A 49-year-old female with a history of multiple sclerosis (off disease-modifying therapy) and untreated focal seizures presented with a generalized tonic-clonic seizure. Prehospital hypoglycemia (glucose 54 mg/dL) was corrected. In the emergency department, she had recurrent seizures requiring benzodiazepines and was noted to be obtunded with vomiting and inability to follow commands. CT head revealed left parietal cortical thickening and sulcal effacement. CTA/CTV were negative. EEG demonstrated focal slowing in the left temporoparietal region. MRI brain showed diffuse left parietal and occipital leptomeningeal enhancement, proteinaceous sulcal material, and extensive T2 hyperintense white matter lesions concerning for demyelination versus neoplasm or encephalitis. CSF demonstrated elevated oligoclonal bands; spinal MRI showed non-enhancing T2 lesions. Given broad differential including malignancy and infection, neurosurgical biopsy was considered but deferred. The patient was treated with corticosteroids and levetiracetam with rapid clinical improvement. Initiation of ocrelizumab was delayed due to recurrent flares, medication nonadherence, and breakthrough seizures. The patient developed neuropsychiatric symptoms, including mood lability and behavioral changes, complicating adherence and requiring multiple readmissions. She was managed with dimethyl fumarate and extended-release levetiracetam.