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

International audienceBACKGROUND: 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

Relationships between grip strength, myotonia, and CTG expansion in myotonic dystrophy type 1

International audienceIn myotonic dystrophy type 1, several studies have suggested causal relationships between CTG repeat length and the severity of symptoms, such as weakness or myotonia. We aimed to explore these relationships in a large population of 144 DM1 patients. All patients underwent clinical and functional assessments using a standardized test for grip strength and myotonia assessment. Myotonia was assessed using a fully automatic software based on mathematical modeling of relaxation force curve. CTG repeat length was statistically correlated with both myotonia and grip strength, which are two major primary neuromuscular symptoms of DM1 patients. However, these relationships are not clinically meaningful and not predictive at the individual level

The diagnostic value of hyperammonaemia induced by the non-ischaemic forearm exercise test

International audienceAims The non-ischaemic forearm exercise test (NIFET) is used as a diagnostic tool for the screening of patients with exercise intolerance and for the diagnosis of various metabolic muscle disorders. The production of lactate and ammonia are generally analysed to guide the diagnosis. The aim of this retrospective study was to determine the level of ammonia rise, which can be suggestive of a muscle disease.Methods This retrospective study involved 1440 patients who underwent NIFET. The clinical files of the patients with hyperammonaemia were methodically studied. Normal values were derived from 60 healthy controls.Results 110 patients with hyperammonaemia were detected. They were classified as either having mild (between 94 and 141 µmol/L) or severe (more than 141 µmol/L) hyperammonaemia. Their diagnosis was studied with respect to the increase in lactate induced by the NIFET.Conclusions Severe postexercise hyperammonaemia, even in the presence of a normal lactate response, is strongly suggestive of a muscle glycogen storage disease. Mild hyperammonaemia in the absence of other abnormalities is most likely non-specific and not indicative of a muscle disease

Development of a French Isometric Strength Normative Database for Adults Using Quantitative Muscle Testing

International audienceOBJECTIVE: To establish a normative database for isometric strength measured by quantitative muscle testing (QMT) for a French adult population.DESIGN: Measurement of maximal voluntary isometric contraction.SETTING: Four clinical centers involved in neuromuscular disorders.PARTICIPANTS: A total of 315 healthy adults (147 men, 168 women) ages 20 to 80 years.INTERVENTIONS: Not applicable.MAIN OUTCOME MEASURE: Isometric torque values of 14 muscle functions (13 bilaterally and neck).RESULTS: This study led to the development of a French isometric strength normative database for adults measured by QMT. For each muscle function, predictive regression models using age, sex, and weight are proposed. Some methodologic issues concerning strength measurement are discussed.CONCLUSIONS: This database can be used to compute relative deficits in muscle strength for 27 muscle functions and also to estimate composite scores for follow-up of patients either during the natural history of their disease or during a therapeutic trial

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

International audienceObjective: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

Assessment of disease progression in dysferlinopathy. A 1-year cohort study

Jain COS Consortium.[Objective] To assess the ability of functional measures to detect disease progression in dysferlinopathy over 6 months and 1 year.[Methods] One hundred ninety-three patients with dysferlinopathy were recruited to the Jain Foundation's International Clinical Outcome Study for Dysferlinopathy. Baseline, 6-month, and 1-year assessments included adapted North Star Ambulatory Assessment (a-NSAA), Motor Function Measure (MFM-20), timed function tests, 6-minute walk test (6MWT), Brooke scale, Jebsen test, manual muscle testing, and hand-held dynamometry. Patients also completed the ACTIVLIM questionnaire. Change in each measure over 6 months and 1 year was calculated and compared between disease severity (ambulant [mild, moderate, or severe based on a-NSAA score] or nonambulant [unable to complete a 10-meter walk]) and clinical diagnosis.[Results] The functional a-NSAA test was the most sensitive to deterioration for ambulant patients overall. The a-NSAA score was the most sensitive test in the mild and moderate groups, while the 6MWT was most sensitive in the severe group. The 10-meter walk test was the only test showing significant change across all ambulant severity groups. In nonambulant patients, the MFM domain 3, wrist flexion strength, and pinch grip were most sensitive. Progression rates did not differ by clinical diagnosis. Power calculations determined that 46 moderately affected patients are required to determine clinical effectiveness for a hypothetical 1-year clinical trial based on the a-NSAA as a clinical endpoint.[Conclusion] Certain functional outcome measures can detect changes over 6 months and 1 year in dysferlinopathy and potentially be useful in monitoring progression in clinical trials.[ClinicalTrials.gov identifier] NCT01676077.The estimated US $4 million needed to fund this study is being provided by the Jain Foundation. The John Walton Centre Muscular Dystrophy Research Centre is part of the MRC Centre for Neuromuscular Diseases (grant MR/K000608/1)

Stature is an essential predictor of muscle strength in children

<p>Abstract</p> <p>Background</p> <p>Children with growth retardation or short stature generally present with lower strength than children of the same chronological age. The aim of the study was to establish if strength was dependent on variables related to stature in a population of healthy children and to propose practical predictive models for the muscle functions tested. A secondary aim was to test for any learning effects concerning strength measured at two successive visits by children.</p> <p>Methods</p> <p>Hand grip, elbow flexion and extension, and knee flexion and extension were measured by fixed dynamometry in 96 healthy subjects (47 girls and 49 boys, aged from 5 to 17 years).</p> <p>Results</p> <p>For the present paediatric population, muscle strength was highly dependent on height. Predictive models are proposed for the muscle functions tested. No learning effect between the first and the second visit was detected for any of the muscle functions tested.</p> <p>Conclusions</p> <p>This work shows that strength measurements using fixed dynamometry are reliable in children when using appropriate standardization of operating procedures. It underlines the particular relationship between body stature and muscle strength. Predictive equations may help with assessing the neuromuscular involvement in children suffering from various disorders, particularly those affecting their stature.</p