The underlying cause of fibromyalgia may be small-fiber polyneuropathy for some patients

This article was originally published on NationalPainReport.com and is being republished here with permission from the editor. 

The underlying cause of fibromyalgia may be small-fiber polyneuropathy for some patients | Fed Up with Fatigue

We’ve all been told fibromyalgia is a diagnosis of exclusion, but how thorough was your doctor in ruling out other conditions that mimic fibromyalgia? I’m sure we were all tested for rheumatoid arthritis, lupus, hypothyroidism, anemia and maybe Lyme disease, if we were lucky.

But I bet there’s one test most of our doctors skipped: a skin biopsy for small-fiber polyneuropathy (SFPN).

SFPN is a neurological condition that causes chronic widespread pain and affects autonomic functions in the body, such as heart rate, blood pressure and sweating.

(Read: What is neuropathy?)

(Read: How is neuropathy diagnosed?)

(Read: What are common causes of neuropathy?)

Multiple studies have confirmed SFPN is extremely common in fibromyalgia patients.

But Anne Louise Oaklander, associate professor of neurology at Harvard Medical School and director of Massachusetts General Hospital’s Nerve Unit, doesn’t think SFPN is just a comorbidity of fibromyalgia; her research suggests SFPN may actually be the cause of fibromyalgia in some patients.

In 2013, Oaklander published a study that found 41 percent of fibromyalgia patients tested positive for SFPN using a skin biopsy versus only 3 percent of healthy controls. Fibromyalgia patients with SFPN were then tested for various causes of the neurological condition, and Oaklander found an interesting trend: The most common cause of SFPN found among patients with fibromyalgia was immune system dysfunction.

These findings could be a game changer for some fibromyalgia patients since SFPN can be treated, and in some cases, cured.

“This provides some of the first objective evidence of a mechanism behind some cases of fibromyalgia,” Oaklander said in a press release. “Identifying an underlying cause is the first step towards finding better treatments.”

Oaklander says many physicians – even some neurologists – have not heard of SFPN, so that’s likely why so many of us with fibromyalgia were never screened for it.

SFPN can cause a range of symptoms reported by fibromyalgia patients, including various manifestations of pain, chronic fatigue, digestive issues, brain fog, headaches and many others.

“A lot of these fibro patients I’ve seen may have gone to see dozens of different doctors over the years,” Oaklander said during an interview. “What happens is [medical providers] haven’t focused on finding what’s called a unifying diagnosis. Instead, they tell the patient, ‘Oh, you have irritable bowel. Oh, you have interstitial cystitis. Oh, you have fibro. Oh, you have chronic fatigue.’ They don’t say, ‘Wait a minute, how likely is it that one person would have six different problems that are not related in some way?’ Because these [small-fiber] nerves go everywhere in the body, one disease can cause many, many different symptoms. [Medical providers] have been looking at this from their own perspective of their medical specialty and not seeing the big picture. Small-fiber polyneuropathy brings the big picture in that it can explain a lot of different symptoms.”

Oaklander’s research found SFPN in fibromyalgia patients is most often caused by an autoimmune response.

“We think we have discovered a new disease where there is what’s called nerve-specific autoimmunity that’s targeting the small fibers,” she said. “It makes sense logically. There are autoimmune diseases that target every single cell in the body. Why wouldn’t there be some patients who have [an] autoimmune [response] directed at the small fibers?

“But it’s a new discovery, and when you make a new discovery, it really takes a long time and a lot of work to get it established. We have a bunch of papers that have evidence for it, but it’s far from proven at this point.”

Oaklander has been using intravenous immunoglobulin (IVIG) to treat patients with SFPN caused by immune dysfunction.

“We have patients who have done much, much better once they’ve started on immunotherapy to where they’ve been able to get out of bed and go back to work,” she said.

And some patients have been cured.

(Watch: Small Fibers, Big Pain: New Research on Fibromyalgia and Small Fiber Neuropathy)

(Read: New research helps unravel the mystery of fibromyalgia)

The problem is IVIG is extremely expensive; treatment can run around $100,000 per year. It’s hard to get insurance coverage for it, so Oaklander and her team are trying to identify a more affordable treatment.

“IVIG is the best we can do right now, and it’s been a breakthrough, but we’d like to find something that’s cheaper, much more available and easier to take,” Oaklander said. “To do that, we’ve actually got to go to the molecular level and the genetic level and understand what’s happening. We have a large National Institutes of Health grant application to prepare for randomized clinical trials of immunotherapy for these patients.”

For now, Oaklander believes patients can benefit from the existing research linking fibromyalgia and SFPN.

“Given that a dozen different [research] authors have published papers that say small-fiber polyneuropathy underlies or contributes to fibromyalgia, it’s fair to say that every single person diagnosed with fibromyalgia should be asking their doctor if they could have small-fiber polyneuropathy as an underlying cause,” she said.

Physicians of patients who live near Massachusetts General Hospital in Boston can request a skin biopsy test by filling out this requisition form. For those living in other areas, visit Neuropathy Commons’ Find Care portal to locate a specialist near you to be evaluated for SFPN.

Now it’s your turn: Would you like to be evaluated for small-fiber polyneuropathy? Why or why not? 


  1. Sue Swain says


    I want to comment on the antidepressant withdrawal symptoms I’ve had with Effexor. It is a BITCH to get off of, but finally after over a month, I am feeling some normalcy. Was placed on this med several years ago for pain control (Fibro, migraines, ankylosing spondylitis). If I missed 1 day withdrawal (disconnected, dizzy, fatigue, etc., rendered me non-functional. Personally, I think it needs to be banned. The down-side, which is the lesser of the two evils is that my joint pain has escalated.

