Measuring myofascial shear strain in chronic shoulder pain with ultrasound shear strain imaging: a case report.

BACKGROUND: Dysfunctional gliding of deep fascia and muscle layers forms the basis of myofascial pain and dysfunction, which can cause chronic shoulder pain. Ultrasound shear strain imaging may offer a non-invasive tool to quantitatively evaluate the extent of muscular dysfunctional gliding and its correlation with pain. This case study is the first to use ultrasound shear strain imaging to report the shear strain between the pectoralis major and minor muscles in shoulders with and without chronic pain. CASE PRESENTATION: The shear strain between the pectoralis major and minor muscles during shoulder rotation in a volunteer with chronic shoulder pain was measured with ultrasound shear strain imaging. The results show that the mean ± standard deviation shear strain was 0.40 ± 0.09 on the affected side, compared to 1.09 ± 0.18 on the unaffected side (p<0.05). The results suggest that myofascial dysfunction may cause the muscles to adhere together thereby reducing shear strain on the affected side. CONCLUSION: Our findings elucidate a potential pathophysiology of myofascial dysfunction in chronic shoulder pain and reveal the potential utility of ultrasound imaging to provide a useful biomarker for shear strain evaluation between the pectoralis major and minor muscles.

Neuromuscular electrical stimulation of humeral adductors in subjects with rotator cuff tear.

INTRODUCTION: In symptomatic patients with rotator cuff tear, MRI and radiographic studies have ascribed the pain symptom to insufficient humeral head depression during arm elevations. The arm adductors such as the teres major and pectoralis major may contribute to depression of the humerus head during arm elevations. Researchers have demonstrated that neuromuscular electrical stimulation (NMES) of the serratus anterior and lower trapezius can control scapular motions and improve acromiohumeral distance. It is unknown, however, if adductor neuromuscular training could help patients with rotator cuff tear. MATERIALS AND METHODS: A cross-sectional study of NMES of the teres major and pectoralis major was conducted on 30 symptomatic subjects with rotator cuff tear. We measured the acromiohumeral distance by ultrasonography and scapular kinematics during arm elevation with a three-dimensional motion tracking system. RESULTS: The acromiohumeral distance significantly increased during NMES of the teres major (0.73 mm, p < 0.001). However, the distance significantly decreased with NMES of the pectoralis major (0.78 mm, p < 0.001). Additionally, scapular upward rotation was greater during NMES of the teres major than during NMES of the pectoralis major (3.4°, p < 0.001). Scapular external rotation decreased significantly more during NMES of the pectoralis major than during NMES of the teres major (1.6°, p = 0.003). CONCLUSIONS: NMES of the teres major can increase acromiohumeral distance and scapular upward rotation during arm elevation. However, the decreased upward and external rotation of the scapula during arm elevation with NMES of the pectoralis major may be associated with subacromial impingement.

Respiratory strength and pectoralis muscle mass as measures of sarcopenia: Relation to outcomes in resected non-small cell lung cancer.

OBJECTIVES: Physical biomarkers to stratify patients with lung cancer into subtypes predictive of outcome beyond tumor-related characteristics are underexplored. This study was designed to investigate the clinical utility of preoperative sarcopenia based on respiratory strength and pectoralis muscle mass to predict the risk of death. METHODS: This retrospective study included 346 consecutive patients undergoing curative-intent resection of non-small cell lung cancer from 2009 to 2013. Respiratory strength and muscle mass were assessed by peak expiratory flow rate and pectoralis muscle index (pectoralis muscle area/body mass index) using preoperative spirometry and chest axial images, respectively. Sarcopenia cutoff points were defined by gender-specific medians of peak expiratory flow rates and pectoralis muscle indices. Survival was compared between patients with sarcopenia and patients without. RESULTS: Sarcopenia was present in 98 patients (28.3%) and was significantly associated with advancing age (P < .001). Patients with sarcopenia exhibited worse 5-year overall survival compared with patients without sarcopenia (69.9% vs 87.2%, P < .001). Multivariate analysis revealed that sarcopenia was an independent adverse prognostic factor (hazard ratio, 1.88; 95% confidence interval, 1.09-3.24; P = .023) after adjustment for gender, age, smoking status, coronary heart disease, diffusing capacity for carbon monoxide, neutrophil-to-lymphocyte ratio, albumin, histologic type, and pathologic stage. CONCLUSIONS: Preoperative sarcopenia as identified by the criteria of low respiratory strength and reduced pectoralis muscle mass is significantly associated with poor overall survival. This may help to develop more individualized management strategies and optimize longitudinal care for patients.

