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Anti-MAG Neuropathy — SCE Neurology MCQ

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HardPeripheral Neuropathy & NeuromuscularAnti-MAG NeuropathySCE Neurology

A 55-year-old man presents with progressive sensorimotor polyneuropathy. He has an IgM paraprotein on serum electrophoresis. Anti-MAG (myelin-associated glycoprotein) antibodies are positive. NCS show a demyelinating pattern with disproportionately prolonged distal motor latencies. What is the diagnosis?

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Correct answer: B — Distal anti-MAG paraproteinaemic demyelinating neuropathy

The best answer is “Distal anti-MAG paraproteinaemic demyelinating neuropathy”. MS care requires phenotype confirmation, relapse assessment, symptom management and specialist disease-modifying therapy; ocrelizumab is an NHS option for eligible early inflammatory primary progressive disease. The alternatives “CIDP with proximal and distal non-uniform demyelination”, “Multifocal motor neuropathy with motor conduction block”, “Hereditary demyelinating neuropathy with uniform slowing”, “AL amyloid neuropathy with painful axonal and autonomic loss” are clinically adjacent possibilities, but they do not match the defining chronology, localisation, physiology, investigation result or UK management sequence in this stem.

Reference: NICE NG220 multiple sclerosis recommendations: https://www.nice.org.uk/guidance/ng220/chapter/Recommendations