Change in muscle volume after steroid therapy in patients with myositis assessed using cross-sectional computed tomography

Abstract

BackgroundSteroid therapy, a key therapy for inflammatory, allergic, and immunological disorders, is often associated with steroid myopathy as one of the side effects. Steroid therapy is considered the first-line therapy for myositis; however, there have been no reports strictly comparing the muscle mass in patients with myositis before and after steroid therapy. Thus, it is currently unclear whether steroid therapy for such patients affects muscle volume in addition to muscle strength. We aimed to determine the change in muscle mass after steroid therapy via cross-sectional computed tomography (CT) in patients with myositis.MethodsData from seven patients with myositis and eight controls, who were all treated with high doses of steroids, were assessed before and after steroid therapy. Clinical factors in patients with myositis included serum muscle enzyme levels and muscular strength. The cross-sectional area of skeletal muscle and the low muscle attenuation rate at the level of the caudal end of the third lumbar vertebra were obtained using CT and measured using an image analysis program for all patients. Data were subjected to statistical analysis using several well-established statistical tests. The Wilcoxon signed-rank test was used for comparing paired data for each patient. The Mann-Whitney U test was used to compare sets of data sampled from two groups. The Spearman’s rank correlation coefficient was used for determining the correlations between two variables. Statistical significance was set at p < 0.05.ResultsMuscular strength and serum muscle enzyme levels improved following steroid therapy in patients with myositis. In both groups, the cross-sectional areas of skeletal muscles decreased (myositis group: p = 0.0156; control group: p = 0.0391) and the low muscle attenuation rate tended to increase (myositis group: p = 0.0781; control group: p = 0.0547). In the myositis group, patients with chronic obstructive pulmonary disease showed a tendency toward muscle volume loss (p = 0.0571).ConclusionIn patients with myositis treated with steroid therapy, muscle mass decreased after steroid therapy suggesting that the improvement in muscle strength was due to factors other than a change in muscle volume. Our study suggests the importance of therapies that not only improve muscle mass but also improve the quality of muscle strength.

Reduction in stiffness of proximal leg muscles during the first 6 months of glucocorticoid therapy for giant cell arteritis: A pilot study using shear wave elastography

“…To the contrary, patients performed on average better after 3 and 6 months, except for the number of chair stands that decreased gradually at follow‐up visits. Nawata et al also reported an improvement in muscle strength after 3 months of glucocorticoid treatment despite a significant reduction in muscle volume.…”

“…A recent case study of Cushing's syndrome myopathy suggested the usefulness of muscle echo intensity as a recovery sign after resolution of the hypercortisolemic state . Moreover, Nawata et al recently used computed tomography and showed a significant reduction in muscle mass ( P = .039) in a mixed group of patients taking glucocorticoids (>30 mg/d) for an average of 3 months. However, the usefulness of computed tomography is complicated by the cost and exposure to ionizing radiation.…”

“…This study focuses on glucocorticoid‐induced myopathy (GIM), a non‐inflammatory condition affecting largely the proximal muscles and associated with muscle weakness, wasting and fatigability. Glucocorticoids, irrespective of the route administered (inhaled, oral or intravenous), have shown to be associated with myopathy . The mechanisms of GIM have been linked to the decline in protein synthesis (anti‐anabolic action) and the rise in the catabolic rate of protein breakdown (catabolic action) .…”

“…The available tests are either invasive or lack feasibility at the bedside with respect to time and availability. Imaging studies employing ultrasound, computed tomography or magnetic resonance imaging are limited but generally focus on morphological changes and muscle mass . In contrast, shear wave elastography (SWE), a relatively new ultrasound technology, offers the opportunity to evaluate a different method of evaluating muscle through its ability to objectively measure tissue stiffness .…”

“…Glucocorticoids, irrespective of the route administered (inhaled, oral or intravenous), have shown to be associated with myopathy. [2][3][4][5][6][7] The mechanisms of GIM have been linked to the decline in protein synthesis (anti-anabolic action) and the rise in the catabolic rate of protein breakdown (catabolic action). 8 These mechanisms can consequently lead to the loss of muscle strength and mass.…”