Pectoralis muscle area and its association with indices of disease severity in interstitial lung disease.

RATIONALE: The pathophysiology of interstitial lung disease (ILD) impacts body composition, whereby ILD severity is linked to lower lean mass. OBJECTIVES: To determine i) if pectoralis muscle area (PMA) is a surrogate for whole-body lean mass in ILD, ii) whether PMA is associated with ILD severity, and iii) if the longitudinal change in PMA is associated with pulmonary function and mortality in ILD. METHODS: Patients with ILD (n = 164) were analyzed retrospectively. PMA was quantified from a chest computed tomography scan. Peripheral oxygen saturation (SpO2), 6-min walk distance (6MWD), and pulmonary function were obtained as part of routine clinical care. Dyspnea and quality of life were assessed using the UCSD Shortness of Breath Questionnaire and European Quality of Life 5 Dimensions questionnaire, respectively. RESULTS: PMA was associated with whole-body lean mass (p < 0.001). After adjusting for age, sex, height, body mass, and prednisone status, PMA was associated with %-predicted forced vital capacity (FVC), %-predicted diffusion capacity (DLCO), resting and exertional SpO2, and dyspnea (all p < 0.05), but not forced expiratory volume in 1 s (FEV1), FEV1/FVC, 6MWD, or quality of life (all p > 0.05). The annual negative PMA slope was associated with annual negative slopes in FVC, FEV1, and DLCO (all p < 0.05), but not FEV1/FVC (p = 0.46). Annual slope in PMA was associated with all-cause mortality (hazard ratio = -0.80, 95% CI:0.889-0.959; p < 0.001). CONCLUSION: In patients with ILD, PMA is a suitable surrogate for whole-body lean mass. A lower PMA is associated with indices of ILD severity, which supports the notion that ILD progression may involve sarcopenia.

Prospect of early vascular tone and satellite cell modulations on white striping muscle myopathy.

Polyphasic myodegeneration potentially causes severe physiological and metabolic disorders in the breast muscle of fast-growing broiler chickens. To date, the etiology of recent muscle myopathies, such as the white striping (WS) phenotype, is still unknown. White striping-affected breast meats compromise the water holding capacity and predispose muscle to poor vascular tone, leading to the deterioration of meat qualities. Herein, this review article provides insight on the complexities around chicken breast myopathies: (i) the etiologies of WS occurrence in chicken; (ii) the metabolic changes that occur in WS defect in pectoralis major; and (iii) the interactions between breast muscle physiology and vascular tone. It also addressed the effects of nutritional supplements on muscle myopathies on chicken breast meats. Moreover, the review explored breast muscle biology focusing on the early preparation of satellite and vascular cells in fast-growth chicken breeds. Transcriptomics and histological analyses revealed poor vascularity in breast muscle of fast growth chickens. Thus, we suggest in ovo feeding of nutrients promoting vascularization and satellite cells replenishment as a potential strategy to enhance endothelium-derived nitric oxide availability to promote vascularization in the pectoralis major muscle region.

Broiler genetics influences proteome profiles of normal and woody breast muscle.

