Lambert-Eaton myasthenic syndrome

(Redirected from Lambert-Eaton syndrome)
Jump to: navigation, search
Lambert-Eaton myasthenic syndrome
Synapse diag3.png
Global view of a neuromuscular junction:
1. Axon
2. Motor end-plate
3. Muscle fiber
4. Myofibril
ICD-10 G73.1
ICD-9 358.1
DiseasesDB 4030
MedlinePlus 000710
MeSH D015624

WikiDoc Resources for

Lambert-Eaton myasthenic syndrome

Articles

Most recent articles on Lambert-Eaton myasthenic syndrome

Most cited articles on Lambert-Eaton myasthenic syndrome

Review articles on Lambert-Eaton myasthenic syndrome

Articles on Lambert-Eaton myasthenic syndrome in N Eng J Med, Lancet, BMJ

Media

Powerpoint slides on Lambert-Eaton myasthenic syndrome

Images of Lambert-Eaton myasthenic syndrome

Photos of Lambert-Eaton myasthenic syndrome

Podcasts & MP3s on Lambert-Eaton myasthenic syndrome

Videos on Lambert-Eaton myasthenic syndrome

Evidence Based Medicine

Cochrane Collaboration on Lambert-Eaton myasthenic syndrome

Bandolier on Lambert-Eaton myasthenic syndrome

TRIP on Lambert-Eaton myasthenic syndrome

Clinical Trials

Ongoing Trials on Lambert-Eaton myasthenic syndrome at Clinical Trials.gov

Trial results on Lambert-Eaton myasthenic syndrome

Clinical Trials on Lambert-Eaton myasthenic syndrome at Google

Guidelines / Policies / Govt

US National Guidelines Clearinghouse on Lambert-Eaton myasthenic syndrome

NICE Guidance on Lambert-Eaton myasthenic syndrome

NHS PRODIGY Guidance

FDA on Lambert-Eaton myasthenic syndrome

CDC on Lambert-Eaton myasthenic syndrome

Books

Books on Lambert-Eaton myasthenic syndrome

News

Lambert-Eaton myasthenic syndrome in the news

Be alerted to news on Lambert-Eaton myasthenic syndrome

News trends on Lambert-Eaton myasthenic syndrome

Commentary

Blogs on Lambert-Eaton myasthenic syndrome

Definitions

Definitions of Lambert-Eaton myasthenic syndrome

Patient Resources / Community

Patient resources on Lambert-Eaton myasthenic syndrome

Discussion groups on Lambert-Eaton myasthenic syndrome

Patient Handouts on Lambert-Eaton myasthenic syndrome

Directions to Hospitals Treating Lambert-Eaton myasthenic syndrome

Risk calculators and risk factors for Lambert-Eaton myasthenic syndrome

Healthcare Provider Resources

Symptoms of Lambert-Eaton myasthenic syndrome

Causes & Risk Factors for Lambert-Eaton myasthenic syndrome

Diagnostic studies for Lambert-Eaton myasthenic syndrome

Treatment of Lambert-Eaton myasthenic syndrome

Continuing Medical Education (CME)

CME Programs on Lambert-Eaton myasthenic syndrome

International

Lambert-Eaton myasthenic syndrome en Espanol

Lambert-Eaton myasthenic syndrome en Francais

Business

Lambert-Eaton myasthenic syndrome in the Marketplace

Patents on Lambert-Eaton myasthenic syndrome

Experimental / Informatics

List of terms related to Lambert-Eaton myasthenic syndrome

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-In-Chief: Raviteja Guddeti, M.B.B.S. [2]

Synonyms and keywords: Eaton-Lambert syndrome; Lambert-Eaton syndrome; LEMS

Overview

Lambert-Eaton myasthenic syndrome (LEMS) is a rare autoimmune disorder which affects the nerve-muscle (neuromuscular) junction.

The disease is usually observed in middle aged and older people but children and young people can be affected, as well. Due to the infrequency of the condition, the exact incidence is unknown.

History

Anderson was the first person to mention a case with possible clinical findings of LEMS in 1953, but Lambert, Eaton and Rooke were the first physicians to substantially describe the clinical and electrophysiological findings of the disease in 1966.[1][2] Auto-immune self antibodies to the pre-synaptic voltage gated calcium channels leads to neuromuscular block.

