Demyelinating Diseases USMLE Step 1 Practice Question
A 29-year-old woman with newly diagnosed multiple sclerosis is started on natalizumab. After 14 months of treatment, she develops progressive confusion, memory loss, and gait disturbance. Brain MRI shows new asymmetric white matter lesions without enhancement. CSF JC virus PCR is negative but remains negative on repeat. Which of the following is most likely?
Answer choices
- AProgressive multifocal leukoencephalopathyCorrect answer
- BImmune reconstitution inflammatory syndrome
- CMS disease breakthrough
- DPosterior reversible encephalopathy syndrome
- ENatalizumab-associated IRIS
- FCryptosporidial meningoencephalitis
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