Wooden or woody breast (WB) is a myopathy of the pectoralis major in fast-growing broilers that influences the quality of breast meat and causes an economic loss in the poultry industry. The objective of this study was to evaluate growth and proteome differences between 5 genetic strains of broilers that yield WB and normal breast (NB) meat. Eight-week-old broilers were evaluated for the WB myopathy and divided into NB and WB groups. Differential expression of proteins was analyzed using 2-dimensional gel electrophoresis and LC-MS/MS to elucidate the mechanism behind the breast myopathy because of the genetic backgrounds of the birds. The percentages of birds with WB were 61.3, 68.8, 46.9, 45.2, and 87.5% for strains 1-5, respectively, indicating variability in WB myopathy among broiler strains. Birds from strains 1, 3, and 5 in the WB group were heavier than those in the NB group (P < 0.05). Woody breast meat from all strains were heavier than NB meat (P < 0.05). Within WB, strain 5 had a greater breast yield than strains 1, 3, and 4 (P < 0.0001). Woody breast from strains 2, 3, 4, and 5 had a greater breast yield than NB (P < 0.05). Six proteins were more abundant in NB of strain 5 than those of strains 2, 3, and 4, and these proteins were related to muscle growth, regeneration, contraction, apoptosis, and oxidative stress. Within WB, 14 proteins were differentially expressed between strain 5 and other strains, suggesting high protein synthesis, weak structural integrity, intense contraction, and oxidative stress in strain 5 birds. The differences between WB from strain 3 and strains 1, 2, and 4 were mainly glycolytic. In conclusion, protein profiles of broiler breast differed because of both broiler genetics and the presence of WB myopathy.

Enhanced transforming growth factor-beta signaling and fibrosis in the pectoralis major muscle of broiler chickens affected by wooden breast myopathy.

Fibrosis has also been recorded as a prominent pathological feature within wooden breast (WB) myopathy of broiler chickens. This study was conducted to evaluate the accumulation of fibril collagen, deposition of the extracellular matrix (ECM) components, and the underlying mechanism mediating the pathogenic fibrotic process in the pectoralis major (PM) muscle of WB-affected birds. Broiler chickens were categorized into the control and WB groups based on the evaluation of myopathic lesions. Results indicated that the total content and area of collagen in cross-sections of the PM muscle, as well as the augmented expression of collagen-I and fibronectin in the ECM, were greatly increased in birds with WB. Wooden breast myopathy upregulated expressions of transforming growth factor-beta (TGF-ß) and the phosphorylation of Smad 2 and 3, thereby activating TGF-ß-mediated Smad signaling pathway, which further enhanced the transcription of profibrotic mediators. In addition, regulators involved in collagen biosynthesis and cross-linking including prolyl 4-hydroxylase, lysyl oxidase, lysyl hydroxylase, and decorin were increased in the WB muscle. Finally, the expressions of both matrix metalloproteinases (MMP) and tissue inhibitor of metalloproteinases (TIMP) were increased in the WB muscle, which might be related with reduced ECM remodeling. Overall, WB myopathy induces severe fibrosis by enhancing ECM deposition and collagen cross-linking in the PM muscle of broiler chickens, possibly via the activation of TGF-ß signaling and the dysregulation of the MMP and TIMP system.

Association of Both Scapular Upward Rotation and Scapulothoracic Muscle Lengths With Shoulder Pain, Function, and Range of Movement.

OBJECTIVE: Our aim was to analyze whether shoulder pain is related to scapular upward rotation (SUR) or to the lengths of the pectoralis minor and levator scapulae muscles. METHODS: This cross-sectional, observational study was carried out in 3 primary-care centers; 54 individuals with chronic shoulder pain participated. Scapular upward rotation and the lengths of the pectoralis minor and levator scapulae muscles were assessed. RESULTS: The level of association was small between shoulder pain and function and (1) the lengths of the pectoralis minor (r = 0.08, P = .93) and levator scapulae (r = -0.01, P = .57) muscles and (2) SUR at 45° (r = 0.17, P = .21), 90° (r = 0.08, P = .57), and 135° (r = 0.10, P = 0.45) of shoulder elevation. CONCLUSION: The relationship was small between shoulder pain and function and (1) SUR (45°, 90°, and 135° of shoulder elevation) and (2) the lengths of the pectoralis minor and levator scapulae muscles. Thus, the use of SUR and pectoralis minor and levator scapulae lengths in shoulder assessment should be undertaken with caution. Other factors such as psychological factors, central/peripheral sensitization, and intrinsic properties of the tissue have to be taken into account.

Surface respiratory electromyography and dyspnea in acute heart failure patients.

