Temperature & Vibration Threshold tests
 

Last year, my neuro decided (after seeing me for 10 yrs) that I should be tested to see if my "thresholds of perception" for temperature and vibration are normal.

Not sure if people here have had this done. It involves putting a transducer on your foot, that can be heated, cooled to varying degrees (...oops, pun not intended). Then you push a button if you feel anything. Similarly for vibration.

The outcome was that "thermal thresholds are elevated from both feet, but vibration thesholds were normal. These data are consistent with small fibre neuropathy"

Is this kind of testing definitive? How have others been diagnosed for small fibre neuropathy? What tests?

Oh ...here are the test results:
44bx.com/misc/thresholds.jpg

Best Wishes,
Steve

What you had--
 

--is called "quantitative sensory testing".

It can certainly be used to detect suspected small-fiber neuropathy. The small fibers subsume the sensations of pain and temperature, and abnormal results on this test point to a dysfunction of those fiber types.

The problem has been that the test had always relied both on the self-reporting of the testee and the interpretation of the tester, and these are not always reliable--there is great individual variation on both sides.

The current gold standard for detecting small-fiber damage is skin biopsy to detect reduced intraepidermal nerve fiber density and damaged/swollen fibers.

Glenn is it quantitative or qualitative. IM not being picky but i have seen it referred to as qualitative and when i discuss these tests at my soon to be visit i want to ask for the right name for obvious reasons. Thanks.

I've actually seen it both ways--
 

--but in most of the clinical application papers I've read that describe the procedure, it's referred to as quantitative, inasmuch as what is being looked at are thresholds for noticing pain as temperatures are increased/decreased, and also the JND--the just noticable difference at which one can discern that the temperature has actually changed.

A fairly consistent finding in this testing (probably the most consistent finding) is that people with small-fiber damage have to have the temperature increased/decreased by a greater amount than do "normals" to say they've noticed an actual change.

Hi Glentaj

Thanks for your comments -- yes, it is indeed called quantitative sensory testing, as this is the title at the top of my test results.

I was un-aware that a skin biopsy can also be used to verify smalll fibre neuropathy - next time I see the neuro I'll raise this with him. Thanks!

I agree with your comments about variability in test results from patient perception. I tried pretty hard to be consistent, but it was always difficult. I know that the computer controlling the test would re-test, and re-test until I was consistent in my responses.

Best wishes,
Steve

K
 

Did your Neuro tell you why it took 10 yrs. to decide to do this..I
would ask if he would update,but check your insurance..Are you sure he's
up to date on PN??? If you really like him just ignore me..What more has
he told you about your PN,and do your meds help?? Hugs to all Sue :)

Ok that answers that and Steve so right.
Glenn or anybody was the resulths of Steve's test normal,or good be better
can you tell from what he has written down or Steve have you seen
the Dr. yet,and please keep all your paper work and continue to do that,
there yours. Look up LJ sheets if you haven't done that yet..Sue

Hi Steve, Thermal threshold testing did show up my small fibre damage, & an EMG showed some damage to the large nerves as well, but thermal threshold testing doesn't always show the small fibre damage as Glentaj said, if i remember right it didn't work for him, but a skin punch biopsy did, the only trouble is finding a lab in Melbourne that does it, i do not know of any myself, but if you have the symptoms of small fibre damage and that thermal test showed abnormal reactions why bother, the important thing is to find the cause, which isn't always easy.
good luck
Brian :)

Brian is quite accurate--
 

--I did have this testing and it came up "normal", but the skin biopsy did show rather definite small-fiber de-enervation and damage.

Part of the reason skin biopsy has replaced quantitative sensory testing, at least at facilities at which the former is available, is that the former is far less subject to individual reporting variation. (It's far more objective to count nerve fibers.)

I think the Neuromuscular Lab at Johns Hopkins will send a test kit and spend about 5 minutes on the phone giving instructions to whoever is to do the punch.

I know they will do this for people out of their area in the U.S., so I assume that the punch could also be done in Australia, then sent to JH for their evaluation...

Cathie

I'm with Glenn on this one, that temperature threshold test is not even being used much anymore. I do believe folks in Australia are at a disadvantage as there is no place doing skin biopsies. I do remember that post that soon a laser procedure that sounds similar to a pulse ox will be available to check for small fiber neuropathy. I do not remember who posted that, was it Dahlek??? I don't think it will be available for a few years.

I believe in the US, the procedure that was used, prior to skin biopsy was sural nerve biopsy. I don't see many folks from Australia having that procedure done either. ???

I would check into the suggestion Cathie made. The only definite way to get a diagnosis of SFN right now is skin biopsy or sural nerve biopsy. I do not know the logistics of sending the tissue to a lab elsewhere to be read, especially across borders. You can make a trip here, hey the dollar has never been lower, we are a cheap 'vacation' destination.

