肌肉减少症的诊断及治疗

肌肉减少症是以骨骼肌质量减少及其功能减退为主要特点的一个复杂的综合征,已有研究证实,肌肉减少症除了发生在老年人外,还与营养不良及很多临床疾病相关。目前对肌肉减少症的研究还处于初期探索阶段,其发病原因及诊疗仍不十分清楚,本文将就目前肌肉减少症的研究进展作一综述。     

老年肌少症患者营养管理的最佳证据总结

目的 提取、评价和综合老年肌少症患者营养管理的相关证据,为制订科学、有效的老年肌少症患者营养管理方案提供循证依据。方法 计算机检索乔安娜布里格斯研究所循证卫生保健中心数据库、Cochrane Library、DynaMed循证医学临床决策网站、英国卫生与临床优化研究所指南网、国际实践指南图书馆、加拿大安大略注册护士协会指南网、WHO指南网、苏格兰校际间指南网、美国临床实践指南网、加拿大临床实践指南信息库、UpToDate临床决策、中国医脉通临床指南网、Web of Science、PubMed、中国知网、中华医学会期刊全文数据库、中国生物医学文献数据库中关于老年肌少症患者营养管理措施的所有证据,检索文献类型包括指南、专家共识、临床决策、证据总结、系统评价或Meta分析,检索时间为建库至2022年1月20日。结果 共纳入18篇文献,包括1篇指南、1篇临床决策、6篇专家共识、10篇系统评价。总结了包含营养筛查和评估、营养素摄入、营养监测和健康教育4个类别的32条证据。结论 该研究总结了老年肌少症患者营养管理的最佳证据,证据总结过程科学、严谨和全面。医护人员应结合实际情境和患者个体因素选择最佳证据,指导老年肌少症患者安全有效地改善机体营养状况,提高生活质量。     

Interrelationship between muscle strength,motor units,and aging

The interrelationship between muscle strength, motor unit (MU) number, and age is poorly understood, and in this study we sought to determine whether age-related differences in muscle strength are moderated by estimates of functioning MU number and size. Eighteen older adults (OA; 67 ± 1.20 years) and 24 young adults (YA; 22 ± 0.74 years) participated in this study. Maximum voluntary pinch–grip strength of the nondominant hand was determined and estimates of MU number were obtained from the abductor pollicis brevis muscle using the noninvasive motor unit number index (MUNIX) technique. The MUNIX technique was also utilized to derive a motor unit size index (MUSIX). An analysis of covariance (Age Group × MUNIX or MUSIX) was used to test heterogeneity of regression slopes, with body mass and gender serving as covariates. We observed that the slope of pinch–grip strength on the estimated number of MUs between YA and OA differed, indicated by an Age Group × MUNIX interaction (p = 0.04). Specifically, after controlling for the effect of body mass and gender, the slope in OA was significantly positive (0.14 ± 0.06 N/MUs, p = 0.03), whereas no such relationship was found in YA (− 0.08 ± 0.09 N/MUs, p = 0.35). A significant Age Group × MUSIX interaction was also observed for strength (p < 0.01). In contrast to MUNIX, the slope in younger adults was significantly positive (0.48 ± 0.11 N/μV, p < 0.01), whereas no such relationship was found in older adults (− 0.30 ± 0.22 N/μV, p = 0.18). These findings indicate that there is an interrelationship between muscle strength, MU numbers, and aging, which suggests that a portion of muscle weakness in seniors may be attributable to the loss of functioning motor units.     

The effect of electrical muscle stimulation on the prevention of disuse muscle atrophy in patients with consciousness disturbance in the intensive care unit

Purpose

Disuse atrophy of the lower limbs of patients with consciousness disturbance has often been recognized as “an unavoidable consequence,” such that the mechanism was not investigated diligently. In this study, we examined the preventive effects of electrical muscle stimulation (EMS) against disuse atrophy of the lower limbs in patients in coma after stroke or traumatic brain injury in the intensive care unit.

Materials and Methods

We evaluated changes in cross-sectional area of lower limb muscles weekly with computed tomography in 6 control group patients and 9 EMS group patients. Electrical muscle stimulation was performed daily from day 7 after admission. We evaluated the anterior thigh muscle compartment, posterior thigh muscle compartment, anterior leg muscle compartment, and posterior leg muscle compartment.

Results

In the control group, the decrease in cross-sectional area progressed in all compartments every week (P < .0001). Cross-sectional areas of all compartments at day 14 were significantly decreased in the control group compared with those in the EMS group at day 7 (P < .001). We were able to limit the rate of muscle atrophy as measured in the cross-sectional areas to within 4% during the period of EMS (days 7-42) in 5 patients. The difference between the control and the EMS groups was statistically significant (P < .001).

