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TENSILON TESTING 

Definition: 

A diagnostic test involving intravenous injection of the chemical edrophonium (tensilon).

What is it used for? 

Tensilon testing is used specifically to aid in the diagnosis of the disease Myasthenia Gravis. In this disease there is problem with the communication between the nerves and the muscles. This communication is controlled by the release of a substance, acetylcholine, from the nerve endings which causes the attached muscle to contract. Normally, the acetylcholine is cleared from the area by an enzymatic reaction to prevent a prolonged action on the muscle. In Myasthenia Gravis receptors on the muscle which respond to the acetylcholine are depleted or inactive, causing the muscle response to be reduced and resulting in weakness. In Tensilon testing, a chemical called edrophonium or Tensilon is injected intravenously. It transiently blocks the clearing of the acetylcholine for a few minutes allowing it to produce a more sustained effect on any muscle receptors present. In patients with Myasthenia Gravis, this results in better muscle contraction and improved strength. This improvement is gauged by the attending physician to determine whether the test is suggestive of Myasthenia Gravis or not.

Preparation: 

There is no preparation needed. The test does involve placement of an intravenous line for a short time so the arms and hands should be easily accessible and clean.

Are there side effects? 

If there are side effects they are usually brief and minor. After injection of the tensilon you may experience a few minutes of increased tearing, salivation and bowel activity. Some people describe a metallic taste in the mouth. The effects of the Tensilon last only 1-3 minutes. Rarely there is a slowing of the heart rate which the attending physician or nurse monitors for. If the heart rate becomes too low, the effects of the Tensilon can be reversed with the injection of another chemical, Atropine.

Where is it done? 

This test is done in hospitals and clinics. It may also be done in physician’s offices if they are equipped for it.

R. O'Brien MD