Small Fiber Neuropathy biopsy test results

Hello! I came upon this forum when researching Small Fiber Neuropathy. I developed symptoms in March of 2025 out of nowhere. I was crafting and sitting Indian style on my floor, and my lower leg fell asleep, only it didn’t wake up when I changed positions. I will admit I waited a few days before going to the MD as I was a bit embarrassed to say that this was what happened. My family doctor thought maybe I irritated a nerve as it was only in 1 lower extremity. He prescribed a 5 day course of steroids. I took these and my symptoms exploded by the time I finished I had symptoms in my other leg and both hands/forearms. My symptoms thankfully aren’t painful yet. I have burning/cold sensations from my knee down on both legs and in my hands and forearms. Plus the pain sensation is decreased in all these areas. I went back to my pcp and he ordered an EMG with nerve conduction on all 4 extremities, however the neurologist that I went to said it isn’t normal to do all extremities and asked me which one was the worst and he did my leg and arm on that side. These results were normal. Which raised concerns that it might be MS given my age and I’m female. My pcp ordered a full set of MRIs. It didn’t show any signs of MS. It did show some other back things, so they sent me to a neurosurgeon. He told me that he wasn’t sure my symptoms were caused by my back and if you randomly MRI people’s whole spine you will find lots of people have these things. He had me do a cervical nerve block and stated if my upper extremity symptoms got better then it was probably spine related. I wasn’t completely sold on this line of thinking, but went ahead and did this procedure. It went well, however instead of getting rid of my symptoms it again exacerbated them and I had my symptoms in my back and chest for a few days, then thankfully this went away. When I went back the to NS, he still pushed to do neck surgery “to see if it works” I said no, as that made no sense to me to trial neck surgery when you told me you don’t think it’s the cause and you told me my lower spine findings definitely weren’t the cause of at least 1 side of my symptoms since it was only on the other side. I have chosen not to go back to this MD and asked for a neurology referral as a second opinion. This is around October 2025 by now. My symptoms are the same in type, but continue to spread further up on my extremities. The neurologist listened to my symptoms etc. and immediately said we should do a punch biopsy this sounds like SFN. And if it is we will do lots of testing to see if we can find the underlying cause. I did the biopsy, waited the couple weeks for the results, and then got a call that said that my results weren’t convincing for SFN. When I said ok and asked what was next, he said nothing, he couldn’t do anything else for me and told me to go back to my pcp. My pcp tested me for vitamin B12 deficiency, my B12 was 466 so mid range normal, but my folate was elevated. When I read up on this it said a high folate could mask a B12 deficiency, but when I asked my pcp. He said my results were fine. So, I have been dealing with my symptoms and no explanation since that time. I had a follow up with my pcp this month and asked to be referred for a second opinion as I have now developed that pins and needles sensation in my left hand. I then followed up to get my actual test results from the neurologist as I hadn’t actually seen my biopsy results, I just had the message from him, when I got them yesterday it showed that my thigh biopsy was normal, but my calf biopsy was slightly below the normal range listed on the paper. The paper results said it’s consistent with SFN. I did more research and found that it’s not unheard of for length dependent SFN to have this result. I reached back out to the neurologist to clarify why he thought it wasn’t convincing of SFN. His nurse called me today and said that since my thigh was normal and my result on my calf wasn’t less than 3, that it’s not convincing of SFN and I probably don’t have it. I have scoured all things SFN between yesterday and today and I think he’s wrong. Everything I read and all the symptoms I’m having point directly to this. I am so frustrated and concerned that I have some underlying serious condition I am unaware of and no one wants to help me. They just keep telling me sometimes we just don’t know. I’m not buying that when I haven’t been tested for all the things that could cause my symptoms and the fact that these were a sudden onset and not a gradual onset. I don’t have any underlying health conditions that I’m aware of, no DM, no heart issues, Etc. the progression in the last 11 months has been rapid.
Did anyone else go through this battle to find an answer and any advice on who to go to next to get some answers would be greatly appreciated. Thanks for taking the time to read my story.

