Assessment of fatty infiltration of the hamstring muscles in chronic proximal hamstring ruptures and effect on clinical outcomes after surgical repair: a novel application of the Goutallier classification.

INTRODUCTION: Increased time to surgery has been previously associated with poorer clinical outcomes after surgical treatment of proximal hamstring ruptures, though the etiology remains unclear. The purpose of this study was to evaluate whether degree of muscle atrophy, as assessed using the Goutallier classification system, is associated with worse outcomes following surgical treatment of chronic proximal hamstring ruptures. MATERIALS AND METHODS: This was a retrospective case series of patients who underwent repair of proximal hamstring ruptures from 2012 to 2020 with minimum 2-year follow-up. Patients were included if they underwent primary repair of a proximal hamstring rupture ≥ 6 weeks after the date of injury and had accessible preoperative magnetic resonance imaging (MRI). Exclusion criteria were allograft reconstruction, endoscopic repair, or prior ipsilateral hip surgery. Patients were administered validated surveys: the modified Harris Hip Score (mHHS) and Perth Hamstring Assessment Tool (PHAT). Fatty atrophy on preoperative MRI was independently graded by two musculoskeletal radiologists using the Goutallier classification. Multivariate regression analysis was performed to evaluate associations of preoperative characteristics with muscle atrophy, as well as mHHS and PHAT scores. RESULTS: Complete data sets were obtained for 27 patients. A majority of this cohort was male (63.0%), with a mean age of 51.5 ± 11.8 years and BMI of 26.3 ± 3.8. The mean follow-up time was 62.6 ± 23.1 months, and the mean time from injury-to-surgery was 20.4 ± 15.3 weeks. The Goutallier grading inter-reader weighted kappa coefficient was 0.655. Regression analysis demonstrated that atrophy was not significantly associated with PHAT (p = 0.542) or mHHS (p = 0.574) at latest follow-up. Increased age was significantly predictive of muscle atrophy (ß = 0.62, p = 0.005) and was also found to be a significant predictor of poorer mHHS (ß = - 0.75; p = 0.037). CONCLUSIONS: The degree of atrophy was not found to be an independent predictor of clinical outcomes following repair of chronic proximal hamstring ruptures. Increasing age was significantly predictive of increased atrophy and poorer patient-reported outcomes.

Gray and white matter abnormalities in children with type 2 and 3 SMA: A morphological assessment.

This study investigated the changes in brain gray and white matter structure in SMA patients and their correlation with the severity of the disease. A total of 43 SMA patients (including 22 type II and 21 type III SMA patients) and 37 healthy controls were evaluated by MRI. The gray matter volume, gray matter thickness, gray matter surface area, and white matter volume of designated brain regions automatically segmented by FreeSurfer, were compared. We evaluate clinical characteristics of SMA and study the correlation between clinical characteristics and structural changes. SMA showed significant bilateral cortical superficial area loss in the frontal, parietal, and temporal lobes and global white matter volume decreases. Moreover, these patients were also found with an increased mean thickness of entire brain and right gray matter. An increased right postcentral gyrus superficial area, right central sulcus volume, and white matter volume of the right postcentral were associated with higher HFMSE scores. CONCLUSION: Type 2 and 3 children SMA had extensive, multifocal, symmetrical gray and white matter alterations. Postcentral gyrus degeneration of SMA was associated with the severity of muscular atrophy. The lack of SMN protein possibly interacted with cerebellar structural changes in somatosensory areas. WHAT IS KNOWN: • MRI has found brain changes in SMA patients, however, there is no unified conclusion and lack of correlation with clinical degree in children SMA with type 2-3. WHAT IS NEW: • Type II and II children SMA had extensive, multifocal, symmetrical gray and white matter alterations. Postcentral gyrus degeneration of SMA was associated with the severity of muscular atrophy. Cerebellar structural changes in somatosensory areas may attribute to the lack of SMN protein.

Quantitative multi-parameter assessment of age- and gender-related variation of back extensor muscles in healthy adults using Dixon MR imaging.

