Time to replace “neuro” preservation with “cephalic” preservation

And the advantages of brain-only – the real “neuro” option

I want to make two main points here. First, the term “neuro” as applied to preserving the head is a misnomer and should be ended. I am among the many people who have adopted and used that term. Now I am calling for it to be replaced. Second, the true neuro option – brain-only preservation – has quite a few advantages over both head and whole body preservation.

Up until the present biostasis has always taken the form of human cryopreservation, or cryonics. Only now are chemical preservation options becoming available in some places. The two larges cryonics organizations in the United States have different options. Cryonics Institute offers only whole body cryopreservation. Alcor offers both whole body and “neuropreservation.” While “neuro” advocates point to several potential advantages for their option, whole body proponents can plausibly point to stronger dislike of that approach.

Although it has been referred to as neuropreservation, this has been a “whole head” approach in almost all cases. The goal is to preserve the brain and therefore the personality. If asked, “Why not just preserve the brain?” there has been a standard answer in two parts.

First, it is difficult to remove a brain from a head that has been perfused. It is easy to think of a brain inside a skull. Surely, you can just open the skull and remove the brain? But there are multiple layers of tissue between the two. Therefore a major reason for leaving the brain in the skull has been to avoid damage to the brain – as well as to avoid the ischemic time incurred during surgical removal.

Second, we want the brain to be well protected in its long journey through time. The skull provides a natural protective enclosure. The head will be further protected by being placed inside a metal canister and secured in place. But the skull provides a first line of defense.

These issues have been addressed and resolved. For an early (2017) discussion of these and other points, see Aschwin de Wolf’s “The Case for Brain Preservation.” (However, while supporting this option for some people, de Wolf still prefers the whole body option.) Based on recent experience it turns out that it is easier to remove a perfused or chemically fixed brain than an untreated brain. The treated brain is firmer due to cross-linking, the viscous cryoprotectant, and the low temperature.

Like many others, I have long referred to the head preservation option as the “neuro” option but I have come to see that as less than ideal. It would more accurately be termed a “cephalic preservation.” Cephalic derives from Greek word kephalē (meaning “head”) and refers to anything related to the head, especially the entire head, including the skull and brain. This usage is not only true to the word’s roots, it also reflects standard medical and anatomical usage. This is how I shall use the term.

Whole body preservation = preservation of the brain inside the skull along with the rest of the body. It may not literally be a whole body in rare cases where a fatal event led to the loss of limbs, but it can be taken as “the entire body or whatever is available to be preserved.”

Cephalic preservation = preservation of the head. This means the brain plus the skull and perhaps part of the spinal cord.

Brain preservation = preservation of the brain only, perhaps with part of the spinal column.

Since neuro preservation has been used to refer to what is actually cephalic preservation, until the reformed usage is widely adopted I will usually refer to preservation of the brain alone as “brain only” preservation. Eventually, perhaps the term “neuro” will be understood to properly apply to brain-only but currently it would be confusing to use it that way.

A common reaction to human cryopreservation is to say that is it “weird” or “creepy.” My reflexive response is: As compared to what? Putting someone in the dirt to be eaten by worms and bacteria? Or shoving them into a big oven and burning them to ash? Whether or not that response sparks any rethinking, I do not know. That kind of gut reaction certainly can apply to whole body preservation.

But cephalic preservation is even more likely to elicit a negative visceral response. It might call up an image such as Jack Nicholson’s frozen face at the end of The Shining. An isolated head will also be associated with decapitation. Associating a method of preservation with capital punishment by guillotine or axe is hardly desirable for proponents of biostasis.

I have carried the cephalons of numerous patients from the operating room to the cooling area, starting with Dora Kent in 1988. Whatever gut reaction I might have had has long been extinguished. That does not mean I am unaware of the reaction that many other people have to even the thought of an isolated head.

The true neuro option – brain-only preservation— greatly reduces that additional perceptual challenge. Beyond that, we can also make a strong positive case for the option. Many people will still prefer to preserve their entire body. This may be on grounds that it might turn out to be easier and faster to repair the existing body rather than to regenerate it. But a whole body preservation is more expensive than neuro preservation. At the time of writing, the difference in cost is $120,000.

