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Lambert-Eaton myasthenic syndrome

Last reviewed: 17 Aug 2025
Last updated: 21 Feb 2024

Summary

Definition

History and exam

Key diagnostic factors

  • presence of risk factors
  • limb weakness
  • dry mouth
  • weakness
Full details

Other diagnostic factors

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

Risk factors

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

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
  • thyroid-stimulating hormone (TSH)
Full details

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-fibre 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

Divulgaciones

JMM declares that he has no competing interests.

Joshua P. Alpers, MD

Staff Neurologist

University of Tennessee Erlanger Neurology

Chattanooga

TN

Divulgaciones

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

Divulgaciones

VCJ declares that he has no competing interests.

Revisores por pares

Olivia Tong, MD

Assistant Clinical Professor

UC Davis Medical Group

CA

Divulgaciones

OT declares that she has no competing interests.

Zaeem Siddiqui, MD, PhD

Associate Professor

Division of Neurology

University of Alberta

Edmonton

Canada

Divulgaciones

ZS declares that he has no competing interests.

Paul Wirtz, MD, PhD

Department of Neurology

Haga Hospital

The Hague

The Netherlands

Divulgaciones

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

Peer reviewer acknowledgements

BMJ Best Practice topics are updated on a rolling basis in line with developments in evidence and guidance. The peer reviewers listed here have reviewed the content at least once during the history of the topic.

Disclosures

Peer reviewer affiliations and disclosures pertain to the time of the review.

Referencias

Nuestros equipos internos de evidencia y editoriales colaboran con colaboradores expertos internacionales y revisores pares para garantizar que brindemos acceso a la información más clínicamente relevante posible.

Artículos principales

Titulaer MJ, Lang B, Verschuuren JJ. Lambert-Eaton myasthenic syndrome: from clinical characteristics to therapeutic strategies. Lancet Neurol. 2011 Dec;10(12):1098-107. Resumen

Skeie GO, Apostolski S, Evoli A, et al. Guidelines for treatment of autoimmune neuromuscular transmission disorders. Eur J Neurol. 2010 Jul;17(7):893-902. Resumen

AAEM Quality Assurance Committee, American Association of Electrodiagnostic Medicine. Practice parameter for repetitive nerve stimulation and single fiber EMG evaluation of adults with suspected myasthenia gravis or Lambert-Eaton myasthenic syndrome: summary statement. Muscle Nerve. 2001 Sep;24(9):1236-8.Texto completo  Resumen

Artículos de referencia

Una lista completa de las fuentes a las que se hace referencia en este tema está disponible para los usuarios con acceso a todo BMJ Best Practice.
  • Lambert-Eaton myasthenic syndrome images
  • Diferenciales

    • Botulism
    • Myasthenia gravis
    • Myopathy
    Más Diferenciales
  • Guías de práctica clínica

    • Updated consensus statement: intravenous immunoglobulin in the treatment of neuromuscular disorders report of the AANEM ad hoc committee
    • Clinical guidelines for immunoglobulin use (second edition update)
    Más Guías de práctica clínica
  • Folletos para el paciente

    Stopping smoking

    Más Folletos para el paciente
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