Quantitative muscle ultrasound detects disease progression in Duchenne muscular dystrophy.

Objective: We assessed changes in quantitative muscle ultrasound data in boys with Duchenne muscular dystrophy (DMD) and healthy controls to determine whether ultrasound can serve as a biomarker of disease progression. Two approaches were used: gray scale level (GSL), measured from the ultrasound image, and quantitative backscatter analysis (QBA), measured directly from the received echoes.

Methods: GSL and QBA were obtained from 6 unilateral arm/leg muscles in 36 boys with DMD and 28 healthy boys (age = 2-14 years) for up to 2 years.

Electrical impedance myography for assessment of Duchenne muscular dystrophy.

Objective: Sensitive, objective, and easily applied methods for evaluating disease progression and response to therapy are needed for clinical trials in Duchenne muscular dystrophy (DMD). In this study, we evaluated whether electrical impedance myography (EIM) could serve this purpose.

Methods: In this nonblinded study, 36 boys with DMD and 29 age-similar healthy boys underwent multifrequency EIM measurements for up to 2 years on 6 muscles unilaterally along with functional assessments.

Loss of electrical anisotropy is an unrecognized feature of dystrophic muscle that may serve as a convenient index of disease status.

Objective: We sought to understand the alteration in the anisotropic, or direction dependent, character of muscle as measured by electrical impedance myography (EIM) in subjects with Duchenne muscular dystrophy (DMD) and its potential to serve as a biomarker of disease status.

Methods: Thirty-six boys with DMD and 27 healthy controls were measured with EIM, with electrical current applied both parallel and perpendicular to the major muscle fiber direction. In addition, muscle extracted from 10 mdx and 10 wild-type mice were measured analogously.

Rasch analysis of the Pediatric Evaluation of Disability Inventory-computer adaptive test (PEDI-CAT) item bank for children and young adults with spinal muscular atrophy.

Introduction: In this study we evaluated the suitability of a caregiver-reported functional measure, the Pediatric Evaluation of Disability Inventory-Computer Adaptive Test (PEDI-CAT), for children and young adults with spinal muscular atrophy (SMA).

Methods: PEDI-CAT Mobility and Daily Activities domain item banks were administered to 58 caregivers of children and young adults with SMA. Rasch analysis was used to evaluate test properties across SMA types.

Inter-session reliability of electrical impedance myography in children in a clinical trial setting.

Objective: High reliability is a prerequisite for any test to be useful as a biomarker in a clinical trial. Here we assessed the reproducibility of electrical impedance myography (EIM) in children by comparing data obtained by different evaluators on separate days.

Methods: Healthy boys and boys with Duchenne muscular dystrophy (DMD) aged 2-14 years underwent EIM of multiple muscles performed by two evaluators on two visits separated by 3-7 days.