--neuropathy of the small, unmyelinated fibers would not show up on standard EMG/NCV studies, as these can only measure activity in larger, myelinated nerves. And, though the QSART is good for measuring activity of certain autonomic nerves, which are also unmyelinated, one might have a small-fiber syndrome of mostly snesory nerves that subsume the sensations of pain and temperature, without autonomic involvement.

The current gold standard for proving damage to small-fiber snesory nerves is skin biopsy to document intraepidermal nerve fiber density, though there are some other experimental procedures being developed to look for this.