Living With Polio
Usefulness of EMG
Post-Polio Health, Volume 28, Number 4, Fall 2012
Ask Dr. Maynard
Frederick M. Maynard, MD
Question: I have a question regarding differential diagnosis specifically utilizing electromyographpy (EMG, a test that measures the electrical activity of muscles at rest and during contraction). I am 63 with a family history of stenosis. I have low back pain, sometimes radiating diagonally to the hip/thigh region and increasing in intensity, leading to sudden inability to rise from sitting to a standing position from my wheelchair.
An MRI shows L4-5 stenosis. My right leg has always been very weak. The neurologist attempted EMG in the right leg but said there is no electrical response and so there is no way to identify nerve root involvement for possibly repairing the problem. Is there another way to do an EMG on an essentially flaccid leg or another test to diagnose the origin?
Answer: The potential usefulness of EMG study of a severely long-term paralyzed post-polio leg is indeed limited. There are no other tests to really substitute for it, but I would offer the following thoughts that may be helpful in deciding what is happening with your back and leg (diagnosis) and what to do (treatment).
EMG study could be done on your stronger leg, because spinal stenosis is commonly, although not always, bilateral. If you have had any new loss of sensation in your right foot or leg, this would suggest the stenosis is significant and producing sensory nerve damage.
Your history of radiating pain down the right leg when getting up/changing position/bending suggests a radiculopathy, or pinched nerve problem, in your low back is more the problem than the spinal stenosis, a narrowed central spinal canal space.
You may want to consider a spinal epidural steroid injection. These injections are usually helpful if there is a chronic pinched nerve or spinal stenosis problem causing your symptoms. Even if the problem is not cured, a temporary improvement is helpful and would support the suspected diagnosis. Injections can also be repeated and help avoid surgery, which has significant risks and unpredictable results.
The natural history of people with imaging-demonstrated spinal stenosis is that after one year one-third get better without specific treatment, one-third stay the same and one-third get worse.
Pain going down a leg when making transitional movements, such as standing up, can be a referred pain that originates from an inflammation in the muscles, joints or ligaments of the lower back, pelvis and hips. Evaluation and treatment by a hands-on physical therapist, massage therapist or chiropractor may also be helpful for either resolving the problem or clarifying the true cause.