lobotomy, surgical procedure for cutting nerve pathways in the frontal lobes of the brain. The operation has been performed on mentally ill patients whose behavioral patterns were not improved by other forms of treatment. The procedure as pioneered by Nobel laureate Egas Moniz in the 1930s consisted of drilling holes through the skull and severing or interfering with nerve fibers to the midbrain, particularly to the thalamus. In a later development, instruments were passed through the eye sockets to sever the connections.

Lobotomies were performed on numerous patients between 1936 and 1956. In approximately one half there was at least temporary relief of symptoms. However, some patients exhibited worse behavior after the operation, and others whose tensions were relieved by the surgery degenerated to a vegetative state. Since the mid-1950s such psychosurgery has been largely abandoned in favor of less radical means of treatment, e.g., the administration of tranquilizers and other chemical substances. Most psychiatrists today do not view lobotomy as an acceptable form of treatment.

Surgical procedure in which nerve pathways in a lobe or lobes of the brain are severed from those in other areas. Introduced in 1935 by António Egas Moniz and Almeida Lima, it came to be used to help grossly disturbed patients. Favoured for patients who did not respond to shock therapy, it did reduce agitation but often caused increased apathy and passivity, inability to concentrate, and decreased emotional response. It was widely performed until circa 1956, when drugs that were more effective in calming patients became available. 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.

Learn more about lobotomy with a free trial on Britannica.com.