Quick Answer
Small fiber neuropathy causes burning pain and temperature sensitivity — often missed by standard nerve tests. Diagnosis requires skin biopsy.
Medically reviewed by Dr. Jitendra Prasad Yadav • NMC 8029 • Kathmandu Neurology Clinic & Cognitive Center
Small fiber neuropathy (SFN) is damage to the small unmyelinated nerve fibers that carry pain and temperature sensation — and autonomic (involuntary) signals. Unlike large-fiber neuropathy (which causes numbness and weakness), SFN causes severe burning pain, temperature sensitivity and autonomic symptoms while sparing touch sensation and motor function.
Symptoms
Burning, stabbing or electric-shock pain in feet/hands (often worse at night), temperature sensitivity (can't tolerate heat/cold), allodynia (pain from light touch), hyperhidrosis or anhidrosis, dry eyes/mouth, orthostatic intolerance, gastrointestinal dysmotility. Crucially: normal strength, reflexes and touch sensation.
Causes
Diabetes and prediabetes (most common), autoimmune (Sjögren's, lupus, celiac), vitamin B12 deficiency, thyroid disease, monoclonal gammopathy, genetic (familial SFN), idiopathic (~50% of cases).
Diagnosis
Standard nerve conduction studies are NORMAL (they test large fibers). Diagnosis requires: skin biopsy (3mm punch biopsy measuring intraepidermal nerve fiber density — the definitive test), quantitative sensory testing (QST), and autonomic testing. Laboratory workup for underlying causes is essential.
When to seek professional evaluation
Small fiber neuropathy is often missed because standard nerve tests are normal — skin biopsy is required for diagnosis.
This guide is educational and does not replace individual medical advice.
Frequently asked questions
Answers reviewed by Dr. Jitendra Prasad Yadav • MBBS, MD (Internal Medicine), FICN (Neurology), FCNV, FIHM • NMC 8029
Supplements only help when a deficiency is present; underlying cause-directed care is needed.
If the underlying cause is corrected early (e.g., improving glucose control, treating vitamin deficiency), improvement may occur. Long-standing neuropathy is often not fully reversible.
Migraine is a neurological condition; headache is one feature. Associated symptoms and functional impact are important for diagnosis.
Aura refers to visual, sensory, or speech symptoms that precede the headache in some people. Both types are migraine; the presence of aura may influence management discussion.
More: All FAQs → · Ask Dr. Jitendra →
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References & Review
Reviewed by Dr. Jitendra Prasad Yadav • Last reviewed: 2026-11-10
- International Classification of Headache Disorders, 3rd edition (ICHD-3).
- Harrison's Principles of Internal Medicine — Neurology sections.
- American Academy of Neurology guidelines for selected conditions (where applicable).
Content is educational and aligns with standard medical references; individual evaluation may vary. External links provide context and do not imply endorsement.