Dissociation Between Recovery of Ocular Motility and Visual Function in Orbital Apex Syndrome Due to Myeloperoxidase-Antineutrophil Cytoplasmic Antibody-Associated Hypertrophic Pachymeningitis

In antineutrophil cytoplasmic antibody (ANCA)-associated hypertrophic pachymeningitis (HP), inflammation can extend to the orbital apex and cause severe visual impairment.A 66-year-old man was hospitalized elsewhere for diabetic ketoacidosis due to untreated diabetes.Although his general condition stabilized, he developed rapidly progressive visual loss in both eyes and was referred to our hospital.At presentation, visual acuity was hand motion in the right eye and no light perception in the left eye.Ocular motility was limited in all directions in both eyes, with proptosis of the left eye.Contrast-enhanced magnetic resonance imaging showed skull-base dural thickening, soft-tissue lesions at both orbital apices, and marked mucosal thickening of the paranasal sinuses.Myeloperoxidase (MPO)-ANCA was positive.Orbital apex syndrome due to MPO-ANCA-associated HP was diagnosed, and he was treated with intravenous methylprednisolone pulse therapy, rituximab, and oral prednisolone.Ocular motility improved markedly; however, at 54 weeks, corrected visual acuity in the right eye had improved only to 0.02 (decimal), and the left eye had no light perception throughout.We report this dissociation between the courses of ocular motility and visual function and discuss its possible mechanisms.