Abstract
A 58-year-old right-handed woman presented with neck pain and right hemibody decreased pain and temperature sensation. Over the next 3 days, she developed left ptosis and miosis. The Horner syndrome was confirmed with 0.5% apraclonidine and neuromyelitis optica immunoglobulin G antibody titres were positive. Magnetic resonance imaging of the cervical spine showed a longitudinally extensive intramedullary expansile lesion more prominent on the left, with post-contrast enhancement extending from C2 to C5, consistent with neuromyelitis optica. This patient was diagnosed with neuromyelitis optica with an associated left Horner syndrome.