Lambert-Eaton Myasthenic Syndrome

What is Lambert-Eaton Myasthenic Syndrome?

Lambert-Eaton myasthenic syndrome (LEMS) is a syndrome of weakness and fatigue due to an auto-immune process. LEMS is often associated with cancer, particularly lung cancer. There may be symptoms of LEMS before the cancer is diagnosed and once the diagnosis of LEMS has been made, the patient must be followed for the development of cancer. Symptoms of LEMS are related to weakness of the muscles, mostly in the proximal legs and arms, but sometimes in the neck, affecting swallowing, breathing, speaking, etc. Early symptoms are problems going up stairs, getting up from the sitting position, and lifting arms over the head. It can also have an impact on involuntary body functions, causing dry mouth and impotence.

What causes Lambert-Eaton Myasthenic Syndrome?

LEMS is caused by antibodies that are produced by the body. These antibodies destroy nerve endings that help regulate the amount of a neurotransmitter that is released. When there is not enough of the neurotransmitters released, the muscles do not contract.

Who gets Lambert-Eaton Myasthenic Syndrome?

LEMS is not hereditary. The symptoms usually begin in young adults. It is not often seen in children. Approximately 1 in one million people have LEMS. 40% of those have cancer.

How is Lambert-Eaton Myasthenic Syndrome diagnosed?

LEMS is diagnosed multiple ways. Blood tests for the antibodies and Tensilon tests can be administered. Electrophysiologic test with repetitive nerve stimulation can also be used for diagnosis.

How is Lambert-Eaton Myasthenic Syndrome treated?

Currently no cure exists for LEMS. The most effective treatment if cancer is present is eradication of the cancer. Symptomatic treatments include medications that increase the release or the abundance of the neurotransmitter for the muscles to respond (3,4-diaminopyridine, pyridostigmine). Other drugs (oral immunosuppressants) can be taken to reduce the production of the antibodies that cause the muscles to stop contracting. Other treatments include plasmapheresis and intraveneous immunoglobulin therapy.

More Information

Muscular Dystrophy Association
The Cleveland Clinic
United States National Library of Medicine