There seems to be quite a large overlap between fibromyalgia and small fiber neuropathy. I recently read a study that claims about 50% of people diagnosed with fibromyalgia show damage to their small fiber nerves.

I have also noted that there is a large overlap between benign fasciculation syndrome and small fiber neuropathy. (Again, studies have shown a high percentage of people diagnosed with BFS show damage to their small fibers if a biopsy is done)

I believe you are correct that a defining feature of fibromyalgia is that there is no damage to the nerves. But then why do so many people diagnosed with fibro show small fiber nerve damage??

It's really hard to say exactly what all this means. Are people being diagnosed incorrectly? Do they have multiple disorders? Is there actually a continuum of disorders that cannot be easily separated? Unfortunately, I don't think anyone knows.............