Prevalence of Lifestyle Risk Factors in Myotonic Dystrophy Type 1

Energy Expenditure, Body Composition, and Skeletal Muscle Oxidative Capacity in Patients with Myotonic Dystrophy Type 1

BACKGROUND

Myotonic dystrophy type 1 (DM1) patients are at risk for metabolic abnormalities and commonly experience overweight and obesity. Possibly, weight issues result from lowered resting energy expenditure (EE) and impaired muscle oxidative metabolism.

OBJECTIVES

This study aims to assess EE, body composition, and muscle oxidative capacity in patients with DM1 compared to age-, sex- and BMI-matched controls.

METHODS

A prospective case control study was conducted including 15 DM1 patients and 15 matched controls. Participants underwent state-of-the-art methodologies including 24 h whole room calorimetry, doubly labeled water and accelerometer analysis under 15-days of free-living conditions, muscle biopsy, full body magnetic resonance imaging (MRI), dual-energy x-ray absorptiometry (DEXA), computed tomography (CT) upper leg, and cardiopulmonary exercise testing.

RESULTS

Fat ratio determined by full body MRI was significantly higher in DM1 patients (56 [49-62] %) compared to healthy controls (44 [37-52] % ; p = 0.027). Resting EE did not differ between groups (1948 [1742-2146] vs (2001 [1853-2425>] kcal/24 h, respectively; p = 0.466). In contrast, total EE was 23% lower in DM1 patients (2162 [1794-2494] vs 2814 [2424-3310] kcal/24 h; p = 0.027). Also, DM1 patients had 63% less steps (3090 [2263-5063] vs 8283 [6855-11485] steps/24 h; p = 0.003) and a significantly lower VO2 peak (22 [17-24] vs 33 [26-39] mL/min/kg; p = 0.003) compared to the healthy controls. Muscle biopsy citrate synthase activity did not differ between groups (15.4 [13.3-20.0] vs 20.1 [16.6-25.8] μM/g/min, respectively; p = 0.449).

CONCLUSIONS

Resting EE does not differ between DM1 patients and healthy, matched controls when assessed under standardized circumstances. However, under free living conditions, total EE is substantially reduced in DM1 patients due to a lower physical activity level. The sedentary lifestyle of DM1 patients seems responsible for the undesirable changes in body composition and aerobic capacity.

Noninvasive Home Mechanical Ventilation in Adult Myotonic Dystrophy Type 1: A Systematic Review

INTRODUCTION

Chronic hypercapnic respiratory failure induces considerable morbidity and mortality in patients with myotonic dystrophy type 1 (DM1). This study systematically reviews the effects of noninvasive home mechanical ventilation (HMV) on gas exchange, quality of life, survival, and compliance in DM1 patients.

METHODS

A systematic Medline and Embase search was performed (January 1995 to January 2020). Records were screened for eligibility criteria, data were extracted from included studies, and risk of bias was assessed. We present findings mainly using a narrative synthesis.

RESULTS

Twenty-eight relevant full-text articles were screened for eligibility criteria. Nine studies were included. Randomized controlled trials were not found. Studies had either an observational (n = 8) or interventional (n = 1) design. In the pooled data analysis, HMV showed to improve mean oxygen saturation with 4.8% and decreased mean carbon dioxide values with 3 mm Hg. Compliance varied widely between studies, from no use to more than 12 h per day. Quality of life was not studied extensively, but some studies reported positive effects of HMV on symptoms of chronic respiratory failure. HMV may improve survival in DM1 patients with chronic hypercapnic respiratory failure.

CONCLUSION

This review shows that HMV can improve gas exchange and relieve symptoms with a possible survival benefit in DM1 patients with chronic hypercapnic respiratory failure. Future studies should focus on developing strategies to optimize the timing of HMV initiation and to promote compliance.

Assessment of muscular strength and functional capacity in the juvenile and adult myotonic dystrophy type 1 population: a 3-year follow-up study

INTRODUCTION

Myotonic dystrophy type 1 (DM1) is a progressive, multisystemic, and autosomal dominant disease. Muscle wasting and weakness have been associated with impaired functional capacity and restricted social participation in affected individuals. The disease's presentation is very heterogenous and its progression is still under-documented.

OBJECTIVE

The aim of the study was to document the progression of muscular strength and functional capacity in the DM1 population over a 3-year period.

