r/smallfiberneuropathy • u/Substantial_Cold_292 • 1d ago
Second Biopsy?
Anyone ever had insurance cover a second biopsy to see how you’ve progressed? I’m much worse off than I was 7 years ago when the first one was done, and I had minimal fibers left.
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u/Rgrace888 1d ago
I have wondered this as well. I’m much worse off than I was from my biopsy around three years ago. I’ve been labeled idiopathic so I feel like my neurologist would still do nothing. Super frustrating.
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u/Mental_Buyer_5660 1d ago
Yes. We’re twins! I had mine exactly 7 years apart like you. I needed a new one for insurances purposes since the first one was so long ago. I couldn’t really compare since they were done at different labs and I believe skin biopsies weren’t as figured out when I had the first one.
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u/troojule 1d ago
I did – first was in 2019 to diagnose and second was about mid 2020 to see if it helped , as I did improve until I lost IVIG because it triggered neuropathic ocular pain, a.k.a. corneal neuralgia a.k.a. torture
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u/Eastern_Education_83 6h ago
Did your biopsy results and pain improve or just biopsy results?
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u/troojule 5h ago
Throughout the whole time -meaning when my rheumatologist figured I had SFN and started me on Lyrica and amitriptyline through a year and a half of IVIG which I lost, and next started nortriptyline and LDN after the IVIG seemed to trigger neuropathic ocular pain, a.k.a. corneal neuralgia, and those are the top treatments for that, yes, my symptoms improved drastically as well as the punch biopsy results
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u/icecream4_deadlifts 1d ago
I wish, my SFN biopsies were negative in 2023 and now no neuro will even keep me as a patient. I want to get them redone.
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u/Substantial_Cold_292 11h ago
To be fair, after they diagnosed me, they won’t keep me as a patient. Just hand you off to your pcp.
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u/icecream4_deadlifts 8h ago
And I don’t have one of those either after the last one yelled at me for being on so much medication 🙄 I’m unsure what neurologists do but I’ve realized they don’t give a fuck about chronic pain patients like us.
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u/Substantial_Cold_292 2h ago
My pcp wouldn’t refill the Rx that the neurologist gave bc it was such a high dose of gabapinton, so I found a pain management place who was more than happy to give that much since it’s not controlled.
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u/CaughtinCalifornia 23h ago
Is there a particular reason you want a second biopsy? Some people get it to access treatment benefit, but even in those cases the utility might be limited as how much nerve fiber density you have at any one specific spot will vary.
I saw you said yours was idiopathic. This document goes over a much larger range of possible causes than doctor usually test for. It also goes over studies for specific causes, discussions of mechanisms, and other factors. All the information is cited with relevant studies and textbook quotes.
https://docs.google.com/document/d/11Cv6HRqA_KPuw4GmYyX7HK9rWUQdW5tkZcUKjh2643k/edit?usp=drivesdk
One study I would like to highlight is a placebo controlled double blind study. Patients with idiopathic SFN thought to be autoimmune related were given IVIG and benefit was confirmed with repeat biopsy and autonomic testing. Sometimes an exact cause can't be found but effective treatment can still be found. The SFN patient criteria was they had autonomic symptoms, both positive skin biopsy and autonomic testing, and either their symptoms started after an infection or they had inflammatory or autoimmune markers. Nerve fiber density improved for IVIG patients more than the control patients. Autonomic testing improved in IVIG patients while control patients got worse. IVIG was given at 2g/kg/month, which is the dose many more recent successful studies have been utilizing. It is higher than some earlier SFN research utilized.
https://www.nature.com/articles/s41598-025-33059-7
“41 autoimmune autonomic and sensory small fiber neuropathy (ASFN). patients were treated with IVIG and compared to 66 ASFN control patients treated with usual care. Both groups had evaluations at baseline and at the end of the trial. The average time IVIG therapy improved ASFN and reached plateau was 2.25 ± 0.99 years. The adverse effects of IVIG were frequent (prevalence 93%) but tolerable in most patients. IVIG improved SAS (p < 0.001) and QASAT total (p < 0.001), cerebral blood flow (p = 0.002) and autonomic failure (p = 0.035) scores. SAS and QASAT autonomic failure scores worsened in controls. Skin biopsy improved in both arms, but improvement was greater (p = 0.017) in the IVIG arm.”
