Tensilon Test Or Edrophonium Test: Its Principle, Procedure And Results

Tensilon test which is also called Edrophonium test is performed for the diagnosis of myasthenia gravis. It is also performed for the differentiation between myasthenia gravis and cholinergic crisis.

If you don’t have enough knowledge about myasthenia gravis, it would be difficult to understand about tenilon test and its principle. So first lets learn about myasthenia gravis.

What is Myasthenia Gravis?

Myasthenia gravis is an autoimmune disease. In this disorder, the post synaptic acetylcholine receptors are destroyed by anti bodies that are formed against it. Thus the person/patient have extreme weak muscles. The reason is not because of neurotransmitter acetlycholine. But it is because of less receptors. There is normal quantity of acetlycholine present but due to absence of enough receptors that acetlycholine is of no use and thus there is muscle weakness.

This disorder is treated with anti acetylcholinesterase such as neostygmine, physostygmine and pyridostygmine. Tensilon or Edrophonium is also one of them but it has very short half life and thus used for diagnostic purposes mainly.

So when these anti cholinesterases are taken, they slow the process of degradation of acetylcholine, the neurotrasmiter and symptoms of myasthenia gravis are improved.

Purpose of Tensilon Test:

As mentioned, there could be two purposes for edrophonium test:

To diagnose mystenia gravis.
To differentiate between mystenia crisis and cholinergic crises.

Principle of Tensilon Test:

The principle of edrophonium test is that, a drug called tensilon antagonises cholinesterases which are enzymes that degrade acetylcholine. In turn less Ach is degraded in more of it is available for receptors. If a person has less receptors, he/she will have improved symptoms of muscle weakness because more Ach will be available which will act on all the receptors and causes muscle contraction.

Tensilon Test Procedure:

Here are the steps that you need to do to perform edrophonium test:

First of all get consent from the patient and tell him/her about the procedure.
Ask whether he/she is already taking some medications or not and about diet.
Keep atropine etc with yourself so that you can reverse edrophonium actions in case the patient condition gets worse.
Start by giving a small dose of tensilon intravenously. You can give it in the arm or back of hand.
After that ask the patient to perform some muscular activities like getting up and down, crossing and uncrossing legs, holding arms overhead etc.

Edrophonium Test Results:

If the patient show relieved symptoms of muscle weekness after injecting a dose of tensilon, it means that the person is a patient of myasthenia gravis.

If the patient symptoms worsen after injection tensilon, it means that the patient has cholinergic crisis and to reverse that you must give atropine.

Tensilon Test Precautions:

Here are some of the things that you need to take care of while performing tensilon test:

Always keep atropine or other antidote with yourself before starting the test.
It is better to perform the test in such a place where emergency resuscitation equipment is available.
Always ask the patient about conditions bradycardia, asthma, low bp, other heart problems etc or any other condition in which edrophonium test is contraindicated (mentioned below).
In case of hematoma under skin at injection site, apply ice and then switch to warm compresses after 24 hours.

Tensilon Test Indications:

This test is advised if:

The doctors suspects that the person has myasthenia gravis.
If the patient of myasthenia gravis has muscle weakness when he/she is taking medications. In this case there could be myasthenia crisis i.e the patient condition has worsen or there could be cholinergic crisis i.e that patient has taken more anti cholinesterases.

Tensilon Test Contraindications:

You should not perform this test if the patient has the following diseases:

Cardiac arrhythmia
Asthma
Hypo-tension
Urinary tract or intestine obstruction
Bradycardia

Tensilon Test Side Effects:

Here are some of the side effects of edrophonium test. If the patient experience any of these you can reverse it with atropine. Or if it is not severe, you can wait 10-15 minutes because tensilon has very short duration of action and that’s why it is the best anti cholinesterase for this test.

Blurred Vision
Constipation
Nausea
Sweating
Salivation
Breath difficulty
Muscle twitching
Fainting
Upset stomach

And all of the side effects of cholinergic agonists. Because tensilon is an indirect cholinergic agonist.

So this was all about tensilon test which is also called edrophonium test. If i have missed something or you wanna add something, kindly use the comment section below to contribute to this post.