biopsy for small nerve fiber

Hi there- In the beginning of your post, you mentioned “small nerve muscle biopsy,” but when you quoted the NP about ordering a kit, it sounds like she was referring to what’s known as a skin punch biopsy. Do you know which biopsy they were recommending?

If your primary symptoms are small fiber sensory neuropathy, then it’s likely you’d need a skin punch biopsy. They take a small sample usually from two points on the most affected limb and count the small nerve fibers. It’s an outpatient procedure, but most clinics take the sample and then have it sent to an outside lab that processes it because not every hospital can process those samples, hence the need for a “kit” and provider trained to take the sample.

This also doesn’t necessarily tell you the type (meaning the cause) of neuropathy you have—mine was a long time ago but they counted the sensory nerves and nerves or glands that had to do with sweating (which is also involved with small fiber nerves).

I was told it can confirm small fiber neuropathy but it can also miss at least 30% of cases (per my neurologist). In my experience, the reason they say it won’t affect the treatment is because if they ruled out all other treatable causes of your SFN (B12 deficiency, excessive B6, current exposure to a chemical, etc.), the treatment remains the same. So some providers don’t even recommend or offer a skin punch biopsy because it may or may not help with diagnosis and it’s not always an option (you need a provider trained to take the sample).

I’m not familiar with the Pittsburgh area, but you’d want to look for a neuromuscular neurologist, usually. To be honest, I didn’t get much help from my neurologist except for diagnosis. Usually their role is to rule out other conditions and see if they can identify a cause of the SFN. If they can’t, then they go to managing symptoms: gabapentin or Lyrica, lidocaine patches, capsaicin or menthol cream, Cymbalta, I’m guessing you’ve heard the schpeel by now.

Definitely pursue further consultations if you don’t feel satisfied with the workup because if they are able to identify a treatable root cause (i.e. B12 deficiency) that’s meaningful. But if not, it goes to symptom management, which I completely recognize can be frustrating. But I personally wouldn’t count on a neurologist for assistance with symptoms management; it’s not usually the box they work in, whether it’s right or wrong.

There are a lot of active discussion here where others have shared what’s worked for them.

Personally for me, PT geared toward pain neuroscience, graded motor imagery (especially using the app Recognise for my lower limbs), topical peppermint oil, and a pain neuroscience treatment like the one used in the app Curable (just as an example—they also have a lot of free pain education resources), comfortable and well-fitting socks (Bombas brand) and shoes, and gentle yoga, is what helped me. But…everyone is different. And I’m afraid of gabapentin and Lyrica so I had to consider other things.

Pretty much none of those recommendations came from a neurologist, except I did have one who was great, but she relocated.

I was a yoga teacher who practiced daily. I am now afraid to do many of the asanas I did regularly up until ten weeks ago. I will look into Curable. Thanks.

That’s tough. I used to practice 2-3 times a week too, and I miss it. I did gentle vinyasa, but I struggle with it mostly though because of joint pain due to a different condition and it’s hard to find asanas to substitute. I’m trying to start small, with anything I can do to get me focused and breathing. It’s hard when I feel like, “But it’s not the same!” Usually in the end, it still feels good in my body.

The neurologist I had who was helpful; she actually suggested restorative yoga, yoga nidra, or gentle flow. She had done a small study on it I think.

Have you considered PT and OT? They may be able to you get back to doing some things you miss and come up with adaptations to make things more accessible.

I’m looking into Curable too. It was recommended to me by a Mayo PT. My disclaimer about it though is that they very much cheerlead the, “If you can change the way you think of pain, you can change your pain!” approach, which is not false (pain is a message your brain sends out because it perceives a threat based on something going on internally or externally, so even if we can’t control what’s going on internally, we can control other factors that influence pain; it sounds a bit “woo woo,” but it’s true), but sometimes I feel like it’s a little oversimplified. I guess that’s the nature of it being an app and not a human tailoring the message for you.

I learned a pain neuroscience approach from my PTs, but it can be hard to find someone who’s knowledgeable and when I was pointed to Curable, it just made it a really easy to point to it as an example of a pain neuroscience approach because they have a lot of free resources and their pain education information I found particularly helpful…even for explaining concepts to my doctors.

My PT had me doing neck extensions which worsened my PN. It was below my neck and down to lower-middle back. Now, I have constant burning in my neck even on the Gabapentin. At first, I did not connect the PT to my worsening symptoms, but when he had me increase the repetitions, I knew. Supposedly, I have mild cervical stenosis and degenerative arthritis in my neck. My EMG of the upper extremities said cervical radiculopathy, but then no one trusts his report (A hand surgeon, a PA for neurosurgeon, rheumatologist, and lastly the PA at the pain clinic). It's all extremely frustrating.

I’m really sorry to hear that. It can be hard to find the right PT. I can relate to getting hurt because of inappropriate or overly aggressive PT. It’s very important to me to work with someone who understands central sensitization and who’s willing to focus on function, meaning getting me back to what’s important to me, even if it may look different than it did before. That’s more what I meant in relation to yoga, not necessarily curing the neuropathy.

If you can return to that pain clinic and get the skin biopsy, just follow their frustrating guidelines and do it. It’s one more possible answer. Get ready for a parade of slow, irrational and frustrating series of doctor visits and tests. I won’t tell you how long it took to get a diagnosis of idiopathic length-dependent small fiber polyneuropathy. And treatment that works! And I’m a nurse!
I advise getting the skin biopsy when it’s offered. Start reading, and save hard copies of all your test results and lab results.
You are one of many on this path. Good luck!

You don't need a biopsy to tell if you have small nerve neuropathy. It can be confirmed with an EMG and Nerve Conduction Study. Both are done at the same appointment and are non-invasive. My neurologist had mine done and could tell me right after. Don't let them do a painful procedure

What you say is true. However, it is only a presumptive diagnosis, based on symptoms and the results of the tests you mention. The biopsy is the gold standard.
Even though I am generally strongly against tests which give you no additional useful information nor additional treatment options, I did have this test. For some reason. I was comforted by the fact that the test directly confirmed that I had a "physical disorder" (less peripheral nerves). Unfortunately, it is also less treatable, even to the extent that most treatments for peripheral neuropathy are usually FDA approved for diabetic neuropathy. New drugs and treatments generally are first FDA approved for diabetic forms. That means insurance generally won't pay for them, although they can be prescribed off label if you're willing to pay for them.

My neurologist also did extensive lab work and 1 important thing was B6 toxicity. So I am not longer taking it. I am also taking Nortripyline. After about 4 weeks I noticed my pain lessening. I have been on 50 mg for 2 months and the pain and burning is almost gone. The only problem still is wearing shoes for more than a couple of hours.

I have the same problem with shoes. All of mine are now shearling lined, which helps a little. Still, I often walk around in flip flops or barefoot even in what passes for winter in the SF Bay Area, where I live. I don't know what I would do if I hadn't become too old for skiing.