INTRODUCTION AND OBJECTIVES: Dyspnea is the most common symptom among hospitalized patients with heart failure (HF) but besides dyspnea questionnaires (which reflect the subjective patient sensation and are not fully validated in HF) there are no measurable physiological variables providing objective assessment of dyspnea in a setting of acute HF patients. Studies performed in respiratory patients suggest that the measurement of electromyographic (EMG) activity of the respiratory muscles with surface electrodes correlates well with dyspnea. Our aim was to test the hypothesis that respiratory muscles EMG activity is a potential marker of dyspnea severity in acute HF patients. METHODS: Prospective and descriptive pilot study carried out in 25 adult patients admitted for acute HF. Measurements were carried out with a cardio-respiratory portable polygraph including EMG surface electrodes for measuring the activity of main (diaphragm) and accessory (scalene and pectoralis minor) respiratory muscles. Dyspnea sensation was assessed by means of the Likert 5 questionnaire. Data were recorded during 3 min of spontaneous breathing and after breathing at maximum effort for several cycles for normalizing data. An index to quantify the activity of each respiratory muscle was computed. This assessment was carried out within the first 24 h of admission, and at day 2 and 5. RESULTS: Dyspnea score decreased along the three measured days. Diaphragm and scalene EMG index showed a positive and significant direct relationship with dyspnea score (p<0.001 and p = 0.003 respectively) whereas pectoralis minor muscle did not. CONCLUSION: In our pilot study, diaphragm and scalene EMG activity was associated with increasing severity of dyspnea. Surface respiratory EMG could be a useful objective tool to improve assessment of dyspnea in acute HF patients.

Influence of Shoulder Position on Functional Control Ratio During Isokinetic Assessment.

CONTEXT: One of the possible mechanisms leading to secondary impingement syndrome may be the strength imbalance of shoulder rotators which is known as functional control ratio (FCR). The FCR is a ratio dividing the eccentric peak torque of the external rotators by the concentric peak torque of the internal rotators. Previous studies have focused on the reproducibility and reliability of isokinetic assessment, but there is little information on the influence of variable shoulder positions on FCR. OBJECTIVE: To compare shoulder FCR across 3 different shoulder abduction positions during isokinetic assessment. DESIGN: Cross-sectional study. SETTING: Biomechanics laboratory. PARTICIPANTS: Thirty-one healthy young university students (age 22.35 [0.95] y, weight 60.52 [9.31] kg, height 168.23 [9.47] cm). INTERVENTIONS: The concentric peak torque of internal rotators and eccentric peak torque of external rotators of right shoulder were measured on an isokinetic dynamometer. MAIN OUTCOME MEASURES: Concentric peak torque of the internal rotators and eccentric peak torque of the external rotators, measured using an isokinetic dynamometer. RESULTS: The concentric peak torque of internal rotators was significantly lower at 120° shoulder abduction compared with other positions (P < .001). The FCR was significantly higher at 120° shoulder abduction than 90° (P = .002) or 60° (P < .001) shoulder abduction because of the lower concentric peak torque. No significant difference was found in the FCR between the other 2 shoulder positions (P = .14). CONCLUSIONS: Shoulder position variations may influence FCR because of weakness of the internal rotators. Rehabilitation and injury prevention training programs should specifically focus on strengthening the internal rotators at more elevated angles of shoulder abduction.

Spasticity-induced Pectoralis minor syndrome: a case-report.

Background: Pectoralis minor syndrome (PMS) develops when the neurovascular bundle compression occurs at the retropectoralis minor space. It may occur due to repetitive overhead activities, traumatic incident, structural causes, myofascial pain syndrome in the pectoralis minor muscle, as well as spasticity of the pectoralis minor muscle. In patients with hemiplegia, adductor muscles along with pectoralis minor muscle spasticity may be present in the upper extremity.Objective: We report a 19-year-old male patient with spastic hemiparesis who was diagnosed with PMS due to spasticity of the pectoralis minor muscle.Method: Diagnosis of PMS was confirmed by Ultrasound-guided 4 cc 1% lidocaine injection to the right pectoralis minor muscle and Ultrasound-guided onabotulinum toxin A injection was performed. Stretching exercises to the pectoral muscles were also added to the rehabilitation program.Result: Complaints of the patient were controlled by botulinum toxin injections at 3-month intervals.Conclusion: It should be kept in mind that spasticity in the upper extremity may develop in the pectoralis minor muscle, and may cause pressure on the neurovascular structures. Ultrasound-guided botulinum toxin injections can be a safe and effective treatment for PMS in a patent with post stroke spastic hemiparesis.