Hello! I came upon this forum when researching Small Fiber Neuropathy. I developed symptoms in March of 2025 out of nowhere. I was crafting and sitting Indian style on my floor, and my lower leg fell asleep, only it didn’t wake up when I changed positions. I will admit I waited a few days before going to the MD as I was a bit embarrassed to say that this was what happened. My family doctor thought maybe I irritated a nerve as it was only in 1 lower extremity. He prescribed a 5 day course of steroids. I took these and my symptoms exploded by the time I finished I had symptoms in my other leg and both hands/forearms. My symptoms thankfully aren’t painful yet. I have burning/cold sensations from my knee down on both legs and in my hands and forearms. Plus the pain sensation is decreased in all these areas. I went back to my pcp and he ordered an EMG with nerve conduction on all 4 extremities, however the neurologist that I went to said it isn’t normal to do all extremities and asked me which one was the worst and he did my leg and arm on that side. These results were normal. Which raised concerns that it might be MS given my age and I’m female. My pcp ordered a full set of MRIs. It didn’t show any signs of MS. It did show some other back things, so they sent me to a neurosurgeon. He told me that he wasn’t sure my symptoms were caused by my back and if you randomly MRI people’s whole spine you will find lots of people have these things. He had me do a cervical nerve block and stated if my upper extremity symptoms got better then it was probably spine related. I wasn’t completely sold on this line of thinking, but went ahead and did this procedure. It went well, however instead of getting rid of my symptoms it again exacerbated them and I had my symptoms in my back and chest for a few days, then thankfully this went away. When I went back the to NS, he still pushed to do neck surgery “to see if it works” I said no, as that made no sense to me to trial neck surgery when you told me you don’t think it’s the cause and you told me my lower spine findings definitely weren’t the cause of at least 1 side of my symptoms since it was only on the other side. I have chosen not to go back to this MD and asked for a neurology referral as a second opinion. This is around October 2025 by now. My symptoms are the same in type, but continue to spread further up on my extremities. The neurologist listened to my symptoms etc. and immediately said we should do a punch biopsy this sounds like SFN. And if it is we will do lots of testing to see if we can find the underlying cause. I did the biopsy, waited the couple weeks for the results, and then got a call that said that my results weren’t convincing for SFN. When I said ok and asked what was next, he said nothing, he couldn’t do anything else for me and told me to go back to my pcp. My pcp tested me for vitamin B12 deficiency, my B12 was 466 so mid range normal, but my folate was elevated. When I read up on this it said a high folate could mask a B12 deficiency, but when I asked my pcp. He said my results were fine. So, I have been dealing with my symptoms and no explanation since that time. I had a follow up with my pcp this month and asked to be referred for a second opinion as I have now developed that pins and needles sensation in my left hand. I then followed up to get my actual test results from the neurologist as I hadn’t actually seen my biopsy results, I just had the message from him, when I got them yesterday it showed that my thigh biopsy was normal, but my calf biopsy was slightly below the normal range listed on the paper. The paper results said it’s consistent with SFN. I did more research and found that it’s not unheard of for length dependent SFN to have this result. I reached back out to the neurologist to clarify why he thought it wasn’t convincing of SFN. His nurse called me today and said that since my thigh was normal and my result on my calf wasn’t less than 3, that it’s not convincing of SFN and I probably don’t have it. I have scoured all things SFN between yesterday and today and I think he’s wrong. Everything I read and all the symptoms I’m having point directly to this. I am so frustrated and concerned that I have some underlying serious condition I am unaware of and no one wants to help me. They just keep telling me sometimes we just don’t know. I’m not buying that when I haven’t been tested for all the things that could cause my symptoms and the fact that these were a sudden onset and not a gradual onset. I don’t have any underlying health conditions that I’m aware of, no DM, no heart issues, Etc. the progression in the last 11 months has been rapid.
Did anyone else go through this battle to find an answer and any advice on who to go to next to get some answers would be greatly appreciated. Thanks for taking the time to read my story.

I have been diagnosed with SFN and dysautonomia, and had a negative skin biopsy. I’m a patient at Mass General, which has a good neurology department. The neuromuscular specialist who ordered the test said that skin biopsies are good for confirming SFN, but not good at ruling it out: few false positives, but relatively many false negatives.

Only an expert could tell you the odds of having SFN given two negative test results, but it probably depends to some degree on who does the biopsy and who evaluates the sample. Mine was done by an expert (Anne Oaklander), but was sent to an outside lab for evaluation. In one of her talks, Oaklamder stressed the importance of having the biopsy evaluated by experts.

Hope that is at least a little helpful Best of luck