Abstract：
Distal motor neuropathies (dHMN) are an heterogenous group of diseases characterized by progressive muscle weakness affecting predominantly the distal muscles of the lower and upper limbs. Our aim was to study the imaging features and pattern of muscle involvement in muscle magnetic resonance imaging (MRI) in dHMN patients of suspected genetic origin (dHMN). We conducted a retrospective study collecting clinical, genetic and muscle imaging data. Muscle MRI included T1-weighted and T2 weighted Short Tau Inversion Recovery images (STIR-T2w) sequences. Muscle replacement by fat was quantified using the Mercuri score. Identification of selective patterns of involvement was performed using hierarchical clustering. Eighty-four patients with diagnosis of dHMN were studied. Fat replacement was predominant in the distal lower leg muscles (82/84 cases), although also affected thigh and pelvis muscles. Asymmetric involvement was present in 29% of patients. The superficial posterior compartment of the leg, including the soleus and gastrocnemius muscles, was the most affected area (77/84). We observed a reticular pattern of fatty replacement progressing towards what is commonly known as \"muscle islands\" in 79.8%. Hyperintensities in STIR-T2w were observed in 78.6% patients mainly in distal leg muscles. Besides features common to all individuals, we identified and describe a pattern of muscle fat replacement characteristic of BICD2, HSPB1 and DYNC1H1 patients. We conclude that muscle MRI of patients with suspected dHMN reveals common features helpful in diagnosis process.
摘要：
远端运动神经病（dHMN）是一组异质性疾病，其特征是进行性肌肉无力，主要影响下肢和上肢的远端肌肉。我们的目的是研究可疑遗传起源（dHMN）的dHMN患者的肌肉磁共振成像（MRI）中肌肉受累的影像学特征和模式。我们进行了一项回顾性研究，收集临床，遗传和肌肉成像数据。肌肉MRI包括T1加权和T2加权短Tau反转恢复图像（STIR-T2w）序列。使用Mercuri评分定量脂肪对肌肉的替代。使用层次聚类进行选择性参与模式的识别。研究了84例诊断为dHMN的患者。下肢远端肌肉以脂肪置换为主（82/84例），虽然也影响大腿和骨盆肌肉。29%的患者存在不对称受累。腿的浅层后部，包括比目鱼肌和腓肠肌,是受影响最严重的地区（77/84）。我们观察到脂肪替代的网状模式正在向通常所说的“肌肉岛”发展，占79.8％。在78.6％的患者中，主要在腿部远端肌肉中观察到STIR-T2w的高强度。除了所有个人的共同特征，我们确定并描述了BICD2,HSPB1和DYNC1H1患者的肌肉脂肪替代模式.我们得出的结论是，疑似dHMN患者的肌肉MRI揭示了有助于诊断过程的共同特征。
