In 1970, a surgeon transplanted the head of one monkey onto the body of another. While the spinal cord couldn't be connected, the the primate patient (victim?) lived eight days. Italian neurosurgeon Sergio Canavero is set on attempting a head transplant on a human, complete with spinal linkage. He calls the procedure HEAVEN. Canavero did have a volunteer lined up—Valery Spiridonov, who suffers from a rare genetic disease causing his spinal muscles to atrophy—but Spiridonov changed his mind after falling in love.
In this video, the Institute of Human Anatomy's Justin Cottle explains how the head transplant could work: