--for small fiber neuropathy is still, as of this writing, a skin biopsy to enumerate the density and condition of the small unmyelinated fibers in "hairy" skin (the type with hair and sebaceous glands).

There are some other avenues of research that are hoping to be able to do this without taking out a chunk of skin--some microelectric conductivity tests patterned after quantitative sensory testing (another, older technology for attempting to determine small fiber function) among them--but those seem to still be some years away from being determined valid and/or reliable.

Just wanted to chime in. You can have small fiber neuropathy, and have normal tests for the above. I feel vibration fine, heat and cold fine, etc, and my sweat test came back totally normal.

I do, however, have the small fiber neuropathy symptoms (non length dependent, burning, shooting, numbness, pressure pain-they all wax and wane), and my two punch biopsies came back with significantly low nerve fiber density, and I was finally able to get diagnosed. So I think the biopsy is really the only sure fire way to know.

Apparently Dr. Peter J. Dyck and his neurology dept. at Mayo Clinic (Rochester MN) do not believe that a skin biopsy is required. As I said before, at least in 2007, they used devices, combined with software, that quantitatively measured sensitivity to vibration, heat, & cold. The doctors told me that they get enough info from this that a biopsy is often not necessary (and they did not biopsy me). Perhaps these devices are proprietary and that is the reason you are unfamiliar with them.

The device that measures heat & cold sensitivity has a piece that attaches to a part of the body, the foot for example, I believe with a metal contact surface. Then a fluid passes through it at a controlled temperature, causing the temperature to rise or fall briefly. The patient is asked whether they felt the change and the answer is recorded. By using different settings, the patient's threshold is discovered, and this is compared to that of a 'normal' population without neuropathy. If your threshold is above the vast majority of the normal population, this supports a diagnosis of probable sensory neuropathy. The result of this test is considered with other results to make the diagnosis.

Dr. Dyck has been studying neuropathy for about 60 years and did some of the pioneering work in this field. Here is his bio at Mayo:
http://www.mayo.edu/research/faculty...d/bio-00025843
Ron

--sounds very much like qualitative (sometimes also called quantitative) sensory testing; perhaps they have some technology over there that has tweaked it a little, but it doesn't sound like anything new.

Take a look at:

http://www.medoc-web.com/about-us/technology/technique

(though this is by a device manufacturer for doing the test, the description of the process is succinct)

http://www.ncbi.nlm.nih.gov/pubmed/12795516

http://www.aetna.com/cpb/medical/data/300_399/0357.html

(I include this one as it shows that at least some insurance companies don't think the reliability/validity of the procedure is all that good--more on that below.)

http://www.neurology.org/content/60/6/898.full


https://www.aanem.org/getmedia/2621c...iques.pdf.aspx

(This last one mentions Dyck's system and also Von Frey Hairs, which almost no neurologist even knows about anymore.)


I had such testing done when I was in the midst of my acute neuropathy phase; my results were within normal limits though the skin biopsy had indicated some rather abnormal results. Many of the reviewers have noted the necessity of skilled interpretation of testing results and the rather subjective nature of patient responses to the stimuli in doing these tests.