Small fiber neuropathy and concomitant diseases

Based on a study of patients who presented to the Mayo Clinic with erythromelalgia, an October 2003 article in the Archives of Dermatology found erythromelalgia to be a small fiber neuropathy.

The causes of small fiber neuropathy can be many.

There are a variety of diseases that may result in a small fiber neuropathy, including diabetes and other glucose dysregulation syndromes (eg, impaired glucose tolerance and metabolic syndrome), thyroid dysfunction, sarcoidosis, vitamin B12 deficiency, HIV, neurotoxic medications (including many chemotherapeutic agents and antiretroviral agents), celiac disease, paraneoplastic syndromes, and paraproteinemias.

This list is not comprehensive. Alcoholism, auto-immune diseases (RA, lupus, Sjögrens), Fabry's, and Hepatitis C may also cause small fiber neuropathy.

Do we all have small fiber neuropathy? How many of us have one of the concomitant diseases that can induce small fiber neuropathy? One study found that up to half of those deemed to have idiopathic small fiber neuropathy had impaired fasting glucose, a pre-diabetic state.

I do not have impaired fasting glucose or any of the other potential concomitant disorders. I was wondering if we could do a head count and see who does. How many here have one of the concomitant diseases that are known to cause small fiber neuropathy?

Yes, I also understand that small fibre neuropathy accompanies a number of other diseases. I have neuropathy in my feet where I also have very active psoriatic arthritis which is an auto-immune disease.

You may also want to check out the discussion I posted a few days ago on small fibre neuropathy?

I researched A LOT before joining to help out with moderation duties and found a number of sides that stated EM is often either secondary to or a predictor of some secondary disease.
Based on the study you read it doesn’t look like all patients need a change in glucose metabolism, just that it is frequent.

Just thought I’d weigh in - I do not have impaired fasting glucose or any of the other concomitant disorders. Very healthy with the sole exception of EM. Like everyone else, I would love to understand why this is happening to me.

I'd be interested to hear more about your experience, nwgirl. Like yourself, I do not have any of the concomitant disorders and, also like yourself, an injury preceded the onset of my EM symptoms.

Yes, EM began after a foot injury. I work out a lot and I ended up with a stress fracture due to overuse. Some poorly made custom orthotics caused a nerve injury in the same area. EM started at the same time as the nerve injury. I have had all sorts of blood tests and examinations and no one can find anything wrong with me. I am very thankful for my health, however I am frustratingly perplexed about the cause of the EM. I have been eating super clean in an attempt to determine if diet will make a difference.

CarterDK said:

I'd be interested to hear more about your experience, nwgirl. Like yourself, I do not have any of the concomitant disorders and, also like yourself, an injury preceded the onset of my EM symptoms.

How was it determined you had developed a nerve injury? There are a lot of similarities between our cases.

The nerve injury was diagnosed based on symptoms as well as EMG/nerve conduction studies. Fortunately, the nerve has healed significantly although not 100% (yet). I was told it can take 1-2 years for a nerve to heal - much slower than bone. Of course I would be thrilled if the EM would disappear if/when the nerve completely heals, but honestly who knows if the two are really even related. Maybe it’s just coincidence. I can’t begin to count the hours I’ve spent pondering that very question. Wouldn’t it be great if we could learn the exact unique CAUSES of our each of our cases of EM? How I wish there were answers and solutions for everyone.

What type of doctor did you go to for the nerve tests? A neurologist or were they ordered by the dermatologist who diagnosed the EM? How was a nerve injury suspected and what did it feel like?

CarterDK, The nerve tests were done by a Physical Medicine & Rehabilitation doctor in a practice which specializes in electrodiagnosis. I was referred by the podiatrist who was treating my foot injury at the time. A nerve injury was suspected due to very localized symptoms of numbness, burning, tingling, and weakness near the site of the original injury on the ball of my foot (esp. when weight-bearing). I would also get intermittent zinging pain up my big toe. These symptoms arose about a month or so after the original injury only after receiving orthotics and wearing them all waking hours. Fortunately, I have had a significant amount of healing in that nerve over time. But EM persists.

I have small fiber neuropathy (SFN) as a result of a long term B12 deficiency. nwgirl, you may want to have your B12 checked if it hasn't been already. Pain in the balls of my feet was one of my early symptoms. Later on a neuroma developed in one foot (swollen nerve). Podiatrist told me to get fitted for off the shelf orthotics for the neuroma, did not work and pain worsened. Eventually had surgery for the neuroma. Recovery was really rough and after several months a B12 deficiency was finally diagnosed.

Note: EM/Nerve Conduction Studies tests will not show SFN, as these test large nerve fibers. I had EM/NCS tests done at two different times, both times my results were normal.

