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$Unique_ID{BRK03692}
$Pretitle{}
$Title{Eaton-Lambert Syndrome}
$Subject{Eaton-Lambert Syndrome Lambert-Eaton Syndrome Lambert-Eaton
Myasthenic Syndrome Myasthenic Syndrome of Lambert-Eaton Myasthenia Gravis
Guillain-Barre Syndrome}
$Volume{}
$Log{}

Copyright (C) 1990, 1991, 1992 National Organization for Rare Disorders,
Inc.

794:
Eaton-Lambert Syndrome

** IMPORTANT **
It is possible that the main title of the article (Eaton-Lambert
Syndrome) is not the name you expected.  Please check the SYNONYM listing to
find the alternate names and disorder subdivisions covered by this article.

Synonyms

     Lambert-Eaton Syndrome
     Lambert-Eaton Myasthenic Syndrome
     Myasthenic Syndrome of Lambert-Eaton

Information on the following disorders can be found in the Related
Disorders section of this report:

     Myasthenia Gravis
     Guillain-Barre Syndrome

General Discussion

** REMINDER **
The information contained in the Rare Disease Database is provided for
educational purposes only.  It should not be used for diagnostic or treatment
purposes.  If you wish to obtain more information about this disorder, please
contact your personal physician and/or the agencies listed in the "Resources"
section of this report.


Eaton-Lambert Syndrome is a neuromuscular disorder that may be an
autoimmune disease.  Major symptoms include muscle weakness and fatigue
especially of the pelvic and thigh muscles.  Other symptoms may include
dryness of the mouth, impotence, pain in the thighs, and a pricking, tingling
or creeping sensation on the skin (paresthesias) around the affected areas.

Symptoms

Eaton-Lambert Syndrome is characterized by weakness and fatigue especially of
the pelvic and thigh muscles.  Other symptoms may include dryness of the
mouth, impotence, pain in the thighs, and a pricking, tingling or creeping
feeling on the skin (paresthesias) around the affected areas.  Some patients
experience double-vision (diplopia), difficulty in articulation of speech
(dysarthria), ptosis (drooping of the upper eyelid), decreased sweating, low
blood pressure when in an upright position (orthostatic hypotension), and
altered reflexes of the pupils of the eyes.  Patients with Eaton-Lambert
Syndrome may not have deep tendon reflexes and lower limbs are affected more
often than upper limbs.

Diagnosis of Eaton-Lambert Syndrome is made by EMG (electromyogram),
which is a record of electrical activity of the muscles, and by electron
microscopy.  The EMG initially shows a small amount of electrical activity in
the muscle.  After stimulation or exercise, there is increased activity in
the muscle.  Electron microscopy (use of an electron microscope which
magnifies tiny images such as bacteria or viruses and is 1000 times more
powerful than an ordinary microscope) may show changes in the postsynaptic
membrane and nerve terminal of nerve cells.

Causes

Eaton-Lambert Syndrome is suspected of being an autoimmune disorder.
Autoimmune disorders are caused when the body's natural defenses (antibodies,
lymphocytes, etc.), against invading organisms suddenly begin to attack
healthy tissue.  Eaton-Lambert Syndrome may involve autoantibodies directed
against part of the terminals of nerves, causing a reduction in the amount of
acetylcholine released at the place where the terminals of nerve cells meet
the muscle (motor end plate) in response to a nerve impulse.  When the nerve
is repeatedly stimulated, it helps the release of acetylcholine, increasing
possible muscle action.  Acetylcholine is a chemical that helps
"communication" between nerve cells and muscles.

Two thirds of Eaton-Lambert Syndrome patients are people with cancer.  Of
Eaton-Lambert Syndrome patients over the age of 40, 70% of men and 30% of
women will have a malignant tumor.  The tumor is usually a small cell
carcinoma of the lung.  Eaton-Lambert Syndrome may occur up to three years
before a tumor is detected.  However, in one third of patients with this
disorder, the syndrome is not related to cancer and may occur at any age.
(For more information, choose "cancer" as your search term in the Rare
Disease Database.)

Affected Population

Eaton-Lambert Syndrome is a rare disorder that affects males and females
equally and tends to occur most often in patients with cancer, especially
small-cell lung cancer (such as oat cell carcinoma of the lung).  In one
third of Eaton-Lambert patients, the syndrome is not related to cancer and
may occur at any age.  There are approximately 400 known cases of Lambert-
Eaton Syndrome in the United States.

Related Disorders

Symptoms of the following disorders can be similar to those of Eaton-Lambert
Syndrome Syndrome.  Comparisons may be useful for a differential diagnosis:

Myasthenia Gravis (MG) is a chronic neuromuscular disease characterized
by weakness and abnormally rapid fatigue of the voluntary muscles, with
improvement following rest.  Any group of muscles may be affected, but those
around the eyes and the muscles used for swallowing are the most commonly
involved.  In Eaton-Lambert Syndrome these head and neck muscles are usually
not affected.  Weakness of the limbs is a frequent characteristic of MG and
is most pronounced at the end of the day and also after exercise.  However,
in patients with Eaton-Lambert Syndrome muscle strength tends to improve
after exercise.  (For more information on this disorder, choose "Myasthenia"
as your search term in the Rare Disease Database).