    Thanks so much for posting this article.

  2. Marilyn says

    I have FM, one of the side effects can be over stimulating flashing/moving ads used to generate money to sponsor having FM articles or blogs being available to others. I could not read this article. I lower page ad moved with every reset of the page, the ad moved at each manual move I made to read further idleness the piece. I tried to see if I could halt it, I could not. I will not be reading these again, sorry for me and others that have this very distracting ad move with each line of text I move.

    • Donna Gregory/FedUpwithFatigue.com says

      I’m not aware of any moving or flashing ads on my site, but I am checking w/ my ad network to verify that. Thank you for letting me know.

      • I don’t have that happening when I’m reading your articles. I know the kind of ads she’s talking about though. It might be browser specific, ad-ware etc.

    • Marc Gelderblom says

      You could install an add blocker, switch browsers, (Chrome, Firefox, Microsoft Edge) I would also suggest your scan your PC for ad-ware.

  3. I don’t know the cause of my fibromyalgia but my dad had it and my niece has it. The three of us are also gluten intolerant. In regard to SFPN, I am leaning toward believing I have it bc every time Ive gotten a massage it triggers alot of pain (a flare) for two or three days. The therapists did not massage my neck at my request. I tried it twice theee years apart and never had one again.

  4. Cindy Fisher says

    I wonder if SFN could be one of the causes of my pain, especially since I developed Burning Mouth Syndrome in November 2016?

  5. It’s been known for awhile that many people with Fibromyalgia have small fiber neuropathy. I often test for SFN in people who have a predominant neuropathic quality to their pain. And sometimes the diagnosis helps them get benefits and healthcare, in an environment where ‘Fibromyalgia’ is often not acknowledged.

    But to call Small Fiber Neuropathy “The Cause” of fibromyalgia is woefully mistaken.
    I reviewed Dr Oaklander’s study, and yes, there’s more evidence that a disproportionate number of people with Fibromyalgia have small fiber neuropathy.
    But association does not prove causality, and she is off-base stating that SFN is the “mechanism behind some cases of fibromyalgia”. There’s no evidence to support that assertion of causality. And a big picture look at the problem suggests otherwise.

    There’s a basic distortion in most medical thinking. I say that as an MD who trained in the best hospitals in America. We’re so enamored with the desire to find a single cause for a disease and treat it with one treatment, that we inappropriately place that framework on diseases that are multifactorial. And it distorts our understanding and therapeutic interventions.

    So a neurologist says the cause is from the nerves. A chiropractor says its from dysfunction in the suboccipital joint or ankle. A rheumatologist says its inflammatory. A psychiatrist says its from stress and anxiety.

    And four blind men walk up to an elephant….

    Lets look at the facts: We know that there a number of physiologic imbalances in fibromyalgia. That includes:
    –Hypothalmic Pituitary Adrenal Axis dysfunction (read a dys-regulated stress response),
    –Mitochondrial dysfunction (read: cellular energy deficit)
    –Increased oxidative stress (biochemical stress that comes from inflammation, toxicants, etc)
    –Elevated inflammatory communication molecules (with or without elevated inflammatory markers)
    –Irritable bowel syndrome and probably intestinal permeability (drives inflammation)
    –Insomnia despite profound exhaustion
    –Decreased pain threshold (central sensitization)

    All of these physiologic changes have the potential interact in a system of ‘vicious cycles’ that perpetuate and can deepen the severity of the problem over time. And they explain ALL the symptoms.

    Depending on genetics and factors we don’t understand, some of those patients develop POTS, some of them have small fiber neuropathy, some of them have rheumatologic diagnoses, and so on.

    So here we have another diagnostic association with Fibromyalgia with a measurable physiologic dysfunction.
    And people want to call it ‘the cause’ of fibromyalgia.

    Seems much less likely to be the cause, than it is an outcome of the same underlying complex multifactorial process.

    The sooner that modern medicine stops aching for ‘one cause for one disease with one treatment’, the sooner we might start understanding multifactorial issues and addressing them multifactorial treatment that emphasizes enabling the body-mind system to shift back to a healthy equilibrium.

    • Adriane says

      Excellent and as a nurse and fibro patient you are so on the right track here. Thank you for taking the time to re-educate!!!

    • So doc, what’s your recommended treatment then for Fibro ? Fibro seems to be an umbrella term that contains a lot of different underlying illnesses. It’s very possibly that the majority of these cases are folks with nerve damage. To me that’s what this article is saying and it seems reasonable. Nerve damage affects many different systems and could explain all the crazy symptoms. It would also explain how there’s not a single cause…there’s tons of different ways to damage the nerves. Maybe the majority isn’t because of an auto immune factor like in SFPN but somehow nerve damage, which then leads to Fibro. Which is like an amplified response to nerve damage.

    • Dr. Shiller you are soooo right.

      Looking so hard for “one cause-one treatment” really ruins research. Testing one treatment or substance at a time to see what works is a lousy way to find a “cure” for complex illnesses. Some treatments or substances when used synergistically may actually provide a cure, but the combination of those substances will never be tested in a research setting because past research has concluded that the substance/s when used individually were ineffective. They then throw the baby out with the bathwater and keep looking for that one “cure.” What a waste of time, money and effort.

      In the meantime people continue to suffer, unable to work, unable to live normal lives.


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