METHODS

Twenty-three individuals with juvenile or adult phenotypes of DM1 were recruited to complete clinical assessments in 2016 and 2019. Maximal isometric muscle strength (MIMS) was evaluated with quantified muscle testing and functional capacity was evaluated with the Mini-BESTest, the 10-m walk test at comfortable and maximal speeds, the Timed Up and Go and the 6-min walk test. Participants also completed three questionnaires: DM1-Activ, Upper Extremity Functional Index and Lower Extremity Functional Scale (LEFS). Subgroup analyses were evaluated for sex, phenotype, and type of physical activity practiced during the 3-year period.

RESULTS

For the whole group, there was a significant decline in the scores of the Mini-BESTest and the LEFS. Also, MIMS significantly declined for prehension, lateral pinch as well as for hip abductors, knee extensors and ankle dorsiflexors muscle groups. Subgroups analyses revealed that men lost more MIMS than women, and that adult phenotype lost more MIMS than juvenile phenotype.

CONCLUSION

Quantified muscle testing is a better indicator of disease progression over a 3-year period than functional tests. Phenotype and sex are important factors that influence the progression of DM1.

Insulin Signaling as a Key Moderator in Myotonic Dystrophy Type 1

Myotonic dystrophy type 1 (DM1) is an autosomal dominant genetic disease characterized by multi-system involvement. Affected organ system includes skeletal muscle, heart, gastro-intestinal system and the brain. In this review, we evaluate the evidence for alterations in insulin signaling and their relation to clinical DM1 features. We start by summarizing the molecular pathophysiology of DM1. Next, an overview of normal insulin signaling physiology is given, and evidence for alterations herein in DM1 is presented. Clinically, evidence for involvement of insulin signaling pathways in DM1 is based on the increased incidence of insulin resistance seen in clinical practice and recent trial evidence of beneficial effects of metformin on muscle function. Indirectly, further support may be derived from certain CNS derived symptoms characteristic of DM1, such as obsessive-compulsive behavior features, for which links with altered insulin signaling has been demonstrated in other diseases. At the basic scientific level, several pathophysiological mechanisms that operate in DM1 may compromise normal insulin signaling physiology. The evidence presented here reflects the importance of insulin signaling in relation to clinical features of DM1 and justifies further basic scientific and clinical, therapeutically oriented research.

Meet and eat, an interdisciplinary group intervention for patients with myotonic dystrophy about healthy nutrition, meal preparation, and consumption: a feasibility study

Purpose: To develop and evaluate an interdisciplinary group intervention for patients with myotonic dystrophy regarding healthy nutrition, meal preparation, and consumption, called Meet and Eat.Materials and methods: A design-based approach was used, exploring experiences and needs of patients with myotonic dystrophy and their next of kin. This resulted in a 4-week interdisciplinary outpatient group intervention to increase awareness and change behavior. In a mixed-method feasibility study this intervention was evaluated with participants and facilitators.Results: Participants reported on social impact of difficulties with eating and drinking (speaking, swallowing, and social embarrassment) and a variety of complaints affecting meal preparation and consumption. Patients and family members expressed the wish to learn from others. After delivery of the intervention, self-reported outcome measures demonstrated improvement on eating and drinking issues in daily life. The qualitative evaluation showed increased awareness and appreciation of the following design principles: peer support, multidisciplinary approach, active involvement of patient with myotonic dystrophy and their next of kin by using personal goals and motivational interviewing.Conclusion: Participation in Meet and Eat seemed to increase insight in patients' condition and ways of management. However, a longer self-management life style program is recommended to change behavior.Implications for rehabilitationPatients with myotonic dystrophy experience physical, cognitive and psychosocial problems to manage healthy nutrition, meal preparation, and consumption;This multidisciplinary group intervention Meet and Eat in patients with myotonic dystrophy appears to be feasible and seems to result in increased insight and management strategies;Peer support, multidisciplinary approach, personal goals, and involvement of family were key factors;To change eating and drinking behavior, a 4-week intervention is too short.

Exercise biology of neuromuscular disorders

Neuromuscular disorders (NMDs) are chronic conditions that affect the neuromuscular system. Many NMDs currently have no cure; however, as more effective therapies become available for NMD patients, these individuals will exhibit improved health and/or prolonged lifespans. As a result, persons with NMDs will likely desire to engage in a more diverse variety of activities of daily living, including increased physical activity or exercise. Therefore, there is a need to increase our knowledge of the effects of acute exercise and chronic training on the neuromuscular system in NMD contexts. Here, we discuss the disease mechanisms and exercise biology of Duchenne muscular dystrophy (DMD), spinal muscular atrophy (SMA), and myotonic dystrophy type 1 (DM1), which are among the most prevalent NMDs in children and adults. Evidence from clinical and preclinical studies are reviewed, with emphasis on the functional outcomes of exercise, as well as on the putative cellular mechanisms that drive exercise-induced remodelling of the neuromuscular system. Continued investigation of the molecular mechanisms of exercise adaptation in DMD, SMA, and DM1 will assist in enhancing our understanding of the biology of these most prevalent NMDs. This information may also be useful for guiding the development of novel therapeutic targets for future pursuit.

