surgical procedure in which the nerve pathways in a lobe or lobes of the brain are severed from those in other areas. The procedure formerly was used as a radical therapeutic measure to help grossly disturbed patients with schizophrenia, bipolar disorder, and other mental illnesses. Lobotomy was introduced in 1935 by two Portuguese neurophysicians, António Egas Moniz and Almeida Lima. The practice was soon widely adopted, largely because there were few other viable therapeutic measures at the time for quieting chronically agitated, delusional, self-destructive, or violent patients.

The lobotomy, or prefrontal leukotomy, involved severing the nerve pathways in the two frontal lobes of the brain, after entry to the brain had been achieved by boring two holes in the skull. This method was soon replaced by the transorbital lobotomy, in which a picklike instrument was forced through the back of the eye sockets to pierce the thin bone that separates the eye sockets from the frontal lobes; the pick's point was then inserted into the frontal lobes where the connections between the lobes were severed. A large proportion of such lobotomized patients exhibited reduced tension or agitation, but many also showed such effects as apathy, passivity, lack of initiative, poor ability to concentrate, and a generally decreased depth and intensity of their emotional response to life.

Lobotomies were performed on a wide scale during the 1940s and up until about 1956, when antipsychotics, antidepressants, and other medications that were much more effective in treating and alleviating the distress of mentally disturbed patients came into use. Lobotomies are no longer performed; however, psychosurgery, the surgical removal of specific regions of the brain, is occasionally used to treat patients whose symptoms have resisted all other treatments.