OBJECTIVES: Investigate sex differences in age-related back extensor muscle degeneration using Dixon MRI and analyze the relationship between quantitative muscle parameters and back muscle strength in healthy adults. METHODS: 105 healthy subjects underwent lumbar Dixon MRI. Fat fraction (FF), cross-sectional area (CSA), functional CSA (FCSA), and relative FCSA (RFCSA) of multifidus muscle (MF) and erector spinae (ES) were quantified. Back extension muscle strength was measured using an external fixation dynamometer. ANOVA with post hoc Tukey correction was used for age group comparisons. Partial and Spearman's correlation analyzed relationships between age, muscle parameters, and muscle strength. RESULTS: MF and ES FF significantly increased with age in both genders (r = 0.55-0.85; p < 0.001). Muscle FF increased prominently for females (40-49 years, MF and 50-59 years, ES) and males (60-73 years, MF and ES). In females, total ES FCSA and RFCSA (r = - 0.42, - 0.37; p < 0.01) correlated with age. While in males, all MF and ES muscle size parameters, except total MF CSA, correlated with age (r = - 0.30 to - 0.58; p < 0.05). Back extension muscle strength correlated with mean FF, total CSA, and total FCAS for MF and ES individually (p < 0.001). The combined MF + ES FCSA correlation coefficient (r = 0.63) was higher than FF (r = - 0.51) and CSA (r = 0.59) (p < 0.001). CONCLUSIONS: Age-related back extensor muscle degeneration varies by muscle type and sex. FCSA has the highest association with back muscle strength compared to FF and CSA. CLINICAL RELEVANCE STATEMENT: The investigation of sex differences in age-related back extensor muscle degeneration utilizing Dixon imaging may hold significant implications for evaluating spine health and enabling earlier intervention. Muscles' FCSA could contribute to acquiring additional evidence for reflecting muscle function change. KEY POINTS: • The multifidus muscle (MF) and erector spinae (ES) fat fraction (FF) increased with age at all lumbar disc levels in females and males. • Age-related changes in muscle morphological quantitative parameters of healthy adults were specific by muscle type and gender. • The muscle functional cross-sectional area (FCSA) measured by Dixon imaging may better monitor back extensor muscle strength changes than muscle FF and cross-sectional area (CSA).

Reliability of Magnetic Resonance Imaging Criteria for the Preoperative Assessment of Rotator Cuff Tears: A Systematic Review.

BACKGROUND: Magnetic resonance (MR) imaging is the most common modality for assessment of the rotator cuff before and after surgery. Several classifications have been described aiming to define main tear characteristics. However, there is still confusion when it comes to the reliability of those classifications. PURPOSE: (1) To identify all MR classifications available in the literature for preoperative assessment of rotator cuff tears, (2) to summarize available data on the reliability of identified classifications, and (3) to assess the methodological quality of reliability studies. STUDY DESIGN: Systematic review; Level of evidence, 4. METHODS: This systematic review was conducted following the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. All studies reporting MR assessment in patients with a superior or posterosuperior rotator cuff tear were included. After identification of the available MR criteria, reliability studies were analyzed. Descriptive statistics were used to summarize findings. Methodological quality was assessed using the Quality Appraisal of Reliability Studies checklist. RESULTS: A total of 75 studies were included in this review. Eight categories of outcomes could be identified. Of the total, 62 studies reported interobserver reliability whereas 32 reported intraobserver reliability of some of the identified criteria. Each category reflected a variety of reliability, ranging from poor to excellent agreement. MR proved to be a reliable imaging modality to detect the structural integrity of the posterosuperior cuff, especially in cases of full-thickness tear; it was also reliable in terms of tear width and length and muscle atrophy based on a tangent sign or Thomazeau classification. All other classifications did not prove acceptable reliability. Methodological quality was high for 23 articles and moderate for 14. CONCLUSION: Preoperative MR is a reliable imaging modality to identify full-thickness tears, measure tear size and morphology, and identify muscle atrophy with tangent sign or Thomazeau classification. All other outcomes and classifications did not show acceptable reliability; therefore, caution is needed when using them for preoperative evaluation of a rotator cuff tear.

