Case report: Tolosa-Hunt syndrome-expanding the neuromyelitis optica spectrum disorder phenotype?

Neuromyelitis optica spectrum disorder (NMOSD) is an autoimmune astrocytopathy caused by the autoantibody of aquaporin-4 (AQP4). Herein, we report a case of Tolosa-Hunt syndrome presenting with abducens palsy and AQP4 antibodies. This was a rare case of AQP4-immunoglobulin G seropositivity in a patient with Tolosa-Hunt syndrome. Our findings may expand the clinical phenotype of NMOSD and indicate that clinicians should consider testing for AQP4 antibodies in patients with Tolosa-Hunt syndrome.