We describe a 60-year-old African American female who initially presented with progressive numbness, tingling, and pain in the feet, evolving into bilateral leg weakness, right foot drop, gait instability, and recurrent falls. Examination revealed bilateral optic disc pallor and saccadic intrusions, right-predominant leg weakness, generalized hyperreflexia, bilateral positive Hoffman signs, wide-based gait, and impaired coordination. Brain MRI showed multiple punctate enhancing foci in the posterior fossa. Spine MRI revealed multifocal leptomeningeal enhancement throughout the cervical, thoracic, and lumbar regions, while whole-body PET demonstrated tracer uptake in the spinal canal and pelvic and inguinal lymph nodes. CSF analysis revealed lymphocytic pleocytosis (95 WBC/µL, 88% lymphocytes), hypoglycorrhachia (20 mg/dL; normal 40-70), elevated protein (197 mg/dL; normal 15-45), markedly increased IgG synthesis rate (232 mg/day; normal 0-8), elevated IgG index (1.49; normal 0.3-0.7), and 11 CSF-restricted oligoclonal bands; infectious and autoimmune panels were negative. Inguinal lymph node biopsy demonstrated focally caseating granulomatous inflammation concerning for atypical necrotizing sarcoid granulomatosis, probable neurosarcoidosis. Unexpectedly, serum aquaporin-4 IgG antibody was strongly positive at 1:1280 via cell-based assay. The patient received high-dose corticosteroids with partial improvement, and recurrent deficits prompted initiation of Rituximab therapy, resulting in clinical benefit.