Myasthenia gravis

Last reviewed: 3 Sep 2022
Last updated: 30 Aug 2022

Summary

Definition

History and exam

Key diagnostic factors

  • muscle strength fatigability
  • ptosis
  • diplopia
  • dysphagia
  • dysarthria
  • facial paresis
  • proximal limb weakness
  • shortness of breath
More key diagnostic factors

Risk factors

  • family history of autoimmune disorders
  • genetic markers
  • cancer-targeted therapy
More risk factors

Diagnostic investigations

1st investigations to order

  • serum acetylcholine receptor (AChR) antibody analysis
  • muscle-specific tyrosine kinase (MuSK) antibodies
  • serial pulmonary function tests
More 1st investigations to order

Investigations to consider

  • striational receptor antibody assays
  • repetitive nerve stimulation
  • single-fibre EMG
  • CT of chest
More investigations to consider

Treatment algorithm

ACUTE

myasthenic crisis

ONGOING

mild to moderate disease (class I to III)

severe (class IV or V) or refractory disease

Contributors

Authors

Robert P. Lisak, MD, FRCP (E), FAAN, FANA

Parker Webber Chair in Neurology

Professor of Neurology

Professor of Immunology and Microbiology

Wayne State University School of Medicine

Detroit

MI

Disclosures

RPL currently serves on an Advisory Board for Argenx for myasthenia gravis (MG), and was an Advisory Board member for Argenx (developing a clinical trial for chronic inflammatory demyelinating polyneuropathy [CIDP]). RPL has been reimbursed by Argenx the manufacturer of efartigimod for serving on a clinical advisory board. RPL has worked with Alexion (testing a treatment for MG); Novartis (design of research related to primary progressive multiple sclerosis [MS] vs. secondary progressive MS); Horizon Pharmaceuticals (advising on MG and neuromyelitis optica spectrum disorder); Takeda (advising on autoimmune diseases); GLG Consulting, Putnam Consulting, Slingshot Consulting, Haven Consulting, Clearview Consulting, Alpha Sites Consulting, and Insights Consulting (providing insights on the current and future treatments of several neuroimmunologic diseases including MS, MG, Guillain-Barré syndrome, chronic inflammatory demyelinating polyradiculoneuropathy, and neuromyelitis optica spectrum disorder). RPL has presented several CME talks for companies with multiple sources of support (no direct payments to RPL). RPL has received clinical trial grants (no direct payments) for studies in MG (Alexion, Argenx, Ra Pharmaceuticals) and MS (Novartis, Teva, Genentech/Roche, Chugai). He has received royalties from Blackwell Press as an editor of the textbook International Neurology, and from Oxford University Press as an editor of a book, Neuroimmunology. RPL is an author of several papers cited in this topic.

Acknowledgements

Dr Robert Lisak would like to gratefully acknowledge Dr Andrea Corse and Dr Ami Mankodi, previous contributors to this topic.

Disclosures

AC and AM declare that they have no competing interests.

Peer reviewers

Vern C. Juel, MD

Associate Professor of Medicine (Neurology)

Duke University

Durham

NC

Disclosures

VCJ declares that he has no competing interests.

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