Eaton-Lambert Syndrome Health Article

Description

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
• fatigue
• 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.

Causes

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.