Abstract
Horner's Syndrome (HS) is a disease characterized by miosis, ptosis, and ipsilateral lack of sweating. It can occur with any injury at the level of the ocular sympathetic system neurons from the hypothalamus to the cervical postganglionic fibers. We present here a case of HS that developed after heart surgery in a 9-year-old boy. Ventricular septal defect, aortic and mitral valves repair, and pacemaker implant procedures were noted in his medical records. Preganglionic HS was diagnosed with bilateral unresponsiveness to a 0.1% adrenaline and positive result in the right eye to 0.5% apraclonidine tests. HS is often related to injuries of the brain stem, upper spinal cord, lung apex tumors and lesions, aortic coarctation, cervical lesions, and carotid lesions have been reported. However, it is rare secondary to heart surgery among the pediatric age group.