Mechanical properties of the shoulder and pectoralis major in breast cancer patients undergoing breast-conserving surgery with axillary surgery and radiotherapy.

Breast-conserving surgery (BCS) and radiotherapy reduce breast cancer recurrence but can cause functional deficits in breast cancer survivors. A cross-sectional study quantified the long-term pathophysiological impact of these treatments on biomechanical measures of shoulder stiffness and ultrasound shear wave elastography measures of the shear elastic modulus of the pectoralis major (PM). Nine node-positive patients treated with radiotherapy to the breast and regional nodes after BCS and axillary lymph node dissection (Group 1) were compared to nine node-negative patients treated with radiotherapy to the breast alone after BCS and sentinel node biopsy (Group 2) and nine healthy age-matched controls. The mean follow-up for Group 1 and Group 2 patients was 988 days and 754 days, respectively. Shoulder stiffness did not differ between the treatment groups and healthy controls (p = 0.23). The PM shear elastic modulus differed between groups (p = 0.002), with Group 1 patients exhibiting a stiffer PM than Group 2 patients (p < 0.001) and healthy controls (p = 0.027). The mean prescribed radiotherapy dose to the PM was significantly correlated with passive shear elastic modulus (p = 0.018). Breast cancer patients undergoing more extensive axillary surgery and nodal radiotherapy did not experience long-term functional deficits to shoulder integrity but did experience long-term mechanical changes of the PM.

Computed tomography-derived area and density of pectoralis muscle associated disease severity and longitudinal changes in chronic obstructive pulmonary disease: a case control study.

BACKGROUND: Muscle wasting is associated with prognosis in patients with chronic obstructive pulmonary disease (COPD). The cross-sectional area of skeletal muscles on computed tomography (CT) could serve as a method to evaluate body composition. The present study aimed to determine the ability of CT-derived pectoralis muscle area (PMA) and pectoralis muscle density (PMD) to determine the severity of COPD and change in longitudinal pulmonary function in patients with COPD. METHODS: A total of 293 participants were enrolled in this study, a whom 222 had undergone at least two spirometry measurements within 3 years after baseline data acquisition. PMA and PMD were measured from a single axial slice of chest CT above the aortic arch at baseline. The emphysema index and bronchial wall thickness were quantitatively assessed in all scans. The generalized linear model was used to determine the correlation between PMA and PMD measurements and pulmonary function. RESULTS: PMA and PMD were significantly associated with baseline lung function and the severity of emphysema (P < 0.05). Patients with the lowest PMA and PMD exhibited significantly more severe airflow obstruction (ß = - 0.06; 95% confidence interval: - 0.09 to - 0.03]. PMA was statistically associated with COPD assessment test (CAT) score (P = 0.033). However, PMD did not exhibit statistically significant correlation with either CAT scores or modified Medical Research Council scores (P > 0.05). Furthermore, neither PMA nor PMD were associated with changes in forced expiratory volume in 1 s over a 3-year periods. CONCLUSIONS: CT-derived features of the pectoralis muscle may be helpful in predicting disease severity in patients with COPD, but are not necessarily associated with longitudinal changes in lung function.

Proximal myofascial pain in patients with distal complex regional pain syndrome of the upper limb.