SFN is diagnosed using either QSART or a sweat test, or with a biopsy. You'll probably need to go to a large neuro clinic for a QSART or sweat test as these require specialized equipment . A biopsy could be performed by a regular physician or neurologist, though must be sent to a special lab for analysis.

I've never been diagnosed with an impaired fasting glucose. For the past year my A1C has been at the upper end of normal. Have at times felt like I have glucose issues, enough that I purchased a glucose meter and monitored myself for a week. Perhaps an oral glucose tolerance test would have showed a problem that fasting does not? This test is rarely done unless a fasting glucose test shows diabetes as it is more costly, because it requires a couple of blood draws and patients don't want to hang around for the two hours it requires.

graciousgeekgirl, thank you for sharing your story. B12 was tested upon my request and surprisingly, it was actually high due to a B complex supplement I had been taking. I have not been tested for SFN. This is such a strange disorder.

Best wishes

As you said it is well known that small fibre neuropathy is one of the causes of EM. I have said this before on a previous discussion that many years ago I saw a registrar neurologist who arranged the normal nerve damage tests which showed only mild nerve damage and not bad enough to cause my symptoms. He suspected small fibre neuropathy and recommended having a skin biopsy done. However, the letter to my GP was written by the consultant who had never even seen me and he said it wasn’t necessary! I was furious at the time. Since then I have seen a dermatologist and it was mentioned about the skin biopsy, but he said it wasn’t sensible to do at the moment as I have poor healing. I was diagnosed with diabetes again quite a few years ago, but it turned out that it was due to my adrenal gland over producing glucose. Now this has been removed my glucose is normal, but it probably was the cause of what I now think is small fibre neuropathy. It really depresses me to think that had they known this years ago I might actually have been able to be helped with my symptoms and my EM might not have got as bad as it is now. Or if it wasn’t possible to stop things going worse at least I would have had a name to put to it, rather than just being made to feel that I was fussing over nothing.

Hi CarterDK, I am new to the group and just noticed your post regarding concomitant diseases. I was diagnosed with EM earlier this year. I also have an underactive thyroid that is now in the normal range with levothyroxine 100mcg daily. I have a real suspicion that the thyroid problem was the start of the problems with my feet. I was diagnosed with plantar fasciitis around the same time as my diagnosis with hypothyroidism. The foot pain was eventually treated with steroid injection. It certainly put the pain away for a long time, around a year or two. Eventually I realised that every time my thyroid was giving me problems my feet would be incredibly painful, I could barely walk at times, however they did not burn at night. For the past few years my feet have gradually gotten worse with the redness and burning. I cannot bear them under the duvet and this is causing difficulty with sleeping. So I for one have a concomitant disease but don't know if there is a connection with the EM. Dee


Have you had your B12 tested? Low B12 can also cause problems with burning feet, called Grierson-Gopalan Syndrome.

If you get tested, you need to know that traditional doctors in the US and many other countries use a normal range that is far too low. 200 - 450 pg/mL is the gray area where neurological symptoms are known to occur. Doctors typically use 200 as the low cutoff (mine was 196 and I had severe symptoms).

Thanks for the info, I will look into it. Dee

Thanks Dee. That's interesting.

My EM has been better lately, most likely from the mexiletine i've been taking. Unlike most here, my symptoms are primarily in my knees. Sometimes I get a sensation like my feet are hot at night, but they're never hot to touch. They don't feel any warmer than the rest of me. The sole of my foot often looks reddish at the same time. Most unusual, walking around makes these symptoms go away. That's the direct opposite of what occurs in my knees. My knees have not flared in a few weeks now either, but continue to look and feel abnormal.

My insurance approved a referral to Johns Hopkins last week. I've been having skin peeling far afield from where I have EM symptoms. So, he's sending me to a research facility.

I saw Dr. Wigley at Johns Hopkins …he is very knowledgeable with raynauds and erythromelagia. He has written a lot of books on raynauds. He is tough to get an appointment witH but is worth the wait. my symptoms also get better when I move around. I do not have pin in my knees but they definitely get red when my feet do.

Thanks for the info, Andrea! I haven't scheduled my appointment yet. I'm not in a terrible rush, since my symptoms aren't really that bad right now. There is still room for improvement though and hopefully they'll have ideas that will be beneficial.

I cannot remember the exact dates but closely after going vegan erythromelalgia reared its ugly head. Three or four years now. Had B-12 checked and it was borderline normal. Take a B-12 supplement occasionally. Flares becoming more regular and hotter. So I plan on going back to the VA and get B-12 shots or maybe a steak!

Just read about a amnitripline/keratine cream. May add that to my arsenal.