--is itself a fairly simple and not particularly invasive procedure; the tough part is getting the samples taken to a lab/facility that has the correct staining equipment and electron microscopes to do an accurate analysis.

What happens is that a small shot of local anesthetic is given in the region from which the sample is to be taken--typically, samples are taken from the side of the upper thigh, the side of the lower calf, and sometimes from the fleshy area right above the elbow (these are the areas which research has "standardized")--and then a small skin sample, typically about three millimeters in diameter and about a millimeter in thickness, is cut out. The procedure takes no more than a few minutes, and a pressure bandage/antibiotic is then applied, and one may be observed a few minutes to make sure bleeding stops. The samples are then sent to be analyzed for intraepidermal nerve fiber density and condition.

I've had this done several times--one of the good things about skin biopsy is that the same general areas can be sampled repeatedly over time and the results compared to see if one has small fiber neuropathy and how it is progressing or reversing. While I know many things can trip off RSD/CRPS flares, this procedure happens so much on the surface that I think it would be unlikely to disturb the body enough to cause one.

I have not had IvIg as no other testing in my case indicated there was direct evidence of autoimmune reaction, though autoimmune mechanisms are one of the leading theories for many people with idiopathic small-fiber neuropathy. Usually IvIg is used in those people who have conditions such as chronic inflammatory demyelinating polyeneuropathy (CIDP) in which autoimmune attack on the nerves can be demonstrated.