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Small fibre neuropathy — SCE Neurology MCQ

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ModerateNeuromuscularSmall fibre neuropathySCE Neurology

A 79-year-old woman presented with burning feet with normal strength and reflexes. On examination, pinprick was reduced distally while vibration and proprioception were preserved. Initial investigations showed: NCS was normal; skin biopsy showed reduced intraepidermal nerve fibre density. What is the most likely underlying mechanism?

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Correct answer: B — selective small fibre degeneration

selective small fibre degeneration is the best answer because the vignette describes Small fibre neuropathy: painful sensory symptoms with normal NCS indicate small fibre neuropathy. JC virus infection of oligodendrocytes is plausible in a neighbouring presentation, but the chronology, examination or investigation pattern does not match the key discriminator here. Small-vessel lipohyalinosis and Large-vessel thromboembolism are less appropriate because they would require different localisation, timing or test findings; Alpha-synuclein neurodegeneration would fit a different syndrome. Clinical pearl: large fibre neuropathy would reduce vibration and NCS amplitudes.

Reference: NICE NG42; ABN myasthenia gravis guidance; EAN/PNS GBS-CIDP guidance