The spinal cord is something you never really notice or think out until there is an abnormality or damage. Yet it is the part of the body that is responsible for controlling all of your conscious and unconscious bodily functions. It is the superhighway that connects the brain to the body and allows you to control your muscular and skeletal system. To put it plainly: it is the electrical wiring that allows you to pilot your meat suit through the world.
Many people (myself included prior to my injury) take the spinal cord a bit for granted. To quote age old wisdom from Futurama: “when you do things right, people won’t be sure you’ve done anything at all.” I think this quote surmises the function of the spinal cord well. You get so used to your body “working” you don’t realizes the intricate complexity of its functioning, until it doesn’t function quite right. It’s truly a “don’t know what you’ve got ’til it’s gone scenario.”
So here’s a rundown of some interesting facts about the spinal cord and spinal cord injuries. I hope you will gain a new appreciation for the spinal cord and all its miraculous intricacies!
The Spinal Cord
The human spine is composed of 33 stacked bones called vertebrae, which house and protect the spinal cord.
There are over 120 muscles, 100 joints and 220 ligaments that support the spine.
There are 1 billion neurons in the spinal cord.
The spinal cord is fully grown when you are 4 years old. After age four it stops growing (although the vertebrae and spinal disks continue to grow).
There are 4 sections of the spinal cord: cervical or C-level (neck), thoracic or T-level (torso), lumbar or L-level (low back) and sacral or S-level (tailbone).
Both humans and giraffes have the same number of cervical vertebrae: 7… But the giraffe’s are obviously much larger.
The spinal cord is basically like an electrical cord that sends signals from your brain around the body, and vice versa.
It can create short-cuts for regular activities such as driving or walking, so the body can go into “auto-pilot.”
The spinal cord is extremely delicate. Imagine it to have the consistency of a banana and the width of your pinky fingernail (about 1.5cm). It seems ironic that something so powerful and crucial, is so fragile and tenuous.
The spinal cord controls voluntary (walking) and non-voluntary movements (breathing, pupil dilation, digestion).
Each section in the spinal cord corresponds to a section of the body and its functions.
The spinal cord is the one thing in the body that doesn’t repair itself if severely damaged. Even with only minor damage, any regeneration or repair is extremely slow.
Nerve cells are the longest cells in the body, the axons can reach up to 1 meter in length for a single cell (and even longer in other species).
There are different types of receptors and pathways for specific sensations and motor function. Meaning if one of the pathways is damaged you may be able to perceive one type of stimuli, but not another. For example, you may be able to feel cold, but not heat or pressure.
Spinal Cord Injury Interesting Facts:
A spinal cord injury can cause a lot of unexpected changes in the body. It is not as simple as just paralysis or not being able to walk. Depending on your level of injury it can result in difficulty breathing, digesting, weakness and many other secondary conditions.
When I am asleep, I walk in my dreams. However, I still consciously know that I use a wheelchair in my dreams. It just simply won’t be there. This is true for many wheelchair users since the brain still knows how to walk, but the signal just doesn’t get to the legs.
The spinal cord is responsible for regulating body temperature through the nervous system. When the body becomes too warm it triggers blood vessels to dilate, and sweat glands to release fluids to cool down the body. Damage to the spinal cord can interrupt this process. After injury the body’s temperature regulation is thrown off. Many people no longer sweat, or sweat way less, This can become particularly dangerous if one is unable to cool down, and can cause spikes in blood pressure or other serious conditions. So it is important to stay cool in the heat and keep warm in the cold.
Before the 1940’s life expectancy after sustaining an SCI was only two years. Paralyzed WWII veterans were the first group of people to move forward and live full lives after injury. This is mainly because antibiotic use was not widespread and many died from infections from bladder, blood and skin issues.
Trauma and associated healing is not necessarily symmetrical across right/left sides of the body. Meaning you might be able to feel or move one side of your body but not the other. A weird one for me is when I get goosebumps, they are more pronounced on the right side of my body.
No two injuries are the same. Even if people have the same injury level, the way this presents in the body due to severity, and method of trauma can be drastically different.
If you are a non-ambulatory wheelchair user and you break your leg, they don’t cast it up, they just leave it to heal on its own.
A spinal fusion is a common procedure after a spinal cord injury to stabilize and strengthen the damaged vertebrae. Depending on the degree of lordosis (spinal curvature) present in the spine prior to surgery, a fusion can result in the spine losing its curvature and straightening out; thus, increasing your height when standing (I used to be 5’5.5″ now I am pushing 5’7″ when standing).
The base metabolic rate of the body decreases as paralyzed muscles atrophy and muscle mass is lost . This manifests for everyone differently, but prior to injury I always had a voracious appetite, now I rarely ever feel hungry which is a huge change.
If motor neurons are damaged there are no reflexes present. The classic example of this is the “knee-jerk” kicking reaction of the leg when the patellar tendon, located just below the kneecap, is struck. If there is motor neuron damage, this reflex is no longer present.
Some people wonder why paraplegics don’t amputate their legs if they are “dead-weight.” While my legs don’t “work” they are still important for balance, counter-weight and stability.. especially when performing transfers. They are also important to store blood and fluids which impacts temperature regulation of the body.
It is also important to note that the nervous system and the spinal cord play a role in general healing and injury recovery. It sends signals from the afflicted area to the brain and rest of the body to encourage healing to happen. When this signal is cut off, it can take longer to recovery from trauma below the level of injury since this healing response “message” is longer able to get through. Therefore it may take longer for these areas to recover than an able bodied person.
Spinal Cord Injuries By the Numbers:
Causes of Spinal Cord Injuries Breakdown:
46% Motor Vehicle Accidents
22% Falls
16% Violence
12% Sports
Average Age at the Time of Injury:
1973-79 average age was 28.7
since 2005 average age is 40.2
SCI Breakdown by Gender
81% Male
19% Female
Types of SCI
30% incomplete quadriplegia
26% complete paraplegia
20% complete quadriplegia
18% incomplete paraplegia
Incomplete spinal cord injuries are characterized by having some sensory or motor function intact below the level of injury. Even if sensation or movement is faint. Simply put messages are still able to be relayed from the brain to the body and vice versa, they are just weakened or abnormal.
Complete spinal cord injuries are characterized by a total lack of sensory and motor function below the level of injury. This does not necessarily mean that the nerves or axons are completely severed, just that they are not functioning appropriately due to trauma. So in the case of a complete injury the brain and the body are not able to communicate.
Treatments for SCIs
There is strong evidence for neuroplasticity and nerve regrowth for some types of incomplete injuries after intense neural retraining exercises. This kind of activity based training is facilitated at organizations like Reyu or Next Step Fitness (and these programs can be done at home as well). It comes down to repetition and re-strengthening the weakened connection. These programs are especially effective when combined with a Functional Electrical Stimulation (FES) program and proper nutrition.
There is currently no cure for complete spinal cord injuries, but there are promising studies involving implanted epidermal spinal stimulators, computer/brain/spinal cord interfaces, injectable bioactive therapies, nerve/tendon transfers, neural scaffolding, bone marrow stem cell injections and even using asparagus to regrow a spinal cord.
