Site Map

Lambert-Eaton myasthenic syndrome

Myasthenic syndrome; Eaton-Lambert syndrome; Lambert-Eaton syndrome; LES

Lambert-Eaton myasthenic syndrome (LEMS) is a rare disorder in which faulty communication between nerves and muscles leads to muscle weakness.

Images

Superficial anterior muscles

Causes

LEMS is an autoimmune disorder. This means your immune system mistakenly targets healthy cells and tissues in the body. With LEMS, antibodies produced by the immune system attack nerve cells. This makes nerves cells unable to release enough of a chemical called acetylcholine. This chemical transmits impulses between nerves and muscles. The result is muscle weakness.

LEMS may occur with cancers such as small cell lung cancer or autoimmune disorders such as vitiligo, which leads to a loss of skin pigment.

LEMS affects men more often than women. The most common age of occurrence is around age 60 years. LEMS is rare in children.

Symptoms

Weakness or loss of movement that can be more or less severe, including:

Weakness is generally mild in LEMS. Leg muscles are mostly affected. Weakness may improve after exercise, but continuous exertion causes fatigue in some cases.

Symptoms related to the other parts of the nervous system often occur, and include:

Exams and Tests

The health care provider will perform a physical exam and ask about the symptoms. The exam may show:

Tests to help diagnose and confirm LEMS may include:

CT scan and MRI of the chest and the abdomen, followed by bronchoscopy for smokers may be done to evaluate for cancer. PET scan may also be done if a lung tumor is suspected. You may be referred to an oncologist (cancer specialist) to determine if other cancer testing is needed.

Treatment

The main goals of treatment are to:

Plasma exchange, or plasmapheresis, is a treatment that helps remove from the body any harmful proteins (antibodies) that are interfering with nerve function. This involves removing blood plasma that contains the antibodies. Other proteins (such as albumin) or donated plasma are then infused into the body.

Another procedure involves using intravenous immunoglobulin (IVIg) to infuse a large amount of helpful antibodies directly into the bloodstream.

Medicines that may also be tried include:

Outlook (Prognosis)

Symptoms of LEMS may improve by treating the underlying disease, suppressing the immune system, or removing the antibodies. However, paraneoplastic LEMS may not respond as well to treatment. (Paraneoplastic LEMS symptoms are due to an altered immune system response to a tumor). Death is due to underlying malignancy.

Possible Complications

Complications of LEMS may include:

When to Contact a Medical Professional

Call your provider if symptoms of LEMS develop.

Related Information

Weakness
Muscle cramps
Myasthenia gravis
Antibody
Cancer
Autoimmune disorders

References

Evoli A, Vincent A. Disorders of neuromuscular transmission. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 26th ed. Philadelphia, PA: Elsevier; 2020:chap 394.

Guptill JT, Sanders DB. Disorders of neuromuscular transmission. In: Jankovic J, Mazziotta JC, Pomeroy SL, Newman NJ, eds. Bradley and Daroff's Neurology in Clinical Practice. 8th ed. Philadelphia, PA: Elsevier; 2022:chap 108.

Moss HE. Eyelid and facial nerve disorders. In: Liu GT, Volpe NJ, Galetta SL, eds. Liu, Volpe, and Galetta's Neuro-Ophthalmology. 3rd ed. Philadelphia, PA: Elsevier; 2019:chap 14.

BACK TO TOP

Review Date: 4/25/2022  

Reviewed By: Joseph V. Campellone, MD, Department of Neurology, Cooper University Hospital, Camden, NJ. Review provided by VeriMed Healthcare Network. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

ADAM Quality Logo
Health Content Provider
06/01/2025

A.D.A.M., Inc. is accredited by URAC, for Health Content Provider (www.urac.org). URAC's accreditation program is an independent audit to verify that A.D.A.M. follows rigorous standards of quality and accountability. A.D.A.M. is among the first to achieve this important distinction for online health information and services. Learn more about A.D.A.M.'s editorial policy, editorial process and privacy policy. A.D.A.M. is also a founding member of Hi-Ethics. This site complied with the HONcode standard for trustworthy health information from 1995 to 2022, after which HON (Health On the Net, a not-for-profit organization that promoted transparent and reliable health information online) was discontinued.

The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. © 1997- 2024 A.D.A.M., a business unit of Ebix, Inc. Any duplication or distribution of the information contained herein is strictly prohibited.

A.D.A.M. content is best viewed in IE9 or above, Firefox and Google Chrome browser.