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Negative EMG

  I have previously posted about my condition.  Long story short.
  Over 18 months ago, I had a spinal for a C-Section.  The spinal
  had to be done a number of times and immediately after, I
  noticed that my right leg, knee down to my toes, were numb
  feeling, tingeling, hot/cold feeling and would fall asleep
  constantly.  I saw a neurologist soon after and he did an EMG
  and a MRI.  EMG came up positive and the MRI was fine.  He told
  me just to wait and that in time my nerve would re-grow.  A year
  later, after I had fallen and sprained my ankle due to the weakness,
  I saw a new neurologist.  Her EMG and MRI came back negative.
  She told me that that did not always mean anything and she was
  sure that I had nerve damage.  She put me on a bunch of medicine
  and told me just to wait it out.  I decided to go to a large
  university here in Michigan and get an oustide EMG.  It also came
  back negative, although the test results were interesting to me.
  The lowest normal would be 51 and I would be 52.  The doctor
  said that was still normal and he thought that my fibers around
  my nerve in L5 were probably damaged, but that an MRI should
  show it.  He told me again, that time would be the only thing I
  could do now.  He told me that although the EMG showed it to
  be negative, that it didn't always mean anything.  
  I am quite frustrated now.  The all have told me that I probably
  have nerve damage, yet the tests don't show it.  Could you
  explain that to me???
  Thanks in advance.
Dear Kristy,
thank you for your question.
There are a few reasons why an EMG can be negative in radiculopathy ( pinched/damaged nerve as it comes out of the spinal cord inside the spinal canal):
1. The test is done too early (less than 3 weeks)
2. The problem is affecting the sensory fibers (those responsible for sensation, so there will be numbness, tingling, pain, but no weakness) only. EMG assesses the motor fiber, so naturally it won't show any abnormalities in this case.
3. The problem is too old (over 6 months), although usually if there is enough damage done, this can be detected as chronic changes.
4. The problem is in the high lumbar region. We just don't have a good way to check this.
MRI is very sensitive, too sensitive at times, it shows abnormalities that do not mean anything, i.e. abnormalities that is common in asymptomatic individuals, such as disc bulging.
If there had been nerve damage affecting the L5 nerve root that is severe enough to cause weakness, the most common symptom is foot drop.
Dragging of foot, toe catching, tripping, etc. There maybe atrophy (loss of muscle bulk to the side of the shin bone, and it is difficult to bend the ankle up toward the head. If the problem is related to the spinal anesthesia, the MRI may not show this, as it really is not a pinched nerve (from a disc or something). Well, I hope this information is helpful. Please don't hesiatate to post followup question or comment.
Good luck to you.

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