Background: LMNA-related muscular dystrophy can manifest in a wide variety of disorders, including Emery-Dreifuss muscular dystrophy (EDMD), limb-girdle muscular dystrophy (LGMD), and LMNA-associated congenital muscular dystrophy (L-CMD). Muscle magnetic resonance imaging (MRI) has become a useful tool in the diagnostic workup of patients with muscle dystrophies. This study aimed to investigate whether there is a consistent pattern of MRI changes in patients with LMNA mutations in various muscle subtypes.
Methods: Twenty-two patients with LMNA-related muscular dystrophies were enrolled in this study. MRI of the thigh and/or calf muscles was performed in them. The muscle MRI features of the three subtypes were compared by the Mann-Whitney U-test. The relationship between the clinical and MRI findings was also investigated by Spearman's rank analyses.
Results: The present study included five EDMD, nine LGMD, and eight L-CMD patients. The thigh muscle MRI revealed that the fatty infiltration of the adductor magnus, semimembranosus, long and short heads of the biceps femoris, and vasti muscles, with relative sparing of the rectus femoris, was the predominant change observed in the EDMD, LGMD, and advanced-stage L-CMD phenotypes, although the involvement of the vasti muscles was not prominent in the early stage of L-CMD. At the level of the calf, six patients (one EDMD, four LGMD, and one L-CMD) also showed a similar pattern, in which the soleus and the medial and lateral gastrocnemius muscles were most frequently observed to have fatty infiltration. The fatty infiltration severity demonstrated higher scores associated with disease progression, with a corresponding rate of 1.483 + 0.075 × disease duration (X) (r = 0.444, P = 0.026). It was noteworthy that in six L-CMD patients with massive inflammatory cell infiltration in muscle pathology, no remarkable edema-like signals were observed in muscle MRI.
Conclusions: EDMD, LGMD and advanced-staged L-CMD subtypes showed similar pattern of muscle MRI changes, while early-staged L-CMD showed somewhat different changes. Muscle MRI of L-CMD with a muscular dystrophy pattern in MRI provided important clues for differentiating it from childhood inflammatory myopathy. The fatty infiltration score could be used as a reliable biomarker for outcome measure of disease progression.
LMNA相关肌营养不良不同临床表型的骨骼肌MRI分析摘要背景：LMNA相关肌营养不良是LMNA基因突变导致的遗传性骨骼肌疾病，具有显著的临床异质性，常见的临床表型包Emery-Dreifus肌营养不良（EDMD）、肢带型肌营养不良（LGMD1B）、婴儿期起病的先天性肌营养不良（L-CMD）。既往研究表明骨骼肌MRI在骨骼肌疾病诊断中具有重要作用。本文报道一组LMNA相关肌营养不良的临床表现、肌肉病理及骨骼肌MRI改变特点。 方法：通过临床表现、病理改变、基因筛查，对符合LMNA相关肌营养不良诊断标准的病例进行临床诊断并纳入研究，共收集22例。对上述22位患者行大腿和/或小腿骨骼肌MRI检查。回顾性分析不同临床表型之间的临床表现、肌肉病理改变及骨骼肌MRI改变特点，探讨临床表型及骨骼肌MRI表现之间的相关性。 结果：根据不同的临床表现，22例患者分别为5例EDMD、9例LGMD、8例L-CMD。大腿骨骼肌MRI检查显示EDMD、LGMD和晚期L-CMD患者大收肌、半膜肌、股二头肌长头及短头、股四头肌肌群出现明显脂肪化，其中股直肌相对保留。早期L-CMD患者股四头肌肌群脂肪化不明显。6例患者（1例EDMD、4例LGMD、1例L-CMD）行小腿骨骼肌MRI检查，所有患者均出现明显的比目鱼肌及腓肠肌脂肪化改变。所有患者股四头肌群脂肪化评分与病程的相关性有统计学意义，股四头肌群脂肪化评分(Y) =1.483+0.075±;病程 (X) (r = 0.444, P = 0.026).。6例L-CMD患者骨骼肌病理可见大量的炎症细胞浸润，骨骼肌MRI检查未见明显水肿改变。 结论：EDMD、LGMD和晚期L-CMD患者在大腿骨骼肌MRI上有相似的脂肪化浸润模式，而早期L-CMD患者在股四头肌群的受累程度则有不同。LMNA相关肌营养不良与婴儿期炎性肌肉病在病理改变上有一定相似，骨骼肌MRI检查有助于鉴别两者。此外，股四头肌群脂肪化增加与疾病的进程有一定的相关性。.
Keywords: Congenital Muscular Dystrophy; Emery-Dreifuss Muscular Dystrophy; LMNA; Limb-Girdle Muscular Dystrophy; Muscle Magnetic Resonance Imaging.