Miller Fisher variant of Guillain-Barré syndrome masquerading as acute sphenoid sinusitis with orbital apex syndrome.

Miller Fisher syndrome (MFS), a variant of Guillain-Barré syndrome, is a rare disorder typically characterized by a triad of ataxia, areflexia, and ophthalmoplegia, which may have a highly variable clinical presentation. We report a case of MFS in a 45-year-old female presenting with sphenoid sinusitis and sixth nerve palsy. She underwent endoscopic sphenoid sinusotomy without improvement, had postoperative deterioration, was diagnosed with MFS, and was treated with intravenous immunoglobulin with complete response. Because of the potential severity of Guillain-Barré syndrome, great vigilance should be taken when examining sixth nerve palsies to prevent misdiagnosis and delay in treatment of the MFS variant of this disease.