--found by skin biopsy could be from either a "typical" length dependent small-fiber neuropathy or from a gangliopathy; the distinction, as Dr. Abhey Moghekar of Johns Hopkins wrote to me, following my finding of one of his papers on this, is that typically, with gangliopathy, oen does not see the length dependent gradient. The percentage reduction in fibers is roughly equivalent from whatever part of the body the skin sample is taken, whereas with length-dependent neuropathy one expects to see much more de-enervation at foot/ankle than at thigh or elbow.

This is because in gangliopathy, when cell bodies die, the fibers disintergrate as well, and there are fewer left in the skin samples.

Of course, there are wide variations in this--it's hardly an exact science, and much of it is theoretical. Even Dr. Moghekar said to me that, given current imaging technology, it would be very hard to confirm a ganglionopathy, as those structures are too small to be imaged; he said, with what I consider typical neurologist humor, that confirmation awaits my autopsy.

On the other hand, I suspect that there are axonopathies that are not length dependent and are not necessarily gangliar. Especially when there is acute onset, toxic and autoimmune possibilities should be suspected. A more vascular etiology, such as in diabetes, would likely start garadually, and be more likely to be length dependent, because it is vascular insufficiency that is killing the nerve fibers, and that happens first in the areas farthest from the seat of blood circulation--the heart.

I too had a start in my right foot, but it spread to my whole body in days. So, was it technically length dependent, but just very acute in onset? Hard to tell.