Thymectomy may not be associated with clinical improvement in MuSK myasthenia gravis.
INTRODUCTION: A randomized trial demonstrated benefit from thymectomy in nonthymomatous acetylcholine receptor (AChR)-antibody positive myasthenia gravis (MG). Uncontrolled observational and histologic studies suggest thymectomy may not be efficacious in anti-muscle-specific kinase (MuSK)-MG. METHODS: The therapeutic impact of thymectomy was evaluated from data collected for a multicenter, retrospective blinded review of rituximab in MuSK-MG. RESULTS: Baseline characteristics were similar between thymectomy (n = 26) and nonthymectomy (n = 29) groups, including treatment with rituximab (42% vs. 45%). At last visit, 35% of thymectomy subjects reached the primary endpoint, a Myasthenia Gravis Foundation of America (MGFA) post-intervention status (PIS) score of minimal manifestations (MM) or better, compared with 55% of controls (P = 0.17). After controlling for age at onset of MG, rituximab, prednisone, and intravenous immunoglobulin/plasma exchange treatment, thymectomy was not associated with greater likelihood of favorable clinical outcome (odds ratio = 0.43, 95% confidence interval 0.12-1.53, P = 0.19). DISCUSSION: Thymectomy was not associated with additional clinical improvement in this multicenter cohort of MuSK-MG patients. Muscle Nerve 59:404-410, 2019.
Clifford, KM; Hobson-Webb, LD; Benatar, M; Burns, TM; Barnett, C; Silvestri, NJ; Howard, JF; Visser, A; Crum, BA; Nowak, R; Beekman, R; Kumar, A; Ruzhansky, K; Chen, I-HA; Pulley, MT; Laboy, SM; Fellman, MA; Howard, DB; Kolb, NA; Greene, SM; Pasnoor, M; Dimachkie, MM; Barohn, RJ; Hehir, MK
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