National Center for Advancing and Translational Sciences Genetic and Rare Diseases Information Center, a program of the National Center for Advancing and Translational Sciences

Lambert Eaton myasthenic syndrome


Other Names:
LEMS; Eaton Lambert syndrome; Lambert Eaton syndrome; LEMS; Eaton Lambert syndrome; Lambert Eaton syndrome; Myasthenic syndrome of Lambert-Eaton; Myasthenic-Myopathic syndrome of Lambert-Eaton See More
Categories:
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]
Last updated: 12/22/2016
The signs and symptoms of LEMS usually appear around 40 years of age and are characterized by muscle weakness, dysautonomia (autonomic nervous system disorders),  and decreased tendon reflexes.[3][4]

Muscle weakness may vary in severity and can lead to:[3]

  • Difficulty climbing stairs
  • Difficulty lifting objects
  • Need to use hands to arise from sitting or lying positions
  • Difficulty talking
  • Difficulty chewing
  • Drooping head
  • Swallowing difficulty, gagging, or choking

Vision issues may additionally occur including:[3]

  • Blurry vision
  • Double vision
  • Difficulty maintaining a steady gaze

Other symptoms may include blood pressure changes, dizziness upon rising, and dry mouth.[3]

Last updated: 12/22/2016

This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. This information comes from a database called the Human Phenotype Ontology (HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Use the HPO ID to access more in-depth information about a symptom.

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Medical Terms Other Names
Learn More:
HPO ID
80%-99% of people have these symptoms
Calcium channel antibody positivity 0030209
EMG: decremental response of compound muscle action potential to repetitive nerve stimulation 0003403
EMG: repetitive nerve stimulation abnormality 0030000
Progressive proximal muscle weakness 0009073
Reduced tendon reflexes 0001315
Xerostomia
Dry mouth
Dry mouth syndrome
Reduced salivation
[ more ] 		0000217
30%-79% of people have these symptoms
Bulbar signs 0002483
Constipation 0002019
Impotence
Difficulty getting a full erection
Difficulty getting an erection
[ more ] 		0000802
Small cell lung carcinoma 0030357
5%-29% of people have these symptoms
Hypohidrosis
Decreased ability to sweat
Decreased sweating
Sweating, decreased
[ more ] 		0000966
Keratoconjunctivitis sicca
Dry eyes
0001097
Orthostatic hypotension due to autonomic dysfunction 0004926
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Last updated: 7/1/2020
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]
Last updated: 12/22/2016
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.[2][6]

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).[2]
Last updated: 12/22/2016

FDA-Approved Treatments

The medication(s) listed below have been approved by the Food and Drug Administration (FDA) as orphan products for treatment of this condition. Learn more orphan products.

  • Amifampridine phosphate (Brand name: Firdapse) - Manufactured by Catalyst Pharmaceuticals, Inc.
    FDA-approved indication: November 2018, amifampridine phosphate (Fridapse) was approved for the treatment of Lambert-Eaton myasthenic syndrome (LEMS) in adults.
    National Library of Medicine Drug Information Portal
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.[2]
Last updated: 12/22/2016

Related diseases are conditions that have similar signs and symptoms. A health care provider may consider these conditions in the table below when making a diagnosis. Please note that the table may not include all the possible conditions related to this disease.

Conditions with similar signs and symptoms from Orphanet
In 60% of LEMS patients, a different diagnosis was initially made such as myasthenia gravis (MG), inclusion body myositis, Guillain-Barré syndrome (GBS), amyotrophic lateral sclerosis (ALS) (see these terms), lumbar canal stenosis, early-phase Parkinson's disease and lower body parkinsonism.
Visit the Orphanet disease page for more information.

Research helps us better understand diseases and can lead to advances in diagnosis and treatment. This section provides resources to help you learn about medical research and ways to get involved.

Clinical Research Resources

  • ClinicalTrials.gov lists trials that are related to Lambert Eaton myasthenic syndrome. Click on the link to go to ClinicalTrials.gov to read descriptions of these studies.

    Please note: Studies listed on the ClinicalTrials.gov website are listed for informational purposes only; being listed does not reflect an endorsement by GARD or the NIH. We strongly recommend that you talk with a trusted healthcare provider before choosing to participate in any clinical study.

Patient Registry

  • The Autoimmune Registry supports research for Lambert Eaton myasthenic syndrome by collecting information about patients with this and other autoimmune diseases. You can join the registry to share your information with researchers and receive updates about participating in new research studies. Learn more about registries.
  • A registry supports research by collecting of information about patients that share something in common, such as being diagnosed with Lambert Eaton myasthenic syndrome. The type of data collected can vary from registry to registry and is based on the goals and purpose of that registry. Some registries collect contact information while others collect more detailed medical information. Learn more about registries.

    Registries for Lambert Eaton myasthenic syndrome:
    Congenital Muscle Disease International Registry
     

Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services. Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Many organizations also have experts who serve as medical advisors or provide lists of doctors/clinics. Visit the group’s website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.

Organizations Supporting this Disease

Organizations Providing General Support

Living with a genetic or rare disease can impact the daily lives of patients and families. These resources can help families navigate various aspects of living with a rare disease.

Financial Resources

  • National Organization for Rare Disorders (NORD) has Disease-Specific Assistance Programs designed to help patients with out-of-pocket costs such as monthly insurance premiums or deductibles. In addition, some programs may provide financial assistance for additional expenses related to a patient's diagnosis such as travel to see a specialist.

These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

Where to Start

In-Depth Information

  • Medscape Reference provides information on this topic. You may need to register to view the medical textbook, but registration is free.
  • The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.
  • Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.
  • PubMed is a searchable database of medical literature and lists journal articles that discuss Lambert Eaton myasthenic syndrome. Click on the link to view a sample search on this topic.

Questions sent to GARD may be posted here if the information could be helpful to others. We remove all identifying information when posting a question to protect your privacy. If you do not want your question posted, please let us know. Submit a new question

  • My husband had Lambert Eaton myasthenic syndrome. Are our two children at risk to develop this condition? See answer

  • My husband has Lambert Eaton myasthenic syndrome.  We read somewhere that this condition may be caused by an anesthetic.  I'm now unable to locate that information.  Is that true?  If so, what anesthetic? See answer


  1. NINDS Lambert-Eaton Myasthenic Syndrome Information Page. Institute of Neurological Disorders and Stroke (NINDS). https://www.ninds.nih.gov/Disorders/All-Disorders/Lambert-Eaton-Myasthenic-Syndrome-Information-Page#disorders-r1. Accessed 12/22/2016.
  2. Stickler, DE. Lambert-Eaton Myasthenic Syndrome. Medscape. May 06, 2016; http://emedicine.medscape.com/article/1170810-overview.
  3. Lambert-Eaton Syndrome. MedlinePlus. 5/30/2016; http://www.nlm.nih.gov/medlineplus/ency/article/000710.htm.
  4. Titulaer, M. Lambert-Eaton myasthenic syndrome. Orphanet. November 2013; http://www.orpha.net/consor/cgi-bin/OC_Exp.php?lng=en&Expert=43393.
  5. Lambert-Eaton Myasthenic Syndrome (LES). Muscular Dystrophy Association (MDA). https://www.mda.org/disease/lambert-eaton-myasthenic-syndrome. Accessed 12/22/2016.
  6. Gozzard, P. Lambert-Eaton myasthenic syndrome. NORD. 2012; https://rarediseases.org/rare-diseases/lambert-eaton-myasthenic-syndrome/.