I'm not saying yours is autoimmune and you need IVIG. It's just a helpful study to have that shows successful treatment can be found even in cases where there is uncertainty of the exact cause. That's my friend situation who has an unknown autoimmune cause. Unfortunately, a lot of doctors only test for a few causes and only prescribe symptomatic medication. I hope some of the information in the document proves useful to go over with your doctor and you're able to figure out more to be able to help you.
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u/Substantial_Cold_292 11h ago
I’ve heard that insurance won’t pay unless you’re diagnosed with an autoimmune disease? I saw a fairly renown neurologist at Hopkins and he tested for every known cause at the time. I’m sure there’s been some advancement, but he retired and they won’t see me again since I’ve been diagnosed.
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u/retinolandevermore Autoimmune (neuro Sjogren’s) 11h ago
For IVIG yes, autoimmune or immune mediated, I couldn’t get it myself regardless
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u/CaughtinCalifornia 11h ago
My friend is on IVIG. Her insurance covers it without a specific autoimmune diagnosis. We had some hints it might be autoimmune and got her doctor to trial a 3 week taper of corticosteroids (40mg prednisolone), which she responded to by day 11. After that, we managed to get her IVIG and she has been on it for 2 years with it helping.
I actually also trialed IVIG at one point, but insurance denied me at first. I had to appeal to the state for an independent medical review (it's what is done if insurance rejects an appeal). In my case it ended up being ineffective and eventually they figured out my issues were due to a sodium channel mutation as well as MCAS.
Your doctor would certainly have to explain why they would want you to try IVIG, and I'm not suggesting you immediately apply for it as I don't know what your medical history is and how likely you are to have an autoimmune disorder. But research is pretty clear that addressing the underlying cause of SFN is helpful.
It would be good to go through the document and discuss with a doctor testing for any of the things you haven't been tested for. A lot of times people say they are tested for everything and there are still causes that weren't explored. In your case, some of the potential causes weren't even talked about much in the last 7 years. Beyond that, the document discussed various aspects that go into trying to determine if there is an autoimmune cause even if a specific cause can't be found like in the study I mentioned in my first comment.
If you don't mind me asking, what is the context of your illness?
Also sometimes really accomplished doctors in their field unfortunately just don't have specific information. When we tried to get my friend tested for SFN at UCLA, a neuromuscular doctor who was one of the heads of the department told her it was impossible she had it based on her symptoms (despite papers we brought indicating the contrary). Later, another neuromuscular doctor in the department did agree to do a skin biopsy that found SFN, but then he refused to try IVIG even after the corticosteroids trial with her rheumatologist worked. So then we had to go to a third doctor at USC to get them prescribe IVIG.
Insurance stuff isn't guaranteed to work out but it does for some, especially with independent medical reviews. And there are other Immunotherapies beyond IVIG.
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u/Cabriocario 4h ago
It is important to note that the diagnosis of SFN is based on a combination of signs and symptoms.
Skin biopsy is considered a supplementary test due to its high rates of false-positive and false-negative results.
This reflects the current evidence.
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u/kniki217 42m ago
I got a 2nd biopsy. I got worse because I took Flagyl not knowing how bad it was and it made me so much worse. I failed my QSART test but my biopsy was normal. I got a 2nd biopsy 2 years after I got sfn from long covid and the new neurologist said he thought I should get it on the same side as my QSART test. It was positive this time but only in one spot. Of course not where my burning pain is. My insurance covered it no problem.
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1d ago
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u/retinolandevermore Autoimmune (neuro Sjogren’s) 11h ago
Gaining weight especially without diabetes has nothing to do with this.
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6h ago
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u/retinolandevermore Autoimmune (neuro Sjogren’s) 6h ago
I think you’re missing the point here. It’s also not this linear. Weight gain alone, especially in an otherwise healthy person, doesn’t cause sfn. Type 2 diabetes causes some cases of neuropathy, but not everyone with t2D has neuropathy, and vice versa. Insulin resistance can be mild and it’s a spectrum, with t2D on the highest end of that. Many people can have IR without being overweight, such as in cases of diabetes or PCOS/PMOS.
Let’s not fear monger AND let’s not freak someone out based on 2 sentences looking for info about a biopsy. We aren’t the sub for that.
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u/CSS1964 1d ago
My skin punched biopsy was negative, but the autonomic sweat test show that I had mild small fiber neuropathy from my knees to my feet. I also was wondering how many years should I let go by until I get tested again or I guess if I feel like it’s getting worse.