Skyn Biopsy
 

Is a Skin Biopsy the sensitivest way to know if one suffer from Small fibers Neuropathic Pain?

Can one assume from a normal skin biopsy that he doesn't have Small fibers Neuropathic Pain?

By the way, why is it only performed on the leg? Does anyone knows?

Thank you,

PS: my skin biopsy is only sheduled for June. It is not easly available here in Portugal.

Skin biopsy--
 

--is currently the "gold standard" for determining the density and condition of the small nerve fibers that subsume the sensations of pain and temperature. Often, in cases of small-fiber neuropathic symptoms, it may be the only abnormal test, but a "normal" skin biopsy may not rule out a problem, as the normal ranges are established statistically--for small fiber density, these are set at the 5 and 95 percentiles as established by the MacArthur protocols from Johns Hopkins medical center--and one may have damage or reduction in density and not fall outside the protocols (this is one reason the condition of the nerves is also evaluated).

In order to check for length-dependent or "die-back" processes, samples are normally taken right above the ankle, the upper thigh, and the upper arm, but samples can also be taken from the lower arm, the face, or theoretically anywhere there is hairy skin.

Filipe... you need to double check what kind of biopsy you are getting.

The sural nerve biopsy is taken at the ankle, only.

The skin biopsy is new, so I'd double check. The sural one can leave you with pain forever...it sometimes damages the nerve badly and is very invasive.

Felipe,
Many surgeons will perform the Sural Nerve Biopsy where they cut out an inch or more of the nerve in the ankle region, leaving a nerve gap that may never repair correctly, leading to pain and discomfort that can exceed the original PN pain, and can be a lasting complication to post surgery.
I would leave that procedure as a very last effort for Dx, or never have it at all, since the results usually only confirm a prior Dx.
This will sometimes have pain and discomfort left........ forever.

The Skin Punch Biopsy, usually taken at 3 places, only removes the top layers of skin about the size of a US dime and heals with 3 small Band-Aids. No after affects whatsoever- a practically non-invasive procedure.
But it is only done in a few places in the US.
But...... Johns Hopkins has a mail-in kit that instructs how to take the samples, that are then sent by mail to Hopkins, for proper preparation and microscopic evaluation by experts.

Hi,

It is in fact a skin punch biopsy and not a nerve biopsy. The Dr that is going to do my biopsy here told me it was done in the leg. I said to him that my problem started in the hands/arms , but he reply me that they only can compare with a database if the biopsy his performed in the leg.

I call Bako (in the US) and they confirmed to me. They told me that they can performe anywhere but they only have normal values to campare with if the sample is taken from the leg (10 cm abobe the ankle).

Anyway did you see my thread "very interesting" ? What ever happen to the Snail venom? Does anyone knows? It had so much potentials on neuropathic pain.

Filipe

PS: Thank you for continuing replying me. I though you were hangry with me because of my obsession with MRIs :)

Filipe,

I answered you about the snail venom... take a look at the other thread. ;)

Glenn if you get a chance could you explain the 5 and 95 percentiles for small fiber nerve density. Does this mean its abnormal only if you have less than 5% or more than 95% of the average small fiber nerve density?

I also would like to know that

That's been the definition.
 

Back when they first started working on this at Hopkins, the reserachers were looking for a way to set a standard, since the degree of intraepidermal nerve fiber density is very individual, both among those with symptoms and those without, and from one spot on the body to another.

It was finally decided to consider a rather narrow range "abnormal", in order to get a fair degree of certainty that neuropathic damage actually existed for those people.

This is initially detailed in:

http://archneur.ama-assn.org/cgi/con...act/55/12/1513

Of course, as I've mentioned, it's possible for one to have small-fiber damage even if one doesn't fall into these rather narrow ranges; it all depends on at what point one started. It is known that intraepidermal nerve fiber density does decrease a bit with age, even in those with no neuropathic symptoms. And, if one starts in the 70th percentile, say, and something happens to reduce that person to the 10th percentile, they would not register as having abnormal density, though they might be greatly symptomatic. This is why a morphological examination of the fibers is also necessary.