Thymectomy may not be associated with clinical improvement in MuSK myasthenia gravis

Katherine M. Clifford, Lisa D. Hobson-Webb, Michael Benatar, Ted M. Burns, Carolina Barnett, Nicholas J. Silvestri, James F. Howard, Amy Visser, Brian A. Crum, Richard Nowak, Rachel Beekman, Aditya Kumar, Katherine Ruzhansky, I. Hweii Amy Chen, Michael T. Pulley, Shannon M. Laboy, Melissa A. Fellman, Diantha B. Howard, Noah A. Kolb, Shane M. GreeneMamatha Pasnoor, Mazen M. Dimachkie, Richard J. Barohn, Michael K. Hehir

Research output: Contribution to journalReview article

19 Scopus citations

Abstract

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.

Original languageEnglish (US)
Pages (from-to)404-410
Number of pages7
JournalMuscle and Nerve
Volume59
Issue number4
DOIs
StatePublished - Apr 2019

Keywords

  • immunosuppressant therapy
  • muscle-specific kinase (MuSK) antibodies
  • myasthenia gravis
  • rituximab
  • thymectomy

ASJC Scopus subject areas

  • Physiology
  • Clinical Neurology
  • Cellular and Molecular Neuroscience
  • Physiology (medical)

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    Clifford, K. M., Hobson-Webb, L. D., Benatar, M., Burns, T. M., Barnett, C., Silvestri, N. J., Howard, J. F., Visser, A., Crum, B. A., Nowak, R., Beekman, R., Kumar, A., Ruzhansky, K., Chen, I. H. A., Pulley, M. T., Laboy, S. M., Fellman, M. A., Howard, D. B., Kolb, N. A., ... Hehir, M. K. (2019). Thymectomy may not be associated with clinical improvement in MuSK myasthenia gravis. Muscle and Nerve, 59(4), 404-410. https://doi.org/10.1002/mus.26404