Thanks. Do you know what they will do if my skin punch is negative? All of my blood tests were great! A1C was 5.5, my B12 was perfect, etc. Now I'm wondering...what will he do if this turns out negative?

I get the impression your doctor saw something in your EMG testing or whatever testing you had so far.

I know it is difficult waiting... but we all do it here and understand.

Diabetes is not the only cause of nerve damage. So it is good your numbers look good so far. That narrows the field.

I had my biopsy and am waiting for the results. It really didn't hurt, so I was pleased about that, but it the top punch on my thigh was sore afterwards.

There are three punches. One is about four or so inches above my ankle. Why wouldn't he do it lower down than that? My pain is only on the soles of my feet, not on my leg. I know they can't punch the soles of your feet, but why not right at the ankle?

Also, I've read that re. the results, anything above 95%, or below 5% is considered positive for SFN.

95% and 5% of what? Of the total amount of nerve fibers that someone is supposed to have? It seems like that's such a big range. Are there a lot of people who have negative biopsies, but still have SFN?

I have so many other symptoms--trouble swallowing at times, and lots of bladder problems--trouble starting to go and trouble emptying, so this would explain so much for me, BUT I have a feeling that my test will be negative. The neuro did say that he switched labs because the one that he used to use only counted nerves, but this one looks at the quality (or something like that) of the nerves.

Nervous wreck waiting.

The 5% and 95% boundaries--
 

--were originally developed at Johns Hopkins, where a lot of the original research into using skin biopsy to determine small-fiber neuropathy was done; the primary researchers (the lead researcher was Dr. McArthur, hence the "McArthur protocols") tested the intraepidermal nerve fiber density on hundreds of subjects of varied ages, some with neuropathy symptoms, most without,and came up with the numbers, and then (to me, rather arbitrarily) decided that figures below the 5th and above the 95th percentile would be considered evidence of definite neuropathy.

That doesn't mean that numbers between those might not represent neuropathy in people with symptoms though. I've written here and elsewhere on numerous occasions how since skin biopsy isn't normally done on asymptomatic people, there's generally no way to know what a symptomatic person's starting point for nerve density was. One can get a skin biopsy showing one is the twenty-fifth percentile and be considered "normal", but there's no way to know if that person was always around there or maybe started at a higher percentile and has been losing fibers due to a neuropathic process.

Fortunately skin biopsy is repeatable and one can have them done over the years--the comparative densities from the biopsy sites, the condition of the nerves as well as the enumeration, and the numerical trends of the time may all be significant clues.