Genotype and other determinants of respiratory function in myotonic dystrophy type 1

New treatments are being developed for myotonic dystrophy type 1 (DM1). To evaluate their efficacy, knowledge about the natural history of respiratory dysfunction and its relationship with the genotype will be crucial. Also needed is information on factors predicting the time-course of respiratory function in DM1. Using data from 283 patients, we built a segmented linear mixed-effects regression model to assess respiratory function changes over time. Respiratory variables associated with the CTG repeat number were identified by multivariate linear regression analysis. Cox proportional-hazards regression was used to estimate hazard ratios (HRs) for starting non-invasive ventilation (NIV). Higher CTG repeat number was associated with peak cough flow impairment (p = 0.007) and with lower values for maximal inspiratory pressure (p <0.0001) and upright vital capacity. A vital capacity decline over time was associated with older age at first evaluation (p <0.0001), higher CTG repeat number (p <0.0001), and higher baseline body mass index (p = 0.0004). NIV initiation was associated with lower peak cough flow (p <0.001) after age and PaCO₂ adjustment. Earlier and closer monitoring with routine peak cough flow determination in adults with congenital DM1, combined with weight control, may diminish the risk of respiratory complications and optimise other aspects of management.

[Update on the respiratory management of patients with chronic neuromuscular disease]

BACKGROUND

Neuromuscular diseases include a wide range of conditions that may involve potentially life-threatening respiratory complications (infection, respiratory failure).

SURVEILLANCE AND PULMONARY FUNCTION TESTS

For patients with neuromuscular diseases, clinical assessment of respiratory function and regular pulmonary function tests are needed to screen for nocturnal respiratory disorders, weakness of the diaphragm and potential restrictive disorders and/or chronic hypercapnic respiratory insufficiency, possibly with couch deficiency. MANAGEMENT OF NOCTURNAL RESPIRATORY DISORDERS AND CHRONIC RESPIRATORY FAILURE: Nocturnal respiratory assistance is an important phase of care for nocturnal respiratory disorders and chronic respiratory failure. This may involve continuous positive airway pressure, adaptative servo-ventilation or non-invasive ventilation with a facial or nasal mask. As needed, diurnal assistance may be proposed by mouthpiece ventilation. Should non-invasive ventilation prove insufficient, or if significant swallowing disorders or recurrent bronchial obstruction develop, or in case of prolonged intubation, tracheotomy may be required.

LOWER AIRWAY OBSTRUCTION

In case of lower airway infection with ineffective cough, physical therapy, associated with air stacking, intermittent positive pressure breathing or mechanical in-exsufflation may be proposed.

PATIENT-CENTERED MANAGEMENT

Care for swallowing disorders, nutritional counseling (cachexia, obesity), vaccinations and therapeutic education are integral elements of patient-centered management aiming to prevent the negative impact of infection and to manage respiratory failure of chronic neuromuscular disease.

Elevated plasma levels of cardiac troponin-I predict left ventricular systolic dysfunction in patients with myotonic dystrophy type 1: A multicentre cohort follow-up study

Objective

High sensitivity plasma cardiac troponin-I (cTnI) is emerging as a strong predictor of cardiac events in a variety of settings. We have explored its utility in patients with myotonic dystrophy type 1 (DM1).

Methods

117 patients with DM1 were recruited from routine outpatient clinics across three health boards. A single measurement of cTnI was made using the ARCHITECT STAT Troponin I assay. Demographic, ECG, echocardiographic and other clinical data were obtained from electronic medical records. Follow up was for a mean of 23 months.

Results

Fifty five females and 62 males (mean age 47.7 years) were included. Complete data were available for ECG in 107, echocardiography in 53. Muscle Impairment Rating Scale score was recorded for all patients. A highly significant excess (p = 0.0007) of DM1 patients presented with cTnI levels greater than the 99^th centile of the range usually observed in the general population (9 patients; 7.6%). Three patients with elevated troponin were found to have left ventricular systolic dysfunction (LVSD), compared with four of those with normal range cTnI (33.3% versus 3.7%; p = 0.001). Sixty two patients had a cTnI level < 5ng/L, of whom only one had documented evidence of LVSD. Elevated cTnI was not predictive of severe conduction abnormalities on ECG, or presence of a cardiac device, nor did cTnI level correlate with muscle strength expressed by Muscle Impairment Rating Scale score.

