Leucotome

Invented by Canadian neurosurgeon Dr. Kenneth G. McKenzie in the 1940s, the leucotome has a narrow shaft which is inserted into the brain through a hole in the skull, and then a plunger on the back of the leucotome is depressed to extend a wire loop or metal strip into the brain.

[1] This type was used by the Nobel Prize-winning Portuguese neurologist Egas Moniz.

[2] Another, different, surgical instrument also called a leucotome was introduced by Walter Freeman for use in the transorbital lobotomy.

A mallet was used to drive the instrument through the thin layer of bone and into the brain along the plane of the bridge of the nose, to a depth of 5 cm.

Due to incidents of breakage, a stronger but essentially identical instrument called an orbitoclast was later used.