Understanding Spinal Cord Injury: Part 1

Last week I discussed the current state of stem cell research and the sociopolitical situation surrounding it. As with any controversial or complex subject being shared with the neophyte it is pointless without a physical, material context to put it in. Many people simply don't know something because it doesn't pertain to them. No-one wants to think about disease, let alone talk about it... why in the world would anyone want to research it? I learned very early on in my injury not to hold others accountable for what they do not fully understand. So much of suffering is purely subjective and experiential, how could they possible grasp what I'M feeling? Or vice versa for that matter? That said, ask yourself, why else would I study any kind of infirmity unless I a. had it, or b. was a doctor? This posting will be to inform those of you who do not understand how spinal cord injury happens and the results it can have. It should help you get a stronger grasp on why stem cells are such an interesting possibility.

Spinal cord injury is one of the least understood conditions on the planet. There are approximately 450,000 spinal cord injury survivors in the United States. Compare that to the millions of cancer patients or those with heart disease. It is simply rare. Every spinal cord injury is different, like a finger print. There are thousands of nerves in the spinal cord, one can be damaged or all of them, or none at all. Consider for a moment what the spinal cord is, in the words of Wikipedia...

"The spinal cord is a long, thin, tubular bundle of nervous tissue and support cells that extends from the brain (the medulla oblongata specifically). The brain and spinal cord together make up the central nervous system (CNS). The spinal cord begins at the occipital bone and extends down to the space between the first and second lumbar vertebrae; it does not extend the entire length of the vertebral column. It is around 45 cm (18 in) in men and around 43 cm (17 in) long in women. Also, the spinal cord has a varying width, ranging from 1/2 inch thick in the cervical and lumbar regions to 1/4 inch thick in the thoracic area. The enclosing bony vertebral column protects the relatively shorter spinal cord. The spinal cord functions primarily in the transmission of neural signals between the brain and the rest of the body but also contains neural circuits that can independently control numerous reflexes and central pattern generators. The spinal cord has three major functions: as a conduit for motor information, which travels down the spinal cord, as a conduit for sensory information in the reverse direction, and finally as a center for coordinating certain reflexes."
Imagine a hefty extension cord like you'll see on any construction site. If you were to cut it cross-wise (see below) you would see a fairly accurate representation of this very important bundle of nerves. 

Now imagine each one of those tiny copper wires as your nerves carrying electrochemical impulses to the brain every millisecond 24 hours a day. If we compare the first picture to the image below of the actual spinal column we can see the similarity clearly. What do you suppose would happen if you were to take that cable in both hands and bend it back and forth very quickly? Those tiny copper wires can and will become frayed. Then what happens? That cord loses its ability to conduct electricity. This is very similar to what happens to the spinal cord should it become damaged. But, you may ask, can't the nerves just grow back? It's not quite that simple. Look at the cross-section again... do you see the black, white, red and green rubber coating covering the copper wire? The equivalent of that coating on a real spinal cord is called Myelin and it is the fatty tissue that insulates the nerve cells. When the that tissue becomes damaged it forms scar tissue that polarizes the impulses to the brain causing essentially a "short" in the circuit. If the entire cord is severed even the nerve cells themselves cannot reconnect and grow a new sheath. Hence the long-term, grim prognosis of severe spinal trauma.

It gets even more complicated still. There are levels of spinal cord injury. The vertebrae of the spine which becomes injured determines the type or "level" of injury. The cervical spine down to the upper thoracic is classified as Quadriplegia or Tetraplegia the lower you go. Once the injury drops below the third or fourth thoracic vertebrae it becomes Paraplegia.

Finally, the true key to getting a grasp on the basics is to understand the definition of Complete and Incomplete injuries. The simple of the two is Complete, it means the cord has been severed, cut completely. The damage of the cord without being severed is called Incomplete. This is where the "finger print" analogy truly comes into the situation. Let's say that you have 2 men. They are both water skiing on a lake and being pulled by the same boat. Suddenly they hit a log and are sent flying. One man hits an underwater stump and breaks the eighth thoracic vertebra and suddenly he is numb from the waist down and cannot move his legs. The second man was not thrown hard or far, but he hits a shallow sandbar on the back of his head. He hears a cracking sound, a quick pain, but his body feels normal. Both men are stabilized and rushed to the hospital. X-rays reveal the man on the stump has crushed his spine. The man on the sandbar merely cracked his third cervical vertebra. One is paralyzed for life, the other will go home in a week. So we see diving, car accident, motorbike, surfing, gun shot... whatever it may be... from the side, back or front... crushed or cracked... even a tumor... Every single injury happened differently and was treated a different way. While yes, many times the outcome may be similar, no two injuries are ever the same.

Clearly we can now see how treating spinal cord injury generally must be done on a case by case basis. When you factor in age, weight, age of injury, lifestyle and amount of therapy it becomes even more complex. Up until now the real treatment has been in progressive physical therapy. The best centers are those who focus solely on rehabilitating injuries to the central nervous system. We can narrow that category down further to those who are committed to continuous movement towards a cure and taking your treatment into your own hands. These facilities are spread throughout the country on such a minimal level many patients devote their entire lives to the cycle of raising money and traveling just for a few days a month, or even a year, to get the level of care they need. Keep in mind the insurance companies will rarely cover even the cost of therapy, let alone travel.

Things are changing however. There is a grassroots movement in medicine that holds exciting promise. I am going to wrap up this portion of the discussion, but next week I'll continue with more on this movement on the horizon, what living with SCI is like and why there is hope in stem cells. Tune in...