Conclusions

Plasma cTnI is highly elevated in some ambulatory patients with DM1 and shows promise as a tool to aid cardiac risk stratification, possibly by detecting myocardial involvement. Further studies with larger patient numbers are warranted to assess its utility in this setting.

Factors influencing compliance with non-invasive ventilation at long-term in patients with myotonic dystrophy type 1: A prospective cohort

This study evaluated compliance with non-invasive ventilation in patients with myotonic dystrophy type 1 and identified predictors of cessation at 5 years in a cohort of patients followed in a specialist center for Neuromuscular Diseases in France. Mechanical ventilation in these patients poses a very strong challenge to caregivers. Factors predicting relative compliance were identified using multivariate linear regressions. Cox proportional-hazards regression was used to estimate hazard ratios associated with risk of cessation. One hundred and twenty-eight patients were included. Compliance during the first year was higher when symptoms of respiratory failure were initially present (+25%, p < 0.003) and lower in the case of acute respiratory failure (-29%, p < 0.003). Long-term compliance was associated with symptoms of respiratory failure (+52%, p < 0.0001) and nocturnal arterial oxygen desaturation (+23%, p < 0.007). Cessation was more frequent in the cases of excessive leaks (HR = 7.81, IC [1.47-41.88], p < 0.01), ventilator dysfunction requiring emergency technical intervention (HR = 12.58, IC [1.22-129.69], p < 0.03) or high body mass index (p < 0.02). Cessation was less frequent for patients with a professional occupation or undergoing professional training (HR = 0.11, IC [0.02-0.77], p < 0.02). Compliance with non-invasive ventilation is poor in patients with no subjective symptoms of respiratory failure. It may be improved with appropriate education and follow-up.

Stanford Chronic Disease Self-Management Program in myotonic dystrophy: New opportunities for occupational therapists

Background.

Chronic disease self-management is a priority in health care. Personal and environmental barriers for populations with neuromuscular disorders might diminish the efficacy of self-management programs, although they have been shown to be an effective intervention in many populations. Owing to their occupational expertise, occupational therapists might optimize self-management program interventions.

Purpose.

This study aimed to adapt the Stanford Chronic Disease Self-Management Program (CDSMP) for people with myotonic dystrophy type 1 (DM1) and assess its acceptability and feasibility in this population.

Method.

Using an adapted version of the Stanford CDSMP, a descriptive pilot study was conducted with 10 participants (five adults with DM1 and their caregivers). A semi-structured interview and questionnaires were used.

Findings.

The Stanford CDSMP is acceptable and feasible for individuals with DM1. However, improvements are required, such as the involvement of occupational therapists to help foster concrete utilization of self-management strategies into day-to-day tasks using their expertise in enabling occupation.

Implications.

Although adaptations are needed, the Stanford CDSMP remains a relevant intervention with populations requiring the application of self-management strategies.

Overweight Is an Independent Risk Factor for Reduced Lung Volumes in Myotonic Dystrophy Type 1

Background

In this large observational study population of 105 myotonic dystrophy type 1 (DM1) patients, we investigate whether bodyweight is a contributor of total lung capacity (TLC) independent of the impaired inspiratory muscle strength.

Methods

Body composition was assessed using the combination of body mass index (BMI) and fat-free mass index. Pulmonary function tests and respiratory muscle strength measurements were performed on the same day. Patients were stratified into normal (BMI < 25 kg/m²) and overweight (BMI ≥ 25 kg/m²) groups. Multiple linear regression was used to find significant contributors for TLC.

Results

Overweight was present in 59% of patients, and body composition was abnormal in almost all patients. In overweight patients, TLC was significantly (p = 2.40×10⁻³) decreased, compared with normal-weight patients, while inspiratory muscle strength was similar in both groups. The decrease in TLC in overweight patients was mainly due to a decrease in expiratory reserve volume (ERV) further illustrated by a highly significant (p = 1.33×10⁻¹⁰) correlation between BMI and ERV. Multiple linear regression showed that TLC can be predicted using only BMI and the forced inspiratory volume in 1 second, as these were the only significant contributors.

Conclusions

This study shows that, in DM1 patients, overweight further reduces lung volumes, as does impaired inspiratory muscle strength. Additionally, body composition is abnormal in almost all DM1 patients.