AN IN-DEPTH ASSESSMENT OF THE TUMOR'S IMPACT ON SARCOPENIA.

Loss of muscle mass is a typical symptom of cancer and it is strongly correlated with poor prognosis. Cancer-related Sarcopenia is unresponsive to conventional dietary changes and exercise, in contrast to age-associated muscle atrophy. This particular type of weakness differs from different kinds of muscle loss in that it is triggered by a number of interrelated mechanisms, notably inflammatory processes, abnormal metabolic processes, proteolysis, and autophagy. This research is to examine evidence supporting the theory that tumors have a causal role in causing muscular atrophy. It seeks to investigate the precise regulators that the tumour generates and how they affect the processes that result in muscle waste. The evaluation looks for new directions for further studies and medical treatments. The analysis is based on a thorough examination of the scientific literature and research that shows how tumor and muscle atrophy are related. It concentrates on studies that clarify the numerous strategies by which malignancies cause the loss of muscle. This article highlights particular mechanisms by which these tumor-derived substances affect the development of muscle loss, including inflammatory processes, metabolic disturbance, proteolysis, and autophagy. The discovery of such targets offers hope for the creation of efficient treatment strategies that can enhance the long-term outlook and quality of life of cancer sufferers who are experiencing muscle loss.

Considerations for a protein-focused screening instrument in clinical nutrition assessment.

Physiological stress during injury and surgery negatively impacts protein balance and muscle mass maintenance. Adequate perioperative protein intake may attenuate muscle atrophy to maintain and facilitate functional recovery, particularly in older adults; yet, screening tools routinely used in clinical settings do not specifically assess protein intake when assessing nutrition risk. Although assessing malnutrition is a priority, suboptimal protein intake in non-malnourished patients should also be identified given protein's critical role in muscle health. This opinion paper highlights the potential for using a clinically appropriate protein-focused screener for rapid and efficient characterization of protein intake.

Acute muscle wasting rate assessment and long-term mortality in critically ill trauma.

BACKGROUND AND OBJECTIVES: To evaluate the relationship between acute muscle wasting rate and long-term mortality in critically ill trauma. METHODS AND STUDY DESIGN: A single-center, retrospective study was conducted in critically ill trauma. Patients with Computed Tomography scans including the L3 vertebra within 24 hours and at 1 week after trauma were recruited. Acute muscle wasting rate was defined as the mean percent variation per day of skeletal muscle index in the first week after trauma. Multivariate logistic regression analysis and receiver operating characteristic curve analysis were performed to determine whether acute muscle wasting rate could help predict hospital malnutrition and 1-year mortality. RESULTS: Skeletal muscle index was 49.3±10.7 cm2/m2 at baseline and decreased to 45.1±9.6 cm2/m2 (p<0.001) at 1 week and 39.8±10.8cm2/m2 (p<0.001) at 1 month after trauma. A sustained decrease of skeletal muscle index was observed from baseline up to 6 months (33.7±8.4cm2/m2, p<0.001) post trauma, and lasted for 1 year (37.7±5.6cm2/m2, p=0.004). Logistic regression analysis showed that acute muscle wasting rate was an independent risk factor for hospital malnutrition and 1-year mortality. Every 1% absolute increase of acute muscle wasting rate was associated with 1.82-fold higher odds of 1-year mortality in critically ill trauma. The area under curve of acute muscle wasting rate was 0.813 for hospital malnutrition prediction and 0.715 for 1-year mortality prediction. CONCLUSIONS: Acute muscle wasting rate was independently associated with higher 1-year mortality and hospital malnutrition in critically ill trauma.

Ultrasound assessment of muscle mass and correlation with clinical outcomes in critically ill patients: a prospective observational study.

