Forelimb treatment in a large cohort of dystrophic dogs supports delivery of a recombinant AAV for exon skipping in Duchenne patients.

Duchenne muscular dystrophy (DMD) is a severe muscle-wasting disorder caused by mutations in the dystrophin gene, without curative treatment yet available. Our study provides, for the first time, the overall safety profile and therapeutic dose of a recombinant adeno-associated virus vector, serotype 8 (rAAV8) carrying a modified U7snRNA sequence promoting exon skipping to restore a functional in-frame dystrophin transcript, and injected by locoregional transvenous perfusion of the forelimb. Eighteen Golden Retriever Muscular Dystrophy (GRMD) dogs were exposed to increasing doses of GMP-manufactured vector. Treatment was well tolerated in all, and no acute nor delayed adverse effect, including systemic and immune toxicity was detected. There was a dose relationship for the amount of exon skipping with up to 80% of myofibers expressing dystrophin at the highest dose. Similarly, histological, nuclear magnetic resonance pathological indices and strength improvement responded in a dose-dependent manner. The systematic comparison of effects using different independent methods, allowed to define a minimum threshold of dystrophin expressing fibers (>33% for structural measures and >40% for strength) under which there was no clear-cut therapeutic effect. Altogether, these results support the concept of a phase 1/2 trial of locoregional delivery into upper limbs of nonambulatory DMD patients.

Wrist flexion and extension torques measured by highly sensitive dynamometer in healthy subjects from 5 to 80 years.

BACKGROUND: Wrist movements become impaired with disease progression in various neuromuscular disorders. With the development of new therapies, thorough measurement of muscle strength is crucial to document natural disease progression and to assess treatment efficacy. We developed a new dynamometer enabling wrist flexion and extension torque measurement with high sensitivity. The aims of the present study were to collect norms for healthy children and adults, to compute predictive equations, to assess the reliability of the measurements and to test the feasibility of using the device in patients with a neuromuscular disease. METHODS: The peak isometric torque of wrist flexion and extension was measured with the MyoWrist dynamometer in 345 healthy subjects aged between 5 and 80 years old and in 9 patients with limb girdle muscle dystrophy type 2 C (LGMD2C) aged between 16 and 38 years old. RESULTS: Predictive equations are proposed for the wrist flexion and extension strength in children and adults. Intra-rater and inter-rater reliability was good with ICCs higher than 0.9 for both wrist flexion and extension. However, retest values were significantly higher by 4% than test results. The dynamometer was applied with no difficulty to patients with LGMD2C and was sensitive enough to detect strength as weak as 0.82 N.m. From our models, we quantified the mean strength of wrist extension in LGMD2C patients to 39 ± 17% of their predicted values. CONCLUSIONS: The MyoWrist dynamometer provides reliable and sensitive measurement of both wrist flexion and extension torques. However, a training session is recommended before starting a study as a small but significant learning effect was observed. Strength deficit can be quantified from predictive equations that were computed from norms of healthy children and adults.

Ankle dorsi- and plantar-flexion torques measured by dynamometry in healthy subjects from 5 to 80 years.

BACKGROUND: Ankle strength is often impaired in some of the most common neuromuscular disorders. Consequently, strength generated around this joint is important to assess, because it has a great impact on balance and gait. The objectives of this study were to establish normative data and predictive equations for both ankle dorsi- and plantar-flexion strength from a population of healthy subjects (children and adults), to assess the reliability of the measurements and to study the feasibility of using a novel dynamometer on a group of patients with a neuromuscular disorder. METHODS: Measurements of maximal isometric torque for dorsi- and plantar-flexion were performed on 345 healthy subjects from 5 to 80 years of age. The feasibility of the method was tested on nine patients diagnosed with type 2A limb girdle muscular dystrophy. RESULTS: The results documented normal strength values depending on gender and age on ankle dorsi- and plantar-flexion. The reliability of the technique was good with no evaluator effect and a small learning effect. The dynamometer was found suitable in the group of patients, even very weak. CONCLUSIONS: The device developed was both reliable and accurate in assessing both ankle dorsi-flexion and plantar-flexion torque measurements from weak patients and children to strong healthy adults. Norms and predictive equations are provided for these two muscle functions.

A Movement Monitor Based on Magneto-Inertial Sensors for Non-Ambulant Patients with Duchenne Muscular Dystrophy: A Pilot Study in Controlled Environment.

