Lambert Eaton myasthenic syndrome

What causes Lambert Eaton myasthenic syndrome (LEMS)?

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.

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.

Last updated on 05-01-20

What is the connection between Lambert Eaton myasthenic syndrome (LEMS) and anesthesia?

LEMS is caused by an interruption in the nerve to muscle electrical impulses. There are medications that act upon the transmission of these impulses that can worsen symptoms of LEMS. There have been cases reported in the literature, where symptoms worsened in untreated individuals or the first symptoms of LEMS occurred in undiagnosed individuals following administration of such medications. In these instances, the medication triggered symptoms of the syndrome that were previously absent or unnoticeable.

Medications that act upon the transmission of impulses between nerve and muscle cells that may worsen symptoms of LEMS, include muscle relaxants (such as succinylcholine) that may be used during anesthesia as well as the following drugs:

Last updated on 05-01-20

Is Lambert Eaton myasthenic syndrome (LEMS) genetic?

The answer to this question is complex. While the condition is not known to follow a specific pattern of inheritance, there appears to be a genetic predisposition to autoimmune diseases in general. Families with a history of Lambert Eaton myasthenic syndrome may benefit from consulting with a genetics professional.

Last updated on 05-01-20

What is the long-term outlook for Lambert-Eaton myasthenic syndrome (LEMS)?

The prognosis for individuals with LEMS varies and is largely dependent on whether there is an underlying cancer or autoimmune disease. The symptoms of LEMS may improve with treatment; however, not all people respond well to treatment and in most instances, symptoms continue to progress over time.

Last updated on 05-01-20

How might Lambert-Eaton myasthenic syndrome (LEMS) be treated?

There is no cure for LEMS. Treatment may vary depending on the individual's age, general health, and whether there is an associated cancer or autoimmune disorder. If cancer or an underlying autoimmune disorder is present, treatment should focus on these conditions first. They may result in symptom relief.

Medications and therapies that may be used to treat Lambert-Eaton myasthenic syndrome include: 3,4-diaminopyridine (enhances acetylcholine release), anticholinesterase agents (e.g., Pyridostigmine), plasma exchange (where blood plasma is removed and replaced with fluid, protein, or donated plasma), intravenous immunoglobulins (IVIG), and medications that suppress the immune system (e.g., prednisone, azathioprine).

Last updated on 05-01-20

Name: American Autoimmune Related Diseases Association (AARDA) 22100 Gratiot Avenue
Eastpointe, MI, 48021, United States
Phone: 586-776-3900 Toll Free: 800-598-4668 Fax : 586-776-3903 Email: Url:
Name: Muscular Dystrophy Association MDA 222 S Riverside Plaza Suite 1500
Chicago, IL, 60606, United States
Toll Free: 1-833-275-6321 (Helpline) Email: Url:

Note, these links are external searches against the National Laboratory of Medicine's drug database. You may need to adjust the search if there are no results found.

Drug Name Generic Name
Firdapse amifampridine phosphate

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