vendex and Myotonic-Dystrophy

Measurement of muscle strength is fundamental for the management of patients with myotonic dystrophy type 1 (DM1). Nevertheless, guidance on this topic is somewhat limited due to heterogeneous outcome measures used. This systematic literature review aimed to summarize the most frequent outcome measures to assess muscle strength in patients with DM1. We searched on Pubmed, Web of Science and Embase databases. Observational studies using measures of muscle strength assessment in adult patients with DM1 were included. From a total of 80 included studies, 24 measured cardiac, 45 skeletal and 23 respiratory muscle strength. The most common method and outcome measures used to assess cardiac muscle strength were echocardiography and ejection fraction, for skeletal muscle strength were quantitative muscle test, manual muscle test and maximum isometric torque and medical research council and for respiratory muscle strength were manometry and maximal inspiratory and expiratory pressure. We successfully gathered the more consensual methods and measures to evaluate muscle strength in future clinical studies, particularly to test muscle strength response to treatments in patients with DM1. Future consensus on a set of measures to evaluate muscle strength (core outcome set), is important for these patients.

Topics: Adult; Humans; Muscle Strength; Muscle, Skeletal; Myotonic Dystrophy; Outcome Assessment, Health Care; Torque

In a randomized clinical trial the efficacy of strength training was studied in patients with myotonic dystrophy (n = 33) and in patients with Charcot-Marie-Tooth disease (n = 29). Measurements were performed at the start and after 8, 16 and 24 weeks of progressive resistance training. Surface electromyography (SEMG) of proximal leg muscles was recorded during isometric knee extension at maximum voluntary contraction (MVC) and at 20, 40, 60 and 80% of MVC. Changes in MVC, maximum electrical activity and torque-EMG ratios (TER) were calculated. Fatigue was studied by determining the changes in endurance and in the decline of the median frequency (Fmed) of the SEMG during a sustained contraction at 80% MVC. These parameters showed no significant changes after the training in either of the diagnostic groups. Only the Charcot-Marie-Tooth training group showed a gradual significant increase in mean MVC over the whole training period (21%). After 24 weeks, the increase in mean RMS was similar (25%), but this was mainly due to a sharp rise during the first 8 weeks of training (20%). The findings indicate that the initial strength increase was due to a neural factor, while the subsequent increase was mainly due to muscle hypertrophy.

Topics: Adult; Case-Control Studies; Charcot-Marie-Tooth Disease; Electromyography; Evoked Potentials; Female; Follow-Up Studies; Humans; Hypertrophy; Isometric Contraction; Leg; Male; Muscle Fatigue; Muscle, Skeletal; Myotonic Dystrophy; Physical Endurance; Stress, Mechanical; Torque; Weight Lifting

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.. 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.. 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.. 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.

Topics: Adult; Disease Progression; Elbow Joint; Exercise; Female; Hand Strength; Humans; Knee Joint; Male; Middle Aged; Muscle Strength; Myotonic Dystrophy; Range of Motion, Articular; Retrospective Studies; Torque; Trinucleotide Repeat Expansion

The leading hypothesis was that a relation exists between muscular strength and functional abilities. Therefore a study was undertaken to quantify such a relationship in a population of subjects with different muscular strengths. This population consisted of healthy subjects and subjects with slowly progressive neuromuscular disorders.. The study included 33 patients with myotonic dystrophy, 29 patients with Charcot-Marie-Tooth disease and 20 healthy subjects. Isokinetic and isometric knee torques were measured on an isokinetic dynamometer at various velocities. The following activities were timed: descending and ascending stairs, rising from a chair, rising from supine, walking at natural speed and walking at maximum speed.. The population covered a wide range of the variables: whereas the healthy subjects performed best (i.e. had the highest knee torques and performed the activities most quickly), the myotonic dystrophy group included the subjects with the lowest knee torques. The natural logarithms (In) of isokinetic extension torque at the highest velocity (120 degrees/s) and those of the time taken to perform the described activities showed the highest levels of correlation. It was found that after correction for age and weight, 56% (walking at natural speed) to 73% (descending stairs) of the variance in the In of the time taken could be attributed to the variance in the In of the torques.. A strong relation between quadriceps strength and timed motor performances were demonstrated. The impact of strength reduction on time taken was most obvious in subjects with considerably decreased strength. Therefore, it is feasible to try to influence muscle strength in patients with relevant strength reduction in order to achieve better functional ability.

Topics: Adolescent; Adult; Case-Control Studies; Charcot-Marie-Tooth Disease; Female; Humans; Isometric Contraction; Knee; Linear Models; Male; Middle Aged; Movement Disorders; Multivariate Analysis; Muscle Contraction; Myotonic Dystrophy; Psychomotor Performance; Time Factors; Torque