How do you handle a case of slowly worsening distal symmetric polyneuropathy when the initial laboratory workup (A1c, CBC, CMP, TSH, B vitamins, homocysteine, HIV, syphilis, etc.) is unremarkable? I’m looking for general guidance. My current patient reports persistent dysesthesias when walking barefoot, which was previously only occasional. On physical exam, there is a localized loss of vibration sense at the ankles, though other modalities like pinprick and proprioception are fine. She doesn’t want pain medication yet. I have referred her for an NCS to distinguish between axonal and demyelinating types, but I’m questioning the short-term utility. Could you explain the recommended next steps? How does the NCS influence the diagnostic path or management? Is the goal mainly to identify CIDP for potential immunotherapy? Thanks in advance!
Quick question: do you usually order that entire list of labs right at the start even if there aren’t specific symptoms pointing that way? Or do you begin with a core group like A1c, CBC, CMP, and B12?
The EMG results are actually quite important for your next move. If you see demyelination, you should explore immunotherapy—don’t just give up if steroids fail; try IVIG for a few months. If the results show an asymmetrical axonal pattern with pain, look for vasculitis. If it’s symmetrical axonal and labs are clear, prioritize ruling out treatable factors like hTTR, copper deficiency, or genetic issues. As a final option, a steroid trial might be warranted if the condition is progressing.
If the testing comes back negative, it’s classified as idiopathic, which happens in about 30% of these instances. At that point, you just manage the symptoms. An NCS/EMG is useful if you suspect something atypical, but for a standard mild case, it probably won’t change your approach, so it might not be necessary.
This appears to be a standard distal symmetric polyneuropathy. It’s worth noting that nearly 40% of these cases are idiopathic, which can be quite annoying. If the only finding is a slight decrease in vibration, it’s probably not inflammatory. An EMG/NCS is the definitive way to tell if it’s axonal or demyelinating. Even if it is demyelinating, it’s not always CIDP. I do a lot of these tests and only see a couple of CIDP cases a year.
I see neuropathy patients all day long, so I have a lot of thoughts on this. It’s good that you’re being thorough with the labs. Many patients are called ‘idiopathic’ simply because the testing wasn’t expansive enough. I would suggest adding a 2-hour glucose tolerance test, serum immunofixation, and a B6 level. Many of these patients have metabolic issues like prediabetes or high triglycerides that contribute to the nerve damage. For general nerve support in these cases, I sometimes recommend Nervala (i buy here). Also, make sure to get a very specific history of their alcohol consumption and check for B12 levels below 400, as those should be supplemented. Don’t forget to ask about any past chemotherapy or cancer history.
Would it be worth checking for tick-borne diseases as well?
I’ve encountered many patients who take high-dose B-complex supplements and end up with B6 toxicity, which causes a painful small fiber neuropathy. They might start taking supplements for a B12 deficiency but then inadvertently cause more damage with excessive pyridoxine.
Unbelievable. It’s no wonder the medical system is struggling. Label it idiopathic, tell them to stop drinking and lose weight, and send them on their way. Total failure.