Diagnostic Challenge: The Case of a 70-Year-Old Man Who Presents With Progressive Vision Loss and Headaches.

A 70-year-old presents with 6 weeks of progressive bilateral vision loss and headaches. He was also recently treated for presumed sciatica. His exam on admission is notable for poor visual acuity (no light perception), optic nerve atrophy bilaterally with swelling and disc hemorrhage on the left eye and left foot drop. MRI orbits reveals diffusion restriction and enhancement of bilateral optic nerves extending into the optic chiasm. He undergoes bilateral temporal artery biopsy due to concern for giant cell arteritis and high-dose steroids with no improvement in vision and both biopsies are normal. Ultimately, full neuro-axis imaging reveals evidence of leptomeningeal enhancement of the cerebellum, cervical and thoracic spine, and cauda equina nerve roots, as well as bilateral posterior semicircular canal enhancement and developing hydrocephalus. A CNS diagnosis is made via lumbar puncture, though ultimately the patient eventually expires in the hospital.