A 46-year-old woman presented with subacute onset of vertigo, tremors, paresthesias, mental status changes, and visual disturbances. Magnetic resonance imaging (MRI) showed radial perivascular enhancement, optic perineuritis, and signs of EICP including globe flattening and optic disc protrusion. Spinal fluid was significant for EICP, hyperproteinorrachia, lymphocytic predominant pleocytosis, and positive GFAP antibodies (1:4098). Neuropsychiatric symptoms improved with IVIG and pulse steroids followed by taper, though she had several relapses early in her course due to insufficient steroid dosing.

Despite overall mental status improvement, she experienced well-formed visual hallucinations with maintained insight that these images were not real. Her vision progressively worsened to essentially absent visual fields bilaterally, despite acetazolamide treatment. Repeat MRI redemonstrated optic perineuritis and EICP findings, but resolution of perivascular enhancement. VPS was performed after vision improvement with lumbar drain. She underwent plasma exchange and transitioned to monthly cyclophosphamide infusions. Her bilateral superior visual fields improved after 6 months of cyclophosphamide and steroid taper; however, she had persistent, non-disturbing visual hallucinations of cartoon characters. Given the absence of other neuropsychiatric features or electroencephalogram correlate, her hallucinations were attributed to CBS.