Neurosurgeon to perform first head transplant: Could it actually work?
John Murphy, MDLinx, 09/22/2016
Italian neurosurgeon Sergio Canavero, MD, made headlines in June 2015 when he announced his plan to perform the first human head transplant in 2017. Now, in the September 19, 2016 issue of Surgical Neurology International, Dr. Canavero and colleagues backed up that audacious plan with a series of proof-of-principle papers that detail their extraordinary surgical procedure—which they described as “the defining event of the 21st century.”
Not surprisingly, the scientific and medical communities have reacted to Dr. Canavero’s head transplant procedure with curiosity, skepticism, and outright scorn.
“Brain transplantation is not ready for prime time,” wrote Arthur Caplan, PhD, Head of the Division of Bioethics at New York University Langone Medical Center in New York, NY, in an editorial in Forbes. “To attempt to move a brain to a new body given what is known about the medicine and science involved, one would have to be out of one’s mind.”
“My answer to Dr. Caplan,” Dr. Canavero said in an interview with Motherboard.com, “is he doesn’t know what he’s talking about. The nutty guy is him, not me.”
Dr. Canavero, who heads the Turin Advanced Neuromodulation Group, in Turin, Italy, acknowledges that others view head transplantation as impossible; but he gives the procedure a 90% chance of success. Plus, he already has his first patient: Valery Spiridonov, 31-year-old Russian man who has Werdnig-Hoffmann disease, a rare but severe form of spinal muscular atrophy.
The procedure (dubbed cephalosomatic anastomosis) is more like a body transplant than a head transplant, literally speaking. Dr. Canavero will essentially remove Spiridonov’s deteriorating body from his head, and replace it with a brain-dead but healthy donor body. It’s expected to be a 36-hour, $15 to $20 million procedure involving at least 150 health care professionals, including doctors, nurses, technicians, psychologists, and virtual reality engineers.
Here’s how they plan to do it:
• Freeze the brain: First, both the recipient and the donor are anesthetized and intubated, and their heads are locked into place. Both patients are given immunosuppressants throughout the procedure. The recipient’s head is then cooled to 10° C (50° F) to halt electrocortical activity, rendering him temporarily brain-dead. (“As close to death as possible,” Dr. Canavero described.) The spinal cords in both patients are cooled as well.
• Sever the neck: To prevent coagulation, the recipient’s head is drained of blood and then flushed with lactated Ringer’s solution. The surgical teams then cut deep incisions around each patient’s neck (at the C5/6 level) and all of the anatomic structures are carefully separated to expose the carotid and vertebral arteries, jugular veins, and spine. Next, vascular surgeons loop silastic cannulas around the carotid arteries and jugular veins, and clamp the vessels at the tips to stop blood flow and prevent air emboli when the head is removed.
• Cut the spinal cord: Of all the steps in this lengthy procedure, this one may be the most critical. Here, the surgeons use a diamond nanoblade to “clean-cut” the spinal cords of both patients simultaneously. Unlike accidental spinal cord injury, which causes widespread damage to the spinal cord, the ultra-sharp severing used in this procedure allows the spinal cord to be reconnected with minimal damage and eventual recovery, Dr. Canavero wrote.
• Fuse the spinal cord: Immediately after decapitation, the recipient’s head is wheeled to the donor body, where the surgeons quickly join the stumps of the spinal cords. Now comes the other critical step: the severed myelinated axons are fused together with a specially-designed polyethylene glycol (PEG) polymer that reseals the cellular membranes of neurons. The “secret ingredients” in this particular PEG are graphene nanoribbons, developed by Rice University scientists, which first act as a conduit and then as a scaffold upon which the neuronal fibers can grow. Electrical stimulation is applied to the fusion point of the spinal cord to accelerate the regeneration of neural connections. In order to reinforce the link, the surgeons attach a few loose sutures around the joined spinal cord.
• Reconnect the rest: To restore circulation, the vascular surgeons remove the silastic cannulas one by one and suture the arteries and veins of the head to those of the new body. After the dura is sutured and clamped watertight, then the trachea, esophagus, vagus and phrenic nerves are reconnected and all the muscles are rejoined. Plastic surgeons suture the skin for optimum cosmetic results.
The recipient is taken to the ICU and kept in an induced coma for three to four weeks. Immunosuppression is continued and the patient is regularly screened for any sign of anti-donor antibodies. After coming out of the coma, Dr. Canavero foresees the recipient will need both physical therapy and psychological counseling; but he expects the patient will be able to walk again within 6 months of the surgery.
Could it actually work?
Dr. Canavero’s colleagues have already shown in mice and in a dog that sensorimotor function can be recovered after severing and re-attaching the spinal cord. His collaborator Xiaoping Ren, MD, of Harbin Medical University in China, performed a head transplant in a monkey in the past year. Still, “the proof of the pudding rests in human studies,” wrote Drs. Canavero and Ren. They hope to perform the first human head transplant on Spiridonov in December 2017.
But the skeptics are many, and they too have science and medicine to back up their positions.
“This is such an overwhelming project, the possibility of it happening is very unlikely,” Harry S. Goldsmith, MD, Clinical Professor of Neurosurgery at the University of California, Davis, said in a 2015 article in New Scientist. “I don’t believe it will ever work, there are too many problems with the procedure.”
Richard Borgens, PhD, Director of the Center for Paralysis Research at Purdue University in West Lafayette, Indiana, told New Scientist, “There is no evidence that the connectivity of cord and brain would lead to useful sentient or motor function following head transplantation.”
“In my opinion, this procedure has no feasibility at all,” Lorenzo Pinessi, MD, Director of the Neurology Clinic at Italy’s University of Turin, told Newsweek. “It is demented.”
For Spiridonov, who faces a mortal disease, the idea isn’t demented at all—just the opposite. “Removing all the sick parts but the head would do a great job in my case,” he told The Atlantic. “I couldn’t see any other way to treat myself.”
Dr. Canavero outlined the ideas behind head transplantation in this September 2015 TEDx talk.