PURPOSE: Muscular atrophy implies structural and functional alterations related to muscular force production and movement. This condition has been reported to be the main reason for generalized muscle weakness; it reflects the severity of the disease and can have a profound impact on short- and long-term clinical outcomes. The purpose of this study was to determine whether muscle atrophy ultrasound parameters early predict muscle weakness, morbidity, or 28-days mortality. METHODS: This was a prospective, observational single center cohort study. Ultrasound was used to determine the cross-sectional area and muscle thickness of the rectus femoris on the first and third day of ICU stay. The main outcome was the incidence of significant muscle atrophy (≥ 10%). RESULTS: Ultrasound measurements were made in 31 patients, 58% (18/31) of which showed significant muscle atrophy. The relative loss of muscle mass per day was 1.78 at 5% per day. The presence of muscle atrophy presents increased risk for limb muscle weakness and handgrip weakness. The 28-days mortality rate was similar in both subgroups. CONCLUSION: The presence of muscle atrophy presents an increased clinical risk for the development of limb ICUAW and handgrip, although these observations were not statistically significant. The results could be used to plan future studies on this topic.

Assessment of the Impact of Physical Activity on the Musculoskeletal System in Early Degenerative Knee Joint Lesions in an Animal Model.

Osteoarthritis (OA) is one of the most prevalent diseases of the osteoarticular system. Progressive destruction of joints is accompanied by development of pathological changes in the muscle tissue, i.e., weakening, atrophy, and remodelling (sarcopenia). The aim of the present study is to assess the impact of physical activity on the musculoskeletal system in an animal model of early degenerative lesions in the knee joint. The study involved 30 male Wistar rats. The animals were allocated to three subgroups of 10 animals each. Each animal from the three subgroups received sodium iodoacetate by injection into the patellar ligament of the right knee joint, whereas saline was administered through the patellar ligament in the left knee joint. The rats in the first group were stimulated to exercise on a treadmill. The animals in the second group were allowed to lead a natural lifestyle (no treadmill stimulation). In the third group, all parts of the right hind limb muscle were injected with Clostridium botulinum toxin type A. The study demonstrated that, compared to the active rats, bone density in the immobilised rats decreased, as indicated by the densitometric assessment of the whole body and the examination of rats' hind limbs and knee joints alone. This clearly evidenced the impact of physical activity on bone mineralisation. The weight of both fat and muscle tissues in the physically inactive rats was reduced. Additionally, the adipose tissue had higher weight in the entire right hind limbs, where monoiodoacetic acid was administered to the knee joint. The animal model clearly showed the importance of physical activity in the early stages of OA, as it slows down the process of joint destruction, bone atrophy, and muscle wasting, whereas physical inactivity contributes to progression of generalised changes in the musculoskeletal system.

The rate and assessment of muscle wasting during critical illness: a systematic review and meta-analysis.

BACKGROUND: Patients with critical illness can lose more than 15% of muscle mass in one week, and this can have long-term detrimental effects. However, there is currently no synthesis of the data of intensive care unit (ICU) muscle wasting studies, so the true mean rate of muscle loss across all studies is unknown. The aim of this project was therefore to systematically synthetise data on the rate of muscle loss and to identify the methods used to measure muscle size and to synthetise data on the prevalence of ICU-acquired weakness in critically ill patients. METHODS: We conducted a systematic literature search of MEDLINE, PubMed, AMED, BNI, CINAHL, and EMCARE until January 2022 (International Prospective Register of Systematic Reviews [PROSPERO] registration: CRD420222989540. We included studies with at least 20 adult critically ill patients where the investigators measured a muscle mass-related variable at two time points during the ICU stay. We followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and assessed the study quality using the Newcastle-Ottawa Scale. RESULTS: Fifty-two studies that included 3251 patients fulfilled the selection criteria. These studies investigated the rate of muscle wasting in 1773 (55%) patients and assessed ICU-acquired muscle weakness in 1478 (45%) patients. The methods used to assess muscle mass were ultrasound in 85% (n = 28/33) of the studies and computed tomography in the rest 15% (n = 5/33). During the first week of critical illness, patients lost every day -1.75% (95% CI -2.05, -1.45) of their rectus femoris thickness or -2.10% (95% CI -3.17, -1.02) of rectus femoris cross-sectional area. The overall prevalence of ICU-acquired weakness was 48% (95% CI 39%, 56%). CONCLUSION: On average, critically ill patients lose nearly 2% of skeletal muscle per day during the first week of ICU admission.

Combined assessment of muscle quality and quantity predicts oncological outcome in patients with esophageal cancer.

