Horner’s syndrome due to giant cell arteritis

We present one of the few documented cases of Horner’s syndrome as a manifestation of biopsy-proven giant-cell arteritis. An 84-year-old man with jaw claudication and slight elevation of ESR (erythrocyte sedimentation rate) presented ptosis and left pupil miosis. A 1% phenylephrine instillation produced dilatation of the affected pupil, suggesting postganglionic rather than preganglionic involvement. Temporal arteritis should be considered in an elderly patient with Horner’s syndrome.