Definition This test is done to help diagnose myasthenia gravis, a condition in which muscles become tired and weak. In this test, a medication called endrophonium, or tensilon, is given into a vein. Then the responses of certain muscles are evaluated.
Who is a candidate for the test? The tensilon test is used to confirm the diagnosis of myasthenia gravis. This test is often used to monitor anticholinesterase therapy, a therapy to treat myasthenia gravis.
How is the test performed? In this test, an intravenous line is placed in a vein. Then the tensilon is given slowly. After a small dose of tensilon has been given, the person is asked to do various exercises to make the muscles tired. Once the muscles are tired, more tensilon is given, and the responses of the muscles to the medication are observed.
What is involved in preparation for the test? A person should request specific instructions from his or her doctor.
What do the test results mean? Normally, tired muscles will not respond after tensilon is given. However, if a person has myasthenia gravis, then the muscles will improve right away in response to the tensilon.
Sometimes a person with myasthenia gravis has a myasthenic crisis. That is, his or her muscle weakness suddenly gets worse. This requires anticholinesterase therapy. When tensilon is given to a person who has myasthenic crisis, muscle strength improves for a short time.
Sometimes a person will experience an overdose of anticholinesterase therapy. This is known as a cholinergic crisis. In this case, tensilon will cause the muscles to become even weaker.
Author: David T. Moran, MD Reviewer: eknowhow Medical Review Panel Editor: Dr John Hearne Last Updated: 26/05/2005 Contributors Potential conflict of interest information for reviewers available on request
