Summary
Definition
History and exam
Key diagnostic factors
- muscle fatigability
- ptosis
- diplopia
- dysphagia
- dysarthria
- facial paresis
- proximal limb weakness
- shortness of breath
Risk factors
- family history of autoimmune disorders
- genetic markers
- cancer-targeted therapy
Diagnostic investigations
1st investigations to order
- serum acetylcholine receptor (AChR) antibody analysis
- muscle-specific tyrosine kinase (MuSK) antibodies
- serial pulmonary function tests
Investigations to consider
- striational receptor antibody assays
- repetitive nerve stimulation
- single-fibre EMG
- CT of chest
Treatment algorithm
severe disease (class IV and V, myasthenic crisis)
mild disease (class I and II)
moderate disease (class III)
severe disease (post-myasthenic crisis): no intolerance or contraindication to immunosuppressants
severe disease (post-myasthenic crisis): intolerance or contraindication to immunosuppressants
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 is an Advisory Board member for Argenx (developing a clinical trial for chronic inflammatory demyelinating polyneuropathy [CIDP]). RPL has worked with Alexion (testing a treatment for myasthenia gravis); Novartis (design of research related to primary progressive MS vs. secondary progressive MS); 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, CIDP, and neuromyelitis optica spectrum disorder); and Teva Pharmaceuticals (two non-branded talks to patient groups about MS). RPL has presented several CME talks for companies with multiple sources of support (no direct payments to RBL). RPL has received clinical trial grants (no direct payments) for studies in myasthenia gravis (Alexion, Argenx, Ra Pharmaceuticals) and MS (Novartis, Teva, Genentech/Roche, Chugai). He has received royalties from Blackwell Press as an editors of a textbook International Neurology. RBL 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. 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.
Differentials
- Lambert-Eaton myasthenic syndrome (LEMS)
- Botulism
- Penicillamine-induced myasthenia gravis
More DifferentialsGuidelines
- Practice advisory: thymectomy for myasthenia gravis (practice parameter update)
- Myasthenia gravis: Association of British Neurologists' management guidelines
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