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Lambert-Eaton myasthenic syndrome

Last reviewed: 5 Oct 2024
Last updated: 21 Feb 2024

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
Full details

Other diagnostic factors

  • dysarthria
  • areflexia
  • ptosis
  • diplopia
  • impotence
  • dysphagia
  • orthostatic hypotension
  • pupillary dilation
  • dyspnea
  • cerebellar ataxia
Full details

Risk factors

  • underlying small cell lung cancer or other malignancy
  • coexisting autoimmune disorder
  • cigarette smoking
  • family history of autoimmune disease
Full details

Diagnostic tests

1st tests 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
  • thyroid-stimulating hormone (TSH)
Full details

Tests 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
  • antinuclear antibodies (ANA)
  • rheumatoid factor (RF)
  • antineutrophil cytoplasmic autoantibodies (ANCA)
  • B12 and methylmalonic acid (MMA)
Full details

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

Jonathan M. Morena, DO

Assistant Professor of Neurology

Duke University Medical Center

Durham

NC

Disclosures

JMM declares that he has no competing interests.

Joshua P. Alpers, MD

Staff Neurologist

University of Tennessee Erlanger Neurology

Chattanooga

TN

Disclosures

JA has been compensated by (1) Alexion, the manufacturer of Soliris and Ultomiris, (2) Argenx, the manufacturer of Vyvgart, and (3) MT Pharma, the manufacturer of Radicava ORS, for participation in advisory boards and speakers bureaus.

Vern C. Juel, MD

Professor of Neurology

Duke University Medical Center

Durham

NC

Disclosures

VCJ declares that he has no competing interests.

Peer reviewers

Olivia Tong, MD

Assistant Clinical Professor

UC Davis Medical Group

CA

Disclosures

OT declares that she 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 topic.

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  • Patient information

    Quitting smoking

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