Small Fiber Neuropathy biopsy test results

I had to read some articles myself to learn how to interpret these biopsies. Mine were the opposite of yours - only the ankles showed reduced nerve fibers. This made my diagnosis length-dependent, and instantly eliminated several disease types from possibility. They can explain all this to you when the results are reviewed.

My understanding is this could be a sampling issue. The samples taken in your lower leg may by chance not have been representative of your condition.

Hi Joanne,
From my research on Length Dependent and Non Length Dependent small fiber neuropathy, I believe having a positive skin biopsy in the proximal thigh is a more typical presentation in non length dependent sfn. You might want to read about it, and see if your symptoms fit, or not. Non length dependent SFN can be in patches, on the trunk of the body, and on the proximal thigh and arms, and may involve the face, arms, tongue. There may be more itching too. Also it tends to be less symmetrical, rather than the standard stocking and glove expression of length dependent sfn. I have been trying to better understand the symptoms of the two types for myself as I am not sure my symptoms are developing in a classic length dependent fashion.

Joanne, I went back and read my biopsy result for SNF. It said that occasionally patients can feel symptoms in the hands first before the lower extremities. I had read elsewhere that length dependent normally starts in the lower extremities and then goes upward. My results also stated that I was not charged for the specimen processing that didn't produce a result. Meaning the one on my lower leg. I have non length dependent SFN. Two days after retiring from my job I woke up with full onset of pinpricks all over. My eyes, face, head arms legs back. All over. If you have ever watched fireflies at night when they light up it reminds me of that. Just one prick right after the other going off. Mine is idiopathic. I didn't have any symptoms of anything so they tested me but nothing came back. I did notice in my left hand from the wrist down to the area between my little and ring finger I had a burning sensation that would come and go all throughout the day. That part has gone away for now. But I have noticed at times that I will have shooting pains in certain areas that will be like across an area of my skin then shooting down. Some of those can be very zap like and sharp. I take alpha lipoic acid daily. I still get the pin pricks whenever they decide to do their thing. They come whenever. Some of the pricks last longer than others. The SNF has affected my heart and it caused my heart rate to accelerate as high as 183 so I take medication for that. I have been taking metoprolol for that and it works but on June 5, I was watching TV and I noticed the same feeling in my chest when it happened before. So I took my heart rate and it only went up to 97 so I took some med. I am now going to have another holter monitor put on this week.

Hi mlorena,
Thank you for sharing what you have experienced with non length dependent sfn, I have been researching, trying to understand just what the symptoms for this are. It must be very disconcerting to have your Heart effected in this way! I also noted the comment on my lab report regarding hands versus feet, as my hands were the first place I noticed, and have developed right along with my feet. But I also have zips, zaps, shooting pain, painful skin, and a lot of itching in other areas of my body. My hands and feet are progressively more and more stiff too, I have no idea if this can be from SFN, but it has developed in tandem with my sfn symptoms. My neuro office has ordered a lumbar MRI to rule out any nerve impingements as possible cause of symptoms in legs, esp right leg. I don't expect them to find much. I am having trouble with Summer heat, as I did last Summer for the first time, I seem to struggle with extremes of temperature, both cold and hot. I am sweating on my torso, and arms, much more than ever before, and experience light headedness. In the Winter it is the opposite, I am cold, especially my feet! The skin biopsy on my foot was low normal, they consider this to be positive, but above my ankle was normal, they did not do one on my thigh. I have had strange ongoing problems due to the skin biopsy which I understand is highly unusual. When I see the neuro, after the MRI next week, I think I will ask about non length dependent sfn. I do feel nervous about having another skin biopsy as I do not want ongoing nerve reactions in more than one location. I appreciate having a place to communicate about this mystifying problem, I have been diligently trying to discover what is happening with my body, for 2 years now, the sfn is the first result I have gotten so far.

Hi Eve, I have been at it for 16 months now. The tachycardia is very scary. It worries me the most. I have a question I want to ask the neurologist. I have heart palpitations, I haven't had hair on my legs or under my arms for quite awhile, I have urinary retention, very bad silent reflux, and chronic gastritis. I have noticed days where I wake up and all of a sudden I feel spent and very tired. It is not always the same time of day. The metoprolol that I am taking can make you tired, however I asked the pharmacist about this and she asked me when I started taking it and it was in July of last year. It is also a low dose. She told me that people can experience being tired and it lasts from 7-10 days. She thinks that what I am feeling is from something else. Except for the tachycardia could I have all these other things as a precursor to the SNF. That is the question for the neurologist. I will make notes of what I read or think and then take it to the Dr. It can be very over whelming to try and remember stuff. I have noticed something else also. I am on the internet a lot and read stuff out loud to my husband. I have noticed that I mispronounce a lot of words. Not simple words. I sometimes have to say them more than once. That is bothersome to me. Not getting answers is hard. My numbers on my biopsy were as follows.
Low normal thigh= 8.3-9.1 abnormal = <8.3 my result was 1.21
Low normal calf= 3.8-5.2 abnormal = <3.8 my result was 1.15 that is not as low as some but its low.

Hi Eve - I too have been trying to get as much specific information I can on my idiopathic PN, thinking that I can focus therapies on what seems to be working best for the folks on here that know more about their type of condition. Except for the sweating, our conditions sound so similar, especially your heat and cold extreme intolerance. However, I have been told that I have severe axonal PN, shown positive by EGD results, so Neuros have said no need to test for SFN. I’m curious, did you have an EGD/nerve conduction study?

Hi - I want to ask a few who have similar symptoms. I have idiopathic axonal sensorimotor PN
and been to Mayo (Feb 2020) and Johns Hopkins in late 2021. Neither place did any biopsy. Other tests confirm the diagnosis. In past year or 18 months, I noticed shins, ankles and feet always cool. Upper part of body has more sweating than usual especially in warmer weather, mainly chesk, back, neck and head. Mayo did all sorts of tests, no autonomic neuropathy but my primary says that PN can cause unusual sweating. Any others have similar symptoms? Ed

I too have s similar problem. My feet on the bottom I cannot feel. If I put a fan on I can feel the top of feet barely. Also the nuerothapy has reached to my knees and I can only feel with a fan.

@mloren I have idiopathic SFN and also experience tachycardia. I understand how it can be scary and worrisome. Turns out I also have autonomic dysfunction and POTS (postural orthostatic tachycardia syndrome). All of these things are related and were diagnosed by my neurologist through lots of testing. Based on your comments above about your tachycardia, I wonder if you have POTS also. I took a beta blocker for awhile but didn’t notice any improvement, only side effects, so I stopped. I’m working with a cardiac rehabilitation doctor at Mayo and that’s truly been the best “treatment” so far. I haven’t found any medication to help the SFN/Autonomic Dysfunction/POTS and experience widespread pain, tachycardia, headaches, pins and needles, shooting pains, fatigue, etc. everyday. The cardiac rehab doctor works with me on exercises that are appropriate for my conditions and it really is helpful, motivating and overall, puts me in a better head space, helping my mental health too. Being in constant pain everyday takes its toll so it’s important for me to focus on mental wellness too.
I just wanted to share some of my story with you, as I see similarities and I know the tachycardia can be scary. I hope you find answers and solutions/treatments that work for you!
Wishing you well,
Robyn