MRI 's

  The patient has all the classic signs of an HNP e.g. numbing sensations down her arm, tingling in fingers etc. etc.. yet the MRI comes up negative..what are the odds of getting a false negative on an MRI? Thank you in advance for your anticipated response.
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This happens often.
The issue of "false negative" is more subtle than you might think. If you strictly define false negative as failure to visualize a structural abnormality that is there, I'd say the rate is very low with MRI. That is, if there is disc or other debris mashing down on neural structures (cord or roots), assuming the study wasn't compromised technically then you get a pretty good view and should be able to catch what's there.
On the other hand, it is often the case that symptoms of nerve root irritation (numbness, tingling, electric shock, pain, etc in the appropriate distribution in a limb) happen without any demonstrated structural lesion.
The purpose of the MRI is not to prove or disprove symptoms - if you have symptoms, you have symptoms and treatment is planned accordingly. The purpose of MRI is to identify structural abnormalities which could be threatening without surgical intervention.
I hope this helps. See your doctor for a treatment plan (physical therapy, ibuprofen, etc) or if you would like a second opinion you may call 800 223-2273, ext 4-5559 (neurology appointments). CCF MD mdf.