The spinal cord, enclosed in the spinal column, functions as a communication gateway between the brain, trunk, and limbs. It does so by way of spinal nerves, which send sensory information from all over the body to the brain and convey central instructions from the brain to the body’s muscles and organs.
There are 31 pairs of spinal nerves, each arising from a segment of the cord and innervating a particular part of the body. They are named after the vertebra from which they emerge. Accordingly, there are 8 pairs of cervical nerves, from C1 to C7, 12 pairs of thoracic nerves, T1 to T12, 5 pairs of lumbar nerves, L1 to L5, 5 pairs of sacral nerves, S1 to S5, and 1 pair of coccygeal nerves.
What happens in spinal cord injury?
Spinal cord injury is most commonly caused by trauma to the spinal cord but there are also non-traumatic causes. As injury occurs, spinal nerves are damaged and the communication between the brain and body is blocked.
Because spinal nerves are responsible for both sensory and motor functions, spinal cord injury may cause loss of both sensation and muscle control. The latter not only leads to paralysis but also dysfunctions in processes such as urine voiding, bowel movement, breathing, and speaking.
The higher injury occurs on the cord, the more nerves are affected, and the more extensive the disability. At the lowest levels, the injuries may result in some loss of functions in the hips and legs, little or no control of the bowel or bladder, and impaired sexual functions but the patient may still be able to work. At lumbar levels, the chance of walking recovery is greatly reduced. Patients will typically require a manual wheelchair or walking braces.
Thoracic injury additionally affects the abdominal, chest, and back muscles. Patients with low cervical injury may also suffer, on top of all that, from loss of control of arms and hands at various degrees.
The high cervical injury usually results in total paralysis from the neck down. In addition, patients may not be able to breathe on their own, and their ability to speak is also reduced.
Read More: Types of Spinal Cord Injury
What are the causes of spinal cord injury?
There are kinds of spinal injuries. The most common ones that we see are from an injury standpoint, are from trauma, often things like car accidents or falls. And there’s a whole spectrum of injuries that affect people of different ages and fragility differently. Young, healthy people, kids, and young adults typically have more high-velocity kinds of injuries from car accidents or skiing accidents and stuff like that.
Whereas people who are older in life, have more fragility like osteoporosis and more chronic disease states that occur later on in life often they have lower energy trauma and spinal injuries like compression fractures, things that happen just from falling from standing height. Typically, what we worry about is, what’s the spinal injury doing to your nervous system.
And so that’s how we sort things out and figure out who needs to be treated, who needs to be operated on, who needs to be treated in a brace. Those things all depend on all those variables. A person’s underlying medical conditions, healthiness, their age matter a lot.
In most cases, the mechanism of spinal cord injury caused by physical trauma is compression of the spinal cord by fragments of fractured vertebrae. Disc problems, such as herniation or bulging, may also cause spinal cord injury.
Overgrowth of vertebral bone tissue can also be the reason behind a slow and progressive spinal cord injury in any region of the spine. With age, ligaments that bind the spine together become thickened and stiff. These ligaments can take up space in the spinal canal and cause progressive spinal cord injuries. Spinal cord injuries can occur due to tumors that grow in the spine.
Read More: Is Hearniated Disc Curable?
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Types of spinal cord injuries
Spinal Cord Injury Types
Complete Spinal Cord Injuries:
Complete SCIs are the most serious and occur when the spinal cord is injured, eliminating the brain’s ability to send signals below the injury site. An injury impacting the lumbar spinal cord, for example, can lead to paralysis below the waist while preserving your motor functions in your upper body and arms (paraplegia). For complete injuries in the cervical spine, however, this often leads to a loss of motor function in the lower and upper body (tetraplegia, which is also known as quadriplegia)
- Incomplete Spinal Cord Injuries Incomplete SCIs commonly result from compression or damage being inflicted on the spinal cord that reduces the brain’s ability to send signals below the injury site. Because of the partially-compromised condition of the spinal cord, incomplete injuries vary drastically from person to person. Some sensory and motor functions may be slightly compromised in some or nearly eliminated in others. Additionally, some incomplete injuries result in triplegia or the loss of sensation and movement in one arm and both legs.
Some of the most common types of incomplete injuries include:
- Anterior cord syndrome: This type of injury, to the front of the spinal cord, damages the motor and sensory pathways in the spinal cord. You may retain some sensation but struggle with movement.
- Central cord syndrome: This injury is an injury to the center of the cord, and damages nerves that carry signals from the brain to the spinal cord. Loss of fine motor skills, paralysis of the arms, and partial impairment, usually less pronounced in the legs, are common.
