Demyelinating Diseases USMLE Step 1 Practice Question
A 39-year-old woman with relapsing-remitting multiple sclerosis treated with natalizumab for 6 months presents with progressive left arm clumsiness, expressive aphasia, and cognitive slowing over 3 weeks. Vital signs: BP 118/76, HR 88, RR 16, Temp 37°C, SpO2 98%. Brain MRI reveals multifocal nonenhancing white matter lesions in the parieto-occipital regions without mass effect or edema. CSF analysis is normal. Which diagnosis best explains these findings?
Answer choices
- ACentral pontine myelinolysis
- BMultiple sclerosis relapse
- CAcute disseminated encephalomyelitis
- DNeuromyelitis optica
- EProgressive multifocal leukoencephalopathyCorrect answer
- FNatalizumab-associated immune reconstitution inflammatory syndrome
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