BACKGROUND: Sarcopenia consists of two dysregulation patterns of body composition, myopenia and myosteatosis. The aim of this study is to compare the preoperative status of various body composition indexes including our newly developed modified intramuscular adipose tissue content (mIMAC) to investigate these clinical values in esophageal cancer patients. METHOD: We assessed preoperative psoas muscle mass index (PMI), IMAC, and mIMAC in 150 esophageal cancer patients. RESULTS: Preoperative high IMAC and low mIMAC status were significantly associated with older age. Preoperative decreased mIMAC was significantly associated with advanced T classification and the presence of distant metastasis and low preoperative mIMAC was an independent prognostic factor for poor overall survival and disease-free survival in esophageal cancer patients. Combined assessment of preoperative mIMAC with PMI could help stratify risk for oncological outcomes. Finally, preoperative PMI and mIMAC were positively correlated with various nutritional factors in esophageal cancer patients. CONCLUSION: Combined assessment between preoperative PMI and mIMAC could stratify risk for oncological outcomes, and preoperative mIMAC might be surrogate marker for aging and nutritional status in esophageal cancer patients.

A Bioelectrical Impedance Analysis for the Assessment of Muscle Atrophy in Patients with Chronic Inflammatory Demyelinating Polyneuropathy.

Objective Muscle atrophy is observed in a subset of patients with chronic inflammatory demyelinating polyneuropathy (CIDP). Its manifestation is associated with a poor functional prognosis and poor response to immunomodulatory therapies. We evaluated muscle atrophy in patients with CIDP using a bioelectrical impedance analysis (BIA). Methods We enrolled 12 patients with CIDP for a BIA of muscle atrophy. Of these 12 patients, 10 were diagnosed with typical CIDP, 1 with multifocal acquired demyelinating sensory and motor neuropathy, and 1 with distal acquired demyelinating symmetric neuropathy. All 12 patients underwent a series of assessments and evaluations, including a BIA and computed tomography (CT). A correlation was found between the skeletal muscle mass determined by the BIA and that found using CT of the muscles. Results The BIA provided values for each patient's skeletal muscle mass index (SMI) ranging from 4.1 to 8.1 kg/m2. Four of the patients with CIDP had SMI values below the threshold for sarcopenia. CT of the patients' muscles provided scores indicating grades of muscle atrophy in the upper and lower extremities. A comparison of the outcomes from these two measures showed a good correlation between their muscle atrophy ratings (p<0.05). Conclusion We found that a BIA and muscle CT provided muscle atrophy assessments of equivalent accuracy. Therefore, a BIA can be a simple alternative to muscle CT that is suitable for regular use in daily clinical practice as a reliable tool for assessing muscle atrophy in patients with CIDP.

Reliable virtual clinical assessment in spino-bulbar muscular atrophy (SBMA).

BACKGROUND: Spino-bulbar muscular atrophy (SBMA), caused by a CAG repeat expansion in the androgen receptor gene, affects adult men and results in muscle atrophy and weakness in the bulbar and limb muscles and signs of partial androgen insensitivity. During the COVID-19 pandemic, outpatients' visits have been reduced to preserve safety of frail patients, and telehealth was largely employed. METHODS: From April to November 2020, we monitored 12 patients with SBMA with telehealth and administered remotely two clinical scales currently used for SBMA: Adult Myopathy Assessment Tool (AMAT) and SBMA-Functional Rating Scale (SBMA-FRS). We compared results with previous and subsequent in-person visits' scores, and assessed the longitudinal changes in AMAT and SBMA-FRS scores during 7 years through the repeated measures analysis of variance (ANOVA). RESULTS: Repeated measures ANOVA of AMAT scores collected during 7 years and including tele-AMAT evaluation showed a steady mean decline of 1-2 points per year. A similar trend of SBMA-FRS scores, with a mean decline per year of about 1 point, was observed. There was no relevant deviation from the model prediction. CONCLUSIONS: Our data show that telehealth is a valid tool to monitor patients with SBMA: AMAT and SBMA-FRS scales can be effectively, reliably and easily administered remotely.

