I have been living with what I thought was idiopathic small fiber sensory neuropathy for the past 12 years.

Decided to go to Johns Hopkins for an evaulation. Results came back as follows:

Normal or negative results for Lyme, TTG, SSa, SSb, endomysial antibody, SPEP, lg quants, TSH (0.57) and SIFE.

Skin biopsy - 25029 distal thigh - right, epidermal nerve fiber density at low
range of normal at approx. 8 fibers/mm
25030 prox thigh - right, epidermal nerve fiber density and
appearance are within a normal range
25028 distal leg - right, epidermal nerve fiber density is reduced
at 2-3 fibers/mm

The three biopsies demonstrate a length-dependent neuropathic process affecting small caliber sensory nerve fibers.

My B6 is elevated at 117 ng/mL where normal is 2.1 - 21.7

Based on the above results the doctor said I had mild small fiber neuropathy. And the tests suggest the cause is the elevated B6. I also had a glucose tolerance test back in 2005 that showed impaired fasting glucose at 108. However, my yearly glucose since then has always been < 100.

The mylegram of my spine that I took with me to JH also shows evidence of lumbar polyradiculopathy. I knew this because I have been seeing a neurosurgeon who is fairly certain that the stenosis is so bad in my lumbar that it is contributing to the PN! In fact, I have scheduled surgery later this month.

My suggestion from JH is to stop my daily B6 supplement of 25 mg sublingual,
treat the lumbar problem conservatively for now, diet and exercise.

Has anyone heard of other cases where the SFN is caused solely by elevated B6? I have been taking the supplement for the past 5-6 yrs along with a multi-vit which also has 18 mg of B6 (as pyridoxine hydrochloride).

I sure would like to hear any feedback you could provide as now I am somewhat torn about the upcoming back surgery. Thanks so much.

Absolutely!!
Get off the B6 .....now!
Too much B6 is proven to cause PN.
Hopkins is one of the best. (I go there, as well.)
Do what they say.... ASAP!

One should not get PN from 25 mg a day. However, there are some people who have elevated B6 with NO daily supplements at all.

I ran into that when I found a study on autistic children that showed that they had elevated B6 naturally with no supplements.

What may happen is that some people cannot convert B6 to pyridoxal form. This requires Vit B2 riboflavin, the pyridoxal kinase enzyme to be active. Some drugs and toxins inactivate this enzyme so B6 will build up in the serum since the body cannot use it.

The PNs from B6 almost all were found with extremely high doses like 500mg a day. This was a common intervention for female PMS...and that is when some PN toxicity neuropathies were reported. And even then it is a very small number of people. It is just not common. They don't use that high dose anymore, and the only people who take it that way are those with a rare condition called B6 dependency.
Most doctors recommend B6 intake of less than 100mg a day.

If I were you, I'd stop all B6 and wait 6mons and get retested to see what level you are at. If you are normal then, you will know it was from the supplement reading high in the serum. If you are still elevated that will tell you that you have something metabolically wrong and you are not utilizing B6 properly.
If you don't convert properly, you would actually be deficient in the tissues. This would suggest using P5P, the activated form.
What form is in your supplement? Can you check? If your levels do return to a more common number, but you still have PN, I'd say the B6 is not the culprit. If you took your dose just before the blood draw, it might be a fluke, a temp reading until the vitamin moved into the tissues. Timing might be a factor as well.

Tomorrow I will look for some studies for you. You can then print them out and share with your doctor.

mrsD,

The 25 mg I have been taking daily is the P5P form. The 18mg from the daily multi-vit is not. I took my daily dosage about 4 hours before my blood was drawn.

There have always been reports of B6 as a cause of neuropathy, but some reports don't even include the doses people might have been using.

This report does give doses and is from 2005:
from http://www.ncbi.nlm.nih.gov/pubmed/1...&ordinalpos=18

Many studies echo this:
Everyone is different. The only way you will find answers to your particular situation is to stop all B6 intake for several months, and see if your PN improves (studies say it does for toxicity). If not, the other factors may be present for you.
I have used P5P 50mg for almost a decade and never had any problem but instead have had nice improvement in my carpal tunnel issues.

mrsD,

Thanks for all of your input. I am going to stop all B6 intake (both the 25 mg P5P and the 18 mg embedded in the multi-vit) for a number of months and see if the PN improves.

I may also move forward with the lumbar stenosis surgery as it is becoming harder and harder to live with and who knows, perhaps it is contributing to the PN as my neurosurgeon believes and not totally ruled out by Johns Hopkins.

If you do not have symptoms elsewhere besides the legs, I would agree with you that the lumbar issue may be your culprit.

Toxic PNs usually appear all over, not only in one place.

I would get tested for Vit D too, next time you have blood work done. Many people are low in this, and low levels contribute to chronic pain, it has been recently discovered.

Good luck on your surgery, if you have it.

mrsD,

My vit D level was checked not long ago and was ok.

My symptoms include the normal burning/stabbing in the feet but also pain coming downward from the low back through the buttock area and into the backs of my legs along with weakness through the legs. It also seems that when my back is flairing up my feet seem to be worse. That is why I have always wondered about some connection between the two or if I'm dealing with two separate issues?

Thanks again for your help and unless I hear any strong reasons why not to have the lumbar surgery, I will probably go ahead with it.

When my PN started back when I was about 30 (years before my son was born)...I had it in both hands and feet, but not the legs.
Mine is a metabolic form, due to low thyroid functions.

I think if there is a toxin, or global metabolic reason, or autoimmune component, there will be symptoms all over the body, and not localized. When localized I think looking for a specific trigger/reason is more helpful.

Please keep us up to date and I wish you a successful surgery should you decide to have that done.

you could well have two different things going on. Peripheral Neuropathy in the feet and sciatica or something similiar from your back through your legs. This has been going on to me for the last ten days. I have sensory motor axonal PN in my legs from the knee down and in my hands. My feet are dead numb. About ten days ago i started to get the constant pain in the lower back which radiated to the outside right upper thigh made my upper right leg numb. It has slowly been getting better but still hurts today. I have been taking muscle relaxer and aleve. I also have buldging and herniated discs in the lumbar and cervical spine but when i have lower back pain usually its more sharp type of pain then this current one and with the usual lower back pain i can find a comfortable postion to lay down or sit whereas with this there is no comfortable position. Because we have PN we are more susceptible to other nerve related injury or symptoms. Its called the double crush phenomenon. Glenn has posted about this many times here and if you do a search on it on here he explains it in much greater detail than i do.

Basically what im saying is that you can have more than one thing going on. Back surgery may help one but not the other.