UNLABELLED: Measurement of muscle strength and activity of upper limbs of non-ambulant patients with neuromuscular diseases is a major challenge. ActiMyo® is an innovative device that uses magneto-inertial sensors to record angular velocities and linear accelerations that can be used over long periods of time in the home environment. The device was designed to insure long-term stability and good signal to noise ratio, even for very weak movements. In order to determine relevant and pertinent clinical variables with potential for use as outcome measures in clinical trials or to guide therapy decisions, we performed a pilot study in non-ambulant neuromuscular patients. We report here data from seven Duchenne Muscular Dystrophy (DMD) patients (mean age 18.5 ± 5.5 years) collected in a clinical setting. Patients were assessed while wearing the device during performance of validated tasks (MoviPlate, Box and Block test and Minnesota test) and tasks mimicking daily living. The ActiMyo® sensors were placed on the wrists during all the tests. Software designed for use with the device computed several variables to qualify and quantify muscular activity in the non-ambulant subjects. Four variables representative of upper limb activity were studied: the rotation rate, the ratio of the vertical component in the overall acceleration, the hand elevation rate, and an estimate of the power of the upper limb. The correlations between clinical data and physical activity and the ActiMyo® movement parameters were analyzed. The mean of the rotation rate and mean of the elevation rate appeared promising since these variables had the best reliability scores and correlations with task scores. Parameters could be computed even in a patient with a Brooke functional score of 6. The variables chosen are good candidates as potential outcome measures in non-ambulant patients with Duchenne Muscular Dystrophy and use of the ActiMyo® is currently being explored in home environment. TRIAL REGISTRATION: ClinicalTrials.gov NCT01611597.

Relationship between muscle impairments, postural stability, and gait parameters assessed with lower-trunk accelerometry in myotonic dystrophy type 1.

This study evaluated gait using lower-trunk accelerometry and investigated relationships between gait abnormalities, postural instability, handgrip myotonia, and weakness in lower-limb and axial muscle groups commonly affected in myotonic dystrophy type 1 (DM1). Twenty-two patients (11 men, 11 women; age = 42 years (range: 26-51)) with DM1 and twenty healthy controls (9 men, 11 women; age = 44 years (range: 24-50)) participated in this study. Gait analysis using lower-trunk accelerometry was performed at self-selected walking pace. Postural stability was measured via center of pressure displacement analysis using a force platform during eyes-closed normal stance. Handgrip myotonia was quantified using force-relaxation curve modeling. Patients displayed lower walking speed, stride frequency, stride length, gait regularity, and gait symmetry. Strength of ankle plantar flexors, ankle dorsal flexors and neck flexors correlated with interstride regularity in the vertical direction (ρ = 0.57, ρ = 0.59, and ρ = 0.44, respectively; all P < 0.05). Knee extension strength correlated with gait symmetry in the anteroposterior direction (ρ = 0.45, P < 0.05). Center of pressure velocity was greater in patients and correlated with neck flexion and ankle plantar flexion weakness (ρ = -0.51 and ρ = -0.62, respectively; both P < 0.05), and with interstride regularity in the vertical direction (ρ = -0.58, P < 0.05). No correlation was found between handgrip myotonia and any other variable studied. Lower-trunk accelerometry allows the characterization of gait pattern abnormalities in patients with DM1. Further studies are required to determine the relevance of systematic gait analysis using lower-trunk accelerometry for patient follow-up and intervention planning.

Longitudinal functional and NMR assessment of upper limbs in Duchenne muscular dystrophy.

OBJECTIVE: To explore the value of nuclear magnetic resonance (NMR) and functional assessments for follow-up of ambulatory and nonambulatory patients with Duchenne muscular dystrophy (DMD). METHODS: Twenty-five 53-skippable patients with DMD were included in this study; 15 were nonambulatory at baseline. All patients underwent clinical and functional assessments every 6 months using the Motor Function Measure (MFM), hand grip and key pinch strength, MoviPlate, and NMR spectroscopy and imaging studies. RESULTS: Upper limb distal strength decreased in nonambulatory patients over the period of 1 year; ambulatory patients showed improvement during the same period. The same applied for several NMRS indices, such as phosphocreatine/adenosine triphosphate, which decreased in older patients but increased in younger ambulatory patients. Fat infiltration in the upper limbs increased linearly with age. Almost all NMR and functional assessment results correlated. CONCLUSIONS: Our results underscore complementarity of functional and NMR assessments in patients with DMD. Sensitivity to change of various indices may differ according to disease stage.

NMR imaging estimates of muscle volume and intramuscular fat infiltration in the thigh: variations with muscle, gender, and age.

Muscle mass is particularly relevant to follow during aging, owing to its link with physical performance and autonomy. The objectives of this work were to assess muscle volume (MV) and intramuscular fat (IMF) for all the muscles of the thigh in a large population of young and elderly healthy individuals using magnetic resonance imaging (MRI) to test the effect of gender and age on MV and IMF and to determine the best representative slice for the estimation of MV and IMF. The study enrolled 105 healthy young (range 20-30 years) and older (range 70-80 years) subjects. MRI scans were acquired along the femur length using a three-dimension three-point Dixon proton density-weighted gradient echo sequence. MV and IMF were estimated from all the slices. The effects of age and gender on MV and IMF were assessed. Predictive equations for MV and IMF were established using a single slice at various femur levels for each muscle in order to reduce the analysis process. MV was decreased with aging in both genders, particularly in the quadriceps femoris. IMF was largely increased with aging in men and, to a lesser extent, in women. Percentages of MV decrease and IMF increase with aging varied according to the muscle. Predictive equations to predict MV and IMF from single slices are provided and were validated. This study is the first one to provide muscle volume and intramuscular fat infiltration in all the muscles of the thigh in a large population of young and elderly healthy subjects.

