Abstract
Horner syndrome, manifesting as ptosis and miosis, arises from disruptions within the oculosympathetic pathway. This syndrome is classified based on the lesion's location along the sympathetic nerve pathway into central, preganglionic, or postganglionic types. While endoscopic transthoracic sympathectomy, a surgical intervention for hyperhidrosis, is associated with several complications, including compensatory hyperhidrosis, Horner syndrome, and pneumothorax, these complications are notably rarer in sympathotomy procedures. Importantly, the incidence of Horner syndrome post-operatively is notably low, particularly in comparison to compensatory hyperhidrosis, with most cases being reversible and not necessitating further intervention. This report delineates a rare case of persistent Horner syndrome following a bilateral sympathotomy at the T3 and L3 levels, performed to alleviate symptoms of palmar and plantar hyperhidrosis. The discussion underscores the rarity of such a complication and explores the implications for surgical practice and patient counselling.