How to Perform a Head Transplant

Just because you shouldn't do something doesn't mean you can't.
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Abandoned military hospital in Beelitz, Germany (Sebastian Niedlich / Flickr)

"Honey? What are you doing down there?"

Clattering at the foot of the shadowy staircase stops abruptly, replaced by the sound of someone trying not to make a sound.

"Oh boy, don't even tell me you're working on those human head-body chimera plans again."

After a long moment, a solitary cough echoes off the basement floor.

***

Many of us know this scene all too well -- torn between home life and the professional demands of experimental surgical fusion of human body parts. Perhaps no one would be more familiar than those close to Dr. Robert White in the 1970s. The Harvard-trained neurosurgeon famously devoted much of his career to what he called a head transplant. In 1970, he "succeeded" in carrying one out, on a monkey.

I qualify succeeded because, while that's the way it was publicized, the monkey chimera remained paralyzed from the neck down. Despite having a machine do his breathing for him, he died after eight days ... only a number of hours of which he was conscious.

The surgeons basically connected the blood vessels, but not the money part: the spinal cord.

"R's head, previously fixed in a Mayfield three-pin fixation ring, will literally hang from the stand during transference, joined by long Velcro straps. The suspension apparatus allows surgeons to reconnect the head in comfort."

So, big whoop, right? Wasn't there a story about a kid in your neighborhood who put the head of one animal onto the body of another and got it to stay alive for a little while? But this scene was more agonizing than anecdotal or whimsical, as Case Western neurosurgeon Jerry Silver remembers it: "When the head would wake up, the facial expressions looked like terrible pain and confusion and anxiety in the animal. ... It was just awful. I don't think it should ever be done again."

White was convinced, though, that his work with cephalosomatic linkage surgery in the monkey was pretty much proof that it was "fully accomplishable in the human sphere." By 1999 he said it was "now possible to consider adapting the head-transplant technique to humans."

People called him a genius. Gave him honorary degrees. People also call(ed) him crazy.

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White's autocerebral hypothermic perfusion in place, 1978 (White, Mayo Clinic Proceedings)


Jump forward to 2013, when last month Italian surgeon Sergio Canavero said that we have at last figured out that issue of connecting the spinal cord. The head transplant is now feasible, said Canavero, and he has a project called HEAVEN that's going to do it.

HEAVEN stands for Head Anastomosis Venture, which is a poor choice of acronyms in an industry constantly sidestepping God-complex accusations. Maybe it's like, ironic in a super self-aware way. That would be unique among the pages of the journal Surgical Neurology International, though, where Canavero dives deep into the specifics of how HEAVEN will work. So deep that we arrive at the existential.

For example, is it a head transplant? Technically it would be a body transplant. Identity remains with the brain. Doesn't it? If the chimera were to have sex and bear a child, though, it would have the genetic identity of the parent's body, not its head.

In Thomas Mann's 1959 novel The Transposed Heads, which is based on a traditional Indian folk tale, the two male protagonists behead themselves, and their heads are magically reattached, but to the other's body. One man's wife, Sita, subsequently has difficulty knowing which to take as her husband: the head or the heart.

Canavero does convey only the most benevolent of intentions, writing of the potential to use head transplants in patients with "horrible conditions without a hint of hope of improvement [that] cannot be relegated to the dark corner of medicine." He mentions tetraplegic patients, those with multi-organ failure, or intractable cancer that involves much of the body but not the head. The first patient to undergo head transplantation, though, "should be someone, probably young, suffering from a condition leaving the brain and mind intact while devastating the body, for instance, but by no means exclusively, progressive muscular dystrophies or even several genetic and metabolic disorders of youth."

Silver remains a non-believer. Earlier this year his team successfully fixed the spinal cords of rats that had them completely severed. Others have done it for dogs and pigs. When Danielle Elliot at CBS asked Silver about Canavero's proclamation that all of this could be done in humans, though, he laughed. "It's light years away from what they're talking about." Silver's experiments involved a clean cut to the spinal cord, and nothing but the spinal cord, and not involving a second animal. He told CBS, "To sever 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 ... Just to do the experiments is unethical."

It seems there are dark corners anywhere you turn.

