Statin-associated necrotising autoimmune myopathy — SCE Neurology MCQ

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ModerateNeuromuscularStatin-associated necrotising autoimmune myopathySCE Neurology

A 63-year-old man presented with progressive proximal weakness continuing after statin cessation. On examination, there was marked hip flexor weakness and no sensory deficit. Initial investigations showed: CK was very high and anti-HMGCR antibodies were positive. What is the most appropriate investigation?

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Correct answer: B — Nerve conduction studies and EMG

Nerve conduction studies and EMG is the best answer because the vignette describes Statin-associated necrotising autoimmune myopathy: anti-HMGCR myopathy persists after stopping statin and needs immunotherapy. DaTSCAN is plausible in a neighbouring presentation, but the chronology, examination or investigation pattern does not match the key discriminator here. MRI internal auditory meatus with gadolinium and Video-EEG telemetry are less appropriate because they would require different localisation, timing or test findings; Serum and CSF autoimmune antibody panel would fit a different syndrome. Clinical pearl: toxic statin myalgia usually improves after withdrawal and CK is lower.

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