Monday 27 April 2015

The head transplant: Stranger than fiction

By Andy Ho, Senior Writer, The Straits Times, 25 Apr 2015

DR SERGIO Canavero, a controversial surgeon in Italy, wants to attempt a head transplant by attaching the head of one person onto another person's body.

He announced recently that he has a volunteer - Mr Valery Spiridonov, 30, a Russian computer scientist who is afflicted with Werdnig-Hoffman disease and confined to a wheelchair.

This disease is an inherited condition with no cure and inevitably fatal. The patient suffers progressive muscle wasting and weakness in the arms and legs. The limbs and trunk become feeble and floppy while breathing, swallowing and feeding may be difficult. The body fails progressively even as the mind stays crystal clear.

But for the breakthrough surgery to happen, Mr Spiridonov needs someone to donate a whole body.

The ideal donor would be a man who is brain-dead and closely matched for age, size and blood group. Transplanting Mr Spiridonov's head onto the donor's body would make him the recipient of the donor's body.

This seems a macabre twist to organ transplantation as we know it, but can it be done? And if the procedure is actually feasible, would the post-transplant individual who survives be Mr Spiridonov?

Dr Canavero, who is with the Advanced Neuromodulation Group in Turin, published a paper in Surgical Neurology International in 2013 giving details of the proposed procedure.

First, two surgical teams will simultaneously sever the spinal cords of both donor and recipient at the neck level using an ultra-sharp blade to minimise damage to all nerves involved.

Next comes the immediate fusion of the severed cord in the recipient's head and neck to the severed cord in the donor's neck and body. Specific chemicals are applied to both cut ends to facilitate cord fusion. Arteries and veins are then reconnected too.

But before the spinal cords are severed, the recipient's head will be cooled down so that his brain suffers no damage when disconnected from his body.

One's normal body temperature is 37 deg C, give or take one degree. When the brain is cooled below 20 deg C, all its electrical activity ceases, so the recipient would be, in effect, brain-dead as well when his spinal cord is actually severed.

In neurosurgical practice, it is well established that running very cold solutions into the brain through the neck for about 45 minutes can cool the brain down to below 12 deg C. It is also well established that if the whole person is cooled down to 12 deg C, life can be sustained without any blood circulation for about 45 minutes. And no nerve or brain damage will occur during these 45 minutes, which would be sufficient for surgeons to connect the recipient's head to the donor body.

In the actual transplant, the recipient's head and neck will be cooled down drastically while the donor's spinal cord is also cooled down - but not his whole body.

In this way, the donor's blood remains warm.

Once both spinal cords are severed cleanly, the blood circulation in the recipient's head must be reconnected to the warm donor body within 45 minutes. The donor's warm blood will then flow into the recipient's brain to bring its temperature up to normal in minutes.

The main technical hurdle is how to fuse the severed spinal cords together for normal neurological function to resume. It won't be easy.

The severed ends of nerves won't rejoin because chemicals are produced at such cuts to prevent further damage. But these chemicals also retard the regeneration of severed nerve ends. Using scar-busters and growth-boosters, nerves severed cleanly during surgery could perhaps be urged to connect up and fuse nicely.

Surgeons will then fuse the neck bones where the spinal cord was severed to stabilise the area. Then muscles, tendons, ligaments and skin are stitched up.

The patient is then put into a medically induced coma for four weeks so the fused spinal cords can recover uneventfully.

Post-coma, the fully conscious patient will wear a neck collar as he learns to sit up, move and walk again. He would have the same face and the same voice. But would he be the same person though?

Try this thought experiment: Say that my head is attached surgically to the healthy body that once belonged to Ah Kau who was found guilty of murder, sentenced to death but given the option to donate his body to me, which he did. Would the post-transplant individual comprising my head with Ah Kau's body deserve to be hanged for the murder that the pre-surgery Ah Kau committed?

Most people would probably say "no" because most of us hold intuitively that it is the brain that defines personhood and identity. That is, most people feel that, first, it is the mind which determines personhood and self-identity; second, that the mind is grounded in the brain; and, thus, it is my functioning brain that offers me a continuous chain of personhood or self-identity over time.

If so, as long as the same brain is functioning, it is the same person. I may be inebriated, so my brain may function only sub-optimally but, as long as it is still functioning to that extent, I am still the same person.

Quite specifically, face transplants suggest that the brain matters more than the face. People who have had successful full face transplants don't have changed self-identities. Though the recipient's new face looks more like the face donor's than his old one, the recipient's self-identity remains intact.

Conversely, my body may change through ageing, plastic surgery, amputation of body parts or transplantation of organs. But I am still me.

So it seems that, unlike my brain, my body needn't be continuously identical over the long run in every part for me to be me. Taken to the extreme, if I have a new body, even if it comes with a new face too, it seems like I am still me as long as it is my brain that is calling the shots.

Arguably then, the post-transplant individual would still be Mr Valery Spiridonov - if Dr Canavero really pulls it off.

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