Just as with a regular old organ transplant, the first step for a head transplant is identifying someone in need. In this case, the "organ" recipient is keeping his or her own head, which is getting transplanted onto a body. While there may be numerous people in the world with illnesses that destroy the body but leave the mind intact (like progressive muscular dystrophies), there's only one guy so far who has come forward willing to try this risky operation (in December 2017): Valery Spiridonov, a 30-year-old Russian with a rare genetic disease that gradually wastes away his muscles.
That's half the equation handled. You still need a donor, but that's not something that can be planned in advance. The donor will have to be matched to Spiridonov (or any other future candidate for the surgery) for height, build and immunotype, and the donor will have to be screened for disorders. Once the donor is in place, there has to be a plan to carry out the operation.
Lucky for Spiridonov, Dr. Canavero has already thought this through. First order of business: an operating room big enough for two surgeries at once. You can't have someone running through the streets to a hospital across town carrying a head in a bucket of ice. The highest chance of success is for the reconnection to occur as quickly as possible (within an hour) [source: Canavero]. There would have to be teams of doctors, nurses and other support staff to cover all different specialties within medicine: neurosurgery, vascular surgery, orthopedics for spine fusion, plastic surgery and many more.
Once the surgery teams are in place, both the recipient and the donor would be prepped as they might for a regular surgery — intubated, ventilated via tracheotomy (remember — heads will be chopped off; ventilation through the mouth won't be very helpful) and given antibiotics. The next and very crucial step is cool. Literally. You'd have to cool the bodies to about 50 degrees F (10 degrees C) [source: Canavero]. Low temperatures like this lead to low blood flow, which provides protective effects on the brain, blunting a lot of biological processes that lead to neural cell death.
With the recipient first lying down and later seated and the donor seated to facilitate the surgical procedures, deep incisions would be made at each neck, exposing arteries, jugular veins and the spine. All muscles in both patients would be color-coded with markers to facilitate later linkage. The spinal cords would get the final cut, leaving some slack for fusion to the new body. Very quickly, the "good" head would be moved to the "good" body and the spinal cord stumps fused within 1-2 minutes. Speed here is key. While bleeding out isn't so much a danger (vessels in the neck would be clamped), the brain desperately needs oxygen and glucose that it can only get if it is attached to the body via the spinal cord. Cooling the patients will help buy the surgeons a little bit of time, but they will still have to work very quickly if they want any hope of the transplant working [source: Canavero].
You might recall the spinal cord fusion being the challenging step with the monkeys in the 1970s. Canavero proposes using a polyethylene glycol (PEG) glue to fuse them. PEG is a widely used plastic with a range of applications in products like toothpaste, skin cream and various medications. PEG has been shown to immediately repair cell membranes damaged by mechanical injury, so Canavero believes it to be a strong candidate to reconnect the spinal cord [source: Borgens]. The spine also would need stabilization, which could be achieved with the help of wires, screws, rods and clamps.
After the surgeon reattaches the cord, he'd quickly sew together the carotid arteries and then reconnect the trachea, esophagus and nerves. The muscles that were marked would be joined, and then everything would get stitched up by a plastic surgeon.
The patient would require sedation in the intensive care unit of the hospital for a minimum of three days, but for the first attempt at the surgery, Canavero will likely induce a coma lasting three to four weeks, just to play it safe. The surgeon expects that, once awake, the patient should be able to talk and feel their face, but they'd require at least a year of physiotherapy before they could fully move their body [source: Canavero].
Thirty-six hours of surgery, years of therapy and $11-13 million later, done [source: Hamblin]! Seems pretty easy, no?