Put Your Head on My Shoulder

Head transplants have been a staple for science fiction stories for a long time, from the monster in Mary Shelley’s Frankenstein to Pierce Brosnan and/or Sarah Jessica Parker having their head attached to a Chihuahua in Mars Attacks! to the movie Futurama: Bender’s Big Score, where Hermes is decapitated, then has Bender obtain an earlier version of his body and do a head transplant using Torgo’s Executive Powder. But how possible is a head transplant? And if it could be done, what are some of the implications?

In a paper published in the June issue of open source journal Surgical Neurology International, Dr. Sergio Canavero of the Turin Advanced Neuromodulation Group says he knows how to perform a complete human head transplant. According to Canavero, the transplant will work if surgeons can successfully link the spinal cord to the head by fusing severed axons, the nerve cells that transmit information to different neurons, muscles and glands. “The greatest technical hurdle to such endeavor is of course the reconnection of the donor’s and recipient’s spinal cords. It is my contention that the technology only now exists for such linkage.”

Surgeons would begin by cutting the cooled spinal cords with an “ultra-sharp blade” (the GEMINI procedure), then put the recipient’s head into a “hypothermia mode” for around 45 minutes between 12°C and 15°C (the HEAVEN process). Canavero belives that such a short time would create virtually no neurological damage. Cut axons would then be reconstituted using molecules such as poly-ethylene glycol (used in areas ranging from industrial manufacturing to pharmaceutical products) or chitosan.

Dr. Canavero has made headlines by using electrical stimulation to awaken a car accident victim who’d been in a persistent vegetative state for two years.

In June of this year, Dr. Jerry Silver of Case Western Reserve Medical School and a team of scientists at Case Western and the Cleveland Clinic successfully restored connectivity in rats whose spinal cords had been completely severed. In the study, the researchers used a chemical that promotes cell growth along with a scar-busting enzyme to create a more hospitable environment for the nerve graft at the injury site.

Although the rats didn’t regain the ability to walk, they recovered a remarkable measure of urinary control, a function that many spinal cord injury patients rank as one of the most important to regain following injury. Canavero argues that such recent advances in reconnective technology give scientists reason to believe the procedure he outlines will be successful in humans. Dr. Silver disagrees.

“It’s light years away from what they’re talking about,” he said. Silver’s research involved single rats, not connecting the spinal cords to heads of other rats. In these experiments, Silver explains, the animals are still able to breath, and their circulation is left intact. “It’s complete fantasy, that you could use [PEG technology] in such a traumatic injury in an adult mammal,” Silver says. “But to severe a head and even contemplate the possibility of gluing axons back properly across the lesion to their neighbors is pure and utter fantasy in my opinion.”

It may be fantasy, but Canavero is hardly the first to look at the possibility of human head transplants.

Vladimir Petrovich Demikhov was a Soviet scientist famous for his experiments in organ transplants during the 30s and 50s. In 1960, he published the first scientific monograph on transplantology, titled “Experimental transplantation of vital organs.” It was a seminal work, starting transplant science as we now know it. He was the first to perform a successful coronary bypass, the first to transplant an auxiliary heart into a warm-blooded animal, and the first to transplant a working heart and lungs into a living animal. But he also transplanted dog heads and upper bodies onto other dogs, effectively creating two-headed dogs.

In 1954 he created the first transplant in a lab on the outskirts of Moscow by grafting the head and forelegs of a smaller dog, Shavka onto a bigger dog, Brodyaga. Both initially survived the procedure and could see and move around independently, but died four days later. None lived for more than 29 days, and they inevitably died because of the tissue rejection. You can see photos from a LIFE magazine article in July, 1959 that documented the surgery. You can also watch video of one of the operations.

Then in 1970 a group of scientists from Case Western Reserve University School of Medicine led by Robert J. White, a neurosurgeon and a professor of neurological surgery inspired by the work of Vladimir Demikhov, transplanted the head of one rhesus monkey onto another’s body. The operation was so successful that once awake, the first transplant subject even tried to bite a doctor. Canavero cites White’s experiment as the first successful primate head transplant, writing that, “The monkey lived 8 days and was, by all accounts, normal, having suffered no complications.” White himself referred to it as a “whole body transplant.” (You can see a two-part interview with Dr. White with some snippets of footage of the operation here and here, and more footage of the surgery here.)

Despite Canavero’s description, Dr. Silver. who was a part of Dr. White’s transplant group, remembers it differently.

“I remember that the head would wake up, the facial expressions looked like terrible pain and confusion and anxiety in the animal. The head will stay alive, but not very long,” the Case Western Reserve University neurologist told CBSNews.com. When doctors attempted to feed the re-connected head, the food fell to the floor. “It was just awful. I don’t think it should ever be done again.”

Even if such a transplant could be done, it would be fraught with ethical issues. Canavero estimates the procedure would cost about $13 million, likely placing such an operation out of the reach of all but the wealthy. He adds that a risk could develop whereby people with adequate funds try to secure the bodies of healthy young individuals on the black market and have them transplanted by dishonest surgeons.

Then there’s the philosophical questions. Dr. Christopher Scott, a bioethicist and regenerative medicine expert at Stanford notes “What is the donor and what’s the recipient? We all have an idea of personhood, right? Of what a person is. You know, a baby or a human becomes a person. And this procedure turns it on its head. Is this a person that the body belongs to, or the person the head belongs to? It’s a chimera, a hybrid person. …Those are some of the deeper questions that we should have a real discussion about.” And what if the body recipient has children? Should we attach a living man’s head to a woman’s body, or vice-versa?

I suspect head transplants will be the fodder of science fiction stories for some time to come.

References

Berko, Lex. Meet the Late Dr. Robert White, Who Transplanted the First Monkey Head. http://motherboard.vice.com/blog/dr-robert-white-transplanted-first-monkey-head. Retrieved 11/15/2013.

Canavero S. HEAVEN: The head anastomosis venture Project outline for the first human head transplantation with spinal linkage (GEMINI). Surg Neurol Int 2013;4, Suppl S1:335-42.

Canavero S., Massa-Micon B., Cauda F., Montanaro, E. Bifocal extradural cortical stimulation-induced recovery of consciousness in the permanent post-traumatic vegetative state. Journal of Neurology, May 2009, Volume 256, Issue 5, pp 834-836.

Elliot, Danielle. Human head transplant is “bad science,” says neuroscientist, CBS News, July 2, 2013 http://www.cbsnews.com/8301-205_162-57591862/

Konstantinov IE. At the cutting edge of the impossible: a tribute to Vladimir P. Demikhov. Tex Heart Inst J 2009;36(5): 453–8.

Langer R.M., Vladimir P. Demikhov, a pioneer of organ transplantation. Transplant Proc. 2011 May;43(4):1221-2. doi: 10.1016.

Lee et al., Nerve Regeneration Restores Supraspinal Control of Bladder Function after Complete Spinal Cord Injury. The Journal of Neuroscience, 26 June 2013, 33(26):10591-10606.

Mangels, John. Cleveland researchers restore bladder control in rats with spinal cord injuries. The Plain Dealer, June 25, 2013. http://www.cleveland.com/science/index.ssf/2013/06/cleveland_researchers_restore.html

Northoff G. Do brain tissue transplants alter personal identity? Inadequacies of some “standard” arguments. J Med Ethics. 1996 Jun;22(3):174–180.

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