The human brain is an amazing piece of biological machinery responsible for everything from dreaming up Shakespeare’s sonnets to the muscle coordination of scoring a World Cup-winning goal. Yet, even if our brains remain spry into our old age, our bodies often don’t. What if we replaced them?
Head transplantation is a revolutionary surgical procedure. It involves transplanting a person’s head onto another person’s body with the primary goal of restoring mobility to those with severe disabilities, particularly paralysis. However, this procedure is still experimental and mainly performed on animals. This raises ethical concerns and significant obstacles for potential human applications. In this article, we will discuss the ethical and practical challenges associated with head transplantation and present a case study of the first human head transplantation in a corpse.
Origins and Evolution
The history of head transplantation dates back to the early 20th century when Charles Guthrie made an unsuccessful attempt on dogs. Subsequent developments by scientists like Vladimir Demikhov and Robert White contributed to our understanding of surgical techniques for vital organ and limb transplantation. In the 1970s, Robert White successfully performed the first cephalic exchange transplantation on a rhesus monkey, demonstrating sensory and motor function restoration. Recent experimental procedures on rodents and cadavers have aimed to assess brain function and refine surgical techniques for potential human applications.
Head Transplantation Procedure
Preparation and Monitoring:
Two surgical teams work simultaneously. Both the recipient and donor are intubated, ventilated, and stabilized. Comprehensive monitoring, including ECG, EEG, oxygen saturation, body temperature, and hemodynamics, is established.
Recipient Hypothermia:
The recipient’s head is significantly cooled to 10°C to achieve profound hypothermia. This is vital to lower metabolic rates.
Donor Body Hypothermia:
The donor’s body undergoes spinal hypothermia to avoid ischemic damage, and cooling helmets can be used. Subdural and epidural spaces are perfused with cold solutions to achieve donor spinal cord hypothermia.
Neck Preparation:
Both surgical teams meticulously prepare each patient’s neck in three phases: anterior and posterior approaches in both recipient and donor, and chimera anastomosis. Key blood vessels, muscles, trachea, esophagus, and nerves are exposed, marked, and prepared.
Spinal Cord Transection:
Under microscopic guidance, the spinal cords in both patients are transected with an ultra-sharp microsurgical blade.
Head Separation and Fusion:
The recipient’s head is separated, exsanguinated, and flushed with iced Ringer’s lactate to prevent coagulation complications. The head is then attached to the donor’s body, and the spinal cords are fused using a specialized glue (chitosan-PEG) and PEG infusion. Sutures secure the connection.
Vascular Anastomosis:
Carotid and jugular silastic cannulae are used for vascular anastomosis, allowing blood to flow from the donor’s body to the recipient’s head.
Dura and Nerve Reconnection:
The dura is sewn, and a spinal cord stimulator is secured. Posterior stabilization is achieved with a screw-and-rod system. Trachea, esophagus, vagus, and phrenic nerves are reconnected.
Muscle and Skin Closure:
All muscles are linked, and the skin is sewn.
Post-Operative Care:
The recipient is transferred to the intensive care unit with a cervicothoracic orthosis brace for close monitoring.
Significant Hardships During Head Transplant Surgeries
Head transplant surgeries present various challenges, starting with the selection of a suitable donor body. The surgery involves a complex set of interventions on both the recipient’s head and the donor’s body, requiring a coordinated effort from multiple surgical specialists. Preservation of postoperative functions like phonation and spontaneous respiration adds to the complexity, demanding meticulous planning and execution. Ischemia time, spinal fusion, and spinal cord reattachment are formidable challenges, with spinal cord reconnection being a critical yet unresolved issue. Postoperative issues, including intensive care and rehabilitation, further complicate the procedure.
Ethical Considerations for Head Transplantation
The ethical aspects of head transplantation are multifaceted. Public and scientific criticism has historically accompanied pioneering medical procedures, often labeling them unnatural or unethical. The lack of substantial data and research on head transplantation has limited scientific debate and understanding of the procedure. The use of immunosuppression raises concerns, as do potential psychosocial issues, such as identity confusion and self-esteem problems for recipients.
First Human Head Transplantation on Cadaver
Human head transplantation experiments on cadavers have been conducted in a controlled laboratory setting to explore the feasibility and technical challenges of the procedure. These experiments aim to test various aspects of head transplantation surgery without involving a living human subject. Some key points related to these experiments on cadavers are:
Feasibility Demonstration:
The primary goal of these experiments is to demonstrate the technical feasibility of connecting a human head to a donor body (cephalosomatic anastomosis) under laboratory conditions.
Surgical Techniques:
Researchers perform surgical procedures on cadavers to practice and refine the intricate surgical techniques involved in head transplantation, such as spinal cord fusion and vascular anastomoses.
Perfusion and Hypothermia:
Experiments often involve using perfusion techniques to cool and protect the brain during the transfer process. This is done to minimize the risk of ischemic injury.
Tissue Compatibility:
Testing the compatibility of the donor body with the recipient’s head, including ensuring a proper match in terms of height and other physical criteria, is another aspect explored.
Long-Term Effects:
Researchers may also study the long-term effects on the transplanted tissues and the overall integrity of the head-body connection.
These experiments have been crucial in advancing the understanding of the challenges involved in head transplantation. It is important to note that successful experiments on cadavers do not necessarily guarantee the procedure’s success in a living human being due to additional complexities and ethical considerations. The ethical and medical hurdles associated with human head transplantation have generated significant debate within the scientific and medical communities.
While these experiments on cadavers have provided insights into the technical aspects of head transplantation, the procedure has not been performed on a living human yet.
Future Implications
The future implications of human head transplantation are profound, albeit laden with complex ethical, medical, and practical challenges. If successfully developed and ethically implemented, this procedure could offer life-saving options for patients with terminal conditions that affect their bodies but spare their brains. It could potentially alleviate organ shortage problems by providing healthy donor bodies for individuals with damaged or non-functional bodies.
However, achieving these goals would require extensive research, advancements in surgical techniques, meticulous patient selection, and a thorough understanding of the psychosocial implications. The ethical considerations surrounding identity, informed consent, and potential unforeseen consequences would also need to be addressed. While the technical feasibility of head transplantation has been explored in cadaver experiments, the journey towards its practical application in living humans is a complex and uncertain path, subject to ongoing scientific, medical, and ethical scrutiny.
Conclusion
Head transplantation surgery remains a complex and ethically challenging field, plagued by significant obstacles and a lack of substantial research. While head transplantation is an innovative concept, there is growing potential in the field of spinal cord stimulation, stem cell therapies, and neural prosthetics to restore mobility for paralyzed individuals. The scientific community must shift its perspective on head transplantation, fostering further analysis and specialized surgeon involvement to assess its feasibility and potential benefits.
Reference
Gkasdaris G, Birbilis T. First Human Head Transplantation: Surgically Challenging, Ethically Controversial and Historically Tempting – an Experimental Endeavor or a Scientific Landmark? Maedica (Bucur). 2019 Mar;14(1):5-11. Greek, Modern. doi: 10.26574/maedica.2019.14.1.5.
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