Department of Family and Community Medicine, University of Toronto, Toronto, ON, Canada.
Brain and Spinal Cord Rehabilitation Program, Toronto Rehabilitation Institute, University Health Network, Toronto, ON, Canada; Department of Medicine, University of Toronto, Toronto, ON, Canada; Department of Kinesiology, University of Waterloo, Waterloo, ON, Canada.
J Clin Densitom. 2018 Jul-Sep;21(3):329-337. doi: 10.1016/j.jocd.2017.06.001. Epub 2017 Jul 11.
Atrophy and fatty infiltration of lower extremity muscle after spinal cord injury (SCI) predisposes individuals to metabolic syndrome and related diabetes and cardiovascular disease. The objective of this study was to prospectively measure changes in muscle atrophy and fat content of distal lower extremity muscles and explore related factors in a cohort of adults with chronic SCI and diverse impairments. Muscle cross-sectional area and density were calculated from peripheral quantitative computed tomography scans of the 66% site of the calf from 70 participants with chronic SCI (50 male, mean age 49 years, C2-T12, American Spinal Injury Association Impairment Scale A-D) at study enrollment and annually for 2 years. Mixed-model repeated measures analysis of variance (rANOVA) examined longitudinal changes in muscle area and density, and regression analyses explored factors related to muscle changes using 16 potential correlates selected a priori. A high degree of individual variation in muscle area and density change was observed over 2 years (range: 8.5 to -22.6 cm; 6.4 to -8.6 mg/cm). Repeated measures analysis of variance revealed significant reductions in muscle area (estimated mean difference [95% confidence intervals] -1.76 [-3.29 to -0.23]) cm, p = 0.025) and density (-1.04 [-1.94 to -0.14] mg/cm, p < 0.024); however, changes in area were not significant with outliers removed. Regression analyses explained a small proportion of the variability in muscle density change; however, none of the preselected variables were significantly related to changes in muscle density after post hoc sensitivity analyses. Lower extremity muscle size and fat content may not reach a "steady-state" after chronic SCI. Progressive atrophy and fatty infiltration of lower extremity muscle may have adverse implications for metabolic syndrome and cardiovascular disease risk and related mortality after chronic SCI.
脊髓损伤（SCI）后下肢肌肉萎缩和脂肪浸润使个体易患代谢综合征及相关糖尿病和心血管疾病。本研究的目的是前瞻性测量慢性 SCI 患者和不同损伤患者下肢远端肌肉萎缩和脂肪含量的变化，并探讨相关因素。70 名慢性 SCI 患者（50 名男性，平均年龄 49 岁，C2-T12，美国脊髓损伤协会损伤分级 A-D）在研究入组时和随后 2 年内每年接受一次外周定量 CT 扫描，测量小腿 66%处的肌肉横截面积和密度。混合模型重复测量方差分析（rANOVA）用于分析肌肉面积和密度的纵向变化，回归分析使用 16 个预先选择的潜在相关因素，探讨与肌肉变化相关的因素。在 2 年内观察到肌肉面积和密度变化的个体差异很大（范围：8.5 至-22.6cm；6.4 至-8.6mg/cm）。重复测量方差分析显示肌肉面积显著减少（估计平均差异[95%置信区间]-1.76[-3.29 至-0.23]cm，p=0.025）和密度（-1.04[-1.94 至-0.14]mg/cm，p<0.024）；然而，去除离群值后，面积变化不显著。回归分析仅能解释肌肉密度变化的一小部分可变性；然而，在事后敏感性分析后，没有一个预先选择的变量与肌肉密度的变化有显著关系。慢性 SCI 后，下肢肌肉大小和脂肪含量可能无法达到“稳定状态”。下肢肌肉的进行性萎缩和脂肪浸润可能对慢性 SCI 后代谢综合征和心血管疾病风险及相关死亡率产生不利影响。
