An edrophonium test helps to diagnose myasthenia gravis. It also helps to decide on probably the most appropriate dose of treatment and to follow up. We’ll explain how it really works in this text!
An edrophonium test, also called Tensilon® test, is a pharmacological test. It consists of injecting edrophonium bromide or edrophonium chloride, that are substances that react with the transmission of nerve impulses on the muscular level.
The target’s to check a patient’s muscular fatigue. Subsequently, doctors prescribe it to diagnose and assess the response to treatment in myasthenia gravis.
This test is taken into account effective and is probably the most commonly used test for this disease. Nevertheless, it should be performed with several precautions. In this text, we’ll explain what the edrophonium test is and what it involves.
What’s the edrophonium test?
The edrophonium test, along with being called the Tensilon® test, can be called the Anticude® test. These names vary because they confer with the brand name of the drug.
Tensilon® is edrophonium chloride, while Anticude® is edrophonium bromide, as a publication of the Agència Valenciana de Salut explains. These drugs act on the neuromuscular level and stop the breakdown of acetylcholine, which is a neurotransmitter that acts within the neuromuscular plate.
That’s, in the world where neurons bind to muscle fibers to stimulate them. By inhibiting the breakdown of acetylcholine, what happens is that a more marked muscle stimulation occurs.
Subsequently, the edrophonium test consists of observing what response takes place on the muscular level. There are diseases, similar to myasthenia gravis, by which there are changes within the muscle fibers resulting from acetylcholine. Subsequently, it’s useful in diagnosing and monitoring this disease.
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When is the edrophonium test obligatory?
Doctors often order the edrophonium test when there’s suspicion that the patient has myasthenia gravis. In addition they use it to regulate the dose of anticholinesterase drugs when a diagnosis of the disease has already taken place and the patients taking these drugs as treatment.
As explained within the previous section, the neuromuscular plate is the location where nerves and muscle fibers communicate. On this area, the nerve secretes a neurotransmitter called acetylcholine, which binds to muscle receptors.
In myasthenia gravis, the immune system produces antibodies that block or destroy the acetylcholine receptors. Because of this, the muscle receives less stimulation. Subsequently, there’s weakness and rapid muscle fatigue.
In myasthenia gravis, the weakness worsens with using the affected muscle. In accordance with Mayo Clinic specialists, symptoms improve with rest.
Because the years go by, symptoms progress, and periods of rest not compensate for the weakness. Greater than half of the patients begin with signs in the attention muscles. Subsequently, two very typical symptoms are drooping of the eyelid and double vision.
What does edrophonium do for myasthenia gravis?
The edrophonium test causes no breakdown of acetylcholine. An enzyme called acetylcholinesterase is chargeable for this breakdown. Because it’s not broken down, there may be more concentration. Subsequently, muscle stimulation is bigger.
When a patient with myasthenia gravis undergoes the edrophonium test, the muscles are more powerful. As well as, this test also makes it possible to guage which is probably the most suitable treatment by way of dosage.
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Previous preparation
Before performing the edrophonium test, it’s vital to take certain features into consideration. The physician must know what medications the patient is taking, including supplements or other herbal remedies.
The explanation is that lots of these substances can interfere with the result. For instance, those that almost all often alter the edrophonium test are acetylcholinesterase inhibitors. These are drugs used to treat dementia, similar to donepezil and rivastigmine.
The thought is that the physician will advise whether or not the patient must discontinue their use before undergoing the test. It’s also possible that the doctor may impose some dietary restrictions throughout the days leading as much as the test.
How is the edrophonium test performed?
A physician performs the edrophonium test and it often takes place in a specialized neurology office. First, a specialist places an intravenous needle into the patient’s arm or hand.
Then, they inject a small amount of edrophonium through the needle. To start to check whether myasthenia gravis is present, the physician asks the person to make repetitive movements.
As an article by Servizo Galego de Saúde explains, the movements may be with different parts of the body. For instance, getting up from a chair, crossing and uncrossing the legs, and keeping the arms raised. The test also studies the voice, asking the patient to count backward from 100.
Throughout the edrophonium test, several doses of the drug are injected. This tests whether the muscle regains strength after each injection. If it does, then the doctor will make a diagnosis of myasthenia gravis.
What does the result mean?
The outcomes of the edrophonium test are frequently immediate. As we explained within the previous section, the patient receives a diagnosis of myasthenia gravis if, after each edrophonium injection, the muscle regains some strength.
Nevertheless, in some cases, other tests are obligatory to substantiate the diagnosis. On this case, if edrophonium produces a transient stimulation, it implies that the disease has worsened. Then again, if injecting the drug weakens the muscle, the test points to an overdose of anticholinesterases.
Risks and proposals
Experts consider the edrophonium test to be effective and secure. Nevertheless, there are several uncomfortable side effects that occur ceaselessly. Nevertheless, they’re temporary and don’t often last greater than just a few minutes.
Nausea and stomach pain are two of probably the most common effects. Shortness of breath, sweating, dizziness, and blurred vision may additionally occur. Other patients experience eyelid twitching, increased salivation, and even fainting.
As with every injection, the location of the injection may bruise. Ideally, the patient should apply pressure or ice throughout the first 24 hours to cut back swelling.
There are few cases by which the edrophonium test has serious repercussions. Subsequently, experts don’t recommend it for individuals with baseline arrhythmias, low heart rate, or arterial hypotension.
The identical is true for patients with sleep apnea and asthma. Although there are indeed limited uncomfortable side effects, in cases where discomfort persists, a specialist can administer an atropine injection to reverse the results.
Myasthenia gravis is the essential reason for this test
An edrophonium test is a useful test to diagnose myasthenia gravis. It’s also useful for monitoring the treatment of this condition.
Problems with drug dosage are common. It’s vital to check these patients recurrently to avoid serious complications. As well as, experts consider this test to be secure and effective, so long as it takes place in a controlled environment.
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