Lambert-Eaton syndrome


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


LES is an autoimmune disorder. This means your immune system mistakenly targets healthy cells and tissues in the body. With LES, 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.

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

LES affects men more often than women. Common age of occurrence is around age 60 years. LES is rare in children.


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

Weakness is generally mild in LES. 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 LES may include:

CT scan and MRI of the chest and the abdomen, followed by bronchoscopy for smokers may be done to exclude cancer. PET scan may also be done if a lung tumor is suspected.


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

Possible Complications

Complications of LES may include:

When to Contact a Medical Professional

Call your provider if symptoms of LES develop.

Review Date: 4/30/2018
Reviewed By: Amit M. Shelat, DO, FACP, Attending Neurologist and Assistant Professor of Clinical Neurology, SUNY Stony Brook, School of Medicine, Stony Brook, NY. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

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