Non-Ambulant Duchenne Patients Theoretically Treatable by Exon 53 Skipping have Severe Phenotype.

BACKGROUND: Exon skipping therapy is an emerging approach in Duchenne Muscular Dystrophy (DMD). Antisense oligonucleotides that induce skipping of exon 51, 44, 45, or 53 are currently being evaluated in clinical trials. These trials were designed on the basis of data available in general DMD population. OBJECTIVES: Our objective was to compare the clinical and functional statuses of non-ambulant DMD patients theoretically treatable by exon 53 skipping and of DMD patients with other mutations. METHODS: We first compared fifteen non-ambulant DMD patients carrying deletions theoretically treatable by exon 53 skipping (DMD-53) with fifteen closely age-matched DMD patients with mutations not treatable by exon 53 skipping (DMD-all-non-53) then with fifteen DMD patients carrying deletions not treatable by exon 53 skipping (DMD-del-non-53). RESULTS: We found that DMD-53 patients had a lower left ventricular ejection fraction, more contractures and they tend to have weaker grips and pinch strengths than other DMD patients. DMD-53 patients lost ambulation significantly younger than other DMD patients. This result was confirmed by comparing ages at loss of ambulation in all non-ambulant DMD patients of the DMD cohort identified in a molecular diagnostic lab. CONCLUSIONS: These prospective and retrospective data demonstrate that DMD-53 patients have clinically more severe phenotypes than other DMD patients.

Upper limb strength and function changes during a one-year follow-up in non-ambulant patients with Duchenne Muscular Dystrophy: an observational multicenter trial.

INTRODUCTION: Upper limb evaluation of patients with Duchenne Muscular Dystrophy is crucially important to evaluations of efficacy of new treatments in non-ambulant patients. In patients who have lost ambulation, there are few validated and informative outcome measures. In addition, longitudinal data demonstrating sensitivity to clinical evolution of outcome measures over short-term periods are lacking. PATIENTS AND METHODS: We report here the results of a one-year multicenter study using specifically designed tools to assess grip, pinch strength, and hand function in wheelchair-bound patients. Our study assessed 53 non-ambulant patients with Duchenne muscular dystrophy aged 17.1 ± 4.8 years (range: 9 - 28.1 years). The average Brooke functional score of these patients was 4.6 ± 1.1. The average forced vital capacity was 44.5% predicted and 19 patients used non-invasive ventilation. Patients were assessed at baseline, 6 months, and one year using the Motor Function Measure and innovative devices (namely the MyoSet composed of MyoGrip, MyoPinch, and MoviPlate). RESULTS: Our study confirmed preliminary data previously reported regarding feasibility of use and of reliability of the MyoSet and the correlation at baseline between distal strength and clinical outcomes such as FVC, Brooke score, age, and duration since loss of ambulation. A significant correlation was observed between the distal upper limb strength and clinical variables. The sensitive dynamometers (MyoGrip and MyoPinch) and MoviPlate captured a 12-month change in non-ambulant Duchenne muscular dystrophy patients of all ages. TRIAL REGISTRATION: ClinicalTrials.gov NCT00993161 NCT00993161.

Upper limb evaluation and one-year follow up of non-ambulant patients with spinal muscular atrophy: an observational multicenter trial.

Assessment of the upper limb strength in non-ambulant neuromuscular patients remains challenging. Although potential outcome measures have been reported, longitudinal data demonstrating sensitivity to clinical evolution in spinal muscular atrophy patients are critically lacking. Our study recruited 23 non-ambulant patients, 16 patients (males/females = 6/10; median age 15.4 years with a range from 10.7 to 31.1 years) with spinal muscular atrophy type II and 7 patients (males/females = 2/5; median age 19.9 years with a range from 8.3 to 29.9 years) with type III. The Brooke functional score was on median 3 with a range from 2 to 6. The average total vital capacity was 46%, and seven patients required non-invasive ventilation at night. Patients were assessed at baseline, 6 months, and 1 year using the Motor Function Measure and innovative devices MyoGrip, MyoPinch, and MoviPlate, which assess handgrip strength, key pinch strength, and hand/finger extension-flexion function, respectively. The study demonstrated the feasibility and reliability of these measures for all patients, and sensitivity to negative changes after the age of 14 years. The younger patients showed an increase of the distal force in the follow-up period. The distal force measurements and function were correlated to different functional scales. These data represent an important step in the process of validating these devices as potential outcome measures for future clinical trials.