BACKGROUND: Patients suffering from complex regional pain syndrome (CRPS) endure myofascial-related pain in at least 50% of cases. AIMS: To evaluate the association of upper limb CRPS with myofascial pain in muscles that might influence arm or hand pain, and to evaluate whether the paraspinal skin and subcutaneous layers' tenderness and allodynia are associated with CRPS. METHODS: A case-control study comprising 20 patients presenting with upper limb CRPS, and 20 healthy controls matched for sex and age, were evaluated in the thoracic paraspinal area and myofascial trigger points (MTrPs) (infraspinatus, rhomboids, subclavius, serratus posterior superior and pectoralis minor) via a skin rolling test. RESULTS: The prevalence of MTrPs in the affected extremity of the subjects was significantly higher than in the right limb of the controls: 45% exhibited active and latent MTrPs in the infraspinatus muscle (χ2 = 11.613, p = 0.001); 60% in active and latent MTrPs in the subclavius muscle (χ2 = 17.143, p < 0.001); and in the pectoralis minor muscle (χ2 = 13.786, p < 0.001). In addition, 55% of the cases exhibited active and latent MTrPs in the serratus posterior superior muscle (χ2 = 15.172, p < 0.001). Significant differences between the groups in skin texture and pain levels (p = 0.01, p < 0.001, respectively) demonstrated that CRPS patients felt more pain, and their skin and subcutaneous layers were much tighter than in the healthy controls. CONCLUSION: There is a high prevalence of MTrPs in the shoulder and upper thoracic area muscles in subjects who suffer from CRPS. We recommend adding an MTrPs evaluation to the standardized examination of these patients.

The Effect of the Wooden Breast Fibrotic Myopathy in Broilers on Fibrillar Collagen Organization and Decorin-Collagen Binding.

The wooden breast myopathy is identified by the palpation of a rigid pectoralis major muscle and results in myofiber necrosis and fibrosis in fast-growing, meat-type broilers. The fibrosis in wooden breast-affected muscle is characterized by the replacement of myofibers with extracellular matrix proteins, especially fibril-forming collagens. Studies have shown differences in collagen organization in fast-growing broiler lines, with tightly packed and highly aligned collagen organizations having a higher phenotypic incidence of wooden breast. The objective of the current study was to analyze collagen fibril organization further in two fast-growing broiler lines (Lines A and B) with incidence of wooden breast compared with a slower growing broiler Line C with no phenotypically detectable wooden breast. The small leucine-rich proteoglycan decorin was also studied for its interaction with collagen by immunogold detection. Decorin binds to fibrillar collagens and organizes their alignment and crosslinking, both of which will affect collagen functional properties. Key findings from the study showed that collagen shifts to larger diameter collagen fibril bundles with the wooden breast myopathy. Specifically, broilers affected with wooden breast from Line A had a more dramatic shift toward larger collagen fibril bundles compared with those affected from Line B. Wooden breast-affected Line A had collagen fibril bundles up to 8.4 µm, whereas Line B maximum size was 5.1 µm. Although decorin-collagen binding was not different overall in the wooden breast myopathy or broiler line, for small-diameter collagen fibril bundles, wooden breast-affected Line A had more decorin-collagen binding than wooden breast-affected Line B. Taken together, these data provide further evidence that multiple fibrotic myopathies are likely in fast-growing meat-type broilers.

Efecto de la miopatía fibrótica de pechuga de madera en pollos de engorde en la organización del colágeno fibrilar y en la unión entre decorina y colágeno. La miopatía de madera de la pechuga se identifica por la palpación de un músculo pectoralis major rígido y da como resultado necrosis y fibrosis de fibras musculares en pollos de engorde de rápido crecimiento. La fibrosis en el músculo afectado por pechuga de madera se caracteriza por la sustitución de las fibras musculares con proteínas de la matriz extracelular, especialmente colágeno que forma fibrillas. Los estudios han demostrado diferencias en la organización del colágeno en las líneas de pollos de engorde de rápido crecimiento, con organizaciones de colágeno altamente alineadas y altamente empacadas que tienen una mayor incidencia fenotípica para la pechuga de madera. El objetivo del presente estudio fue analizar la organización de las fibrillas de colágeno en dos líneas de pollos de engorde de rápido crecimiento (Líneas A y B) con una incidencia de pechos de madera en comparación con la Línea C de pollos de engorde de crecimiento más lento, sin pecho de madera detectable fenotípicamente. El proteoglicano pequeño decorina rica en leucina también se estudió por su interacción con el colágeno mediante detección por el método inmunogold. La decorina se une a los colágenos fibrilares y organiza su alineación y sus enlaces cruzados, los cuales afectarán las propiedades funcionales del colágeno. Los hallazgos más importantes del estudio demostraron que el colágeno se organiza en fibrillas de mayor diámetro en la miopatía de pechuga de madera. Específicamente, los pollos de engorde afectados con la pechuga de madera de la Línea A mostraron una tendencia mayor para mostrar paquetes de fibrillas de colágeno más grandes en comparación con los afectados de la Línea B. La Línea A afectada por la pechuga de madera tuvo paquetes de fibrillas de colágeno de hasta 8.4 µm, mientras que el tamaño máximo de la Línea B fue de 5.1 µm. Aunque en general, el enlace entre la decorina y colágeno no fue diferente en la miopatía de madera de la pechuga o en la línea de pollos de engorde con haces de fibrillas de colágeno de diámetro menor, la línea A afectada por pechuga de madera tuvo más uniones de decorina-colágeno en comparación con la línea B afectada por pechuga de madera. En general, los datos proporcionan evidencia adicional de que es más probable la presentación de miopatías fibróticas múltiples en pollos de engorde de rápido crecimiento.