Pathophysiology

The disease is of autoimmune origin, that is, it is caused by antibodies that are directed against the antigens of the neuromuscular junction. In 1989, the previously anticipated antibodies were demonstrated to be directed against presynaptic calcium channels, which are located in neuromuscular junction (see synapse) and are responsible for the efficient release of acetylcholine. The antibodies prevent normal function of calcium channels and thus prevent the release of acetylcholine that is essential for normal nerve-muscle interactions, which maintain the normal muscle strength (see synapse, nerve, neuron, muscle).

There are also some patients that do not carry these antibodies in their serum samples and the exact cause of disease in these cases still remains to be determined. In cases with both LEMS and lung cancer (usually small cell type), the antibodies are suggested to be aimed at cancer cells and to bind and affect the antigens in neuromuscular junction accidentally. LEMS can be observed in other types of cancer including the transitional cell carcinoma of the bladder.

Approximately 50% of LEMS cases have an identifiable malignancy.

Causes

LEMS is usually a solitary diagnosis but lung cancer (small-cell histology) may accompany the disease in some cases. It may also be associated with cancers such as lymphoma, non-Hodgkin's lymphoma, T-cell leukemia, non-small cell lung cancer, prostate cancer, and thymoma.

Diferentiating from other Diseases

Both the etiology and the clinical findings of Lambert-Eaton myasthenic syndrome may resemble myasthenia gravis, but there are many substantial differences between clinical presentations and pathogenetic features of two disorders. In patients with affected ocular and respiratory muscles, the involvement is not as severe as myasthenia gravis.

Natural History, Complications and Prognosis

Possible complications include:

The symptoms of Lambert-Eaton syndrome may improve by treating the underlying disease, suppressing the immune system, or removing the antibodies. However, not everyone responds well to treatment.

Diagnosis

Symptoms

Symptoms may include:

  • Weakness or loss of movement that can be more or less severe, including:
    • Difficulty chewing
    • Difficulty climbing stairs
    • Difficulty lifting objects
    • Difficulty talking
    • Drooping head
    • Need to use hands to get up from sitting or lying positions
  • Swallowing difficulty, gagging, or choking
  • Vision changes such as:

Symptoms related to the autonomic nervous system usually occur, and include:

  • Blood pressure changes
  • Dizziness upon standing
  • Dry mouth

Laboratory Findings

  • Antibodies to calcium channels
  • Incremental response in repetitive nerve stimulation - incremental response is an increased response of muscle fibers to very high frequencies of electrical stimulation. Observed increase in the response of muscle fibers proves that there is a difficulty with the release of acetylcholine and this difficulty can be overwhelmed by intensive stimulation.

Chest X-ray

Treatment

The main goals of treatment are to:

  • Identify and treat any underlying disorders, such as lung cancer
  • Give treatment to help with the weakness

Corticosteroids, azathioprine and 3,4-diaminopyridine are used in treatment of LEMS with limited success. In some cases with a progressive and intractable course, plasma exchange or intravenous immunoglobulin can be tried.

A treatment called plasma exchange usually improves symptoms. Plasma exchange involves removing blood plasma from the body and replacing it with donated plasma. This helps to make sure that any harmful proteins (antibodies) that are interfering with nerve function are removed from the body.

Plasmapheresis may also be effective. During this treatment, the blood is removed from the body. The plasma is separated, the antibodies are removed, and the plasma is returned to the body.

Medications that suppress the immune response, such as prednisone, may improve symptoms in some cases. Medications may also include:

  • Anticholinesterase medications such as neostigmine or pyridostigmine (although these are not very effective when given alone)
  • 3,4 diaminopyridine works by blocking K+ channel efflux in nerve terminal so that action potential duration is increased. Ca2+ channels can then be open for longer time and allow greater acetylcholine release to stimulate muscle at end plate.

References

  1. Lambert-Eaton-Rooke syndrome at Who Named It
  2. E. H. Lambert, L. M. Eaton, E. D. Rooke. Defect of neuromuscular conduction associated with malignant neoplasms. American Journal of Physiology, Bethesda, Maryland, 1956, 187: 612-613.


de:Lambert-Eaton-Rooke-Syndrom

Linked-in.jpg