In some of last month’s more bizarre news, Italian brain boffin Sergio Canavero claims to have performed the first human head transplant. Could this be the next big thing in the Neuro sphere? Well, probably not. See, the thing is, while he may well have transplanted a head onto a new body, both were – well – dead. It’s a bit like taking the engine out of a car, swapping it into another car and proclaim you were successful without turning the key and making sure the thing runs. At best, this result is academic and at worst deceptive.
Canavero has had some purported success before. In January last year, he claimed to have successfully transplanted the head of a monkey. Whilst this is true, the monkey never regained consciousness and its life support was turned off 20 hours after the operation for “ethical reasons”. Even if the monkey had regained consciousness, no-one bothered trying to reconnect the spinal cord so it would have been permanently paralysed. Very successful, then.
He also transplanted the head of a rat in May this year. Well, kind of. He had a living rat with a dead head attached to it. Hardly a head ‘transplant’. In fact, all this showed was the viability of a method known as Cephalosomatic Anastomosis which is the process of anaesthetising an animal, cutting its spinal cord and keeping the brain alive until it can be attached to anther body. The head was removed and reattached a number of times. The best part is that this wasn’t even novel. It had been done before in 1970.
All the dead head wrangling has proven is that it is indeed possible to sow a head onto a body.
So, to summarise, Canavero’s progress to date has been to stick a dead head on a mouse multiple times, demonstrating that the head could be preserved when removed and transplant a monkey’s head without it regaining consciousness. This brings us to now. All the dead head wrangling has proven is that it is indeed possible to sow a head onto a body.
Sure, it might have its uses in demonstrating that you can keep tissue alive in the head while you’re operating but it’s a far cry from the patient living a normal life after the op. We’re not even at the stage that they’re alive yet.
There are some significant issues with transplanting heads that may mean it’s an implausibility to get working. You don’t need a PhD in Neuroscience or be a Consultant Neurosurgeon to know it’s not trivial to reconnect a head. The neck area is one of the body’s most critical areas. It carries – obviously – sections of the circulatory system, the trachea and the oesophagus. All rather important, but not that difficult to reconnect in the grand scheme of things.
The more difficult parts to get reconnected are all the nervous connections. The spinal cord runs right through the neck and any problems with reconnecting that could affect someone’s ability to move, or even make them paralysed. Worse still, basic functions like breathing, heart rate and reflexes are controlled from the brain stem, so if the connections are damaged you’ll at best have severe health problems. There’s also a bunch of muscles that’ll need reconnecting.
“[If] you put the head of [a] musician on the body of a builder, it may well prove to be like trying to play an Xbox game on a PlayStation.”
As you can tell, these are all rather important. And they’re not trivial to get right. The spinal cord is a complex tissue, and can’t simply be sown together. Scientists have had some success in repairing a severely damaged cord, but this was not totally severed so there was some material to work with. Also, it was in a child so the nervous system still had some plasticity. Even then, the outcome was considered “borderline miraculous”.
Adding even more to the pile of doubt is the fact that the nervous system to some extent develops alongside the brain, so either you’d have to learn most basic functions from scratch again or stuff just wouldn’t work. As Cardiff University Neuroscientist Dean Burnett puts it in a recent Guardian article “[If] you put the head of [a] musician on the body of a builder, it may well prove to be like trying to play an Xbox game on a PlayStation. Except, infinitely more traumatic.” To make matters even worse, there’s immune system rejection; imagine that, your body attacking your brain.
So we still don’t know how to reconnect a head to a body despite the excitement and even if we did we’ve no idea how successful, if at all, it would be. Let’s just say I’m not holding out for any franken-heads any time soon.
Last modified: 9th December 2017