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What is Lambert-Eaton syndrome

Lambert-Eaton syndrome is an autoimmune disorder in which faulty communication between nerves and muscles leads to muscle weakness. In this syndrome, substances 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. Lambert-Eaton syndrome may occur with cancers such as small cell lung cancer or autoimmune disorders such as vitiligo, which leads to a loss of skin pigment. Symptoms may include: weakness or loss of movement that can be more or less severe, 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 can occur such as: blurry vision, double vision, and problems keeping a steady gaze. 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.

Lambert Eaton myasthenic syndrome (LEMS) is a disorder of the neuromuscular junction. The neuromuscular junction is the site where nerve cells meet muscle cells and help activate the muscles.[1] This syndrome occurs when antibodies interfere with electrical impulses between the nerve and muscle cells. It may be associated with other autoimmune diseases, or more commonly coincide with or precede a diagnosis of cancer such as small cell lung cancer. Symptoms may include muscle weakness, a tingling sensation in the affected areas, fatigue, and dry mouth.[1] Treatment of an underlying disorder or cancer is the first priority of treatment.[2]

LEMS is a disorder of the immune system, also known as an autoimmune disorder. Autoimmune disorders occur when the body’s defense system against foreign organisms (antibodies) attack healthy tissue. LEMS occurs when part of the neuromuscular junction is damaged. The neuromuscular junction is the area between a nerve cell and a muscle cell, where communication occurs through the release of a chemical signal, called acetylcholine (ACh). This results in muscle contraction or movement. When individuals have LEMS, this process is blocked and ACh is not effectively released from nerve cells.[5][6]

In instances where LEMS is associated with cancer, the cause may be related to the body’s attempt to fight the cancer and accidental attack of nerve fiber endings, especially the voltage-gated calcium channels found there. The trigger for the cases not associated with cancer is unknown.[5][2]

This information is provided by the National Institutes of Health (NIH) Genetic and Rare Diseases Information Center (GARD).

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