- Brown – Sequard syndrome: This variety of injuries is the product of damage to one side of the spinal cord. The injury may be more pronounced on one side of the body; for instance, movement may be impossible on the right side but may be fully retained on the left.
- Tetraplegia: These injuries, which are the result of damage to the cervical spinal cord, are typically the most severe, producing varying degrees of paralysis of all limbs. Sometimes known as quadriplegia, tetraplegia eliminates your ability to move below the site of the injury.
- Paraplegia: This occurs when sensation and movement are removed from the lower half of the body, including the legs. are typically more severe when they are closer to the top vertebra.
- Triplegia: Triplegia causes a loss of sensation and movement in one arm and both legs, and is typically the product of an incomplete spinal cord injury.
Read also – All You Need to Know About Spinal Tumors
How does it affect the brain?
To check if the patient is in spinal shock, check the bulbocavernosus reflex (S3). Spinal shock means that the patient does not have the bulbocavernosus reflex. The anal sphincter will not contract when the reflex is absent. In spinal shock, the peripheral neurons are temporarily unresponsive to the brain stimuli. The injury is similar to a hurricane that wipes out everything and shocks everything.
The brain sends a signal, and we are going to see if that signal is present in the destroyed areas. Complete spinal cord injury is the loss of motor and sensation below the level of the lesion following a spinal cord injury. Incomplete means spinal cord injury with some neurological function distal to the injury. It can be motor, sensory, or sacral sparing, which can be voluntary rectal tone, anal contraction, or perianal sensation.
How does it affect another part of the body?
The sensory level is used when there is no motor level to test, such as in the thoracic spine. Neurogenic shock is hypotension and bradycardia following acute spinal cord injury, due to disruption of the autonomic pathway and loss of the sympathetic tone to the heart. There will be widespread vasodilation with a decrease in systemic vascular resistance due to injury to the descending sympathetic system. Monitoring with swan Ganz may be helpful for careful fluid management. Swan Ganz will guide the appropriate fluid management and resuscitation.
You may give vasopressors to the patient to treat the hypotension. Hypotension and tachycardia are hypovolemic shock. Hypotension and bradycardia are neurogenic shocks. Autonomic dysreflexia occurs in complete spinal cord injury due to sympathetic overcharge (increased activity).
Uncontrollable sympathetic output associated with certain triggers. Usually unchecked visceral stimulation such as fecal impaction or obstruction of the Foley catheter. It occurs in patients with spinal cord injuries above T6. It can be fatal. Patients will get headaches, agitation, almost malignant hypertension, sudden very high blood pressure, and profuse sweating.
Treatments options for spinal cord injury
The spinal cord connects the brain to the body. When you disconnect everything below, injury points disappear. When there is an injury, most spinal cords simply have had a transient compression of the spinal cord. That’s what we call a contusion.
What happens is that the spinal cord is squeezed away from the compression site and nerve fibers are like rubber bands; if they’ve been pulled apart at a certain speed, they break. Very early on, doctors developed a rat model of spinal cord injury. The first thing we found was that you only need about 10% of the fibers in the spinal cord for a minimum to recover walking. So, what we saw in animals is true in humans and that gave us hope because if we only had to regenerate 10% of the spinal cord, it’s doable.
Picture someone in a wheelchair who has an injury to their spinal cord. If you told that person to walk again, do you think their life would return to normal? The answer is not necessary. This is because injury to the spinal cord causes many more problems than not being able to walk. Further, if you think about it, this devastating condition can happen to any of us or our loved ones in an instant due to a car crash, a sports accident, or even a simple fall.
The spinal cord causes many beyond the inability to walk or move.
For instance, individuals often lose the ability to voluntarily control their bladders and bowels. They can develop severe pain that does not respond to pain medicine, they can lose normal sexual function which reduces the quality of life, and can be devastating for couples who want to have children. And top of all that, spinal cord injuries often cause progressive disease throughout the body, which manifests as a metabolic syndrome.
Also read – How to Choose a Spine Doctor or Clinic for Spine Treatment?
You may have heard of metabolic syndrome in the context of obesity. However, this condition commonly develops after spinal cord injury even in lean, otherwise healthy individuals. Indeed, clinical studies with human subjects and data from laboratories show that spinal cord injury leads to excess adipose or fat accumulation, the elevation of blood lipids like cholesterol and LDL, which can clog arteries, and excessively high blood glucose.
