--is often referred to as "delayed summation"--the damaged nerves seem to be delayed in their response to weak stimuli but the response builds over some seconds until it is out of proportion to what it should be, and then it recedes over some seconds to minutes back to baseline (whatever that is for you).

This is actually quite common in small-fiber neuropathies and is also common with central pain syndromes that come from MS, Stroke, combined atrophy from B12 deficiency, and other syndromes that affect the spinothalamic sensory tracts.

I still get this, especially on my face, though it's certainly better than it was years ago during my most acute phases of this. And I do get twitching and a sort of rolling vibration at times in small muscles, as well as cramping, but I find if I take magnesium citrate religiously these are lessened.

The numbers on your skin biopsy report certainly represent a diminishing of small-fiber density, and they might represent a considerable one as who know what level you started at before symptoms. Since the procedure is rarely done on people without symptoms except occasionally for research purposes, no one can tell what your original normal levels of nerve fiber density were (they vary quite a bit, though they tend to lessen with age).

I am fortunate that my period of most severe symptoms lasted about six months and then the symptoms slowly--VERY slowly--began to recede. They are still not all gone, but I would say I am 90% better. Subsequent skin biopsies over the years have indicated I am getting some degree of re-enervation, though whether I could ever get back to what was normal for me is unlikely. Since no cause was ever found, I have to attribute the improvement to the resolution of whatever process caused all this in the first place--likely some acute autoimmune or "molecular mimicry" situation, and judicious dietary and supplement regimens.

Nerve regrowth, when it does happen, is ridiculously slow--about 1mm per day is cited even under optimal conditions. So small fibers that regenerate from sources in the spinal column down to the feet, say, may continue to re-enervate for years. AND--regrowing nerves often cannot take the exact same pathways they once did, and have to fight over, around, and through other tissue; one can get some really weird sensations when that happens, as the brain has trouble interpreting the signals from incomplete nerve pathways. This eventually dies down if the nerves are truly regenerating, but it feels often like an exacerbation of symptoms initially, which is why a lot of us keep long term symptoms diaries as this is not evident except in long-term retrospect.