I had this test also, and had carpal tunnel surgery.
When the the doctor got the results, he showed me where it showed 'absent'. I said what does that mean. He replied, time for surgery !. (meant there was NO response/twitching to the signal for one of the zaps.. Not good. Often the number is lower than normal, but not 0.)
I was getting more than numbness and tingling. I would get severe pain at night, that was helped somewhat with splits and advil. So I wasn't that surprised.