Endoscopic thoracic sympathectomy (ETS) is surgery to treat sweating that is much heavier than normal. This condition is called hyperhidrosis. Usually the surgery is used to treat sweating in the palms or face. The sympathetic nerves control sweating. The surgery cuts these nerves to the part of the body that sweats too much. If blushing fails to respond to conservative medical treatment or behavioural therapy, then surgical sympathectomy is an option: this can be done either by open or endoscopic approaches. Video Assisted Thoracic Sympathectomy is now usually the preferred technique.