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Introduction/Aims: Very few studies analyzing the pattern of muscle involvement in magnetic resonance imaging (MRI) of patients with McArdle disease have been reported to date. We aimed to examine the pattern of muscle fat replacement in patients with McArdle disease. Methods: We performed a retrospective study including all patients with genetically confirmed McArdle disease followed in our center from January 2010 to March 2021. Clinical data were collected from the medical record. Whole‐body MRI was performed as part of the diagnostic evaluation. The distribution of muscle fat replacement and its severity were analyzed. Results: Nine patients were included. Median age at onset was 7 y (range, 5–58) and median age at the time when MRI was performed was 57.3 y (range, 37.2–72.8). At physical examination, four patients had permanent weakness: in three the weakness was limited to paraspinal muscles, whereas in one the weakness involved the paraspinal and proximal upper limb muscles. Muscle MRI showed abnormalities in six of the seven studied patients. In all of them, fat replacement of paravertebral muscles was found. Other muscles frequently affected were the tongue in three, subscapularis in three, and long head of biceps femoris and semimembranosus in two. Discussion: Our findings suggest that paraspinal muscle involvement is common in McArdle disease and support the need to include this disease in the differential diagnosis of the causes of paraspinal muscle weakness. Involvement of the tongue and subscapularis are also frequent in McArdle disease. [ABSTRACT FROM AUTHOR]

Background: Cushing's syndrome (CS) is associated with skeletal muscle structural and functional impairment which may persist long‐term despite surgical removal of the source of cortisol excess. Prevalence of sarcopenia and its impact on Health‐Related‐Quality of Life (HRQoL) in 'cured' CS is not known. There is a need to identify easy biomarkers to help the clinicians recognise patients at elevated risk of suffering sustained muscle function. Patients and Methods: We studied 36 women with CS in remission, and 36 controls matched for age, body mass index, menopausal status, and level of physical activity. We analysed the skeletal muscle mass using dual‐energy X‐ray absorptiometry, muscle fat fraction using two‐point Dixon magnetic resonance imaging and muscle performance and strength using the following tests: hand grip strength, gait speed, timed up and go and 30‐s chair stand. We assessed HRQoL with the following questionnaires: SarQoL, CushingQoL, SF‐36. We calculated the sarcopenia index (SI; serum creatinine/serum cystatin C × 100). Results: Prevalence of sarcopenia, according to the European Working Group on Sarcopenia in Older People (EWGSOP), was greater in CS as compared with controls (19% vs. 3%; p <.05). Patients with sarcopenia had a lower SarQoL score than those without sarcopenia (61 ± 17 vs. 75 ± 14; p <.05), and scored worse on the items pain, easy bruising and worries on physical appearance (p <.05 for all comparisons) of the CushingQoL questionnaire. Patients with sarcopenia had poorer physical functioning on SF‐36 than those without sarcopenia (60 ± 23 vs. 85 ± 15; p <.01). SI was lower in patients with sarcopenia than those without (71 ± 3 vs. 77 ± 2; p =.032), and was associated with intramuscular fatty infiltration, worse performance on the 30‐s chair stand test, slower gait speed, and worse muscle weakness‐related HRQoL, as measured using the SarQoL questionnaire (p <.05). The optimised cut‐off value for the SI ratio to diagnose sarcopenia was 72, which yielded a sensitivity of 73% and a specificity of 90%. Conclusions: Sarcopenia is common in patients with CS in long‐term remission, and associated with impaired quality of life. The SI is a potential biomarker allowing clinicians to identify patients at high risk of muscle dysfunction. [ABSTRACT FROM AUTHOR]

Background: Late‐onset Pompe disease (LOPD) is a genetic disorder characterized by progressive degeneration of the skeletal muscles produced by a deficiency of the enzyme acid alpha‐glucosidase. Enzymatic replacement therapy with recombinant human alpha‐glucosidase seems to reduce the progression of the disease; although at the moment, it is not completely clear to what extent. Quantitative muscle magnetic resonance imaging (qMRI) is a good biomarker for the follow‐up of fat replacement in neuromuscular disorders. The aim of this study was to describe the changes observed in fat replacement in skeletal muscles using qMRI in a cohort of LOPD patients followed prospectively. Methods: A total of 36 LOPD patients were seen once every year for 4 years. qMRI, several muscle function tests, spirometry, activities of daily living scales, and quality‐of‐life scales were performed on each visit. Muscle MRI consisted of two‐point Dixon studies of the trunk and thigh muscles. Computer analysis of the images provided the percentage of muscle degenerated and replaced by fat in every muscle (known as fat fraction). Longitudinal analysis of the measures was performed using linear mixed models applying the Greenhouse–Geisser test. Results: We detected a statistically significant and continuous increase in mean thigh fat fraction both in treated (+5.8% in 3 years) and in pre‐symptomatic patients (+2.6% in 3years) (Greenhouse–Geisser p < 0.05). As an average, fat fraction increased by 1.9% per year in treated patients, compared with 0.8% in pre‐symptomatic patients. Fat fraction significantly increased in every muscle of the thighs. We observed a significant correlation between changes observed in fat fraction in qMRI and changes observed in the results of the muscle function tests performed. Moreover, we identified that muscle performance and mean thigh fat fraction at baseline visit were independent parameters influencing fat fraction progression over 4 years (analysis of covariance, p < 0.05). Conclusions: Our study identifies that skeletal muscle fat fraction continues to increase in patients with LOPD despite the treatment with enzymatic replacement therapy. These results suggest that the process of muscle degeneration is not stopped by the treatment and could impact muscle function over the years. Hereby, we show that fat fraction along with muscle function tests can be considered a good outcome measures for clinical trials in LOPD patients. [ABSTRACT FROM AUTHOR]

Objective: To analyze the microRNA profile in serum of patients with Adult Onset Pompe disease (AOPD). Methods: We analyzed the expression of 185 microRNAs in serum of 15 AOPD patients and five controls using microRNA PCR Panels. The expression levels of microRNAs that were deregulated were further studied in 35 AOPD patients and 10 controls using Real‐Time PCR. Additionally, the skeletal muscle expression of microRNAs which showed significant increase levels in serum samples was also studied. Correlations between microRNA serum levels and muscle function test, spirometry, and quantitative muscle MRI were performed (these data correspond to the study NCT01914536 at ClinicalTrials.gov). Results: We identified 14 microRNAs that showed different expression levels in serum samples of AOPD patients compared to controls. We validated these results in a larger cohort of patients and we found increased levels of three microRNAs, the so called dystromirs: miR‐1‐3p, miR‐133a‐3p, and miR‐206. These microRNAs are involved in muscle regeneration and the expression of these was increased in patients' muscle biopsies. Significant correlations between microRNA levels and muscle function test were found. Interpretation: Serum expression levels of dystromirs may represent additional biomarkers for the follow‐up of AOPD patients. [ABSTRACT FROM AUTHOR]