EMGs and ***: Reassurance Found

Hey All,

I was doing a bad thing today. I was googling symptoms as I have been worrying for the last two weeks or so about my symptoms. But, I found some reassuring information that I don’t thing anyone has ever posted on the site. It supports what everyone has said about EMGs. The fact that one clean EMG rules out *** once symptoms start.

The information comes from a chat transcript from Dale J. Lange, M.D., Co-Director, MDA/ALS Program,
Mt. Sinai School of Medicine and Medical Center in New York. Below are excerpts from the chat.

QUESTION - If *** was progressing very slowly, at what point would it show on an electromyography (EMG) test? Is it possible that an EMG done too early in the course of the disease comes out "clear"?

DR. LANGE - Yes, to some degree -- and EMG cannot show abnormalities if the disease is not affecting the muscles studied. However, clinically affected muscles should not be normal.

(So, If you have an EMG in the area where symptoms are present…the EMG will find something!)

QUESTION -- Does that mean that an EMG is just the backup to a positive clinical examination?

DR. LANGE -- The EMG is much more sensitive than the clinical examination. The clinical exam usually does not show weakness until 30-40% of anterior horn cells [spinal motor neurons] are lost. EMG will pick this up earlier.

(Essentially, the EMG is a very sensitive test and will find things that could have been missed on the clinical exam. Therefore a clean EMG would pick up on denervation very early!)

QUESTION -- Have you ever known about a patient that has been diagnosed with *** after having a "clean" EMG?

DR. LANGE -- A completely normal EMG, and that includes the tongue and facial muscles affected in bulbar-onset ALS, is incompatible with the diagnosis.

(Clean EMG means no ***! Very simple!)


Hope this helps some people doubting clean EMG’s, including myself.

Tony

Its nice to read that again.

I actually read that once too on that site.

I was told my most of the neros and my primary that the (emgs) the test. .............period. clean test............no worries.................

I still worried...........but probably unnessisarily (sorry no spell check)

The thing I don't get is that if a clinical exam is much less sensitive than an EMG, than why would a neurologist (like the one I went too) not see an EMG as necessary if a clinical exam is passed?

There are a few things that were difficult for me to understand the first time I read this too. Some additional clarification from doctors after the fact reminded me just how "devilish" it can be to rely on snippets from the "net", without context, to help you understand complex medical areas.

Two things:

One, the diagnosis of MND is triggered by abnormal clinical signs, supported by abnormal EMG findings of a distinct pattern. That said, the doctor's comments above speak to the sensitivity of the EMG, and its value as a diagnostic tool. Honestly, massagefan, your question speaks to why neuros generally view it of no value and potentially wasteful to conduct an EMG on a patient that does not exhibit telltale features of a suspected disease progression. Indeed, many will refuse to do it. But, in a "spercharged" area such as **S, where an abnormal finding could mean a terminal outcome, doctors may rely on EMG to calm a patient down or provide concrete evidence to a potentially anxious patient that no basis for concern exists. Thus, the comment above should not be taken in the context of your question - it is instead made simply to illustrate the sensitivity, and thus reliability, of the diagnostic potential of the EMG test.

Second, and this is the one I REALLY grappled with when I first read this Q&A some time back, the doctor's commets regarding testing affected muscles also lacks context. Many of us OFTEN struggled with the poosibility of an EMG being performed in the "wrong place", or "missing affected areas". Simply put, this is also without basis. By its very nature **S is a disease of prgressive degeneration of nerve pathways along a specific channel(s) that ultimately causes nerve disfunction and leads to muscle degeneration. This process is not sporadic, and does not "set in" on a single muscle or muscle grouping in the absence of biologically associated nerve and muscle groupings. Thus, many doctors, for example, will avoid testing the foot itself, due to the unreliability and difficulty in generating accurate EMG readings in such a fine muscle grouping. Instead, they will test muscles in the lower leg (medical name(s) I forget right this second) that share biologically connected pathways with the "problem area" and the location is reliable as an indicator for the presence of disease. Simple rule of thumb, if you told the doctor the general area you were experiencing problems, and he/she tested based on your description, they tested in the right places to pick something up if something sinister exists.

I hope that helps. I know when I first read that Q&A - I had more questions than answers.

JG

Ok- that makes sense to me....I'm sure any self-respecting neurologist wouldn't let you walk out of the office if they thought you had anything suspicious. Mine basically said, "if you decide you want an EMG, you'll need to call us so we can order it for you"...said with annoyance. Which I translated into "You don't need one but if you must persist you can have one"

So, I opted out....