Background: Horner syndrome (HS), also known as Claude-Bernard-Horner syndrome or oculosympathetic palsy, comprises ipsilateral ptosis, miosis, and facial anhidrosis.
Case report: We report herein the case of a 67-year-old man who presented with congenital HS associated with ipsilateral hypoplasia of the internal carotid artery (ICA), as revealed by heterochromia iridis and confirmed by computed tomography (CT).
Conclusions: CT evaluation of the skull base is essential to establish this diagnosis and distinguish aplasia from agenesis/hypoplasia (by the absence or hypoplasia of the carotid canal) or from acquired ICA obstruction as demonstrated by angiographic CT.
Keywords: computed tomography; congenital horner syndrome; heterochromia iridis; internal carotid artery agenesis.