Cary D. Buckner, M.D. talks about the Tensilon test for Myasthenia Gravis
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Host: You use to call this to do this test called the tensilon test. Is that being done anymore? Male: We do that test still and that’s a very important test and I need to tell you a little bit about the acetylcholine to explain the test but we talked about acetylcholine that travels across from the nerve to the muscle. Now, there’s a substance called the acetylcholinesterase. It’s a mouth ball but that breaks down the acetylcholine. So the acetylcholine doesn’t just hang around in neuromuscular junction it gets released and attaches to a receptor and soon after it’s broken down by acetylcholinesterase. Now the tensilon or edrophonium test is injected intravenously and what's it’s called. It’s called the acetylcholinesterase inhibitor and says that five times fast and that blocks the action of the acetylcholinesterase which supposes to breakdown the acetylcholine. Therefore the acetylcholine around longer and it can attach the receptor to come off, reattach again. It improves this normal acetylcholinerase process. Host: So it shows an improvement to keep right. Male: Right an improvement, so what you see clinically you inject the medication and you watch something improve. This is very important when you do the tensilon test. You have to have something you feel is objective enough that you can measure. So ideally someone would have a droopy eyelid. You inject the tensilon and the eye opens up. Something you can really test objectively or the eyes are skewed and you inject and they're straight now. Host: Can any people have myasthenia gravis in the tensilon test that doesn’t really prove enough? Male: Yes, that can happen. I have had patients with negative tensilon test, very often it happens with people who would offer as much experience who again don’t have that solid, objective finding that you have say for sure “Yes, they definitely improve during this test” and I wanted to talk a little bit about one thing that I was taught. When I was a resident something called the poor man’s tensilon test. You don’t have tensilon. You don’t have an IV and what you do is because myasthenia gravis with the rest of the muscle that muscles we’re trying to improve. If you use the muscle the muscle weakens. So if a patient has droopy eyelid then you can stress the system by making them look up and that strains the muscle that makes the lid also rise up the lid also. So you made them look up for about a minute and you see that the tosses or the droopy eye gets worst. And then you leave the room, you turn the lights off and you let them sleep and close their eyes for about five minutes that’s resting the muscle. You go back in and you see if the droopy eyelids improved and then you go ahead again and stress the system and see the droopy eyelid get worst.
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