscle MRI and ultrasound for facioscapulohumeral muscular dystrophy: complementary imaging biomarkers

Objective

To assess the overlap of and differences between quantitative muscle MRI and ultrasound in characterizing structural changes in leg muscles of facioscapulohumeral muscular dystrophy (FSHD) patients.

Methods

We performed quantitative MRI and quantitative ultrasound of ten leg muscles in 27 FSHD patients and assessed images, both quantitatively and visually, for fatty infiltration, fibrosis and edema.

Results

The MRI fat fraction and ultrasound echogenicity z-score correlated strongly (CC 0.865, p < 0.05) and both correlated with clinical severity (MRI CC 0.828, ultrasound CC 0.767, p < 0.001). Ultrasound detected changes in muscle architecture in muscles that looked normal on MRI. MRI was better in detecting late stages of fatty infiltration and was more suitable to assess muscle edema. Correlations between quantitative and semi-quantitative scores were strong for MRI (CC 0.844–0.982, p < 0.05), and varied for ultrasound (CC 0.427–0.809, p = 0.026–p < 0.001).

Conclusions

Quantitative muscle MRI and ultrasound are both promising imaging biomarkers for differentiating between degrees of structural muscle changes. As ultrasound is more sensitive to detect subtle structural changes and MRI is more accurate in end stage muscles and detecting edema, the techniques are complementary. Hence, the choice for a particular technique should be considered in light of the trial design.

Validation of MRC Centre MRI calf muscle fat fraction protocol as an outcome measure in CMT1A

OBJECTIVE

To translate the quantitative MRC Centre MRI protocol in Charcot-Marie-Tooth disease type 1A (CMT1A) to a second site; validate its responsiveness in an independent cohort; and test the benefit of participant stratification to increase outcome measure responsiveness.

METHODS

Three healthy volunteers were scanned for intersite standardization. For the longitudinal patient study, 11 patients with CMT1A were recruited with 10 patients rescanned at a 12-month interval. Three-point Dixon MRI of leg muscles was performed to generate fat fraction (FF) maps, transferred to a central site for quality control and analysis. Clinical data collected included CMT Neuropathy Score.

RESULTS

Test-retest reliability of FF within individual healthy calf muscles at the remote site was excellent: intraclass correlation coefficient 0.79, limits of agreement -0.67 to +0.85 %FF. In patients, mean calf muscle FF was 21.0% and correlated strongly with disease severity and age. Calf muscle FF significantly increased over 12 months (+1.8 ± 1.7 %FF, p = 0.009). Patients with baseline FF >10% showed a 12-month FF increase of 2.9% ± 1.3% (standardized response mean = 2.19).

CONCLUSIONS

We have validated calf muscle FF as an outcome measure in an independent cohort of patients with CMT1A. Responsiveness is significantly improved by enrolling a stratified patient cohort with baseline calf FF >10%.

Tracking disease progression non-invasively in Duchenne and Becker muscular dystrophies

BACKGROUND

Analysis of muscle biopsies allowed to characterize the pathophysiological changes of Duchenne and Becker muscular dystrophies (D/BMD) leading to the clinical phenotype. Muscle tissue is often investigated during interventional dose finding studies to show in situ proof of concept and pharmacodynamics effect of the tested drug. Less invasive readouts are needed to objectively monitor patients' health status, muscle quality, and response to treatment. The identification of serum biomarkers correlating with clinical function and able to anticipate functional scales is particularly needed for personalized patient management and to support drug development programs.

METHODS

A large-scale proteomic approach was used to identify serum biomarkers describing pathophysiological changes (e.g. loss of muscle mass), association with clinical function, prediction of disease milestones, association with in vivo ³¹ P magnetic resonance spectroscopy data and dystrophin levels in muscles. Cross-sectional comparisons were performed to compare DMD patients, BMD patients, and healthy controls. A group of DMD patients was followed up for a median of 4.4 years to allow monitoring of individual disease trajectories based on yearly visits.

RESULTS

Cross-sectional comparison enabled to identify 10 proteins discriminating between healthy controls, DMD and BMD patients. Several proteins (285) were able to separate DMD from healthy, while 121 proteins differentiated between BMD and DMD; only 13 proteins separated BMD and healthy individuals. The concentration of specific proteins in serum was significantly associated with patients' performance (e.g. BMP6 serum levels and elbow flexion) or dystrophin levels (e.g. TIMP2) in BMD patients. Analysis of longitudinal trajectories allowed to identify 427 proteins affected over time indicating loss of muscle mass, replacement of muscle by adipose tissue, and cardiac involvement. Over-representation analysis of longitudinal data allowed to highlight proteins that could be used as pharmacodynamic biomarkers for drugs currently in clinical development.

CONCLUSIONS

Serum proteomic analysis allowed to not only discriminate among DMD, BMD, and healthy subjects, but it enabled to detect significant associations with clinical function, dystrophin levels, and disease progression.

Cross-sectional serum metabolomic study of multiple forms of muscular dystrophy

Muscular dystrophies are characterized by a progressive loss of muscle tissue and/or muscle function. While metabolic alterations have been described in patients’‐derived muscle biopsies, non‐invasive readouts able to describe these alterations are needed in order to objectively monitor muscle condition and response to treatment targeting metabolic abnormalities. We used a metabolomic approach to study metabolites concentration in serum of patients affected by multiple forms of muscular dystrophy such as Duchenne and Becker muscular dystrophies, limb‐girdle muscular dystrophies type 2A and 2B, myotonic dystrophy type 1 and facioscapulohumeral muscular dystrophy. We show that 15 metabolites involved in energy production, amino acid metabolism, testosterone metabolism and response to treatment with glucocorticoids were differentially expressed between healthy controls and Duchenne patients. Five metabolites were also able to discriminate other forms of muscular dystrophy. In particular, creatinine and the creatine/creatinine ratio were significantly associated with Duchenne patients performance as assessed by the 6‐minute walk test and north star ambulatory assessment. The obtained results provide evidence that metabolomics analysis of serum samples can provide useful information regarding muscle condition and response to treatment, such as to glucocorticoids treatment.

Integrating clinical and genetic observations in facioscapulohumeral muscular dystrophy

PURPOSE OF REVIEW

This review gives an overview of the currently known key clinical and (epi)genetic aspects of facioscapulohumeral muscular dystrophy (FSHD) and provides perspectives to facilitate future research.

RECENT FINDINGS

Clinically, imaging studies have contributed to a detailed characterization of the FSHD phenotype, and a model is proposed with five stages of disease progression. A number of clinical trials have been conducted regarding exercise and diet aiming to reduce symptoms. Genetically, at least two different mechanisms (FSHD1 and FSHD2) lead to double homeobox 4 (DUX4) expression in skeletal myocytes, which is expected to be necessary for the disease. Disease severity is most likely determined by a combination of the D4Z4 repeat size and its epigenetic state.

SUMMARY

FSHD is one of the most common muscular dystrophies and is characterized by a typical distribution of muscle weakness. Progress has been made on clinical as well as on (epi)genetic aspects of the disease. Currently, there is no cure available for FSHD. For successful development of new treatments targeting the disease process, integration of clinical and pathogenetic knowledge is essential. A clinical trial toolbox that consists of patient registries, biomarkers and clinical outcome measures will be required to effectively conduct future clinical trials.