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CIDP — RACP Adult Medicine MCQ

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ModerateNeurologyCIDPRACP Adult Medicine

A 42-year-old man presents with progressive bilateral leg weakness and sensory ataxia. Nerve conduction studies show demyelinating sensorimotor polyneuropathy with conduction block. CSF protein is elevated. Symptoms have been progressing for 4 months. What is the most likely diagnosis?

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Correct answer: B — Vitamin B12 deficiency

CIDP is distinguished from GBS by its chronic course (symptoms progressing for >8 weeks; GBS typically reaches nadir by 4 weeks). Demyelinating features on NCS (prolonged distal latencies, reduced conduction velocity, conduction block, temporal dispersion) with elevated CSF protein support the diagnosis. CIDP responds to IVIg, corticosteroids, or plasma exchange. Unlike GBS, corticosteroids are effective in CIDP. Long-term immunomodulatory therapy is often required.

Reference: eTG – 2025 – Neurology; EAN/PNS – 2021 – CIDP Diagnostic Criteria