What is the importance of a MUSk test when taking medicines? My neuro says it is important due to the fact that it affects a different type of the muscle if it is positive. anybody had a positive musk test and can anybody explain?

The MUsK is another antibody that was identified as having to do with MG about 7 years ago. After it's discovery, several MGer's previously thought to be seronegative became positive on the blood tests. My neuros, when trying to reconfirm my diagnosis, run both the ACHr and MUsK tests together. The MUsK seems to show more in people that don't have occular involvement right away, but more so in the neck, back, arms and shoulders. Generally, people positive for ACHr don't show MUsK. The MUsK form seems to respond better to certain types of therapy such as plasma exchange, according to a report from the American Academy of Neurology report from 2003. So your doctor wants it for dx and treatment purposes, I'm sure.

It's because of the discovery of the MUsk antibody that I don't believe anyone is truely seronegative - they just haven't found the rest of the antibodies connected with MG yet! I'm one of those people which is why my dx is constantly being questioned.

Hope this helps!

Hi Becky,

I was curious what that test was also. I was diagnosed in 01 and had a positive result from the blood work, but I know that I didn't have that test. In 03, a year after the tymectomy he repeated the same blood work, which showed even higher levels than the first, which surprised him. He doesn't order lab work any longer, as he said it would serve no purpose. You are a wealth of information, thank you!

Take care,
Pat

Well, now the frustration grows...my 1st visit with this neuro (supposedly knowledgable in this area) because my repetitive EMG was decremental, he agreed that my dx is MG.....last wk, he now is questioning it because I'm seronegative on both achr & musk abs...even suggested the Mayo clinic....I think these Drs. need to be comfortable themselves with the dx to stay with the plan....then, when I mentioned that on my last cardio treadmill the Dr stopped me cuz of dypsnea that he could not explain, he now wants another treadmill test to confirm or get more info....in the meantime I'm on the Mestinon & do feel better, tho still have shortness of breath with any exertion, just not as bad...but walking is still problematic, slow & not very far...difficult sometimes just to walk out to the barn to feed my horses....

According to Dr A. Vinent, "The Autoimmune Spectrum Of Myasthenia", "there are still patients with typical generalized MG who do not have a serum antibody defined by a laboratory test. These patients often have less severe symptoms & are more responsive to standard treatments than the Musk-antibody positive patients. Since their electrophysiology, thymic pathology & resopnse to thymectomy tend to be similar to those in patients with early AchR-MG,we proposed that they have ACHR antibodies undetectable by current laboratory tests. At least a proportion of these patients have ACHR antibodies detectable by an immunofluorescent method using human embryonic kidney cells to express ACHRs at high density."

Wasn't it you Becky who put in her quote? I think I should send this to my neuro doc, he must not have seen this one.....I'm certainly in this category, & am not as severely affected as many of you, tho a long way from normal & can't do many things I could before....boy, am I frustrated...

Sorry for the long post, in the corner Dottie

I'm also MuSK positive, and i was told that having an thymectomy was a waste. I had my thymectomy back in 1996, and i just found last year that i was MuSK positive.

Dottie, it is so frustrating to get the dx, have it questioned over and over because you don't fit someones "mold". Being seronegative is not so unusual that it should cause someone to remove a dx, but same with the droppy eye - mine doesn't droop so that is what causes most of my dx questions. It's the pits!

As for the shortness of breath and still having problems walking, the virus I have has contributed to that on me (I now know since I had the antivirals!) for all those years. Now, when I take the Mestinon it clears up any weakness. The virus causes weakness too, much like the MG, but with feeling. For me the MG gives no feeling-I'm just weak.

Please don't let them get you too frustrated, and remember that there are so many different things that can cause the same symptoms that it can make your head spin! I'm sure your neuro just wants to be absolutely certain especially if the Mestinon isn't giving you real strong relief. One question though, aren't you the one that was given the Mestinon 180 for day use too? I'm curious if regular Mestinon wouldn't help you more.

Dottie, no!!!! That's awful news! And here I was thinking that you, at least, have been given a diagnosis with similar symptoms to mine.

I wish I could lend you my positive antibody tests. T\I've got two and they're not doing me any good any way. Actually if I could just borrow your emg decrement results I could get a diagnosis too! Okay, I'm just trying to have a sense of humor about this . . .

I can understand your frustration, oh boy can I. Hang in there. Let us know.

Ally

Dottie: I just wanted to say one more thing. Be very careful about the Mayo. I wasted thousands, and I mean thousands, of dollars going there and ended up with a neurologist who (I felt) wasn't very knowledgeable about mg. And I asked and asked for a sf emg and didn't get one, based on his opinion that it wasn't the best test for mg. That said, they are supposed to have a great mg lab. Please, if you do go, just be careful that you get a neuro who specializes in mg. Don't settle for anything less and assume you'll be sent to the right place. And don't assume that because they're the Mayo they'll want to dig and dig for an answer. They're no more interested in that (in my experience) than any other doctor.

Just my two cents.

Ally

Ally, you're not the first person I've heard have wasted time, money and hopes with the Mayo. Amazes me since they have such a world wide reputation to live up to. Maybe they've just gotten too big for all our own good! I'm sorry you're still looking for the elusive dx also. Some of them question you if the antibodies are all you're missing, some if you have the antibodies without the "right" EMG! Some of us just can't win! Hope you both get some answers that stick soon!

Actually i was going to go to th eMayo here but i'm glad i didn't, plus my insurance would of been out of network.