Demyelinating Diseases USMLE Step 1 Practice Question
A 31-year-old woman with multiple sclerosis on interferon-beta therapy presents with progressive confusion, cognitive decline, and behavioral changes over 4 weeks. Vital signs: BP 118/76, HR 88, RR 16, Temp 37.2°C, SpO2 98%. Brain MRI reveals new periventricular white matter lesions. CSF analysis shows JC virus PCR positive; oligoclonal bands negative. She denies fever, headache, or neck stiffness. Which diagnosis best explains these findings?
Answer choices
- ASecondary progressive MS
- BProgressive multifocal leukoencephalopathyCorrect answer
- CNatalizumab-associated IRIS
- DAutoimmune encephalitis
- EMitochondrial encephalomyelopathy
- FInterferon-beta-induced demyelinating encephalopathy
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