Thermal threshold testing
 

Has anybody had this, and is it a reliable indicitor for SFN?

I have a host of SFN-like symptoms which are slowly but surely getting worse. Had two NCV/EMG tests and a fair amount of other tests, all negative. I do have quite severe auto-immune hypothyroidism which I'm being treated for but I'm still not stablilised on a dose.

Anyway, I had requested a skin biopsy but getting one of those is virtually impossible here in the UK, so instead they're giving me thermal threshold testing - which in itself was pretty difficult to get. Am I finally going to get some sort of neuropathy diagnosis?

You may, but may not.
 

Thermal threshold testing, also known as quantitative or qualitiative sensory testing (I've seen both used), was one of the more prominent tests for determining small-fiber neuropathy problems before skin biopsy was developed.

In essence, electrodes that can assume various temperatures are affixed to body parts, and the patient reports when temperature seems to be increasing/decreasing, when the sensation gets painful, and when a difference is just noticable. In this way, the functioning of the small nerve fibers that subsume the sensations of pain and temperature can be evaluated.

The problems with the testing include wide individual variation in the snesory abilities of individuals, which may be natural variations and not indicative of neuropathy, and also the need to rely on the individual reporting of the test subject.

Certainly, this type of testing can indicate neuropathy if there are wide abnormalities of reported sensation, but it is not as exacting as skin biopsy. I had this testing done, and did not have reports outside normal ranges to the changing temperatures, while my skin biopsy rather definitely showed reduced intraepidermal nerve fiber density and damage.

Yes, i have had that test & it did confirm small fibre damage for me, at that time the symptoms were mild compared to later on when it really got a lot worse, doesn't seem to work for everyone though.

Brian :)

So, I had the test last week, and all I could think was how laughably imprecise it was.

As expected, I was a bit abnormal but not enough to say anything for sure. My cold/heat-detection tests were in the normal range, every time, at every site they did... and they were the most important ones apparently.

My cold/heat pain thresholds were often elevated but I found it quite a tricky test. At what point do you say something's painful? Yeah, you can feel it, yeah, it's cold, but is it painful? For me to actually click a button to say I'm feeling pain, it'd probably actually need to be hot enough to cause some damage, which obviously it can't do.

So, I'm still in no-mans land with no SFN diagnosis either way, and am waiting to see if the doctors here in the UK will give me a skin biopsy, which is still in trials here and not widely used. Otherwise, I am going to have get it done on my next visit to the US, or see if I can a pack sent over an analyzed stateside. What a pain.

I had my first visit to a consultant neurologist last week. The testing carried out, manually, seemed very primitive in approach, amongst other things I was wacked all over my legs with the rubber reflex hammer. In his letter to me the consultant says that he has requested " limited nerve conduction studies and somatosensory-evoked potentials". I wonder whether the latter is the same as described above ?

No, it's not the same--
 

--although it may feel the same.

Evoked potential testing also involves stringing up people with electrical wires, but it is used to determine if there is demyelination/signal delay or change in the sensory processing that goes on between the eyes (visual evoked potential or VEP), ears (auditory evoked potential or AEP) or skin (somatosensory evoked potential or SSEP) and the brain. You'd be hooked up to brain electrodes and asked to watch stimuli, listen to stimuli, or feel stimuli and the testing person will be watching your brain waves on an oscilloscope to see reaction/times and patterns.

These tests are often used when central nervous system conditions are suspected but not readily apperceptible by MRI or other imaging--a lot of people have had MS diagnoses confirmed this way, for example.

The Wikipedia article is actually a pretty good explanation of these:

http://en.wikipedia.org/wiki/Evoked_potential

Here is something that mite remotely help?
 

Basic nerve conduction studies are contingent upon the Professionals conducting the studies and the equipment they use. Also this alternative factor CAN come into play....
http://www.onecallmedical.com/PDFs/E...0ISSUE%205.pdf
These basic tests lead up to the qusart testings... but there ARE aspects that are clearly key to what all could call 'good tests'!
Because of so many professional, mechanical and environmental factors, be prepared with any new doc you see...that they will want tests of their own. To the docs? This is a way to see the issues under controls that they are familiar with.
As for key SFN issue, could you elaborate? Like are you sweating less? or More? Has your skin become abnormally dry or super oily [tho dry is the usual symptom, it's not exclusive] IF so... take a look at this site [it's up in the 'stickies' I believe, but, DO read the intro to see how the vascular system is connected to the nerve and lymphatic system and what it all can mean....while this site is for Diabetics? There are many, many connections to what anyone with neuropathy has - Go to the "Diabetes in Skin Disease' Section and click on.... go from there. It's very informative!
Just remember? That how tests are read are only as good as both the testors and the readers of such tests! And, yes! It is a heap of a lot of 'subjective'? But still, numbers are numbers...and another doc mite read those numbers a bit to a lot differently. Be sure to get copies of these tests so should you choose to get a second opinion? They've some sort of base/basis to go on.... Never hurts, you know?
Good luck! And, keep faith and hope that something GOOD will result!

Westie? Some neuro's seem very primitive? See this site [click on the blue] for a clue as to ALL they mite be looking for:
http://www.neuroexam.com/content.php?p=2

Hope for all, please, don't lose it! Treat NOW and avoid all the dreaded worst, if possible! Hope again - j