Neurosurgeon Sergio Canavero, shown here at Molinette Hospital in Turin, has proposed doing the first human head transplant.
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Neurosurgeon Sergio Canavero, shown here at Molinette Hospital in Turin, has proposed doing the first human head transplant.

Human Head Transplant Proposed—How Did We Get Here?

Yes, in case you haven’t heard, a doctor in Italy has announced plans to transplant a guy’s head onto a new body two years from now. Sound nuts?

Many of the headlines say so. “No, Human Head Transplants Will Not Be Possible by 2017,” said Popular Science. The International Business Times pronounced head transplants “not a thing.”

When I started talking about this at work, reactions included words like crazy, and impossible. There were jokes about Ted Williams’ head, currently frozen in Arizona and awaiting a new body. Meanwhile, stories started popping up from online gamers suggesting the whole thing was a hoax designed to sell video games.

But I’m not so sure we should blow this off, whether it’s going to happen in 2017 or not. The more I read about the history of transplants, and spinal cord surgery, and experiments involving monkey heads, the more questions I have. And the less it all seems like a joke.

Experiments are already happening in animals, and the proposed human transplant does not appear to be a marketing hoax: the neurosurgeon, Sergio Canavero, is presenting his plans in June at a surgical conference.

If he does actually try to go through with it, suddenly head transplants will be a thing. And even if the plan fizzles, we might want to figure out whether we even want to go there, before someone does.

And what would we make of it if someone did go there? It might well be impossible to deliver what the public might expect: a person who walks around perfectly normal except for their mismatched body. But what if a head-transplant patient—say someone who was dying of an incurable disease, or a quadriplegic with failing organs—were to live several years attached to a paralyzed body? Is that a success?

Then there are the legal and ethical issues, and dollars-and-cents practicalities. Is it OK to use an entire body to save one person, when the organs could save many? Will we pay for it? Would you, if you could save your husband or wife’s head? (Answer that one carefully.)

Canavero leads a think tank called Turin Advanced Neuromodulation Group, and he wrote a paper proposing his GEMINI spinal-cord fusion procedure in February. Here’s a TEDx talk he gave about his plan (in English; and a more recent talk in Italian).

The head in question is that of Valery Spiridonov, a 30-year-old Russian computer programmer who stepped forward in April as a volunteer; the body would come from a brain-dead donor. Spiridonov suffers from Werdnig-Hoffman disease, a degenerative genetic condition that affects nerves and muscles. He has not walked since he was one year old, according to an interview with Motherboard, which also spoke to Canavero.

The challenges would include keeping his brain alive during the transfer, piecing together the severed spinal cords and getting them to communicate, and keeping the body from rejecting the head, to name a few. This article by Helen Thomson in New Scientist gives the best overview I’ve seen so far of the procedure and hurdles.

There are plenty of fascinating science questions that I hope to write about later, but first, let’s look at the history. Have head transplants been done with anything that could be considered success in other animals?

To be clear, I’m not condoning the experiments below. Many wouldn’t muster with today’s animal research standards, which exist for good reason. But we can look at a few of the milestones in head swapping.

1908: Head added to dog. Charles Guthrie grafted one dog’s head onto another’s neck, attaching arteries so that blood flowed first to the decapitated head, then to the other head. The head was without blood flow for about 20 minutes, and regained only minimal movement.

1950s: More two-headed dogs. Vladimir Demikhov, a pioneer in human heart and lung transplants, grafted the upper bodies of young dogs onto the shoulders of other dogs, creating dogs with two heads, both able to move, see, and even lap up water. Without drugs to prevent rejection by the immune system, most lived only a few days, but one reportedly held out for 29 days. (See images from LIFE magazine’s 1959 story here. Warning: may be disturbing.)

People weren’t too happy about these experiments at the time. Even a tribute to the late Dr. Demikhov notes that it was unclear to many other surgeons what medical value the grafted dogs held.

1965: Dog brain transplant. Robert White of Cleveland Metropolitan General Hospital transplanted the brains of six dogs into the necks of other dogs, to show that the brains could be kept alive in another body. The brains showed EEG activity and took up oxygen and glucose. No word on what, if anything, they made of being trapped in a neck.

1970: First head transplant in a monkey. Robert White transplants the entire head of a rhesus monkey onto another monkey’s body. The monkey could see, hear, and taste, but White did not attempt to fuse the spinal cord. The monkey lived for several days after the surgery (reports vary from three to nine days). (See Motherboard’s video interview with White about his work below.)

2002: Low-temp head transplant in a rat. Scientists in Japan graft infant rats’ heads onto the thighs of adults, to test cooling the brain  to prevent brain damage with oxygen loss. The young rats’ brains continued to develop for three weeks.

2013: Canavero proposes human head transplant. In Surgical Neurology International, he outlines a procedure involving a clean cut to the spinal cord to minimize damage and using polyethylene glycol (PEG) to fuse the spinal cord.

2014: Head transplants in mice. Xiao-Ping Ren and colleagues in China report a head-swapping experiment in mice, resulting in a white mouse with a black head, and vice versa. The mice live up to three hours after being removed from a ventilator. That’s not long, but by keeping the donor body’s brainstem, the body is able to continue to control its own heartbeat and breathing.

February 2015: Canavero details head-transplant procedure. In an editorial in Surgical Neurology International, Canavero proposes cooling the head and donor body to limit cell damage from oxygen loss, and fusing the spinal cord with a process called GEMINI, which uses PEG and electrical stimulation, which has been shown in other studies to promote spinal cord repair.

So, some success, depending how you define it, though I doubt these results will have many people rushing to the front of the line for a head transplant.

To follow the latest on Canavero’s proposal, I’ll be at the American Academy of Neurological and Orthopedic Surgeons meeting in Annapolis this June when he gives a keynote address on head transplantation.