Conclusion

Electrical muscle stimulation is effective in the prevention of disuse muscle atrophy in patients with consciousness disorder.     

The additive value of sarcopenia,myosteatosis and hepatic encephalopathy in the predictivity of model for end-stage liver disease

BackgroundSince the use of the Model for End-Stage Liver Disease (MELD) score for establishing the prognosis of cirrhotic patients has been introduced, questions have been raised whether complications of liver cirrhosis would provide additional information. Myosteatosis, sarcopenia and hepatic encephalopathy (HE) are frequent in cirrhosis and may affect prognosis.Aim of the study was analyzing if these factors are independently related to survival and may improve the accuracy of MELD.Methods249 cirrhotics that underwent abdominal CT-scan were enrolled. For each patient, information about previous episodes of HE and muscle alterations were obtained. Patients were followed until transplantation or death.ResultsHistory of HE, MELD, sarcopenia and myosteatosis were independently associated with mortality. The MELD-Sarco-Myo-HE score added accuracy to the MELD score alone for 6- and 3-months mortality. By removing HE, as the only not quantifiable parameter of the model, no relevant decrease in accuracy for 6- and 3-months mortality detection was observed.ConclusionsThe accuracy of MELD in predicting 3- and 6-months mortality may be improved by considering the muscle alterations. A model considering the above parameters may classify more accurately over 30% of the patients.     

The Effects of Aging on Hypoglossal Motoneurons in Rats

Aging can result in a loss of neuronal cell bodies and a decrease in neuronal size in some regions of the brain and spinal cord. Motoneuron loss in the spinal cord is thought to contribute to the progressive decline in muscle mass and strength that occurs with age (sarcopenia). Swallowing disorders represent a large clinical problem in elderly persons; however, age-related alterations in cranial motoneurons that innervate muscles involved in swallowing have been understudied. We aimed to determine if age-related alterations occurred in the hypoglossal nucleus in the brainstem. If present, these changes might help explain alterations at the neuromuscular junction and changes in the contractile properties of tongue muscle that have been reported in older rats. We hypothesized that with increasing age there would be a loss of motoneurons and a reduction in neuronal size and the number of primary dendrites associated with each hypoglossal motoneuron. Neurons in the hypoglossal nucleus were visualized with the neuronal marker NeuN in young (9–10 months), middle-aged (24–25 months), and old (32–33 months) male F344/BN rats. Hypoglossal motoneurons were retrograde-labeled with injections of Cholera Toxin β into the genioglossus muscle of the tongue and visualized using immunocytochemistry. Results indicated that the number of primary dendrites of hypoglossal motoneurons decreased significantly with age, while no age-associated changes were found in the number or size of hypoglossal motoneurons. Loss of primary dendrites could reduce the number of synaptic inputs and thereby impair function.

The muscle protein synthetic response to the combined ingestion of protein and carbohydrate is not impaired in healthy older men

Aging is associated with a progressive decline in skeletal muscle mass. It has been hypothesized that an attenuated muscle protein synthetic response to the main anabolic stimuli may contribute to the age-related loss of muscle tissue. The aim of the present study was to compare the muscle protein synthetic response following ingestion of a meal-like amount of dietary protein plus carbohydrate between healthy young and older men. Twelve young (21 ± 1 years) and 12 older (75 ± 1 years) men consumed 20 g of intrinsically l-[1-¹³C]phenylalanine-labeled protein with 40 g of carbohydrate. Ingestion of specifically produced intrinsically l-[1-¹³C]phenylalanine-labeled protein allowed us to assess the subsequent incorporation of casein-derived amino acids into muscle protein. Blood samples were collected at regular intervals, with muscle biopsies obtained prior to and 2 and 6 h after protein plus carbohydrate ingestion. The acute post-prandial rise in plasma glucose and insulin concentrations was significantly greater in the older compared with the younger males. Plasma amino acid concentrations increased rapidly following drink ingestion in both groups. However, plasma leucine concentrations were significantly lower at t = 90 min in the older when compared with the young group (P < 0.05). Muscle protein-bound l-[1-¹³C]phenylalanine enrichments increased to 0.0071 ± 0.0016 and 0.0072 ± 0.0013 mole percent excess (MPE) at 2 h and 0.0229 ± 0.0016 and 0.0213 ± 0.0024 MPE at 6 h following ingestion of the intrinsically labeled protein in the young and older males, respectively, with no differences between groups (P > 0.05). We conclude that the use of dietary protein-derived amino acids for muscle protein synthesis is not impaired in healthy older men following intake of protein plus carbohydrate.