--is likely the most common type of neuropathy; most diabetic neuropathy begins with dysfunction of the smaller, unmyelinated fibers that subsume the sensations of pain and temperature (and often diabetes produces autonomic symptoms, which also involves small fibers).

Small fibers are also preferentially affected in a number of autoimmune and toxic conditions.

Certainly, there are many neuropathic conditions that are more global, affecting both large and small fibers. There do seem to be a lot of people, though, who show up with "normal" EMG/NCV studies (the ones that measure larger fiber functioning) that have abnormal qualitiative sensory tests, sudomotor axon reflex tests, or skin biopsies (that measure small fibers). These small-fiber tests are relatively recent, though, compared with those for larger fibers, and many older docs/neuros are not as conversant with the possibility of small-fiber syndromes as they perhaps ought to be.