Irisin Serum Levels and Skeletal Muscle Assessment in a Cohort of Charcot-Marie-Tooth Patients.

Background: Charcot-Marie-Tooth (CMT) indicates a group of inherited polyneuropathies whose clinical phenotypes primarily include progressive distal weakness and muscle atrophy. Compelling evidence showed that the exercise-mimetic myokine irisin protects against muscle wasting in an autocrine manner, thus possibly preventing the onset of musculoskeletal atrophy. Therefore, we sought to determine if irisin serum levels correlate with biochemical and muscle parameters in a cohort of CMT patients. Methods: This cohort study included individuals (N=20) diagnosed with CMT disease. Irisin and biochemical markers were quantified in sera. Skeletal muscle mass (SMM) was evaluated by bioelectric impedance analysis, muscle strength by handgrip, and muscle quality was derived from muscle strength and muscle mass ratio. Results: CMT patients (m/f, 12/8) had lower irisin levels than age and sex matched healthy subjects (N=20) (6.51 ± 2.26 vs 9.34 ± 3.23 µg/ml; p=0.003). SMM in CMT patients was always lower compared to SMM reference values reported in healthy Caucasian population matched for age and sex. Almost the totality of CMT patients (19/20) showed low muscle quality and therefore patients were evaluated on the basis of muscle strength. Irisin was lower in presence of pathological compared to normal muscle strength (5.56 ± 1.26 vs 7.67 ± 2.72 µg/ml; p=0.03), and directly correlated with the marker of bone formation P1PN (r= 0.669; 95%CI 0.295 to 0.865; p=0.002), but inversely correlated with Vitamin D (r=-0.526; 95%CI -0,791 to -0,095; p=0.017). Surprisingly, in women, irisin levels were higher than in men (7.31 ± 2.53 vs 5.31 ± 1.02 µg/ml, p=0.05), and correlated with both muscle strength (r=0.759; 95%CI 0.329 to 0.929; p=0.004) and muscle quality (r=0.797; 95%CI 0.337 to 0.950; p=0.006). Conclusion: Our data demonstrate lower irisin levels in CMT patients compared to healthy subjects. Moreover, among patients, we observed, significantly higher irisin levels in women than in men, despite the higher SMM in the latter. Future studies are necessary to establish whether, in this clinical contest, irisin could represent a marker of the loss of muscle mass and strength and/or bone loss.

Muscle wasting assessment tools for prostate cancer.

Prostate cancer and its treatment may induce muscle wasting. Body composition and muscle functionality are rarely assessed in patients with prostate cancer from developing countries due to the limited availability of high-quality equipment for routine diagnosis. This cross-sectional study evaluated the association between several simplistic techniques for assessing muscle mass and function with a more complex standard of reference for muscle wasting among Mexican men with prostate cancer. Muscle wasting was highly prevalent, yet it was presumably associated with aging rather than cancer and its treatment itself. The restricted availability of specific equipment in clinical settings with technological limitations supports using unsophisticated techniques as surrogate measurements for muscle wasting. The left-arm handgrip dynamometry displayed the highest correlation with the standard of reference and exhibited an acceptable predicted probability for muscle estimation. Combining several simplistic techniques may be preferable. We also developed and internally validated a manageable model that helps to identify elderly patients with prostate cancer at risk of muscle depletion and impairment. These findings promote the early recognition and treatment of muscle wasting alterations occurring among older adults with prostate cancer.

MRI-based 3-dimensional volumetric assessment of fatty infiltration and muscle atrophy in rotator cuff tears.

