--needs to be investigated.

It is certainly possible to have small fiber neuropathy and lose muscle mass due to disuse of the muscles caused by pain or numbness symptoms. But small fiber neuropathy, which by definition involves sensory/autonomic nerves and not motor ones, will not by itself cause muscle wasting--that would seemingly involve the neuropathy having a larger, myelinated fiber component as well. When those nerves deteriorate, signals cannot get to the muscles and muscle mass loss is a common result. (Properly functioning motor nerves are constantly sending "maintenance" signals down the pathways to keep up a slight contraction, often known as "tone", even when the muscles are not consciously being contracted or extended. Damaged nerves result in loss of "tone" first, then loss of mass.)

There are certainly neuropathy syndromes that involve primarily small fibers,but many that involve a mix of large and small fibers. One may show a positive skin biopsy and still have a "mixed" fiber situation. Often, though, damage to larger nerves doesn't show on NCV/EMG until it has progressed considerably.

Though I don't know how easy it would be to get the various tests where you are, I would think a round of testing for antibodies specific to peripheral nerve would be in order--take a look at that section at:

www.lizajane.org