Re: EMG results

Posted By CCF MD mdf on July 09, 1998 at 09:49:10:

In Reply to: EMG results posted by Sandy on July 09, 1998 at 07:27:53:






This is a 2nd request of a question I posted on 6/25 in reponse to your initial
answer on 6/24.  Can the results from an EMG, nerve conduction and needles, during which
I was tested from fingertip to neck, be misdiagnosed.  The results came back
as CTS requiring surgery.  However, I have 3 herniated cervical discs,
C3/4, C5/6, C6/7, also with surgery recommended.  Can the EMG actually tell
which situation is causing the problems?  I have a checkup with my PCP in
2 weeks and would like to understand how they determine a diagnosis from this
test before discussing it with him again.  Thank You.
=
Any test may be misinterpreted, or the underlying disease process may be so complicated as to render successful interpretation of the test impossible. Philosophically speaking, every time I order a test (EMG, MRI, EEG, etc), I try to have a specific question in mind so I am prepared to understand the answer in its clinical context.
The distinction between neuropathy (damage to nerve) and radiculopathy (damage to nerve root) can be fairly straightforward on EMG/NCS.
In neuropathy, conduction of signals along the nerve may be impaired (amplitude or conduction velocity or both), and the needle test may show abnormal muscle electrical activity related to loss of controlling input from the nerve.
In radiculopathy, the nerve itself is OK, so conduction will not be abnormal. But the muscle still may show abnormal responses because the nerve root damage prevents proper controlling signals from getting to the muscle. Also, with nerve root damage, often you will find abnormalities in paraspinous muscles when doing the needle exam.
You may have both, and this may lead to some confusion. For example, clinically it is sometimes difficult to tell the difference between median neuropathy (CTS) and a lower cervical radiculopathy. Distribution of the pain is similar, and sometimes weakness patterns overlap. The EMG may show signs of median neuropathy because you may in fact have one. But having one doesn't mean you can't have the other.
In general, I am very conservative as far as recommending surgery. If you have been advised to have surgery, you may wish to have a second opinion. If the second opinion is "yes" then you can procieed with better peace of mind and have fewer second thoughts after the procedure. If the second opinion is "no" you may feel confused but it's better to try to sort things out before anyone proceeds with surgery.
In some cases, surgery is absolutely the way to go. You just want to be sure that applies to you.
I hope this helps. As you know, this is for your general education. Specific comments regarding diagnosis, prognosis, and treatment options must come from your doctor after appropriate evaluation. CCF MD mdf.