Lambert-Eaton syndrome
Myasthenic syndrome; Eaton-Lambert syndrome; Lambert-Eaton myasthenic syndrome; LEMS; LES
Lambert-Eaton syndrome (LES) is a rare disorder in which faulty communication between nerves and muscles leads to muscle weakness .
Muscle weakness
Weakness is reduced strength in one or more muscles.
Causes
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.
Autoimmune disorder
An autoimmune disorder occurs when the body's immune system attacks and destroys healthy body tissue by mistake. There are more than 80 types of aut...
Antibodies
An antibody is a protein produced by the body's immune system when it detects harmful substances, called antigens. Examples of antigens include micr...
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.
Small cell lung cancer
Small cell lung cancer (SCLC) is a fast-growing type of lung cancer. It spreads much more quickly than non-small cell lung cancer. There are two typ...
Vitiligo
Vitiligo is a skin condition in which there is a loss of color (pigment) from areas of skin. This results in uneven white patches that have no pigme...
Symptoms
Weakness or loss of movement that can be more or less severe, including:
- Difficulty climbing stairs or lifting things
- Drooping of the head
- The need to use the hands to get up from a sitting or lying position
- Problems talking
-
Problems chewing or swallowing, which may include gagging or
choking
Choking
Choking is when someone is having a very hard time breathing because food, a toy, or other object is blocking the throat or windpipe (airway). A cho...
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Vision changes, such as
blurry
vision, double vision, and problem keeping a steady gaze
Blurry
There are many types of eye problems and vision disturbances, such as: HalosBlurred vision (the loss of sharpness of vision and the inability to see ...
Symptoms related to the other parts of the nervous system often occur, and include:
- Blood pressure changes
- Dizziness upon standing
- Dry mouth
Exams and Tests
The health care provider will perform a physical exam and ask about the symptoms. The exam may show:
- Decreased reflexes
- Possible loss of muscle tissue
- Weakness or paralysis that gets slightly better with activity
Tests to help diagnose and confirm LES may include:
- Blood tests to look for the antibodies that attack the nerves
-
Electromyography
(EMG) to test the health of the muscle fibers
Electromyography
Electromyography (EMG) is a test that checks the health of the muscles and the nerves that control the muscles.
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Nerve conduction velocity
(NCV) to test the speed of electrical activity along nerves
Nerve conduction velocity
Nerve conduction velocity (NCV) is a test to see how fast electrical signals move through a nerve.
Treatment
The main goals of treatment are to:
- Identify and treat any underlying disorders, such as lung cancer
- Give treatment to help with the weakness
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.
Antibodies
An antibody is a protein produced by the body's immune system when it detects harmful substances, called antigens. Examples of antigens include micr...
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:
-
Drugs that suppress the
immune system's response
Immune system's response
The immune response is how your body recognizes and defends itself against bacteria, viruses, and substances that appear foreign and harmful....
- Anticholinesterase drugs to improve muscle tone (although these are not very effective when given alone)
- Drugs that increase the release of acetylcholine from nerve cells
Outlook (Prognosis)
Symptoms of LES may improve by treating the underlying disease, suppressing the immune system, or removing the antibodies. However, not everyone responds well to treatment.
Possible Complications
Complications of LES may include:
-
Difficulty breathing, including
respiratory failure
Respiratory failure
Respiratory acidosis is a condition that occurs when the lungs cannot remove all of the carbon dioxide the body produces. This causes body fluids, e...
- Difficulty swallowing
-
Infections, such as
pneumonia
Pneumonia
Pneumonia is a breathing (respiratory) condition in which there is an infection of the lung. This article covers community-acquired pneumonia (CAP). ...
- Injuries from falls and problems with coordination
When to Contact a Medical Professional
Call your provider if symptoms of LES develop.
References
Evoli A, Vincent A. Disorders of neuromuscular transmission. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine . 25th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 422.
Sanders DB, Guptill JT. Disorders of neuromuscular transmission. In: Daroff RB, Jankovic J, Mazziotta JC, Pomeroy SL, eds. Bradley's Neurology in Clinical Practice . 7th ed. Philadelphia, PA: Elsevier; 2016:chap 109.
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Superficial anterior muscles - illustration
Superficial muscles are close to the surface of the skin. Muscles which lie closer to bone or internal organs are called deep muscles.
Superficial anterior muscles
illustration
Review Date: 5/30/2016
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, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.