Anyway, don't let all this worry about "ethical questions" wear you out -- you're going to need your energy for the surgery. Here's how Canavero says to do it ("lays out the groundwork"). Oh and also the estimated cost is $13 million. Okay, ready?

***

For purposes of these instructions, we use the "body transplant" perspective, which I prefer. The body recipient will be herein referred to as R, and the donor body as D (a brain-dead patient matched for height, build, immunotype, and ideally sex; and without any active systemic and brain disorders).

You'll need a specially designed operating suite large enough to accommodate two surgeries conducted simultaneously by two separate surgical teams. Again, I can't stress this enough, do not do this alone.

What we're going to do is cool R's head to such a low temperature that you can disconnect and reconnect it to D's body, whose head has been removed by your second surgical team. Once R's head has been detached, it will have to be reconnected to the circulatory flow of D within one hour. So do not make other plans, take a break, or even take a phone call while the R's head is detached. An hour is not a lot of time to reattach a head, especially for someone who's never done it before. (Everyone.)

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Inducing local hypothermia in the spine (Negrin, 1973)


Both R and D should be put on breathing machines and ventilated through tracheotomies. Keep their heads locked in place with rigid pin fixation. Constantly monitor them with electrocardiography, EEG, and transcranial measurement of oxygen saturation. Keep a radial artery line. A 25G temperature probe may be positioned into R's brain (deep in the white matter), but a TM thermistor should do.

R's head should be cooled to 10 degrees Celsius, while D's body will only receive spinal hypothermia, as diagramed above. That way body temperature won't be altered and we avoid damaging D's major organs. R lies on his back initially, then is placed in the standard neurosurgical sitting position. D is upright throughout. You'll probably want a custom-made turning stand to use as a sort of crane for shifting R's head onto D's neck. As Canavero writes, "R's head, previously fixed in a Mayfield three-pin fixation ring, will literally hang from the stand during transference, joined by long Velcro straps." This lets you "reconnect the head in comfort."

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Biventricular cooling for deep brain hypothermia in monkey (White, 1978)


Make deep incisions around each patient's neck, carefully separating all the anatomical structures. Expose the carotid and vertebral arteries, jugular veins and spine. All muscles in both R and D would be color-coded with markers to facilitate later linkage. Don't take out R's thyroid gland.

Cut through the vertebrae at C5 or C6 in both R and D, after appropriate laminectomies, a durotomy. Expose the spinal cord.

Under the operating microscope, simultaneously clean-cut both patients' spinal cords.

Once R's head is separated, transfer it onto D's body, whose head is also off.

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(White et al, 1971)


"The vascular anastomosis for the cephalosomatic preparation is easily accomplished by employing bicarotid-carotid and bijugular-jugular silastic loop cannulae." Remove the tubes individually, and sew the arteries and veins of the transplanted head together with those of the new body. Importantly, during head transference, clamp the vessels to avoid air embolisms. "Upon linkage, D's flow will immediately start to rewarm R's head."

Reconstruct the vertebral arteries.

Length-adjust and fuse the two cord stumps. If you forget this step, your patient will be paralyzed. Also remember, this is the part that many believe to be impossible. Canavero suggests using "a chitosan-polyethylene glycol glue" and infusing polyethylene glycol or a derivative into the patient's blood. Beyond that you're kind of on your own.

Okay now sew the dura "in a watertight fashion." Stabilize the spine anteriorly and then posteriorly "with a mix of wires/cables, lateral mass screws and rods, clamps and so forth, depending on cadaveric rehearsals."

Connect the trachea and esophagus.

Connect the vagi and phrenic nerves.

Connect all muscles using the marks you made before. Oh man, I think I forgot to tell you about marking the muscles. Do your best.

Connect the skin. Canavero recommends that ideally the skin is sewn by a plastic surgeon, "for maximal cosmetic results." But like if the cosmetic surgeon is busy, or you feel like cosmetic results aren't really a legit concern under these conditions, do your best.

Bring R to an intensive care unit where he/she should be kept sedated for three days with a cervical collar in place.

Finally, for subsequent "body image and identity issues" once the patient wakes up, refer them to a psychiatrist.

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James Hamblin, MD, is a senior editor at The Atlantic.

 
 

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