Altered Cocontraction Patterns of Humeral Head Depressors in Patients with Subacromial Pain Syndrome: A Cross-sectional Electromyography Analysis.

BACKGROUND: In approximately 29% to 34% of all patients with subacromial pain syndrome (SAPS) there is no anatomic explanation for symptoms, and behavioral aspects and/or central pain mechanisms may play a more important role than previously assumed. A possible behavioral explanation for pain in patients with SAPS is insufficient active depression of the humerus during abduction by the adductor muscles. Although the adductor muscles, specifically the teres major, have the most important contribution to depression of the humerus during abduction, these muscles have not been well studied in patients with SAPS. QUESTIONS/PURPOSES: Do patients with SAPS have altered contraction patterns of the arm adductors during abduction compared with asymptomatic people? METHODS: SAPS was defined as nonspecific shoulder pain lasting for longer than 3 months that could not be explained by specific conditions such as calcific tendinitis, full-thickness rotator cuff tears, or symptomatic acromioclavicular arthritis, as assessed with clinical examination, radiographs, and magnetic resonance arthrography. Of 85 patients with SAPS who met the prespecified inclusion criteria, 40 were eligible and agreed to participate in this study. Thirty asymptomatic spouses of patients with musculoskeletal complaints, aged 35 to 60 years, were included; the SAPS and control groups were not different with respect to age, sex, and hand dominance. With electromyography, we assessed the contraction patterns of selected muscles that directly act on the position of the humerus relative to the scapula (the latissimus dorsi, teres major, pectoralis major, and deltoid muscles). Cocontraction was quantified through the activation ratio ([AR]; range, -1 to 1). The AR indicates the task-related degree of antagonist activation relative to the same muscle's degree of agonist activation, equaling 1 in case of sole agonist muscle activation and equaling -1 in case of sole antagonistic activation (cocontraction). We compared the AR between patients with SAPS and asymptomatic controls using linear mixed-model analyses. An effect size of 0.10 < AR < 0.20 was subjectively considered to be a modest effect size. RESULTS: Patients with SAPS had a 0.11 higher AR of the teres major (95% CI, 0.01-0.21; p = 0.038), a 0.11 lower AR of the pectoralis major (95% CI, -0.18 to -0.04; p = 0.003), and a 0.12 lower AR of the deltoid muscle (95% CI, -0.17 to -0.06; p < 0.001) than control participants did. These differences were considered to be modest. With the numbers available, we found no difference in the AR of the latissimus dorsi between patients with SAPS and controls (difference = 0.05; 95% CI, -0.01 to 0.12; p = 0.120). CONCLUSIONS: Patients with SAPS showed an altered adductor cocontraction pattern with reduced teres major activation during abduction. The consequent reduction of caudally directed forces on the humerus may lead to repetitive overloading of the subacromial tissues and perpetuate symptoms in patients with SAPS. Physical therapy programs are frequently effective in patients with SAPS, but targeted approaches are lacking. Clinicians and scientists may use the findings of this study to assess if actively training adductor cocontraction in patients with SAPS to unload the subacromial tissues is clinically effective. The efficacy of training protocols may be enhanced by using electromyography monitoring. LEVEL OF EVIDENCE: Level II, prognostic study.

Cross-sectional and longitudinal assessment of muscle from regular chest computed tomography scans: L1 and pectoralis muscle compared to L3 as reference in non-small cell lung cancer.

