--while the skin biopsy to test for intraepidural nerve fiber density is not a common test, and many places have no idea what it is, it's certainly offered through more places than Therapath.

I had mine done at the Cornell-Weill Center for Peripheral Neuropathy. It's also done at Massachusetts General, The Jack Miller Center in Chicago, Johns Hopkins in Baltimore, where it was first researched and developed, and a few other tertiary centers. And Hopkins will send a kit to physicians now so that skin samples can be taken and sent back to their lab for analysis.

The samples need a certain type of staining and electron microscopy for analysis, and that's why this procedure, which is the current gold standard for diagnosing small-fiber damage, is not more widely available.