--to determine intraepidermal small-fiber nerve density and condition is a very quick and non-invasive procedure--small amounts of local anesthetic are injected at the sites and then a small circle of skin, about 3mm in diameter and 1 mm in thickness, are excised. The whole procedure takes only a few minutes; samples are usually taken from the calf near the ankle, from the proximal thigh, and often from the arm near the elbow, to check if there is a distal to proximal gradient or "die back" (nerves in lower density or worse condition farther away from the center of the body). A few band-aids and one is done.

These samples are then sent to specialty labs at which special stains are used to bring out the nerves and then they are examined by electron microscopy. Not many places do this--Johns Hopkins, Jack Miller in Chicago, Cornell-Weill/Columbia Presbyterian, Massachusetts General are among the more well-known that have the facilities, and the trained pathologists, to do so.