This topic has been annoying me for years. Why do some MG patients, who obviously have MG, have negative SFEMG's? Is it as simple as too much fat?
http://www.smpp.northwestern.edu/~sm...2005POIntl.pdf
Quote:
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With a ‘typical’ fat layer thickness of 9 mm above the biceps muscle (Durnin and Wormersley, 1974) the amplitude of the surface EMG fell by 80.2%.
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A SFEMG needle has to go through the skin first, then subcutaneous fat and then the muscle. This article clearly shows that fat does indeed lower the frequency of the reading. I knew that this can happen when doing an EKG of the heart, so I figured it had to happen during a SFEMG. Or an RNS.
We all know about hydration, warmth of muscles, Mestinon and other drugs and things like technician experience, etc. effecting a SFEMG. But fat?
Women inherently have more fat than men. It's for a reason!
But what if that does indeed interfere with the SFEMG results?
I am just putting this out there in a continued effort to understand why the medical community keeps saying that the SFEMG is the "gold standard" for diagnosing MG (instead of a clinical exam and common sense and antibodies and Tensilon tests and . . . ).
Any thoughts on this? Last year I did find a bunch of information that says that men's muscles fatigue more quickly than women's do. It seems that this issue is a lot more complex than what neuros say about it. Thanks for any input or sharing your own experiences.
If we're the "weaker" sex, it sure seems a lot harder to prove it.
Annie