Eaton-Lambert syndrome, also called Lambert-Eaton myasthenic syndrome (LEMS), is a rare disorder affecting the muscles and nerves. LEMS is known to be associated with small cell lung cancer. It may also be associated with cancers such as lymphoma , non-Hodgkin's lymphoma, T-cell leukemia, non-small cell lung cancer, prostate cancer , and thymoma .
The primary symptom of LEMS is muscular weakness or paralysis that varies in intensity and location throughout the body. Other symptoms of LEMS include tingling sensations on the skin, double vision, difficulty maintaining a steady gaze, and dry mouth or difficulty in swallowing.
The first signs of LEMS tend to be:
- changes in vision
- decreased posture and muscle tone
- difficulty in chewing or swallowing
- difficulty in climbing stairs
- difficulty in lifting simple objects
- speech impairment
- a drooping head
- and/or a need to use hands to get up from a sitting or lying position
LEMS is often misdiagnosed as myasthenia gravis because of the similarities between the symptoms of these two disorders.
The symptoms of LEMS are the result of an insufficient release of neurotransmitter by nerve cells. Neurotransmitter is a chemical which passes signals from the nerve cells to the muscles in order for the muscles to move. The decreased level of neurotransmitter causes a muscle reaction to the nerve signal that is lower than normal. The underlying cause of the lower-than-normal neurotransmitter release seen in LEMS patients is believed to be related to a malfunction of the patient's own immune system (an autoimmune reaction).
This autoimmune reaction is caused by antibodies that a patient produces in response to small cell lung cancer, or one of the other cancers associated with LEMS.
Since continued use of the muscles may lead to a build-up of the neurotransmitter to normal levels, symptoms of LEMS can often be lessened or alleviated by use of the affected muscles. Myasthenia gravis, another disorder that has symptoms similar to LEMS, is caused by a blockage of neurotransmitters by antibodies. Symptoms of myasthenia gravis do not improve with continued muscle use. The improvement in symptoms that is observable in LEMS patients often helps to differentiate LEMS from myasthenia gravis.
LEMS is aggravated by neuromuscular blocking agents used during surgery; certain antibiotics , such as aminoglycoside and fluoroquinolone; magnesium; calcium channel blockers; and iodinated intravenous contrast agents used for medical imaging.
The goal of treatment for LEMS patients is to improve muscle strength while also treating the cancer or other underlying disorder that is causing LEMS.
When possible, patients affected with LEMS should undergo a physical therapy program that is tailored to their health status and abilities. This may include stretching and flexibility manuevers as well as light strength and cardiovascular exercises. Symptoms of LEMS tend to be aggravated by prolonged exercise, so any physical therapy undertaken should be relatively short in duration.
Some LEMS patients are not able to undergo physical therapy because of their current state of health. In these cases, plasmapheresis (also called plasma exchange), a procedure in which blood plasma is removed from the patient and replaced, may be recommended. This procedure can be effective in a majority of LEMS patients.
Medications that suppress the immune response or that suppress the antibodies responsible for the weakness have also been shown to improve LEMS symptoms in some patients.
Alternative and complementary therapies
Yoga and other stretching exercises may be effective treatments for alleviating the physical symptoms of LEMS patients. Some LEMS patients also report improvement of symptoms after deep body massage or hydrotherapy.
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Myasthenia Gravis Foundation of America, Inc. 5841 Cedar Lake Road, Suite 204, Minneapolis, MN 55416. (800) 541-5454. <http://www.myasthenia.org/>.
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Paul A. Johnson, Ed.M.
—An immune reaction in which the body attacks healthy tissue, mistaking it for a foreign antigen.
—A chemical that is released at the end of a nerve to transmit a signal to another nerve or to a muscle.
—Also called plasma replacement, this technique is used to replace a patient's blood plasma, usually with donated plasma.