Some other testing in the autonomic realm, imply small fiber neuropathy, but, even with those being abnormal on me, they still did skin biopsies....and eventually that muscle biopsy.

Perhaps you can start putting pressure on your health care system to offer this test?

I was approached
 

by a neuro who wanted me as his patient [but didn't believe I had what I'd been diagnosed with] to have the sural biopsy... He referred me to his mentor, a neuro dept head [not the neuro #3 I'd first seen and had diagnosed me]
This second neuro head was pretty much sceptical that I an an autoimmune neuropathy, saying that: patient he sees who have this are in wheelchairs. I replied: Maybe because I got treatment IN TIME I'm not in a wheelchair? He ultimately agreed with me and my conclusions [and my docs''] that I'd met essentially 9 out of 12 evaluation criteria for diagnosis and treatment. AND that a sural biopsy wasn't necessary. BTW Most insurances do NOT cover this procedure as it's now considered too risky anymore-except in the most confounding of situations. Punch biopsies are going to become more common soon, trials are almost done about this, And I've read that somewhere in AU they are doing tests/trials for this procedure [can't remember where tho! Durn].
One thing to keep in mind about any nerve tests is IF you are comfy! Too hot or too cold can skew your test #'s...Here is a site:
http://www.onecallmedical.com/PDFs/E...0ISSUE%205.pdf
I'd had one Nerve conduction test early in the Am...The room was very cold...my feet were rapidly turning blue...The doc gently 'rubbed' my feet. I alternately ahhed at the warmth of his hands and almost squirmed/screamed from the rubbing of those hands. He had a space heater put into the room, but I suggested that a hairdryer on lo might be safer and easier to use in the long run..Not had a test since then...But at least my feet were tepid for the test? Now that is for regular nerve tests. I've not had the temp.threshold test either. I 'passed' good or bad all the key ones for diagnosis. AND I think I'm grateful I didn't have to do the more well 'unique' ones! Good thoughts and pain-free moments! - j

Dahlek

I for some reason thought you had posted that thread on the new procedure, which places a device similar to a pulse oximeter, on the finger, and it can sense the density of nerve fibers. Sorry, I guess, I mis-spoke or mis-posted.

One of our members posted that....for the life of me I can't remember who or on what thread....if you are out there, help!??

My doc will not do a sural nerve biopsy on me....I agree it is 'old technology' now and seems to have fallen out of favor. It was the technology probably 5 years back. I had my skin biopsy in Fall 2004, and it seemed to be well established technology back then, here in the US. Doc says nothing would be gained by sural nerve biopsy now, and I would likely have severe effects, and my feet are uncooperative enough....I agree that there is no need to damage them more. I meant to say, sural nerve biopsies were the precursor to intraepidermal nerve fiber density testing....AND that there is a newer technology on the horizon, from what I remember of that post.

Intraepidermal nerve fiber density testing is the 'new technology' for now until the laser thing comes into the public realm....which will likely increase the number of small fiber neuropathy cases diagnosed.

It is difficult to watch people struggle for a diagnosis, when the technology exists, and is actually very easy to do, and it is unavailable to them. That is my beef.

If any one remembers that discussion on the new finger test for nerve fiber, please post the reference. I would like to read it again, myself.

This, I think, was the article about laser techniques posted here:
 

http://www.medscape.com/viewarticle/563262_6


The references that have to do with the technique from the above article:

Truini A et al. (2004) Laser evoked potentials for assessing sensory neuropathy in human patients. Neurosci Lett 361: 25–28

Chiang HY et al. (2005) Skin denervation, neuropathology, and neuropathic pain in a laserinduced focal neuropathy. Neurobiol Dis 18: 40–53

Perretti A et al. (2003) Is Ross syndrome a dysautonomic disorder only? An electrophysiologic and histologic study. Clin Neurophysiol 114: 7–16

Granovsky Y et al. (2005) Thermoreceptive innervation of human glabrous and hairy skin: a contact heat evoked potential analysis. Pain 115: 238–247


Truini seems to be a big resercher in the area of alternate ways to assess small-fiber syndromes; take a look at:

http://www.biomedcentral.com/1471-2377/7/21

http://brain.oxfordjournals.org/cgi/...t/awg227v1.pdf

http://content.nejm.org/cgi/reprint/349/3/305.pdf

Thank you all so much for your comments on this thread. You've made me aware that we are lacking in skin biopsy diagnostic testing here in Oz! I'll bring this topic up with my neuro, but in the meantime, all I have to point at is my quantitative temperature threshold tests.....

Best wishes
Steve.

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