It is kind of like the search for the Holy Grail.....

I think that of all causes, maybe next to diabetes, "idiopathic" must be the most common....I wonder if most of us will ever really know.

There are likely hundreds of hereditary neuropathies yet discovered.
Likely as many toxic causes as there are chemicals out there, including meds and vaccines;
Likely many traumatic and 'iatrogrenic' causes of neuropathy, such as spinal procedures, and those oh so innocuous spinal anesthesias and other things they squirt into out spinal canals;
Likely many post infectious causes, such as the Lyme that doesn't exist or is cured with 2 doxy's.

Many, many reasons will never even be pursued, since too many physicians and drug companies, medical device companies would be 'pursued'.

Eh, it is what it is. We all so hope we can find the cause, since we hope that cause is treatable and would stop our neuropathy, but, I fear that is the minority of cases.