Brief Answer:
Detailed explanation below

Detailed Answer:
Hello,

I understand you concern with the diagnosis of SFN and the symptoms of your daughter. Generally SFN affects small nerve fibers like light sensation and autonomous fibers (that cause the sweating and other vascular changes) but don't affect the big fibers like motor fibers so it is uncommon with SFN to have motor symptoms like muscle weakness.
On the other hand the skin biopsy for SFN is a test that has high sensitivity and specificity so if she was found in biopsy to have SFN chances are she does have it.
The reason for her symptoms I think can be related to the subjectivity of weakness. Having a good neurological examination will reveal if she really has muscle weakness or is a subjective feeling that is confused as such. The doctor can test the strength of her muscles and if the strength of the muscles is reduced then she does have muscular weakness and other conditions should be considered as well. If on neurological examination the muscular strength in her legs is normal then the weakness is not objective and it might be confused with other sensation problems and SFN is very likely.

Because she has had SFN in biopsy she needs to have the tests to try to find the cause of it, how have their results been: CBC, ERS, metabolic enzymes, lipids, TSH, FT4, ANA, ACE level, B12 and MMA, fasting glucose and glucose tolerance test, serum immunofixation, gliadin and transglutaminase antibody, SS-A, SS-B, HIV tests, etc.

To conclude i would say that:
- because the skin biopsy has identified SFN, due to its high accuracy related to this diagnosis, very likely your daughter has SFN
- the confusion may come due to the real sensation of weakness which needs to be confirmed clinically with reduced muscle strength in examination
- she will need to have the tests above to try to identify a possible cause of the symptoms
- SFN is a chronic condition that will be with the patient long term but generally most of the patients respond well to treatment if it is oriented to the proper cause so it is important to follow the instructions of the doctor related to treatment and follow ups.

Hope I have answered your query. Let me know if I can assist you further.

Regards,
Dr. Antoneta Zotaj
General & Family Physician

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Brief Answer:
Deep tendon reflexes and motor function are related to large fiber neurons

Detailed Answer:
Hello,

The reduced or absent reflexes and also the reduced muscle strength are functions of large neural fibers so it does not seem to be related to SFN. Very likely she might also have another condition causing these.
Did she do the EMG (electromyogram) , NCT (nerve conduction tests) and muscle biopsy? These would give more information if the problem is due to the nerve or to the muscle. If the problem is due to the nerve that feeds the muscle then it seems like motor neuropathy if it is the muscle then it can be myositis or a late onset myopathy.
Examinations of the spine to rule out spinal stenosis or other problems with the spine might be helpful to rule out problems there, like MRI of the spine.

There are many receptor studies and immune studies to be done as these most of the times are considered to be related to immune responses.

The doctors are faced with many difficulties and dilemmas in diagnosis and her treatment as the clinical signs and biopsy findings don't seem to be matching and the workup for these conditions is generally very wide.

As for the treatment for small fiber neuropathy, generally the treatment is directed towards the pain management and not towards the disease itself unless a cause is identified and have treatment specific for that cause. In the case of your daughter if she does not have pain and all the examinations come out normal then probably the treatment with antidepressants and anticonvulsants (which are generally used for neurological pain) are not going to helpful as she does not have any pain.

To conclude i would say that the doctors need to do more extensive tests to try to figure out the weakness and loss of reflexes as it does not seem to be a typical feature of SFN. Because her symptoms are not related to pain or sensation probably treatment of SFN would be directed only towards a possible cause of it as pain management will not be effective due to lack of pain.

Hope I have answered your query. Let me know if I can assist you further.

Regards,
Dr. Antoneta Zotaj
General & Family Physician

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Brief Answer:
It is a pleasure

Detailed Answer:
Hello,

Thank you for your warm message, it is my pleasure to answer to your questions. I am a believer in Jesus and i so appreciate your blessings.

As for the treatment please discuss it with the doctor. You may ask him if gabapentine is used to slow down the progress of the neuropathy or is just directed to pain management. If it is directed to just pain management then your daughter and the doctor may discuss on whether it is beneficial to take it or not.
On the other hand please be aware of possible withdrawal symptoms if gabapentine is stopped suddenly (it might need gradual dose reduction before stopping it, in case this will be considered).

I wish you all the blessings and quick healing to your daughter.

Regards,
Dr. Antoneta Zotaj
General & Family Physician

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