Spinal Cord Injury Primer

There are currently about 450,000 people in the U.S. living with SCI. About 10,000 new cases occur each year. Of those, about 82% involve men between the ages of 16 and 30, and 36% are the result of some sort of motor vehicle accident. And while the type of SCI is in the hands of circumstance, resultant quadriplegia/tetraplegia is slightly more common than paraplegia.

Billy's Injury

Billy's C5 cervical vertebra -- cervical, meaning neck, and vertebrae, meaning the rings of bone that support the spinal cord and constitute the spinal column, or backbone -- had been shattered, and his C5 vertebra cracked. In other words, Billy broke his neck. There were splinters of his C5 imbedded in his spinal cord, and the vertebrae were subluxated (dislocated).

 

As you may know, the spinal cord is the main neural (nerve) pathway for the body -- it conducts nerve impulses from the brain to the millions of other nerves that control every part of your body, from breathing to scratching your nose or wiggling your toes. Injuring your spinal cord is like squeezing or cutting a water hose -- the water/nerve impulses just stop, or slow to a trickle,depending on the severity of the injury.

So What Exactly Does A Spinal Cord Injury Affect?

 

Well, that depends on where the injury is, and how severe it is. Most people think that a spinal cord injury (SCI) means the spinal cord is cut, like a rope clipped in two with a scissors. This is the kind of SCI suffered by Christopher Reeve -- his spinal cord has a 20mm (about half an inch or so) gap in it. In truth, that kind of SCI is quite rare. Here's a brief, simple primer:

Types of Spinal Cord Injuries

 

Most SCIs are crush injuries and pressure injuries, or combinations of these. These injuries usually result from vertebrae subluxation -- simply put, dislocated vertebrae. The bones get knocked out of their usual positions and press against the spinal cord.

 

Any amount of pressure can affect SC function, even the lightest, most brief impact. A thump on the SC no greater than the playful flick of a finger you'd give your little brother in the back of his head would significantly affect SC function. It's that sensitive. Pressure causes the SC to swell, pressing against the walls of the spinal canal (the tunnel that runs up through the back of your vertebrae); even more pressure, especially if accompanied by subluxation or other vertebrae trauma, crushes the SC. To picture an SC crush injury, think of bashing a stalk of celery in the middle. It's still in once piece, but the connective matter at the injury site is mush. If you not only subluxate but also crack or break vertebrae, or get bone splinters driven into the SC, you've got real problems.

SCI affects both motor function and sensory function -- being able to move, and to feel.

As we said, how SCI affects the body depends on the location and severity of the injury.

Check out the diagram to the right. You can see that different nerves that control different motor functions are located in different vertebrae (see also the cervical nerves diagram above). Whichever vertebra is injured, the nerves in that vertebra and all the others below it are affected. Imagine that a nerve impulse from your brain is a car, and the spinal cord is a traffic tunnel. If the tunnel collapses, the car can go no farther than that point. For example, your C3 vertebra is wired to the nerves that control your diaphragm -- that's the muscle at the base of your lungs that enables you to breathe in and out. If C3 is damaged, you can't breathe without a mechanical respirator. If C4 is damaged, you can't move your arms, and so on down the line, including thoracic (middle back), lumbar (lower back), and sacral (pelvic) vertebrae.

Finally, SC injuries can also affect things like bowel and bladder function, sexual function, blood pressure and circulation, and lots more. SCI even affects your skin -- if you lay in bed without turning for long enough, you can develop bedsores, wounds which occur in places where the skin breaks down from constant pressure. Many SCI patients, when sick from any cause quickly develop pneumonia, an illness caused by infection and fluid in the lungs. Indeed, pneumonia used to be the number-one killer of severe SCI patients -- they would literally drown within days of their injury. The pneumonia is caused both by constantly lying on one's back, which makes breathing more difficult, and by the gradual collapse of the lungs caused by poor diaphragm function.

What else does SCI do?

 

Most people afflicted with SCI for any length of time undergo changes in their bodies. Muscles atrophy leaving arms and legs extremely thin, or in cases of complete SCI injury, flat. Stomachs become distended from lack of muscles holding in the organs. Neuropathy can occur in all extremities. In quadriplegics, for example, the hands curl to fists from lack of finger movement, muscle and tendon tightening.

 

Spasticity is the involuntary movement of muscles caused by stimulus beneath the level of the injury. Spasticity is manifested by a shaking of the body or body parts in a seemingly uncontrollable fashion. Although uncomfortable, sometimes painful and certainly weird to look at, spasticity exists in all SCI people. Extreme levels of spasticity can be a sign of illness.

Weight shifting
When you see a person in a wheelchair, leaning forward, lying back or to the side, don't be alarmed. That person is "weight shifting". Able bodied individuals who sit for any length of time unconsciously will shift from side to side when they become uncomfortable. A paralyzed person who cannot move must shift the weight from the ischials (those bony protuberances in your back side) to allow the blood flow freely. Failure to do this can cause decubitus.

Decubitus
This condition is more commonly known as "bed sores". Decubitus can in fact be any opening of the skin in response to irritation, or lack of blood flow. Every paralyzed person is more prone to this condition simply by the fact that movement is impossible.

Incontinence
Most SCI individuals have some form of incontinence. Bladder functions (peeing) is done by some form of catheterization or indwelling catheter. Bowel functions are achieved through a combination of digital stimulation of the anus and suppositories. Although each individual has multiple methods to choose from to overcome their incontinence, most SCI individuals are totally incontinent.