Lambert-Eaton myasthenic syndrome

Last reviewed: 20 Apr 2022
Last updated: 26 Apr 2019

Summary

Definition

History and exam

Key diagnostic factors

  • history of small cell lung cancer or other malignancy
  • history of autoimmune disorder
  • history of cigarette smoking
  • family¬†history of autoimmune disease
  • limb weakness
  • dry mouth
  • weakness
More key diagnostic factors

Other diagnostic factors

  • dysarthria
  • areflexia
  • ptosis
  • diplopia
  • impotence
  • dysphagia
  • orthostatic hypotension
  • pupillary dilation
  • dyspnea
  • cerebellar ataxia
Other diagnostic factors

Risk factors

  • underlying small cell lung cancer or other malignancy
  • coexisting autoimmune disorder
  • cigarette smoking
  • family history of autoimmune disease
More risk factors

Diagnostic investigations

1st investigations to order

  • nerve conduction studies
  • low-frequency repetitive nerve stimulation
  • anti-P/Q voltage-gated calcium-channel serology
  • chest CT scan
  • anti-acetylcholine receptor (AChR) serology
More 1st investigations to order

Investigations to consider

  • serial PFTs
  • total-body fluoro-2-deoxyglucose positron emission tomography (FDG-PET) scan
  • bronchoscopy
  • high-frequency or tetanic repetitive nerve stimulation (RNS)
  • single-fiber electromyography
  • HLA haplotyping
  • thyroid-stimulating hormone (TSH)
  • antinuclear antibodies (ANA)
  • rheumatoid factor (RF)
  • antineutrophil cytoplasmic autoantibodies (ANCA)
  • B12 and methylmalonic acid (MMA)
More investigations to consider

Emerging tests

  • alpha-1A P/Q voltage-gated calcium-channel subunit antibodies
  • anti-SOX1 antibodies

Treatment algorithm

ACUTE

severe respiratory or bulbar weakness

ONGOING

without severe respiratory or bulbar weakness

Contributors

Authors

Joshua P. Alpers, MD

Staff Neurologist

University of Tennessee Erlanger Neurology

Chattanooga

TN

Disclosures

JPA declares that he has no competing interests.

Vern C. Juel, MD

Associate Professor of Neurology

Department of Neurology

Duke University Medical Center

Durham

NC

Disclosures

VCJ declares that he has no competing interests.

Peer reviewers

David Stickler, MD

Assistant Professor

Medical University of South Carolina

Charleston

SC

Disclosures

DS declares that he has no competing interests.

Zaeem Siddiqui, MD, PhD

Associate Professor

Division of Neurology

University of Alberta

Edmonton

Canada

Disclosures

ZS declares that he has no competing interests.

Paul Wirtz, MD, PhD

Department of Neurology

Haga Hospital

The Hague

The Netherlands

Disclosures

PW is an author of a number of references cited in this monograph.

  • Lambert-Eaton myasthenic syndrome images
  • Differentials

    • Botulism
    • Myasthenia gravis
    • Myopathy
    More Differentials
  • Guidelines

    • Evidence-based guideline: intravenous immunoglobulin in the treatment of neuromuscular disorders
    • Screening for tumours in paraneoplastic syndromes: report of an EFNS task force
    More Guidelines
  • Patient leaflets

    Quitting smoking

    More Patient leaflets
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