way back in 2003 i was diagnosed via emg/ncs with peripheral neuropathy. the neurologist that did the test referred me to columbia presbyterian hospital in manhattan. the first thing that they wanted to do to look for a cause, before blood tests, glucose tolerance tests, a1c, spinal tap or anything else was a nerve biopsy on the sural nerve. I read up on it on the braintalk peripheral neuropathy forum which was the active one at the time with some of the same posters who are here still, and ran not walked to another neurologist who gave me a full testing workup without the sural nerve biopsy.
you must become fully involved in understanding and researching the testing, diagnosis and treatment of your medical issues, because it is you who will be the one who will be suffering or debilitated when unneeded or damaging procedures, surgeries or Rx's are done or presecribed to you.