Passive muscle stiffness increases at multiple stretch levels and correlates with motor function in children with Duchenne muscular dystrophy (DMD), a new study published in the journal Ultrasound in Medicine and Biology found.

Therefore, it could be used by itself or in combination with other tests as a noninvasive tool to monitor the progression of the disease.

It is very important to have a reliable, noninvasive technique to routinely evaluate muscle health and the effect of treatments in DMD. The aim of the present study was to evaluate passive muscle stiffness as a potential tool to diagnose and follow the progression of DMD.

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The team led by Hong-Ying Wang from Guangzhou Medical University in Guangdong, China recruited 26 boys with DMD and 20 age-matched controls. They then collected shear wave elastography videos while the gastrocnemius medius muscle was dynamically stretched.

They compared shear modulus at different ankle angles between patients with DMD and healthy controls. The results showed that the passive muscle stiffness of the gastrocnemius medius was significantly higher in patients with DMD compared to controls at multiple stretch levels. 

The shear modulus at an angle of 10 degrees dorsiflexion was the most accurate in differentiating patients from controls. Motor function grading was also a significant determinant of passive muscle stiffness at that ankle angle.

“Passive muscle stiffness may potentially serve as a useful non-invasive tool to monitor disease progression in DMD patients,” the researchers concluded. 

It is important to note that this was a cross-sectional study and it cannot reflect the dynamic changes in the affected muscle and the effect of therapeutic interventions. It also had a small sample size and evaluated only 1 type of muscle. More research with a larger number of patients and evaluating other muscles is needed to validate these findings. 

Reference

Yu HK, Liu X, Pan M, et al. Performance of passive muscle stiffness in diagnosis and assessment of disease progression in Duchenne muscular dystrophy. Ultrasound Med Biol. 2021;7(21). doi:10.1016/j.ultrasmedbio.2021.09.003

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