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Small Fibre Neuropathy – Diagnosis — SCE Neurology MCQ

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HardPeripheral Neuropathy & NeuromuscularSmall Fibre Neuropathy – DiagnosisSCE Neurology

A 68-year-old has burning feet, thermal hypoalgesia and preserved vibration. Nerve-conduction studies are normal. A distal-leg biopsy shows 4.1 intraepidermal fibres/mm; the laboratory fifth centile is 4.8 for age and sex. Which interpretation is best?

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Correct answer: E — Low age-adjusted IENF density supports small-fibre neuropathy

Explanation lettering: D = shown as A · E = shown as D · A = shown as E

A is correct. Small fibres are not assessed by routine nerve-conduction studies. A distal-leg IENF density below validated age- and sex-adjusted norms supports small-fibre neuropathy in the matching phenotype. There is no universal cut-off. Skin biopsy does not establish large-fibre disease, and a morbid sural biopsy is not required to validate this result.

Reference: EFNS/PNS skin-biopsy guideline: https://onlinelibrary.wiley.com/doi/10.1111/j.1529-8027.2010.00269.x