A lobotomy, or leucotomy, is a form of psychosurgery, a neurosurgical treatment of a mental disorder that involves severing connections in the brain's prefrontal cortex. Most of the connections to and from the prefrontal cortex, the anterior part of the frontal lobes of the brain, are severed. It was used for psychiatric and occasionally other conditions as a mainstream procedure in some Western countries for more than two decades, despite general recognition of frequent and serious side effects. While some people experienced symptomatic improvement with the operation, the improvements were achieved at the cost of creating other impairments. The procedure was controversial from its initial use in part due to the balance between benefits and risks. Today, lobotomy has become a disparaged procedure, a byword for medical barbarism and an exemplary instance of the medical trampling of patients' rights.
The originator of the procedure, Portuguese neurologist António Egas Moniz, shared the Nobel Prize for Physiology or Medicine of 1949 for the "discovery of the therapeutic value of leucotomy in certain psychoses", although the awarding of the prize has been subject to controversy.
The use of the procedure increased dramatically from the early 1940s and into the 1950s; by 1951, almost 20,000 lobotomies had been performed in the United States and proportionally more in the United Kingdom. The majority of lobotomies were performed on women; a 1951 study of American hospitals found nearly 60% of lobotomy patients were women; limited data shows 74% of lobotomies in Ontario from 1948–1952 were performed on women. From the 1950s onward lobotomy began to be abandoned, first in the Soviet Union and Europe. The term is derived from Greek: λοβός lobos "lobe" and τομή tomē "cut, slice".