Background: Computed tomography (CT) is increasingly used in clinical research for single-slice assessment of muscle mass to correlate with clinical outcome and evaluate treatment efficacy. The third lumbar level (L3) is considered as reference for muscle, but chest scans generally do not reach beyond the first lumbar level (L1). This study investigates if pectoralis muscle and L1 are appropriate alternatives for L3. Methods: CT scans of 115 stage IV non-small cell lung cancer patients were analyzed before and during tumor therapy. Skeletal muscle assessed at pectoralis and L1 muscle was compared to L3 at baseline. Furthermore, the prognostic significance of changes in muscle mass determined at different locations was investigated. Results: Pearson's correlation coefficient between skeletal muscle at L3 and L1 was stronger (r=0.90, P<0.001) than between L3 and pectoralis muscle (r=0.71, P<0.001). Cox regression analysis revealed that L3 (HR 0.943, 95% CI: 0.92-0.97, P<0.001) and L1 muscle loss (HR 0.954, 95% CI: 0.93-0.98, P<0.001) predicted overall survival, whereas pectoralis muscle loss did not. Conclusion: L1 is a better alternative than pectoralis muscle to substitute L3 for analysis of muscle mass from regular chest CT scans.

Effect of breast cancer surgery on chest tightness and upper limb dysfunction.

This study aimed to investigate the possible changes in anterior chest tightness after breast cancer surgery. We also try to investigate whether anterior chest tightness is associated with upper-limb dysfunction after breast cancer surgery. Eighty-three women who underwent breast cancer surgery were evaluated before and 2 weeks, 3 months, and 9 months after surgery. Anterior chest tightness was measured using the length of the pectoralis minor muscle through 2 methods (length from the coracoid process to the fourth rib and linear distance from the table to the posterior acromion with supine position). Shoulder range of motion and the K-DASH (Korean version of Disability Arm and Shoulder Questionnaire) score were measured to quantify functional performance of upper limb. Anterior chest tightness of patients with breast cancer significantly increased after surgery. Upper limb dysfunction was observed such as reduced shoulder range-of-motion and increased K-DASH score over time. Increase in chest tightness was correlated with shoulder range-of-motion reduction. Chest tightness was not correlated with K-DASH score directly. However, shoulder range-of-motion reduction was significantly correlated with K-DASH score. Chest tightness and upper limb dysfunction increased in breast cancer survivor. Increase in chest tightness after surgery is associated with upper limb dysfunction and careful attention is required.

Overflow using proprioceptive neuromuscular facilitation in post-stroke hemiplegics: A preliminary study.

Hemiplegia is the classic condition resulting from a stroke. To assist in recovery, the overflow method can be employed to stimulate the affected limb, using the healthy contralateral lower limb (LL) to activate the plegic upper limb (UL) musculature. The aim of this study was to evaluate the immediate effect of overflow using the PNF method on the plegic upper limb muscles of post-stroke individuals in the acute and chronic stages, as well as on the muscles of healthy individuals. A total of 22 individuals participated in the work, comprising 8 healthy individuals (control group), 6 post-stroke acute stage individuals (acute group), and 8 post-stroke chronic stage individuals (chronic group). The participants were assessed using a questionnaire with sections for personal and disease data and application of the ICF scale and the Fugl-Meyer index. The three groups were submitted to electromyographic evaluation, using the posterior deltoid (PD), anterior deltoid (AD), pectoralis major (PM), and external oblique (EO) muscles in four different positions: P1 (resting the UL, with the LL contralateral to the affected limb positioned in diagonal); P2 (resting the UL, with manual resistance in the contralateral LL); P3 (affected UL positioned in diagonal, with manual resistance in the contralateral LL) e P4 (affected UL positioned in diagonal, with fixed point and manual resistance in the contralateral LL). The electromyography results revealed no significant differences between most of the positions for the four muscles evaluated (p > 0.05). However, high clinical relevance (d > 0.8) was found for muscle activation in positions 2 and 4. It could be concluded that for post-stroke individuals in the acute and chronic stages, overflow using PNF effectively increased activation of the PD, AD, PM, and EO muscles in the P2, as well as position 4.