These individuals also develop a condition called fatty liver disease. Compared to the general population this collection of metabolic problems increases the risks for diabetes by six times and the risk for heart disease by more than eight times in spinal cord-injured individuals. Surveys of the spinal cord injury community consistently show that regaining the ability to walk is fairly low on their priority list.
The metabolic problems significantly increase mortality after spinal cord injury. While the evidence is clear that spinal cord injury triggers metabolic problems, diabetes, and heart disease, most of the research over the past 30 years has focused on making people walk again. This, of course, would be a welcome change for them, but it won’t necessarily solve all of their problems.
The reason is that the spinal cord pathways that control walking, the pathway shown here are not the same as the ones that control organ functions. What many people may not realize is that in addition to connecting them to our muscles, we have nerves from the spinal cord that connect to all of our organs.
Recovery tips for spinal cord injury
The spinal cord is the body’s informative super highway, constantly buzzing with electrochemical signals between the brain and the rest of the body. This precious bundle of nerve fibers runs through a cavity within each vertebra. This protects the cord along its length but even bony armor can’t protect the spinal cord from the worst injuries. With enough force, this delicate cord can get damaged, cutting off all communication to and from the body below the injury site and leaving the patient paralyzed. This devastating injury happens to an estimated half a million people each year across the globe.
To make things worse, the damage is irreversible. Neurons of the central system don’t seem to be able to regrow their axons the long, spindly projections that link them to other neurons. Scientists are working to understand why these injured nerves can’t repair themselves and regrow their axons.
At the same time researchers are trying to reboot the regeneration process. So far most of the research has been done on rodents with researchers using three broad strategies to try to tackle the problem:
The first strategy is to change the environment swirling around the damaged nerves to make them more growth-friendly by dialing down chemicals that inhibit the ability of nerves to regenerate. One set of molecules that are suspected of blocking regeneration is called chondroitin sulfate proteoglycans (CSPGs).
The second strategy is to introduce factors that work directly on the cellular machinery of the damaged neurons to boost their capacity to heal themselves. For example, the researchers are trying to make the neurons more receptive to pro-growth signals from their neighbors. Receptor molecules called integrins seem to disappear as neurons mature so researchers are looking for ways to smuggle integrins back into damaged neurons. Researchers are also experimenting with adding in the growth factors themselves.
The third strategy has the potential to combine many aspects of the first two. A study in rats has shown that mesenchymal stem cells (MScs)naturally home in on the site of injury and protect against secondary damage caused by the immune system.
They also appear to promote axon regeneration, repair damage to the axon’s insulating layer of myelin, and may be able to directly transform into new neurons. A small trial using MSCs in humans was completed last year and the results are due to be reported soon. Successful therapy will likely involve a combination of these ideas, hopefully giving patients with spinal cord injuries a brighter future.
When to see a doctor
World Spinal Cord Injury Day’ is observed to focus on the rising spinal cord injuries around the world. Damage to the spinal cord can damage the nerves that result in devastating injuries. Most often these injuries are caused due to car accidents or sudden high-velocity impacts to the spinal cord.
Spinal cord injuries are the most devastating neural injuries that also affect the body’s functioning and sensations. These injuries can be life-threatening at times if no timely aid is provided. With a little caution and safety, these injuries can be avoided.
More than 40,000 adults and children with spine disorders come to various clinics each year. The clinical teams work across medical specialties and locations, so you can feel comfortable knowing you are receiving the collaborative benefit of all clinic expertise that applies to your condition. They customize a care plan by considering expertise across specialties. With all that expertise working together, you can rest assured you will be in good hands.
Clinic experts use advanced technology and diagnostic tools to accurately diagnose and understand your spine condition, including advanced neuroimaging (MRI or CT myelography), electrodiagnostic evaluation, assessment of bone health, and screening for autoimmune, and inflammatory spine diseases to name a few.
Doctors bring the most advanced discoveries in medical science to patients faster through cutting-edge research and clinical trials. Some examples of this are robotic advances that aim to improve accuracy and patient outcomes, 3D printing technology for surgical planning, and emerging regenerative medicine treatment options like stem cell trials for degenerative spine conditions.
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About Author
Dr. Eshan Nerkar
Neurologist And Neurosuegeon
Dr. Eshan Nerkar, Consultant Brain & Spine Surgeon in Nashik specializes in Spine Surgery. He practices at AXON Brain & Spine Clinic. He is one of the best neurosurgeons in Nashik with more than 10 years of experience. He has performed more than 1000 surgeries related to brain and spinal surgery procedures.