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Spinal Cord Injury Levels

The spinal cord is one of the most crucial parts of the body. It relays signals from the brain to the body’s extremities.

It ensures that you can move every finger and wiggle every toe on cue. The spinal cord also controls life-saving reflexes, regulates heart rate, maintains proper breathing, and helps the body stay at the proper internal temperature.

Despite being protected by the spine, the spinal cord can still be damaged. The consequences can range from minor to catastrophic.

Spinal Anatomy

The spinal cord runs from your brain stem to around the first or second lumbar vertebrae—around 40 cm. This long cord of nerves is contained within the spine. The spine consists of several individual vertebrae that fit together solidly enough to protect the spinal cord, but loosely enough to allow flexibility.

Anatomy of the Spine

Anatomy of the Spine

The spine is divided up into several categories (called levels) of vertebrae. It starts with 7 cervical vertebrae (“C1” – “C7”) located in your neck. The 12 thoracic vertebrae (“T1” – “T12”) start at the shoulders and extend down the upper back. The 5 lumbar vertebrae (“L1” – “L5”) begin near the small of your back or your belly button, then flow into your 5 sacral vertebrae (these fused vertebrae are collectively called “5”) and then to the 4 coccygeal vertebrae (these fused vertebrae are collectively called “4”). The sacral and coccygeal vertebrae are located in the pelvis.

The sections of vertebrae roughly correspond to distinct sections of the spinal cord.  Each section is responsible for certain tasks.

  • The spinal cord within the cervical vertebrae assists breathing and control arm movements.
  • The spinal cord within the thoracic vertebrae assists the chest and abdominal muscles.
  • The spinal cord within the lumbar vertebrae assists leg movements, hip movements, and bladder/bowel control.
  • The spinal cord within the sacral and coccygeal vertebrae assists bladder/bowel control, balance, and sexual functions.

While there are many types of spine injuries, few impact the spinal cord. Injuries involving the spinal cord are usually the most severe.

Spinal Cord Injuries

Spinal cord injury classification falls into two main categories. Traumatic injuries can cause severe damage to the entire body, making spinal cord damage seem even more impactful. Car crashes, falls, sports injuries, violence, and diving in shallow water can cause a traumatic injury to the spine and lead to a spinal cord injury. Illness/non-traumatic injuries can strike in a wide number of ways. Spinal cord inflammation from other injuries can cause damage after an injury. Illnesses such as cancer, osteoporosis, multiple sclerosis, and arthritis can lead to spinal cord injuries.

Spinal cord injuries do not affect the population evenly. According to the National Spinal Cord Injury Statistical Center,

  • there were approximately 54 cases of spinal cord injuries per one million people in the United States, or around 17,000 new cases of spinal cord injury in 2016.
  • there are about 282,000 people in the US living with spinal cord injuries.
  • the average age at time of injury is 42a stark increase from the average age of 29 in the 1970’s.
  • about 80% of spinal cord cases occur in males.
  • non-Hispanic Whites incurred 63.5% of spinal cord injuries, non-Hispanic Blacks incurred 22% of spinal cord injuries, Hispanics incurred 11% of spinal cord injuries, Asians incurred 2% of spinal cord injuries, and Native Americans incurred 0.5% of spinal cord injuries in the United States in 2016.
  • car crashes are the leading cause of spinal cord injury, followed by falls, violence, and sports injuries, respectively.
  • the most common result of spinal cord injuries is incomplete tetraplegia (45%), followed by incomplete paraplegia (21.3%), complete paraplegia (20%), complete tetraplegia (13.3%), and complete recovery by hospital discharge (0.4%).

Complete and Incomplete Spinal Cord Injuries

Spinal cord injuries fall into one of two categories: complete or incomplete.

After an injury, the spinal cord usually goes into “spinal shock.” During spinal shock, the body temporarily reduces its reflexes in all areas or may completely lose reflexes in an area. This may cause an injury to appear much worse than it is.

Complete spinal cord injuries cause permanent, irreversible damage. These injuries cause quadriplegia and paraplegia. Conversely, incomplete spinal cord injuries result from partial damage to a region of the spinal cord. Incomplete injuries have a range of severities. Often, the completeness of an injury is not known until six to eight weeks after the injury, when swelling is reduced, spinal shock is treated, and other concomitant injuries are addressed.

Depending on where an injury is, different functions may be impaired. Every injury is unique and will have differing repercussions. The injury-related dysfunctions listed here are a general outline of the more common possibilities. Not all patients have the same injury, and so this should not be used as a definitive guide.

Cervical Spinal Cord Injuries

Injuries to the spinal cord in the cervical region are typically the most severe. Even small injuries to this area may be fatal. This region of the spinal cord is closest to the brain, so injuries are also the most likely to affect the brain itself.

