Optic disc edema in glial fibrillary acidic protein autoantibody-positive meningoencephalitis

Background: Glial fibrillary acidic protein (GFAP) autoantibody-positive meningoencephalitis is a newly described entity characterized by a corticosteroid-responsive meningoencephalomyelitis. Some patients with GFAP autoantibody-positive meningoencephalitis have been found to have optic disc edema, which has previously not been well characterized. Methods: We performed a retrospective, observational case series of Mayo Clinic patients found to have GFAP-IgG and optic disc edema from January 1, 2000, to December 31, 2016. We identified 40 patients with GFAP-IgG seropositivity by tissue-based immunofluorescence and cell-based assay. Patients were screened for the following inclusion criteria: 1) serum, cerebrospinal fluid, or both that yielded a characteristic astrocytic pattern of mouse tissue immunostaining with confirmation of IgG reactive with specific GFAPa isoform by cell-based assay; 2) meningoencephalitis or encephalitis; and 3) optic disc edema. We excluded those with coexisting aquaporin-4-IgG or insufficient clinical information. Results: Ten patients had optic disc edema and met inclusion criteria. The median age was 39.5 years and 60% were men. Visual acuity was unaffected and disc edema was bilateral in all cases. Mild vitreous cell was noted in 3 patients. The optic disc edema resolved with corticosteroid treatment but resulted in mild optic atrophy in 2 patients. The median lumbar puncture opening pressure was 144 mm H₂O (range, 84-298 mm H₂O). Brain MRI revealed radial perivascular enhancement in all except 1 patient. Fluorescein angiography was available for 1 patient with optic disc edema, which showed leakage from the venules. Conclusions: Patients with GFAP autoantibody-positive meningoencephalitis can have optic disc edema that can mimic papilledema. The cause of the optic disc edema remains uncertain, but most patients did not have raised intracranial pressure.