Medical Revolutions

Spinal Implants – Technological Hope for the Paralyzed

By November 9, 2019 No Comments

It’s actually a little terrifying to sit and think about just how fragile the human body is. While you may feel pretty solid, the truth is we humans are mostly just sacks of water. It’s easy to lose a limb in a moment of inattention.

A few decades ago, if you lost a hand or a foot, that would be the end of it. These days however, surgeons can reattach blood vessels, muscles and peripheral nerves with advances microsurgery. In many case people regain most or nearly all of their original sensation and dexterity. Depending on the exact circumstances.

It’s a modern medical miracle, but despite our hyper-advancement at mending what has been broken, when it comes to the central nervous system, that is the brain and spinal cord, things aren’t so simple.

The Backbone of the Problem

The spinal cord is a thick bundle of nerves that run from the base of the brain down to a point just above your butt, where the tail would be in some other mammals. All your peripheral nerves that operate your body from the neck down attach to the spinal cord, from where they are linked to the brain. When you think about moving an arm or leg your brain sends the signal to the spinal cord which routes it to the right peripheral nerves.

If your spinal cord is damaged or severed, the brain can no longer communicate with anything below the spot where the break is. That’s a terrifying situation and nothing can destroy a person’s quality of life quite like paralysis. Being trapped partly or wholly in your own body is no joke.

The problem is that, unlike peripheral nerves, the spinal cord doesn’t regrow itself. There are many, complicated reasons for this that only experts in the field really understand. What I’ve taken from my limited reading on the subject is that the spinal cord is way too complex. Some of the cell structures can’t divide and reconfigure themselves. On top of this, our own injury responses, such as scarring and inflammation, prevent any chances that this incredibly dense and complex information conduit can fix itself.

This is probably why evolution has placed the spinal cord in such a tough container, to minimize the chances of the cord being broken, at least before we can reproduce. As a result, spinal cord injuries severe enough to cause paralysis aren’t that common, but there are still millions of people suffering from this terrible fate.

Luckily there are several advances that have emerged which all show some promise. One recent breakthrough has even had dramatic effects that seem like science fiction. These are some of the main approaches that are either in use or being trialled.

Drugs, Drugs, Drugs

We all know that sitting at a desk for hours at a time can be harmful for your spine, but there are easy ways to go about this and this generally isn’t something that causes paralysis anyway. Spinal cord injury actually happens in two stages. There’s the primary injury, which is the actual accident. Then there’s the secondary injury. The swelling and scarring are two examples as I mentioned above.

Most drug treatments to reduce the secondary injury that kills off spinal nerves have only been tested in animals. Inhibiting certain proteins seems to prevent cell death. Binding iron through chelation also seems to help in animal models. There are many more promising treatments that are not ready to try in humans yet, but they are waiting their turn.

One drug that has seen some limited use as something that prevents scarring and inflammation is methylprednisolone. The problem is that it also causes harms of its own that are generally seen as worse than the benefits. The main focus of research for this drug is finding a way to delivery it without the nasty side effects.

Stem Cells

I’ve spoken about stem cells in my article on regenerative medicine, but in the context spinal cord injury research they are especially important. Stem cells are basically like the cells that we develop from while in the womb. We all start as a single cell, that then repeatedly splits until a complete fetus is ready to be born.

Obviously we aren’t amorphous blobs made from a collection of identical cells. We have liver cells, skin cells, brain cells and so on. That means the original cells have to differentiate and become the different sorts of cells the body needs to function. The idea then, is to take undifferentiated cells,stem cells, and inject them at the injury site. Coaxing them into becoming the sorts of cells needed to bridge the gap.

Research is still in the early days, but patients who have taken part in stem cell trials have shown an overall improvement in their level of motor function compared to before receiving the treatment. It will be years before we really know if stem cells will work, but this is a long game worth playing.

The Tech Solution

While we all hope that simply taking a pill or injecting a cell cocktail is all that’s needed to fix a spinal injury, those types of solutions are not perfected overnight. There will be a lot of trial and error. Blind alleys and unpredictability. As is to be expected with biology and biochemistry. Where we don’t quite have all the answers yet.

In the meantime, engineering and modern technologies such as implantable electronics has shown some remarkable results and are more predictable. In reality we will probably have to rely on artificial, non biological solutions until the biotechnology is mastered, but that isn’t necessarily a bad thing. The final spinal cord injury solutions is likely to be some mix of engineering, chemistry and biology anyway. It’s just that the engineering solutions seems to be the most promising short-term research areas right now.

Feeling a Little “Gelly”

Hydrogels are a example of materials science applied to the problem of spinal injury. They are an artificial substance that closely resembled the structural material outside of cells. Remember how there’s a problem with getting medicines into the places they need to go safely? Hydrogels are one way this can be done. This gel can be injected to fill wound gaps in the spine and mixed with all sorts of drugs which will then go directly where they need to be. Released at a predictable rate over a long period of time.

Brain Interfaces

I’ve written a more in-depth article about Brain Computer Interfaces, but they are a very promising technology that can help people with paralysis become mobile again. So, to be clear, this technology is not aimed at repairing the spine, but bypassing it to allow for brain-controlled movement.

A BCI reads information from the brain and then sends it somewhere to be put to use. For example, a quadriplegic woman was able to feed herself using a robotic arm. That means we can make robotic exoskeletons for people to help regain the same independence they had before their injury.

It’s not perfect, since the person is indeed still paralyzed, but it’s a huge step forward. Not to mention that BCI tech developed to help such people can also be used by able-bodied people for all sorts of amazing purposes.

The Big Breakthrough – Spinal Implants

I was prompted to write this article mainly because 2018 seems to be the year of the spinal implant. It seems that all of a sudden a whole bunch of stories were released about research results indicating the reversal of severe paralysis using implant technology.

The key research paper was published in Nature with the title Targeted neurotechnology restores walking in humans with spinal cord injury. In it the researchers describe how test subjects who have lost the use of their legs due to spinal injury regained much of their motor control. In some cases, subjects could walk again, although not with the same strength and fluidity as before.

There are some thing you need to know up front about this technique. First of all, it will not work for someone who has a completely severed spinal cord. Instead, it is effective for patients who have had their spinal cords crushed and become non-functional below the injury site. There is still a tenuous connection across the injury, but it is too damaged to work.

The implant is a little like a pacemaker. It sends continuous electrical impulses through the injured part of the spine. This amplifies the signal across those nerves and also seems to revive spinal nerves that have gone dormant.
While the technique is not completely new, the team who published in Nature have upgraded the technology significantly. It’s more granular and intelligent. Individual nerve bundles are targeted and higher numbers of electrodes are used.

Within days of implantation, wheelchair-bound subjects began to regain some walking ability. After a few weeks of therapy and training they were up and about!

Here’s a Mayo Clinic video about a paralyzed man who learned walking again:

Hope Springs Eternal

Paralysis is such a devastating ailment that any hope of a cure or treatment is worth celebrating. While there is still no substantive cure on the market, there are so many avenues being explored I have little doubt that within this century a broken spine will be no more of an issue than a broken leg. For now I think those lucky few, such as the implant recipients, are an example of what science and technology can do for to transcend our human limits.