Metabolic syndrome in patients with myotonic dystrophy type 1

INTRODUCTION

The aim of this study was to assess the frequency and features of metabolic syndrome (MetS) in myotonic dystrophy type 1 (DM1).

METHODS

We studied 66 DM1 patients (50% men, aged 41.9 ± 10.5 years, disease duration of 19.3 ± 8.6 years). New worldwide consensus criteria for MetS from 2009 were used.

RESULTS

Components of MetS were present at the following frequencies: hypertriglyceridemia 67%; low HDL cholesterol 35%; hypertension 18%; central obesity 14%; and hyperglycemia 9%. MetS was present in 11 (17%) patients. The presence of MetS was not associated with patients' gender, age, disease severity, disease duration, or CTG repeat length (P > 0.05). Patients with MetS had significantly lower total SF-36 scores as a measure of quality of life in comparison to patients without MetS (P < 0.05).

CONCLUSION

Although certain components of MetS were very frequent in patients with DM1, only 17% met the criteria for MetS.

Impact of habitual exercise on the strength of individuals with myotonic dystrophy type 1

OBJECTIVE

It remains unclear whether habitual physical activity can attenuate the rate of progressive muscle strength loss in individuals with myotonic dystrophy type 1 (DM1). The aim of this study was to identify whether there were any strength differences between DM1 patients who were habitually active or sedentary.

DESIGN

Knee extension, handgrip, and elbow flexion quantitative strength measurements were investigated in the DM1 patients using isokinetic dynamometry. Strength was compared between the patients who followed self-selected formal exercise plans for at least 1 yr, those who were sedentary (controls), and those who initiated or terminated a formal exercise routine.

RESULTS

Physically active DM1 patients with midrange CTG repeat size (100-500 CTG repeat sizes) had significantly stronger handgrip and knee extension and elbow flexion torques as compared with their sedentary counterparts with the same CTG repeat range. The DM1 patients who began a formal exercise routine experienced a significant improvement in knee extension torque measurements (+24.3%) in comparison with those who were habitually active or sedentary.

CONCLUSIONS

These data suggest that there is an association between physical activity and strength. This may be shown to be a useful tool for the management of this condition. Further investigations into the relationships between physical exercise, muscle weakness, and genetic factors are needed before evidence-based recommendations can be made.

Nationwide patient registry for GNE myopathy in Japan

Background

GNE myopathy is a slowly progressive autosomal recessive myopathy caused by mutations in the GNE (glucosamine (UDP-N-acetyl)-2-epimerase/N-acetylmannosamine kinase) gene. This study aimed to (1) develop a nationwide patient registry for GNE myopathy in order to facilitate the planning of clinical trials and recruitment of candidates, and (2) gain further insight into the disease for the purpose of improving therapy and care.

Methods

Medical records of genetically-confirmed patients with GNE myopathy at the National Center Hospital of the National Center of Neurology and Psychiatry (NCNP) were retrospectively reviewed in order to obtain data reflecting the severity and progression of the disease. We also referred to items in the datasheet of the nationwide registry of dystrophinopathy patients in the Registry of Muscular Dystrophies (Remudy). Items selected for the registration sheet included age, sex, age at onset, past history and complications, family history, body weight and height, pathological findings of muscle biopsy, grip power, walking ability, respiratory function, cardiac function, willingness to join upcoming clinical trials, and participation in patient associations. A copy of the original genetic analysis report was required of each patient.

Results

We successfully established the Remudy-GNE myopathy. Currently, 121 patients are registered nationwide, and 93 physicians from 73 hospitals collaborated to establish the registry. The mean age at onset was 27.7 ± 9.6 years, and 19.8% (24/121) of patients could walk without assistance. Mean presumed durations from onset to use of assistive devices (cane and/or braces) and a wheelchair, and loss of ambulation were 12.4, 15.2, and 21.1 years, respectively. Three patients had a past history and/or complication of idiopathic thrombocytopenia. To share the progress of this study with the community, newsletters were published on a regular basis, and included information regarding new phase I clinical trials for GNE myopathy. The newsletters also served as a medium to bring attention to the importance of respiratory evaluation and care for respiratory insufficiency.

Conclusion

The Japanese Remudy-GNE myopathy is useful for clarifying the natural history of the disease and recruiting patients with genetically-confirmed GNE myopathy for clinical trials.

Electronic supplementary material

The online version of this article (doi:10.1186/s13023-014-0150-4) contains supplementary material, which is available to authorized users.