Objective To observe any differences in the morphology of the lumbar multifidus (LM) muscles between normal subjects and persons with chronic lumbar disc herniation (CLDH).Methods Thirty-two persons with CLDH and thirty-five matched,healthy controls performed various maneuvers in prone lying.Ultrasound imaging was used to measure the antero-posterior diameter (A-P),lateral diameter (Lat),cross sectional area (CSA) and flattening ratio (FR) of the bilateral LM muscles at the L4/5 level.Results In the control subjects,A-P,Lat,CSA and FR were not significantly different between the left and right sides.In those with CLDH,A-P,Lat and CSA were significantly smaller on the painful side than on the no-pain side,and this difference showed asymmetry between the two sides.Average A-P,Lat,FR and muscle CSA were all significantly smaller among the CLDH subjects on both sides compared with the controls.Conclusion CLDH induces asymmetric local atrophy of the bilateral multifidus muscles which can be detected and measured using ultrasound.

BACKGROUND:Extracellular vesicles can regulate insulin resistance and control inflammatory response by participating in intercellular communication,while repairing skeletal muscles and promoting skeletal muscle regeneration,which is expected to be a novel treatment modality for sarcopenic obesity. OBJECTIVE:To review the biogenesis of extracellular vesicles,their biological functions,their relationship with sarcopenic obesity,and recent advances in the pathogenesis,diagnosis,and treatment of sarcopenic obesity. METHODS:The first author performed a computer search of PubMed,Embase,CNKI and other databases for relevant studies involving extracellular vesicle in sarcopenic obesity.The search keywords were"extracellular vesicle,exosome,sarcopenic obesity,obese sarcopenia,skeletal muscle regeneration,skeletal muscle mass regulation"in English and Chinese,respectively.The search period was from June 2022 to November 2022.After screening,87 articles were included for further review. RESULTS AND CONCLUSION:Extracellular vesicles are important vectors of bidirectional cell communication and participate in the regulation of normal physiological and pathological processes through autocrine,paracrine and endocrine ways.Sarcopenic obesity is a complex multi-factor disease.Extracellular vesicles are involved in the occurrence and development of sarcopenic obesity mainly by regulating the inflammatory response of skeletal muscle and the homeostasis of muscle cells.Cytokines secreted by adipose tissue and skeletal muscle are released into the extracellular circulation through extracellular vesicle encapsulation and interact with each other to promote skeletal muscle insulin resistance and lipogenesis,which is the main pathophysiology of skeletal muscle atrophy in sarcopenic obesity.Extracellular vesicles not only promote the development of sarcopenic obesity by providing specific pathogenic markers,but also are a valuable diagnostic indicator of sarcopenic obesity.Release of extracellular vesicles from skeletal muscle during exercise enhances metabolic response and promotes skeletal muscle regeneration.Extracellular vesicles can not only be used as therapeutic targets for sarcopenic obesity but also be used to treat sarcopenic obesity by loading drugs to effectively improve drug bioavailability.