Demyelinating Diseases USMLE Step 1 Practice Question
A 52-year-old man with primary progressive MS on natalizumab for 2 years develops progressive weakness and cognitive decline. New brain MRI shows multiple cavitary white matter lesions with surrounding edema. Serum JC virus antibody is positive and CSF JC virus PCR is negative. Which of the following is the most appropriate next step?
Answer choices
- AContinue natalizumab and obtain repeat CSF in 1 month
- BPerform brain biopsy for definitive diagnosis
- CDiscontinue natalizumab immediatelyCorrect answer
- DAdd corticosteroids and continue natalizumab
- EIncrease natalizumab dose
- FStart intravenous immunoglobulin and monitor clinical status with serial MRI
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