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

Muscle Nerve. 2019 Apr;59(4):404-410. doi: 10.1002/mus.26404. Epub 2019 Jan 14.


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.

Keywords: immunosuppressant therapy; muscle-specific kinase (MuSK) antibodies; myasthenia gravis; rituximab; thymectomy.

Publication types

  • Multicenter Study
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Age of Onset
  • Aged
  • Child
  • Cohort Studies
  • Female
  • Humans
  • Immunoglobulins, Intravenous / therapeutic use
  • Male
  • Middle Aged
  • Myasthenia Gravis / genetics*
  • Myasthenia Gravis / therapy*
  • Prednisone / therapeutic use
  • Receptor Protein-Tyrosine Kinases / genetics*
  • Receptors, Cholinergic / genetics*
  • Retrospective Studies
  • Rituximab / therapeutic use
  • Thymectomy*
  • Treatment Outcome
  • Young Adult


  • Immunoglobulins, Intravenous
  • Receptors, Cholinergic
  • Rituximab
  • MUSK protein, human
  • Receptor Protein-Tyrosine Kinases
  • Prednisone