Department of Neurology, Nagoya University Graduate School of Medicine, Japan; Department of Neurology, National Hospital Organization Suzuka Hospital, Japan.
Department of Neurology, Yokkaichi Municipal Hospital, Japan.
J Neurol Sci. 2022 Aug 15;439:120317. doi: 10.1016/j.jns.2022.120317. Epub 2022 Jun 8.
Sporadic inclusion body myositis (sIBM) is often accompanied by signs suggestive of denervation on electromyography (EMG), which mimics neurogenic disorders. Hence, the current study aimed to assess reinnervation after denervation in sIBM and its clinical impllcation.
We retrospectively examined consecutive muscle biopsy specimens collected from 109 sIBM patients who were referred to our institution for diagnostic muscle biopsy from 2001 to 2018. Reinnervation after denervation in sIBM patients was assessed via muscle biopsy and EMG. The levels of acetylcholine receptor subunit γ (Chrng) and muscle-specific kinase (MuSK) mRNA, which are markers of denervation, were examined using real-time polymerase chain reaction. Response to treatment was defined as an increase of grade 1 or higher in two or more muscle groups as assessed using the Medical Research Council scale.
In total, 93 (85.3%) of 109 sIBM patients had reinnervation after denervation on histological examination and/or EMG. The mean disease duration before biopsy was significantly longer in patients with reinnervation after denervation than in those without (p < 0.00001). Patients with denervation had significantly higher levels of Chrng and MuSK mRNA than those without. The proportion of patients who responded to immunosuppressive therapies was smaller in the patients with denervation than those without (p < 0.05). However, there was no significant difference regarding time from onset to using a walking aid between the two groups.
Reinnervation after denervation is associated with disease duration and short-term response to therapy in individuals with sIBM.
散发性包涵体肌炎（sIBM）常伴有肌电图（EMG）提示失神经支配的征象，类似于神经源性疾病。因此，本研究旨在评估 sIBM 中的失神经再支配及其临床意义。
我们回顾性检查了 2001 年至 2018 年间我院因诊断性肌肉活检而就诊的 109 例 sIBM 患者的连续肌肉活检标本。通过肌肉活检和 EMG 评估 sIBM 患者失神经后的再支配情况。使用实时聚合酶链反应检测乙酰胆碱受体亚基γ（Chrng）和肌肉特异性激酶（MuSK）mRNA 的水平，这些标志物用于评估失神经支配。治疗反应定义为使用医学研究委员会量表评估的两个或更多肌肉群的等级增加 1 级或更高。
在总共 109 例 sIBM 患者中，有 93 例（85.3%）在组织学检查和/或 EMG 上有失神经后的再支配。有再支配的患者活检前的平均疾病持续时间明显长于无再支配的患者（p<0.00001）。有失神经支配的患者 Chrng 和 MuSK mRNA 水平显著高于无失神经支配的患者。有失神经支配的患者对免疫抑制治疗的反应比例明显低于无失神经支配的患者（p<0.05）。然而，两组患者从发病到使用助行器的时间没有显著差异。
在 sIBM 患者中，失神经后再支配与疾病持续时间和短期治疗反应相关。
