TI 20160515

Johnny: How Human Head Transplants Could Work In 2009, Cincinnati Bengals wide-receiver Chris Henry was involved in a tragic automobile accident. The accident left him with such grave injuries that he was pronounced brain-dead at the hospital. As Henry was not signed up to be an organ donor, his mother, Carolyn Henry Glaspy, found herself with the choice of what to do with his organs. Glaspy consented to donate her son's lungs, liver, kidneys and pancreas to four different strangers. Her decision saved the lives of several people desperately clinging to life on the transplant list. She even met them after the operations to see how her son lived on through the organ recipients. This story, and the many other similar ones out there, is simultaneously heartbreaking and heartwarming. How would the emotions change if the conversation wasn't about organ transplants but rather an entire body transplant? What if surgeons were able to place the head of someone with an intact brain onto the body of someone brain-dead like Chris Henry? Would Henry's mother have made the same choice, knowing her son's body was still walking the planet but with another brain controlling it? How would the recipient feel with a totally different body? Would this new person be good at football? Iris: Furthermore, if we're going so far as to swap heads on bodies, where would we stop? What if they attached a woman's head or a child's head? How would this type of operation even work? From Monsters to Mice: A History of Head Transplants The idea of pulling together a human from parts of other humans is nothing new. Perhaps the most famous example in literature is the imaginings of Mary Shelley in her novel "Frankenstein" (1818). As you probably remember, in this tale a scientist named Frankenstein assembles a monster from different parts of graveyard corpses and gives it life in the laboratory. Outside the pages of fiction, scientists have experimented quite a bit with assemblages of animals. Let's look at a few examples involving head transplants. In 1954, Russian doctor Vladimir Demikhov performed a series of experimental operations creating two-headed dogs. He successfully grafted the head and forelegs of one dog onto the neck of another. Amazingly, both heads could see, hear, smell and swallow. The longest any one of his experimental animals lived was 29 days. By modern standards, such an experiment seems cruel and unnecessary; however, Demikhov was motivated by his sincere interest in saving human lives. He hoped to gather all he learned from the dog experiments and apply it to human transplants. Felicity: At the time, only bone, blood vessels and corneas had been successfully transplanted in humans. Transplants on larger organs like kidneys were attempted, but the organs were always rejected. Demikhov and his team had their sights set on creating a tissue bank with a storehouse of organs to be used any time someone was in need of a transplant. Fast-forward to 1970 in the United States where head transplant experiments were attempted with rhesus monkeys. Dr. Robert White in Cleveland was able to perform a head transplant where the monkey survived neurologically intact for 36 hours, although it could not move. After nine days, the head was rejected by the monkey's immune system, and the animal died. The largest obstacle cited by the transplant team was the inability to connect the spinal cord（脊髓）. Since then, experiments have continued in China with mice, and some progress has been made in the understanding of spinal cord connection. And while nothing has been tried yet with humans, an Italian surgeon and member of a think tank devoted to the advancement of brain stimulation named Sergio Canavero is convinced he has a method to transplant a human head that will work and is gearing up to try it out. Johnny： The Plan: Cut Off Head. Reattach to New Body. 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. Iris： 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).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). 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. Felicity： 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. You might recall the spinal cord fusion being the challenging step with the monkeys in the 1970s. Canavero proposes using a polyethylene glycol (PEG) 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. The spine also would need stabilization, which could be achieved with the help of wires, screws, rods and clamps. Johnny： 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 Thirty-six hours of surgery, years of therapy and $11-13 million later, done Seems pretty easy, no? Iris： The Biggest Challenges for Head Transplanters and Transplantees As all experiments thus far have shown, the biggest challenge with this surgery will be reconnecting the spinal cord. But that's just the largest hurdle in the operating room. A host of potential post-op problems need to be addressed, too. If everything goes smoothly during the surgery (and that's a big "if"), the first concern after the operation will be head rejection. You don't want the body fighting against the head, so regular blood samples and biopsies will have to be performed to confirm no antidonor antibodies have been formed. There's also the chance that the surgery will largely work and the head will get attached and accepted by the new body, but there will be smaller issues that didn't go so well during the surgery. For example, some nerves associated with the vocal cords loop down from the brain, down the neck and back up again. Reconnecting them may pose a larger challenge to the surgeons, and speech may be affected. The esophagus might not be totally leak-proof after reattachment, leading to potential complications with digestion. Felicity： Perhaps the biggest deal of all will be the psychological impact on the recipient of the new body. Unlike many other organ transplants, a full body transplant will always be visible to the recipient — a constant reminder that their body is not their own. Patients who have received hand transplants are an excellent comparison point, as they have an ever-present visible reminder of the transplant. These transplant recipients have had to figure out how to mourn the loss of their hand and come to terms with their sense of self and body image. And that's just for a hand. Imagine the degree to which an entire new body will affect the psychology of a patient. Even if someone is medically determined to be a suitable candidate for the surgery, a psychiatric evaluation will be a necessity to make certain they can handle their new life with a new body.