--is VERY unlikely to have anything to do with the reduction in small nerve fiber density that the skin biopsy showed (though obviously, nerve impingment in the spine and adjacent nerve roots can cause neurological symptoms of their own). The decreased ankle reflexes may be related to the lumbar situation, though.

Given the skin biopsy and QSART results, you definitely seem to have something attacking the small, unmyelianted nerve fibers that subsume the sensations of pain and temperature and underlie many autonomic functions. It's not unusual for people to get both sensory symptoms and autonomic ones from small-fiber syndromes, though for many the autonomic ones remain minor and subclinical (they often manifest in sweating or blood pressure difficulties).

It's also not unusual for people with small-fiber syndromes to have normal nerve conduction/EMG results--these test only measure gross action of larger, myelinated nerves.

The length dependency implies "die-back"--in many neuropathies, the fibers farthest from body center mafunction first and more severely, as they are more difficult to get oxygen and nutrients to, and waste proudcts out from, especially if there is some sort of small-vessel circulatory problem, which is common in diabetes (the most common cause of small-fiber syndromes) and autoimmune ANA vascular/collagen/connective tissue disorders (an underappreciate cause of small-fiber syndromes).

You should see:

http://neuromuscular.wustl.edu/sensory-pain.html

http://neuromuscular.wustl.edu/sensory-small.html

http://neuromuscular.wustl.edu/nother/diabetes.htm

http://neuromuscular.wustl.edu/antib...tml#vasculitis

As to the progression/prognosis, very hard to say--some people have slowly progressive course, some plateau, some even reverse, but al lot of this may depend on whether the cause is actually findable. I understand why the IVIg was recommended, as this has a decent record of slowing/arresting autoimmune attacks, but it is very expensive. I defintiely would look into supplementation threads here to try to maximize your nerve healling environment.