In 2017, Italian neurosurgeon Sergio Canavero attempts to perform the first human head transplant. This follows a series of earlier experiments with animals and human cadavers. In 2015, he announced plans to operate on a live human patient within two years. His goal appeared outlandish at first, but gained some credibility the following year, when researchers in China grafted the head of a monkey onto a completely new body, building upon a similar achievement half a century earlier.*
Canavero’s patient is Valery Spiridonov,* a 30-year-old Russian man with Werdnig–Hoffmann disease (the most severe type of spinal muscular atrophy) and declining health who volunteers to offer his head for Canavero’s studies. When first announced, popular opinion about the potential head transplant was generally quite negative, with Canavero being criticised on ethical grounds and a number of doubts expressed from experts regarding the state of technology readiness.
The procedure involves cooling the head and donor body to -15°C (5°F). This extends the time that their cells can survive without oxygen, which is vital for avoiding neurological damage. As soon as tissue around the neck has been dissected, major blood vessels are linked using tiny tubes, before the spinal cords of each person are cut (with high precision) and the head is transferred onto its new body. This new “combined” body is fused together – using polyethylene glycol to flush both ends of spinal cord and encourage nerve growth – followed by injections of the same chemical over a period of several hours.
Assuming the patient survives to this stage, measures are then taken to prevent the body’s immune system from rejecting the head. They are kept in a coma for three or four weeks to ensure they are completely stationary. Implanted electrodes provide electrical stimulation, which helps to strengthen nerve connections. After a year or so, it is hoped that the person is able to walk around. Regardless of how successful this particular operation is, knowledge gained from the surgery helps to improve this procedure in the future.