Clinical implication of denervation in sporadic inclusion body myositis

• Published in: Journal of the neurological sciences 2022-08, Vol.439, p.120317-120317, Article 120317
• Main Authors: Noda, Seiya, Murakami, Ayuka, Kazuta, Tomoyuki, Hirano, Satoko, Kimura, Seigo, Nakanishi, Hirotaka, Matsuo, Koji, Tsujikawa, Koyo, Yamada, Shinichiro, Iida, Madoka, Koike, Haruki, Kuru, Satoshi, Katsuno, Masahisa
• Format: Article
• Language: English
• Subjects: Denervation; Muscle biopsy; Prognosis; Sporadic inclusion body myositis
• ISSN: 0022-510X; 1878-5883
• DOI: 10.1016/j.jns.2022.120317

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