Section 3342, Department of Neurology, Copenhagen Neuromuscular Center, Rigshospitalet, Copenhagen University, Blegdamsvej 9, 2100, Copenhagen, Denmark.
Department of Radiology, Rigshospitalet, Copenhagen University, Blegdamsvej 9, 2100, Copenhagen, Denmark.
J Neurol. 2019 May;266(5):1127-1135. doi: 10.1007/s00415-019-09242-y. Epub 2019 Feb 18.
Unlike most muscular dystrophies that progress symmetrically at a constant rate, facioscapulohumeral muscular dystrophy (FSHD) is characterized by stepwise, asymmetric progression of muscle wasting, and weakness. Muscle tissue is progressively replaced by fat; however, its relation to preceding inflammation is unclear. In this longitudinal study of FSHD, we assessed muscle inflammation and fat replacement and their relation quantitatively. We also investigated whether fat replacement in muscle varies along its length.
Forty-five patients with FSHD were evaluated twice, 14 months apart. Using MRI sequences with short TI inversion recovery (STIR), we quantified the degree of STIR hyperintensity in muscles (≥ 2 SD above control intensity). STIR hyperintensities (STIR+) suggest edema or inflammation. We used Dixon MRI to quantify fat content.
Of 370 thigh muscles, 83 were STIR+ at baseline and 103 at follow-up. The highest frequency of STIR+ was seen in muscles with inter-mediate fat content (40-60% fat). The progression of fat replacement was higher in STIR+ muscles (5.0 ± 4.0%) vs. STIR- muscles [2.3 ± 3.3% (P < 0.0001)]. In addition, muscles with severe STIR+ at baseline had a higher fat replacement progression than muscles with milder STIR+ (R = 0.39, P = 0.001). The fat content was higher in the distal part vs. proximal part of most muscles (P < 0.05). However, the progression of the fat replacement was uniform along the length of all the muscles.
Muscles with STIR+, indicating inflammation, have a faster progression of fat replacement than STIR- muscles, and the fat replacement progression correlated with the severity of STIR+.
与大多数以恒定速度对称进展的肌肉萎缩症不同，面肩肱型肌营养不良症（FSHD）的特征是肌肉萎缩和无力呈阶段性、不对称进展。肌肉组织逐渐被脂肪取代；然而，其与先前炎症的关系尚不清楚。在这项 FSHD 的纵向研究中，我们定量评估了肌肉炎症和脂肪替代及其关系。我们还研究了肌肉长度上脂肪替代是否存在差异。
45 例 FSHD 患者在 14 个月时进行了两次评估。我们使用短 TI 反转恢复（STIR）磁共振成像（MRI）序列来定量评估肌肉中 STIR 高信号的程度（高于对照强度的 2 个标准差）。STIR 高信号（STIR+）提示水肿或炎症。我们使用 Dixon MRI 来定量脂肪含量。
在 370 个大腿肌肉中，83 个在基线时和 103 个在随访时为 STIR+。STIR+的最高频率见于脂肪含量中等（40-60%脂肪）的肌肉。STIR+肌肉的脂肪替代进展更高（5.0±4.0%），而 STIR-肌肉为[2.3±3.3%（P<0.0001）]。此外，基线时严重 STIR+的肌肉比轻度 STIR+的肌肉具有更高的脂肪替代进展（R=0.39，P=0.001）。大多数肌肉的远端部分的脂肪含量高于近端部分（P<0.05）。然而，所有肌肉的脂肪替代进展在长度上是均匀的。
STIR+（提示炎症）的肌肉脂肪替代进展比 STIR-肌肉更快，脂肪替代进展与 STIR+的严重程度相关。
