measurements-motor-function-other-clinical-outcome-parameters

Measurements of Motor Function and Other Clinical Outcome Parameters in Ambulant Children with Duchenne Muscular Dystrophy

While the number of new treatment options tested in patients with Duchenne muscular dystrophy (DMD) is increasing, there is still no defining of the most ...

University of Basel

chuv

University Children's Hospital Bern

The purpose of this ethics approved trial was to correlate quantitative MRI with functional abilities in both ambulant and non-ambulant Duchenne muscular dystrophy (DMD). Twenty patients with genetically confirmed DMD were recruited. Physical assessment was performed using the motor function measurement (MFM) scale. Axial 3T MRI scans of the thighs were acquired using T1-weighted in- and opposed-phase images (TR = 20 ms, TE1 = 2.45 ms, TE2 = 3.68 ms, flip angle = 15°) to calculate the relative fat fraction according to the two-point Dixon method in the knee extensors, flexors, and adductor muscles. The average MFM was 65.3 % and correlated negatively to age (r (2) = 0.60). Overall mean fat fraction correlated positively to age (r (2) = 0.51-0.64). An average of 5 % increase in mean fat fraction per year was calculated. Mean fat fraction of the quadriceps showed a high negative correlation (r (2) = 0.93) to the D1 (standing position and transfers) component of the MFM. A cutoff for mean fat fraction of 50 % predicted loss of ambulation with a sensitivity of 100 % and a specificity of 91 %. Therefore, quantitative muscle MRI seems to be a promising endpoint for short clinical trials evaluating the effect of newer treatments on the time of loss of ambulation in DMD.

Quantitative MRI and loss of free ambulation in Duchenne muscular dystrophy.

In muscular dystrophies quantitative muscle MRI (qMRI) detects disease progression more sensitively than clinical scores. This prospective one year observational study compared qMRI with clinical scores in Duchenne muscular dystrophy (DMD) to investigate if qMRI can serve as a surrogate outcome measure in clinical trials. In 20 DMD patients the motor function measure (MFM) total and subscores (D1-D3) were done for physical examination, and the fat fraction (MFF) of thigh muscle qMRI was obtained using the two-point Dixon method. Effect sizes (ES) were calculated for all measures. Sample size estimation (SS) was done modelling assumed treatment effects. Ambulant patients <7 years at inclusion improved in the MFM total and D1 score (ES 1.1 and 1.0). Ambulant patients >7 years (highest ES in the MFM D1 subscore (1.2)), and non-ambulant patients (highest ES in the total MFM score (0.7)) worsened. In comparison the ES of QMRI was much larger, e.g. SS estimations for qMRI data were up to 17 fold smaller compared to the MFM total score and up to 7 fold to the D1 subscore, respectively. QMRI shows pathophysiological changes in DMD and might serve as a surrogate outcome measure in clinical trials.

Quantitative muscle MRI: A powerful surrogate outcome measure in Duchenne muscular dystrophy.

The development of new therapeutic agents for the treatment of Duchenne muscular dystrophy has put a focus on defining outcome measures most sensitive to capture treatment effects. This cross-sectional analysis investigates the relation between validated clinical assessments such as the 6-minute walk test, motor function measure and quantitative muscle MRI of thigh muscles in ambulant Duchenne muscular dystrophy patients, aged 6.5 to 10.8 years (mean 8.2, SD 1.1). Quantitative muscle MRI included the mean fat fraction using a 2-point Dixon technique, and transverse relaxation time (T2) measurements. All clinical assessments were highly significantly inter-correlated with p < 0.001. The strongest correlation with the motor function measure and its D1-subscore was shown by the 6-minute walk test. Clinical assessments showed no correlation with age. Importantly, quantitative muscle MRI values significantly correlated with all clinical assessments with the extensors showing the strongest correlation. In contrast to the clinical assessments, quantitative muscle MRI values were highly significantly correlated with age. In conclusion, the motor function measure and timed function tests measure disease severity in a highly comparable fashion and all tests correlated with quantitative muscle MRI values quantifying fatty muscle degeneration.

Timed function tests, motor function measure, and quantitative thigh muscle MRI in ambulant children with Duchenne muscular dystrophy: A cross-sectional analysis.

Article	Year
Quantitative MRI and loss of free ambulation in Duchenne muscular dystrophy. Journal of neurology\| PubMed ID: 23138982	2013
Quantitative muscle MRI: A powerful surrogate outcome measure in Duchenne muscular dystrophy. Neuromuscular disorders : NMD\| PubMed ID: 26096788	2015
Timed function tests, motor function measure, and quantitative thigh muscle MRI in ambulant children with Duchenne muscular dystrophy: A cross-sectional analysis. Neuromuscular disorders : NMD\| PubMed ID: 29174526	2018

Andrea Klein

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