Ultrasound scans can be useful to monitor muscle changes in patients with glucocorticoid-induced muscle disease or steroid myopathy, and could become an effective routine procedure for those with Cushing’s disease, a study reports.
Glucocorticoid-induced myopathy, marked by muscle weakness without pain, fatigue and muscle wasting (atrophy), is an adverse effect of glucocorticoid use and a symptom of Cushing’s syndrome, including Cushing’s disease.
In the management of steroid myopathy, there is a lack of tools to identify the beginning of the myopathy process before the clinical symptoms appear. Ultrasounds have been widely used to assess muscle thickness and architecture, including muscle fiber length and the angle of orientation between muscle fibers and tendons. Ultrasounds also enable clinicians to evaluate muscle composition through a parameter called muscle echo intensity. This parameter reflects the muscle content of fibrous and fat tissue.
Studies have reported the clinical benefit of using ultrasounds to track muscle problems and recovery, yet few have looked at the usefulness of this tool for patients with steroid myopathy. Therefore, a team of scientists with the University of Turin, in Italy, sought to investigate if ultrasound scans could detect the muscle alterations in patients with Cushing’s disease and glucocorticoid-induced myopathy, who were at different stages of muscle disease.
The study tested 33 patients, including 28 women, with a median age of 48 years. Two groups of patients were studied: 20 who had active Cushing’s disease and 13 who had remitted disease (defined as at least two years without signs and symptoms of the disease).
The researchers measured walking speed and handgrip strength, total body and limb muscle mass quantified by bioelectrical impedance analysis (BIA), and muscle thickness and composition by ultrasounds.
Both study groups showed comparable levels of handgrip strength, walking speed, muscle thickness and muscle mass indices. A significant proportion (14 out of 33 people) presented muscle loss.
However, ultrasound-measured echo intensity – which reflects the fiber and fat composition of muscles – was significantly higher in three leg muscles among patients with the active disease. This suggests a higher deposition of fat into muscle (myosteatosis) in those patients, compared to those with remitted disease.
Given that muscle thickness was similar between both groups, these findings indicate that “the muscle mass recovery after resolution of the hypercortisolemic [excess cortisol] state seems longer than the muscle structure recovery,” the researchers wrote.
They also noted that bioelectrical impedance — an electrical-based method to estimate body fat and muscle mass — underestimated the prevalence of low muscle mass compared with ultrasound assessments of muscle thickness.
Importantly, the ultrasound measurements of echo intensity correlated inversely with physical performance and muscle strength — the higher the echo intensity, the poorer the walking speed and handgrip strength of patients.
Researchers conclude that their study “provided preliminary evidence that the ultrasound-derived measurements of muscle thickness and echo intensity can be useful to detect and track the changes of muscle mass and structure in patients with steroid myopathy.”
They also suggest that these patients should be assessed for muscle mass, strength, and performance using ultrasound scans as part of their routine examinations.