I'm in another online SFN group and someone in that group posted about their positive experience with finding a Neurologist who really knew SFN.

This woman had a negative punch biopsy initially. She found this new neurologist 2 years later who put lidocaine cream on her fingertips, waited a few minutes, and the result was her fingers didn't winkle up. Apparently, if you don't have nerve damage, you fingers will wrinkle up. Very interesting.

This woman did have another punch biopsy after that and it was indeed positive.

I will try this... I know that according
To the doctor who did my arm EMGs
When I was pregnant years ago, I had
Significant damage then.

Okay... I just did this test with the lidocaine Aspercreme
And my fingers (I did the left hand) did wrinkle some.
Not as much as a long bath would do. About 1/2 as much
As a bath.

I don't have any numbness or pain in that hand either.

http://www.ncbi.nlm.nih.gov/pmc/arti...r-04-00126.pdf

I hope this link works.. This iPhone can be difficult.
If the link doesn't work, I'll get it again tomorrow.

Anyway, this link explains the lidocaine test and even
Has 1 to 4 grades of wrinkling.

Would little pieces of a lidocaine patch do the same thing, you think?

<edit>

I tried putting two on my fingers and two n my toes. Didn't notice anything, but it was probably a bogus test.

From the mechanism described, this would seem to be best at detecting degrees of small fiber autonomic neuropathy.

What also struck me, though not in a good way, is that the authors acknowledge that small fiber neuropathy is generally the first presentation in diabetics (it often remains predominantly so), that EMG/NCV cannot detect small-fiber neuropathy, but they sort of dismiss skin biopsy with the phrase "IENFD as a screening test for small-fiber dysfunction in diabetes cannot be used as a screening tool due to its invasiveness and need for high-level expertise in obtaining and interpreting the sample."

It would me much more instructive, and clinically convincing, to see how this method correlates with skin biopsy results, as the latter is the current gold standard for determining small-fiber neuropathy. Also, skin biopsy is hardly invasive and it is not hard to obtain samples--the biopsies are punch biopsies--though it does require electron microscopy and special stains to examine samples (which perhaps Singapore has limited or no access to). Perhaps this will be tried on a large scale at a neuropathy center soon.

I think the lidocaine has to be present in a concentrated amount.
The patches release only some over a long period of time-- a trickle effect.

So concentration may be a big factor and needed to get the wrinkling. Therefore, I do think the cream would be best to try.
My fingers started wrinkling within 10 minutes. In the study they mention 30 minutes. I sort of gooped it on and rubbed it in.
I didn't go past the first joint either or around the sides.

I'll do my right hand tonight. It tends to be more symptomatic than my left.

Is the cream you use prescription?

No... it is the new Aspercreme Lidocaine that this thread is about.

The Emla in the study is very similar:
from https://en.wikipedia.org/wiki/Lidocaine/prilocaine

The Aspercreme is only lidocaine at 4% strength.

Emla was originally RX and used prior to biopsies, wart removal, or other dermatological lesions. It was commonly used for children having blood draws. Typically it was applied, covered with saran wrap for about 30 minutes, to force it deeply into the skin, before the tests.

Our FDA had resisted allowing lidocaine OTC ever. But times have changed, I see, and now it seems allowed OTC in strengths below 5%. This study was done with EMLA because the Aspercreme version was not available then....and also because doctors are familiar with EMLA.

I am performing this test later. I wish there was an area of the foot that worked. I have cobfirmed large fiber. I have to me, possible small fiber. To the lidocaine batman!