|Gummy bear head transplant, courtesy of flickr user Ella Phillips|
In a widely circulated Boston Globe editorial this summer, Steven Pinker told bioethicists to “get out of the way” of scientific progress. There is abundant human suffering in the world today, he said, and the last thing we need is a bunch of hand wringing to slow down efforts to attenuate or even eliminate it. The prospect of head transplantation, however, has the potential to make us all a bit more appreciative of our local bioethicists. Even if there were not any technical issues (of which, there are of course plenty), coming to terms with the muddier personal and societal issues inherent in a procedure such as this could take quite a while. Nevertheless, Dr. Sergio Canavero is not planning to wait around and wants to perform a human head transplantation by the end of 2017. Are we ready?
Dr. Jordan Amadio, an Emory neurosurgery resident and co-founder of Neurolaunch, led a discussion on the topic at the Emory Center for Ethics Neuroethics Program’s November “Neuroethics, Neuroscience, and the News” series. As a neurosurgeon he was able to shed light on the technical aspects of Dr. Canavero’s proposal to a full room of students and faculty members from across the humanities and sciences (the topic drew quite a bit of interest on campus). In short, Dr. Amadio was skeptical. Unlike peripheral nerves, spinal nerves do not readily regenerate (but see this ref). There has been an enormous effort in neuroscience and physiology to understand how to regenerate spinal nerves. If this problem could be solved, spinal cord injuries would be less likely to lead to debilitating paralysis. However, Canavero believes he is ready to move beyond this prodigious hurdle using ultra-sharp instruments to cleanly sever the spinal cord with minimal tissue damage (unlike the traumatic break due to a car accident, for example) and using “fusogens” like polyethylene glycol (also commonly used as a clinical laxative) to fuse the donor and recipient spinal cord segments. Dr. Amadio’s conclusion on the science was clear: there is no strong evidence that Canavero’s “Gemini spinal cord fusion” protocol will work (as an aside, the protocol was published as an editorial in Surgical Neurology International).
Undoubtedly, researchers will continue to explore how to regenerate spinal nerves. So if the procedure were technically feasible, should it be attempted? There are huge risks involved, even for a terminally ill prospective patient. As Dr. Hunt Batjer, the president of the American Academy of Neurological surgeons commented to CNN, “there are a lot of things worse than death.” Debilitating, unmanageable neuropathic pain, for example, is a real possibility. Who knows whether one individual’s brain and spinal cord could communicate effectively with another’s spinal cord and body? NYU medical ethicist Dr. Arthur Caplan notes that “The brain is not contained in a bucket—it integrates with the chemistry of the body and its nervous system.” He calls the idea of head transplantation “rotten scientifically and lousy ethically.” Researchers are only beginning to understand the ways in which peripheral organs such as the gut (our “second brain”) and the microbiome within it affect brain function and mood. While this remains an emerging area, it is becoming clear that – no matter how sharp the knife – one cannot cleanly separate the brain (or the mind) from the body.
|Will head transplants waste potential organ donations?|
There are also considerable concerns related to justice and fairness. The donor for such a procedure would have to be a young, healthy individual who likely died of a traumatic brain injury but whose body was in pristine condition for transplant. There is a considerable opportunity cost here for the thousands of patients waiting for organ donations. In fact, nearly two dozen people die in the US every day while waiting for an organ donation. This donor body could end up providing many critical organs, which would all be lost should Dr. Canavero’s procedure fail. At what probability for success would this opportunity cost be acceptable? At first glance, this seems like the opposite of the trolley problem – should you try to save one person while putting five or more at higher risk of death? I’d also add, who are you saving? The body or the head?
What would this surgery mean for personal identity? Apparently Dr. Canavero believes that the body is simply a vehicle for the brain and that we should not let deteriorating bodies limit our lifespans. This seems to be an extreme view that glosses over the role of the body (below the brainstem) in an individual’s sense of self. To quote Frederik Svenaeus from his 2012 article on organ transplantation and personal identity, “The self becomes attuned through its bodily being, and such attunement is necessary for all forms of human understanding (that we know about).” In other words, even if your brain was kept alive, you might not be. Granted, a patient with a severe degenerative disease (like Canavero’s first volunteer) may not be concerned about identity issues with a pressing need to extend his life, but this concept should give pause to those hoping that in the future they could simply trade in their bodies as they start to fail. Not to mention, the definition of self and identity may differ across cultures.
|Head transplants: 1960's science fiction come to life|
For his part, Dr. Canavero does have some mainstream support. Dr. Michael Sarr, a retired Mayo Clinic surgeon and Editor-in-Chief of the academic journal Surgery was quoted in The Guardian as saying, “I’m confident that at least in theory the operation will work. The science is there.” Canavero, too, dismisses his critics, claiming that all scientific revolutionaries were dismissed early on. So, are we ready for this? It may not matter as ethicists, surgeons, and the world will just have to watch as Dr. Canavero continues to push forward, full speed “a-head.”
Want to cite this post?
Purcell, Ryan (2015). Getting aHead: ethical issues facing human head transplants. The Neuroethics Blog. Retrieved on , from http://www.theneuroethicsblog.com/2015/12/getting-ahead-ethical-issues-facing.html