Department of Physical Therapy, University of Florida, Gainesville, FL, USA.
Department of Physiology and Functional Genomics, University of Florida, Gainesville, FL, USA.
J Neurol. 2019 Nov;266(11):2752-2763. doi: 10.1007/s00415-019-09481-z. Epub 2019 Jul 26.
Duchenne muscular dystrophy (DMD) is characterized by damage to muscles including the muscles involved in respiration. Dystrophic muscles become weak and infiltrated with fatty tissue, resulting in progressive respiratory impairment. The objective of this study was to assess respiratory muscle quality and function in DMD using magnetic resonance imaging and to determine the relationship to clinical respiratory function.
Individuals with DMD (n = 36) and unaffected controls (n = 12) participated in this cross sectional magnetic resonance imaging study. Participants underwent dynamic imaging of the thorax to assess diaphragm and chest wall mobility and chemical shift-encoded imaging of the chest and abdomen to determine fatty infiltration of the accessory respiratory muscles. Additionally, clinical pulmonary function measures were obtained.
Thoracic cavity area was decreased in individuals with DMD compared to controls during tidal and maximal breathing. Individuals with DMD had reduced chest wall movement in the anterior-posterior direction during maximal inspirations and expirations, but diaphragm descent during maximal inspirations (normalized to height) was only decreased in a subset of individuals with maximal inspiratory pressures less than 60% predicted. Muscle fat fraction was elevated in all three expiratory muscles assessed (p < 0.001), and the degree of fatty infiltration correlated with percent predicted maximal expiratory pressures (r = - 0.70, p < 0.001). The intercostal muscles demonstrated minimal visible fatty infiltration; however, this analysis was qualitative and resolution limited.
This magnetic resonance imaging investigation of diaphragm movement, chest wall movement, and accessory respiratory muscle fatty infiltration provides new insights into the relationship between disease progression and clinical respiratory function.
杜氏肌营养不良症（DMD）的特征是肌肉损伤，包括呼吸肌。进行性肌肉无力和脂肪浸润导致进行性呼吸功能障碍。本研究的目的是使用磁共振成像评估 DMD 患者的呼吸肌质量和功能，并确定与临床呼吸功能的关系。
36 名 DMD 患者和 12 名无影响的对照组参与者参与了这项横断面磁共振成像研究。参与者进行了胸部动态成像，以评估膈肌和胸壁的运动，并对胸部和腹部进行化学位移编码成像，以确定辅助呼吸肌的脂肪浸润。此外，还获得了临床肺功能测量值。
与对照组相比，DMD 患者在潮气量和最大呼吸时的胸腔面积减小。DMD 患者在最大吸气和呼气时的前后方向上的胸壁运动减少，但在最大吸气时（相对于身高归一化）只有在最大吸气压力低于 60%预测值的一部分患者中，膈肌下降才会减少。所有评估的三个呼气肌的肌肉脂肪分数均升高（p<0.001），脂肪浸润程度与预测最大呼气压力的百分比呈负相关（r=−0.70，p<0.001）。肋间肌显示出最小的可见脂肪浸润，但这种分析是定性的，分辨率有限。
这项关于膈肌运动、胸壁运动和辅助呼吸肌脂肪浸润的磁共振成像研究提供了关于疾病进展与临床呼吸功能关系的新见解。