BACKGROUND: The Goutallier and Warner Classification systems are useful in determining rotator cuff reparability. Data are limited on how accurately the scapular-Y view used in both systems reflects the 3-dimensional (3-D) changes in fatty infiltration (FI) and muscle atrophy (MA). Tendon retraction in the setting of a cuff tear may also influence the perception of these changes. This study's objectives were to (1) measure the 3-D volume of the supraspinatus muscle in intact rotator cuffs, and with varying magnitudes of retraction; (2) measure the 3-D volume of FI in the supraspinatus muscle in these conditions; and (3) determine the influence of tendon retraction on measured FI and MA using the Goutallier and Warner Classification Systems. METHODS: Between August 2015 and February 2016, all shoulder magnetic resonance images (MRIs) at the Portland VA Medical Center were standardized to include the medial scapular border. MRIs and charts were reviewed for inclusion/exclusion criteria. Included MRIs were categorized into 4 groups based on rotator cuff retraction. Supraspinatus muscle and fossa were traced to create 3-D volumes. FI and MA were measured within the supraspinatus. The supraspinatus muscle was graded among 6 physicians using the Goutallier and Warner classification systems. These grades were compared to 3-D measured FI and MA. The influence of tendon retraction on the measured grades were also evaluated. RESULTS: One hundred nine patients met inclusion/exclusion criteria. Ten MRIs for each group (N = 40) were included for image analysis. Supraspinatus volume tracings were highly reproducible and consistent between tracers. Supraspinatus muscle volumes decreased while global FI and MA increased with greater degrees of tendon retraction. In muscles with less than 10% global fat, fat concentrated in the lateral third of the muscle. In muscle with more than 10% global fat content, it distributed more diffusely throughout the muscle from medial to lateral. In comparing the scapular-Y to a medial cut, there was no consistent trend in FI whereas MA was more accurate at the medial cut. CONCLUSION: Parasagittal imaging location did not significantly influence the Goutallier score; however, assessment of MA using the Warner score leads readers to perceive less MA medially regardless of the magnitude of tendon retraction. The pattern of FI within the supraspinatus muscle changes from a laterally based location around the muscle-tendon junction to a more diffuse, global infiltration pattern when the whole muscle fat content exceeds 10%.

Quantitative assessment of muscle mass and gene expression analysis in dogs with glucocorticoid-induced muscle atrophy.

The present study aimed to quantitatively evaluate muscle mass and gene expression in dogs with glucocorticoid-induced muscle atrophy. Five healthy beagles received oral prednisolone for 4 weeks (1 mg/kg/day), and muscle mass was then evaluated via computed tomography. Histological and gene expression analyses were performed using biopsy samples from the biceps femoris before and after prednisolone administration. The cross-sectional area of the third lumbar paraspinal and mid-femoral muscles significantly decreased after glucocorticoid administration (from 27.5 ± 1.9 to 22.6 ± 2.0 cm2 and from 55.1 ± 4.7 to 50.7 ± 4.1 cm2, respectively; P<0.01). The fast- and slow-twitch muscle fibers were both atrophied (from 2,779 ± 369 to 1,581 ± 207 µm2 and from 2,871 ± 211 to 1,971 ± 169 µm2, respectively; P<0.05). The expression of the growth factor receptor-bound protein 10 (GRB10) significantly increased after prednisolone administration (P<0.05). Because GRB10 suppresses insulin signaling and the subsequent mammalian target of rapamycin complex 1 activity, increased expression of GRB10 may have resulted in a decrease in protein anabolism. Taken together, 1 mg/kg/day oral prednisolone for 4 weeks induced significant muscle atrophy in dogs, and GRB10 might participate in the pathology of glucocorticoid-induced muscle atrophy in canines.

Costly immunometabolic remodelling in disused muscle buildup through physical exercise.

The mechanisms underlying the immunometabolic disturbances during skeletal muscle atrophy caused by a plethora of circumstances ranging from hospitalization to spaceflight missions remain unknown. Here, we outline the possible pathways that might be dysregulated in such conditions and assess the potential of physical exercise to mitigate and promote the recovery of muscle morphology, metabolism and function after intervals of disuse. Studies applying exercise to attenuate disuse-induced muscle atrophy have shown a pivotal role of circulating myokines in the activation of anabolic signalling pathways. These muscle-derived factors induce accretion of contractile proteins in the myofibers, and at the same time decrease protein breakdown and loss. Regular exercise plays a crucial role in re-establishing adequate immunometabolism and increasing the migration and presence in the muscle of macrophages with an anti-inflammatory phenotype (M2) and T regulatory cells (Tregs) after disease-induced muscle loss. Additionally, the switch in metabolic pathways (glycolysis to oxidative phosphorylation [OXPHOS]) is important for achieving rapid metabolic homeostasis during muscle regeneration. In this review, we discuss the molecular aspects of the immunometabolic response elicited by exercise during skeletal muscle regeneration. There is not, nevertheless, consensus on a single optimal intensity of exercise required to improve muscle strength, mass and functional capacity owing to the wide range of exercise protocols studied so far. Despite the absence of agreement on the specific strategy, physical exercise appears as a powerful complementary strategy to attenuate the harmful effects of muscle disuse in different scenarios.