This difference is due to two expenses: many additional liters of expensive cryoprotectant and, more significantly, additional cost in storage over the decades. Ten heads can fit into the same space as a single whole body. Enough funding must be provided to ensure that only a small percentage need be taken out of investments annually to cover that extra volume. Storage cost scales with volume because of numerous factors including quantity of liquid nitrogen, cost of land, security, and so on.

Storing only the brain and not the entire head would further reduce costs, probably by at least 50%. The brain will be protected not by the skull but by a customized case. This will allow more efficient spatial packing. Based on the amounts currently allotted to storage, the brain-only option could be $10,000 to $15,000 less expensive than cephalic storage (and something like $130,000 less than whole body storage. For those not using life insurance to fund the process, this could make all the difference.

There are seven other benefits to brain-only, starting with two or three relevant to improving cultural acceptance. The following list restates and heavily borrow from Aschwin de Wolf’s earlier essay on this blog.

Public perception: Brain-only reduces the “yuck factor.” We noted the unfortunate associations common with head-only preservation. The same applies to a lesser extent to a whole “dead” body. Somehow a naked brain does not elicit the same reaction, or to a much lesser degree. Perhaps because they lack the unpleasant associations of heads or non-living bodies and may be more associated with scientific investigation. Given that biostasis has to be accepted – or at least tolerated – by society, this factor matters.

Public ceremony compatible: Brain-only preservation is compatible with a burial ceremony (or even cremation), which could yield greater acceptance and support by family members. The brain can be extracted with limited damage to the skull (and not at the front), making it easy for a funeral home to prepare the body for viewing if that has been specified. A body without a head is unsuitable for viewing, to put it mildly.

Organ donation compatible: In principle, brain-only preservation is compatible with whole-body organ donation. In ideal circumstances this option could be pursued in a way that benefits both the quality of brain preservation and organ donation.

Logistics: Occasionally, patients may need to be relocated if the biostasis storage organization moves, or in case of major emergencies. Whole body patients are difficult to move outside the storage area. (Inside, some containers can be pushed to a new space because they are mounted on wheels, at least in the case of steel cryogenic dewars.) Brain-only patients would be even easier to move in bulk than cephalic patients. Also, since brains have a status as organs, they may be accepted by organizations that would not be willing to store isolated heads.

Fracturing reduction: Other things being equal, tissue fracturing scales with sample size and tissue heterogeneity, which favors brain-only cryopreservation in terms of mitigating thermal stress at low temperatures. Given its lower long-term storage cost, brain-only cryopreservation also permits more affordable intermediate temperature storage (ITS).

Permits emergency fixation: In case there is an unexpected and long-term liquid nitrogen delivery issue, isolated brains can be immersed in a chemical fixative to prevent decomposition.

Enables Immersion vitrification: Isolated brains can be immersed in a chemical fixative (such as glutaraldehyde), followed by immersion cryoprotection, a procedure called “immersion vitrifixation” (or iVitrifixation). This may be preferable under certain circumstances.

The immersion vitrification option is under review at present. If chemical preservation is to be used in combination with cryopreservation – what we have called aldehyde-stabilized cryopreservation or vitrifixation – the best way to do it is fixation by perfusion followed by cryoprotectant perfusion. In some cases, particularly when there has been extensive ischemia, the only option has been a “straight freeze” (freezing without cryoprotectant). Brain-only allows for chemical stabilization followed by immersion cryoprotection, yielding an ice-free preservation.

Immersion vitrifixation takes advantage of the fact that, at low temperatures, metabolism is reduced at a faster rate than diffusion of a chemical. iVitrifixation protocols are still being explored and is currently being used by only one organization, Tomorrow Biostasis although it is not an option but a clinical decision at the time of writing. Given the public perception advantages, other organizations may adopt this low-cost option in future.

Please join us in replacing “neuro” with “cephalic” and in encouraging more cryonics organizations to offer the brain-only option.