Frequency and features of myasthenia gravis developing after thymectomy

Eur J Neurol. 2020 Jan;27(1):175-180. doi: 10.1111/ene.14052. Epub 2019 Aug 12.

Abstract

Background and purpose: Thymectomy is an effective treatment for myasthenia gravis (MG) with anti-acetylcholine receptor (AChR) antibodies. We rarely encounter patients who develop MG after surgery for thymic tumors. This study aimed to investigate the characteristics and frequency of post-thymectomy onset (PostTx) MG.

Methods: We reviewed the clinical information of thymoma-associated MG in 158 patients. Of these, 18 (11%) patients with PostTx MG were identified.

Results: The presence of anti-AChR antibodies (82%) and electrophysiological abnormalities (50%) was confirmed before thymectomy in patients with PostTx MG. The clinical characteristics of PostTx MG were similar to those of pre-thymectomy onset (PreTx) MG. In PostTx MG, the duration between thymectomy and MG onset were distributed as < 6 months (early-onset PostTx MG) and ≥ 6 months (late-onset PostTx MG). Notably, some patients with late-onset PostTx MG were associated with thymoma relapse.

Conclusion: Our results suggest that approximately 11% of patients with thymoma-associated MG were PostTx MG and pre-surgical assessment of anti-AChR antibody titer or electrophysiological testing may predict PostTx MG development. However, no difference in clinical manifestation and prognosis was observed between PreTx MG and PostTx MG.

Keywords: anti-acetylcholine receptor antibody; myasthenia gravis; thymectomy.

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Autoantibodies / analysis
  • Child
  • Electrophysiological Phenomena
  • Female
  • Humans
  • Male
  • Middle Aged
  • Myasthenia Gravis / epidemiology*
  • Myasthenia Gravis / immunology
  • Myasthenia Gravis / surgery*
  • Postoperative Complications / epidemiology*
  • Prognosis
  • Receptors, Cholinergic / immunology
  • Retrospective Studies
  • Thymectomy*
  • Thymoma / complications
  • Thymoma / surgery
  • Thymus Neoplasms / complications
  • Thymus Neoplasms / surgery
  • Treatment Outcome
  • Young Adult

Substances

  • Autoantibodies
  • Receptors, Cholinergic