“…Horner syndrome (HS) is associated with a constellation of symptoms, including ipsilateral myosis, ptosis, enophthalmos, and facial anhidrosis, and is due to a disruption of any part of the ipsilateral sympathetic innervation. [ 1 , 2 ] HS can be divided into 3 types according to the localization of the sympathetic lesion: central (first-order neuron), preganglionic (second-order neuron), and postganglionic (third-order neuron). The causes of HS include stroke in the posteroinferior cerebellar artery, trauma, tumors, cluster migraine, and carotid dissection.…”