In January, Dr Canavero told New Scientist he had moved closer to his goal by conducting a series of experiments on animals and human cadavers, with the help of Chinese and South Korean scientists. The transplant of Spiridonov's head to the body of a human in a vegetative state is expected to take place at Harbin Medical University in China.
Dr Canavero is working closely with Xiaoping Ren from the university, who has performed a monkey head transplant and more than 1000 head transplants on mice.
How it will work
The transplant is supposed to take place in two stages, which Dr Canavero refers to as HEAVEN ("head anastomosis venture") and Gemini (the subsequent spinal cord fusion), Newsweek reported.
It's expected to take 36 hours and involve at least 150 doctors, nurses, technicians, psychologists and virtual reality engineers - costing around $26 million.
First, the body and head will be cooled so the cells don't die when deprived of oxygen during surgery, Dr Canavero explained to New Scientist. The neck of the patient will then be severed and the crucial blood vessels hooked up to tubes while the spinal cord on the head and the body are severed with a $260,000 diamond nanoblade.
The head will then be moved on to the donor body and the two ends of spinal cord fused together using polyethylene glycol, which encourages the fat in cell membranes to mesh.
The muscles and blood supply will be then stitched up and the patient put into a three or four-week coma to let the body heal itself while embedded electrodes stimulate the spinal cord to strengthen the new nerve connections.
The patient could take 12 months to heal, if they ever do.
Will it work?
John Adler, a neurosurgeon and professor emeritus at Stanford University's School of Medicine, told Newsweek: "Conceptually, much of this could work, but the most favourable outcome will be little more than a Christopher Reeve level of function."
The Superman actor was paralysed from the neck down after a horseriding accident. Spiridonov could be left with serious brain damage or a never-before-seen type of mental illness, if he even survives.
Dr Hunt Batjer, president elect of the American Association for Neurological Surgeons, told CNN: "I would not wish this on anyone. I would not allow anyone to do it to me as there are a lot of things worse than death."
One of Dr Canavero's countrymen in the field, Lorenzo Pinessi, director of the Neurology Clinic at University of Turin, said: "This procedure has no feasibility at all. It is demented."
Arthur Caplan, founder of the Division of Bioethics at New York University's School of Medicine and perhaps Dr Canavero's biggest critic labelled him "a charlatan, a quack and a self-promoter" who's "peddling false hope."
Many experts in the field are concerned the Italian, who is set to publish in seven papers in the journals Surgery and CNS Neuroscience & Therapeutics over the coming months, is more concerned with drumming up publicity than waiting for reliable scientific evidence.
The possibilities
There is a history to all this, and it's a gruesome one. In 1908, American physiologist Charles Guthrie sewed a second head onto a dog's neck and watched as its nostrils started twitching again.
In the 1950s, Soviet transplant pioneer Vladimir Demikhov transferred 20 puppy heads onto adult dogs alongside their existing heads, using a "blood vessel sewing machine" to minimise time without oxygen. They survived for up to a month, although he reported strange results including the new head biting the ear of the other, and "tugging as if trying to separate itself from the recipient's body."
American neurosurgeon Robert White successfully performed a head transplant on a monkey in 1970. It was paralysed from the neck down but was able to hear, smell, taste and move its eyes, until it died after nine days.
Dr Canavero is a longtime fan of Dr White, who once wrote: "The Frankenstein legend, in which an entire human being is constructed by sewing various body parts together ... will become a clinical reality early in the 21st century."
Michael Sarr, editor of Surgery and a surgeon at the Mayo Clinic in Minnesota, had previously expressed concern about the "multiple ethical issues and multiple considerations of informed consent and the possibility of negative consequences of a head transplant."
But he has since told Newsweek Dr Canavero's technique has the potential to treat traumatic spinal cord injury patients."He's a little bit fantastic, but he's a serious guy. He's not just a showboat. This is not science fiction. This is now science. There's experimental work that supports the concept of nerve membrane fusion."
Dr Canavero's profile on the American Academy of Neurological and Orthopaedic Surgeons says he "entered neurosurgery with the goal of transcending human limits".
It's a terrifying thought.