An assessment of morphological and pathological changes in paravertebral muscle degeneration using imaging and histological analysis: a cross-sectional study.

BACKGROUND: The high signal of paravertebral muscle (PVM) on T2-weighted image (T2WI) is usually considered to be fatty degeneration. However, it is difficult to distinguish inflammatory edema from fatty degeneration on T2WI. The purpose of this study was to identify different types of PVM high signal in patients with low back pain (LBP) through magnetic resonance imaging (MRI) and histology. METHODS: Seventy patients with LBP underwent MRI. The signal change of multifidus both on T2WI and fat suppression image (FSI) was quantified by Image J. Furthermore, 25 of the 70 patients underwent surgery for degenerative lumbar disease and their multifidus were obtained during the operation. Histological analysis of the samples was performed by HE staining. RESULT: Three types of PVM signal changes were identified from the MRI. Type 1 (n = 36) indicated fatty degeneration characterized by a high signal on T2WI and low signal on FSI. High signal on both T2WI and FSI, signifying type 2 meant inflammatory edema (n = 9). Type 3 (n = 25) showed high signal on T2WI and partial signal suppression on FSI, which meant a combination of fatty degeneration and inflammatory edema. Histological results were consistent with MRI. Among the 25 patients who underwent surgery, type 1 (n = 14) showed adipocytes infiltration, type 2 (n = 3) showed inflammatory cells infiltration and type 3 (n = 8) showed adipocytes and inflammatory cells infiltration. CONCLUSION: From our results, there are three types of pathological changes in patients with PVM degeneration, which may help to decide on targeted treatments for LBP.

Sarcopenia in critically ill children: A bedside assessment using point-of-care ultrasound and anthropometry.

BACKGROUND & AIMS: Due to the lack of validated methods of muscle assessment, sarcopenia is not well described in critically ill children. The main objectives of this study were to assess muscle wasting using point-of-care ultrasound (POCUS) and anthropometry, as well as its association with nutrition delivery in PICU. METHODS: This was a single-center, prospective cohort study, including consecutive children admitted to the PICU. Quadriceps femoris muscle thickness (QFMT) and anthropometrics measurements were performed at admission and then weekly until the 14th day of the PICU stay. The three moments of assessment were defined as T0 (baseline), T1 (7th day) and T2 (14th day). For analysis purposes, participants assessed only in T0 and T1 were defined as Subgroup 1, while those assessed in T0, T1 and T2 were defined as Subgroup 2. Actual total daily intake was determined by patient intake records until discharge or during the first 14 full days of PICU admission. RESULTS: In all, 119 patients were included with a median age of 12.0 months (IQR 4.0-42.5). In Subgroup 1, QFMT significantly decreased between T0 and T1 (-12.93 ± 14.07 %; p < 0.001), and the same was observed in Subgroup 2 (-13.81 ± 13.05 %; p < 0.001). However, no differences in QFMT was observed between T1 and T2 (-2.06 ± 13.80 %; p = 0.936). Triceps skinfold thickness, mid-upper arm circumference, and upper arm muscle area presented a similar pattern of changes between periods in both groups. Decrease of QFMT at T1 was significantly correlated with the cumulative protein deficit in both subgroups, but not with the cumulative energy deficit. CONCLUSION: Substantial muscle wasting occurs early in critically ill children and may be related to insufficient protein delivery. Anthropometric measurements are valuable in PICU and POCUS has the potential to play a major role in sarcopenia assessment during critical illnesses. TRIAL REGISTRATION: Brazilian Clinical Trials registry, registration number: RBR-85YYGN.