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Meningococcal Meningitis — UKMLA MCQ

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HardInfectious DiseasesMeningococcal MeningitisUKMLAMRCEM SBAMRCP Part 1PARAPSA

A 41-year-old receiving natalizumab for multiple sclerosis develops three weeks of progressive aphasia, right-sided weakness and visual inattention. MRI shows asymmetric subcortical T2/FLAIR hyperintensity extending to U-fibres, with little mass effect and no typical relapsing-remitting pattern. What is the most appropriate confirmatory investigation?

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Correct answer: B — CSF JC-virus DNA using an ultrasensitive PCR assay

The best answer is “CSF JC-virus DNA using an ultrasensitive PCR assay”. Progressive focal deficits and atypical white-matter lesions during natalizumab exposure demand urgent assessment for progressive multifocal leukoencephalopathy. MRI should be reviewed promptly and CSF tested for JC-virus DNA with an ultrasensitive PCR assay. A negative initial result does not fully exclude PML when clinical and radiological suspicion remains high; repeat CSF or biopsy may then be needed. Serum antibody index estimates treatment risk but does not confirm active CNS infection, and further natalizumab should not be given while evaluation proceeds.

Reference: MHRA: Natalizumab and progressive multifocal leukoencephalopathy: https://www.gov.uk/drug-safety-update/natalizumab-tysabri-progressive-multifocal-leukoencephalopathy-updated-advice-to-support-early-detection