Horner Syndrome Due to Spontaneous Internal Carotid Artery Dissection

Horner syndrome is a constellation of neurological findings consisting of ipsilateral ptosis, miosis, and anhidrosis. Partial Horner syndrome, comprising ipsilateral ptosis and miosis in the absence of anhidrosis, is a well-documented but uncommon manifestation of internal carotid artery dissection. We report the case of a 42-year-old male patient who presented with ipsilateral ptosis and miosis and was subsequently diagnosed with internal carotid artery dissection. In this case report, we discuss the anatomy of the oculosympathetic pathway and the pharmacological diagnosis for a better understanding of the localization of the lesions causing Horner syndrome.