Guillain-Barre Syndrome is an autoimmune disease which occurs when the
body's defense system attacks the nerves, damaging the nerve's myelin and
axon.  Nerve signals are delayed and altered, causing weakness and paralysis
of the muscles of the legs, arms, and other parts of the body.  Abnormal
sensations such as numbness or tingling also occur.  If muscle nerves are
damaged, the patient experiences aching and weak muscles, shortness of
breath, and difficulty in swallowing.  If the autonomic nervous system is
damaged, the patient may experience alterations of blood pressure, heart
rate, vision, body temperature, bladder function, and blood chemistries.
(For more information on this disorder, choose "Guillain" as your search term
in the Rare Disease Database).

Therapies:  Standard

Symptoms of patients with Eaton-Lambert Syndrome are often relieved or
improved with Guanidine.  This drug increases the release of acetylcholine in
the muscles.  Immunosuppressive drugs such as prednisone and azathioprine may
also relieve symptoms.

If cancer is present, treatment of Eaton-Lambert Syndrome first involves
treatment directed at the cancer.  This may result in relief of Eaton-Lambert
symptoms as well.

Other treatment is symptomatic and supportive.

Therapies:  Investigational

The FDA has approved the following drug for testing as treatment for Eaton-
Lambert Syndrome in patients:

The orphan drug dynamine is being tested for treatment of Eaton-Lambert
Syndrome.  The drug is manufactured by Mayo Foundation, Rochester, MN.

Plasmapheresis may be of benefit in some cases of Eaton-Lambert Syndrome.
This procedure is a method for removing unwanted substances (toxins,
metabolic substances and plasma parts) from the blood.  Blood is removed from
the patient and blood cells are separated from plasma.  The patient's plasma
is then replaced with other human plasma and the blood is retransfused into
the patient.  More research is needed before plasmapheresis can be
recommended for use in all but the most severe cases of Eaton-Lambert
Syndrome.

The National Cancer Institute conducts clinical trials on new drugs being
tested for lung cancer and other forms of cancer.  To learn about locations
of these investigations, contact the Cancer Information Service, 1-800-4-
CANCER.

Clinical trials are underway to study the orphan drug 3,4-diaminopyridine
for the improvement of strength in patients with Eaton Lambert Syndrome.
Interested persons may wish to contact:

     Donald B. Sanders, M.D.
     Box 3403
     Duke University Medical Center
     Durham, NC  27719
     [phone]

to see if further patients are needed for this research.

This disease entry is based upon medical information available through
January 1992.  Since NORD's resources are limited, it is not possible to keep
every entry in the Rare Disease Database completely current and accurate.
Please check with the agencies listed in the Resources section for the most
current information about this disorder.

Resources

For more information on Eaton-Lambert Syndrome, please contact:

     National Organization for Rare Disorders
     P.O. Box 8923
     New Fairfield, CT 06812-1783
     [phone]

     Myasthenia Gravis Foundation, Inc.
     53 W. Jackson Blvd., Suite 1352
     Chicago, IL 60604
     1-800-541-5454
     [phone]

     NIH/National Institute of Neurological Disorders & Stroke (NINDS)
     9000 Rockville Pike
     Bethesda, MD  20892
     [phone]
     [phone]

     Muscular Dystrophy Association, National Office
     3561 E. Sunrise Dr.
     Tucson, AZ  85718
     [phone]

References

CECIL TEXTBOOK OF MEDICINE, 18th Ed.:  James B. Wyngaarden, and Lloyd H.
Smith, Jr., Editors; W.B. Saunders Co., 1988.  Pp. 1106, 1633, 2285, 2287.

INTERNAL MEDICINE, 2nd Ed.:  Jay H. Stein, ed.-in-chief; Little, Brown
and Co., 1987.  Pp. 999-1000.

THE MERCK MANUAL, Volume 1, 14th Ed.:  Robert Berkow, M.D., ed.-in-chief;
Merck, Sharp, and Dohme Laboratories, 1982.  Pp. 1213, 1450-1451.

AUTONOMIC DYSFUNCTION IN LAMBERT-EATON MYASTHENIC SYNDROME.  R. K.
Khurana, et al.; J Neurol Sci (May 1988; issue 85 (1)).  Pp. 77-86.

EATON-LAMBERT SYNDROME AS A HARBINGER OF RECURRENT SMALL-CELL CARCINOMA
OF THE CERVIX WITH IMPROVEMENT AFTER COMBINATION CHEMOTHERAPY.  G. P. Sutton,
et al.; Obstet Gynecol (Sept 1988; issue 72 (3 Pt 2)).  Pp. 516-518.

3,4-DIAMINOPYRIDINE IN THE TREATMENT OF LAMBERT-EATON MYASTHENIC
SYNDROME.  McEvoy, K.M., N Eng J Med, (1989, issue 321).  Pp.  1567-1571.