Fibro/chronic pain remodels epidermal nerve fiber density (ENFD) or low ENFD causes fibro/pain? Are skin biopsy with fibro inconclusive?

junkcrap50

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I had an appointment with my neurologist to try and find the source of my muscle pains which started with methylation supplements (aching, lactic acid build up feeling with every small movement like climbing stairs, brushing hair, standing). I do have some very mild autonomic problems (low HRV, tachycardia, dilated pupils), but not textbook ones and not as severe/obvious as many on here. I asked about small fiber neuropathy and requested a skin biopsy.

Here's what he said:
-skin biopsies are not consistent
-skin biopsies are not specific enough
-referencing some fibro studies, he believes that fibro/chronic pain can remodel epidermal small nerve densities.
-his chronic pain patients who have textbook neuropathy symptoms (pins and needles, burning, numbness, etc.) do not respond very well to neuropathy medications/treatment, where as his pure neuropathy patients do respond well.
-even if my skin biopsy was abnormal, he would not diagnose me with SFN because I have no sensory deficit (no typical SFN symptoms).
-recommends genetic testing and referral to Dallas mitochondrial specialist center

Yet, he said he would order the skin biopsy if I really want it. Should I get the skin biopsy anyway?

Also, for those more knowledgeable about SFN, what do you think about his view of fibro/pain remodeling small fibers?

I disagree with him, but I haven't read much SFN literature yet. I asked him why does he think that is the direction of cause and effect. Why not the reverse - small fibers cause fibro? But he referenced some fibro papers.

I leaning towards getting the skin biopsy to rule it out and maybe a different neurologist or doctor would have a different opinion on the small fibers.

Thanks.
 

Pyrrhus

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I asked about small fiber neuropathy and requested a skin biopsy.

Here's what he said:
-skin biopsies are not consistent
-skin biopsies are not specific enough
I was under the impression that skin biopsies are the "gold standard" for diagnosing Small Fiber Neuropathy (SFN).

-even if my skin biopsy was abnormal, he would not diagnose me with SFN because I have no sensory deficit (no typical SFN symptoms).
I was under the impression that SFN was a neuropathological finding, not a syndrome, and that diagnosis did not require any specific symptoms.

-referencing some fibro studies, he believes that fibro/chronic pain can remodel epidermal small nerve densities.
I have seen a few fibromyalgia studies that speculated that pain could theoretically "remodel" neural pathways, but I have never seen evidence for that or for your doctor's assertion.
 

katabasis

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Your doctor brings up an interesting but not rigorously proven idea, and I think you need to put at least some stock in his clinical experience in treating neuropathy. Nonetheless I wonder whether your autonomic problems put you in a different category from 'pure' chronic pain patients with something like peripheral neuropathy anyway. I don't think it would hurt to get a skin biopsy if insurance will cover it - it never hurts to have more information, though it seems like your doctor is suggesting he wouldn't act on the results. In that case, maybe it would make sense to get a neuropathy panel done. Theories notwithstanding, if you can see a clear immunological cause for the neuropathy, there's a target for treatment. My neurologist who is treating my SFN asserts that the pertinent antibodies correlate well with likelihood of successful treatment with something like IVIG.
 

junkcrap50

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Thank you very much for your responses. I've lost all interest in pursuing my health lately, due to crash and hope loss, and can barely bring myself to read about SFN. So I appreciate your replies.

I was under the impression that skin biopsies are the "gold standard" for diagnosing Small Fiber Neuropathy (SFN).

I was under the impression that SFN was a neuropathological finding, not a syndrome, and that diagnosis did not require any specific symptoms.

I have seen a few fibromyalgia studies that speculated that pain could theoretically "remodel" neural pathways, but I have never seen evidence for that or for your doctor's assertion.
Yeah it sounded like like the remodeling was speculation and not proven. Thanks.

Your doctor brings up an interesting but not rigorously proven idea, and I think you need to put at least some stock in his clinical experience in treating neuropathy. Nonetheless I wonder whether your autonomic problems put you in a different category from 'pure' chronic pain patients with something like peripheral neuropathy anyway. I don't think it would hurt to get a skin biopsy if insurance will cover it - it never hurts to have more information, though it seems like your doctor is suggesting he wouldn't act on the results. In that case, maybe it would make sense to get a neuropathy panel done. Theories notwithstanding, if you can see a clear immunological cause for the neuropathy, there's a target for treatment. My neurologist who is treating my SFN asserts that the pertinent antibodies correlate well with likelihood of successful treatment with something like IVIG.
Yes, clinical experience matters and I believe him that chronic pain patients generally don't respond to treatment as well. But most clinical experience describes patients generally, and unique cases will get missed.

Is the neuropathy panel the CellTrend test for SFN antibodies: TS-HDS and FGFR3? Are there other labs that do those antibodies or others? I didn't think so.

Interesting, going to look up the exact antibody names on CellTrend's website, I noticed they have a section on their panel for antibodies relating "Complex regional pain syndrome (CRPS)." I don't think I have that either really, but another reason to test.
 

katabasis

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Is the neuropathy panel the CellTrend test for SFN antibodies: TS-HDS and FGFR3? Are there other labs that do those antibodies or others? I didn't think so.
TS-HDS and FGFR3 (especially the former) are the two most inculpatory antibodies for SFN, but keep in mind that not every SFN sufferer will be positive for them. Fundamentally, the SFN disease process has yet to be fully understood, and there are a lot of nerve antibodies that could be responsible for or at least somehow reflective of SFN. In addition to TS-HDS and FGFR3, I think it would also be good to look at antiganglioside antibodies (these are what I tested positive for), and maybe also an autoimmune encephalopathy panel, which covers various GPCRs, ion channels, etc. Mayo Clinic does both of these other panels. According to my neurologist, insurance companies are not too discriminating with which antibodies you have when it comes to proving there's an autoimmune component to SFN. If you wanted to try IVIG, getting at least one positive on those would probably be very helpful.
 

poohsilk

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Hello, your original post mentions muscle pain and not much description about any nerve pain so it puzzles me that you were going to a neurologist for it unless you are r hypothesizing the origins of pain.
I know that when I used to take a lot of methylcobalamin I had nerve pains. when I stopped them it went away. I do occasionally take methylcobalamin as well as the other B12 sublingually, and I slow down when I feel nerve pain. It may take some time to recuperate from those or from methylfolate.
 

junkcrap50

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it puzzles me that you were going to a neurologist for it unless you are r hypothesizing the origins of pain.
Neurologists specialize and treat muscular-skeletal disorders.

Nerve pain can present in different ways. Though I admit, the way I describe it / feel it is not common at all. I have found a few people on here who describe their small fiber neuropathy pain/symptoms like me. I also wanted to rule out as much as possible.