Cervical spinal cord injuries almost always result in quadriplegia. The most severe spinal cord injuries are generally C1 – C4 spinal cord injury. Injury to C1 – C4 always cause quadriplegia, and can cause problems with breathing, speaking, and bladder/bowel function.

Injuries to the C5-C7 areas have ranging levels of impact:  

  • C5 Spinal Cord Injury: A person may be able to lift their arms and bend their elbows, but elbows cannot be extended. Wrist and hand motions are likely debilitated. Speaking is possible, but breathing is weakened.
  • C6 Spinal Cord Injury: A person can lift arms and bend elbows, and may be able to bend the wrist back. Elbow extensions, wrist extensions, and finger motions are not likely. Like the C5 injury, speaking is possible. Breathing will be weakened.
  • C7 Spinal Cord Injury: Shoulders, arms, elbows, and wrists are not affected. Some finger extension may be possible.
  • C8 Spinal Cord Injury: Objects can be loosely grasped and released. Some hand movement may still be impaired.

No matter the location of the cervical spinal cord injury, the patient will likely need assistance in day to day life. Bowel control is limited, but can be controlled with special equipment.Patients with cervical spinal cord injuries may also experience neurogenic shock. Neurogenic shock disrupts the spinal cord’s autonomic pathways. This affects the body’s blood pressure and can cause a lower heart rate. If not recognised and treated, neurogenic shock can cause organ failure.

The recovery process for these injuries mainly focuses on stabilizing the affected area. Most injuries to this region are permanent. Most rehabilitation focuses on learning how to use non-affected areas to regain as much autonomy as possible.

Thoracic Spinal Cord Injuries

Injuries in the thoracic area of the spinal cord cause complications with muscles in the upper chest, mid back, and abdominal region. The injuries in this area are generally divided between injuries between T1 – T5 and T6 – T12. As the spinal cord injury most common level, thoracic spinal cord injuries are most commonly seen and treated by hospitals worldwide.

T1 – T5 spinal cord injury affect more of the upper body. While arm and hand functions are usually left unaffected (except for T1 injuries), patients often incur paraplegia, or the loss of trunk and leg movement. T6 – T12 spinal cord injury usually impacts the abdominal and back muscles. Patients will likely still incur paraplegia, but may be better able to control balance in the trunk of the body. These injuries also usually result in limited to no bowel control.

Recovery differs vastly from patient to patient. Patients with thoracic spinal cord injuries can usually maintain a higher level of autonomy using a motorised wheelchair, but will likely still need assistance for many tasks.  Depending on the severity of the injury, patients may be able to stand with a brace or standing frame. Many patients are able to learn how to drive modified cars.

Lumbar Spinal Cord Injuries

L1 – L5 spinal cord injury affects the hips and legs. Most of the upper body is left unaffected. Bowel control is usually impaired.  The specific muscles affected are dependent on which of the vertebrae are affected.

  • L1 – L2 injuries affect hip bending and flexing.
  • L3 injuries affect straightening the knee.
  • L3 injuries affect bending the foot upwards.
  • L4 injuries affect toe extension.

Injuries in this region are less life-threatening than cervical or thoracic injuries. Some patients are able to walk with braces; some may need a wheelchair. Depending on the severity of the injury, patients may be able to recover with physical therapy.

ASIA/ISCoS Exam and Grading System

This system of tests is used to help diagnose a spinal cord injury and classify the severity and extent of the damage. This test is completed by doctors within 72 hours of the injury, and is an important part of discerning a realistic prognosis for the patient. The grade received on the test is dependent on both the patient’s ability to feel touches to various regions of the body and the patient’s motor abilities.

  • Grade A: Complete dysfunction of sensory and motor function in the body below the injury location.
  • Grade B: Very limited sensation in areas below the injury location.
  • Grade C: Approximately 50% of muscles below the injury location cannot operate in extensions against the force of gravity.
  • Grade D: Most muscles can be moved against the force of gravity below the injury location.
  • Grade E: All motor and sensory function has returned.

Sacral Spinal Cord Injuries

S1 – S5 Spinal Cord Injury is generally the least impactful. Patients are usually able to walk, but bowel control and sexual function may be impaired. Injuries to this area are very rare, and usually only occur as a result of direct impact (i.e. falling directly on the area) or due to comorbid illnesses.  

Important Questions to Ask a Doctor

If you or a loved one has just incurred a spinal cord injury, be sure to maintain clear and open communication with your doctor. Important questions you may want to ask include:

  • What complications could arise from this injury? What signs should we be on the lookout for? How can complications be prevented?
  • What is the goal of rehabilitation therapy in this case? What is the best case scenario for recovery?
  • What should I be looking for in a rehabilitation centre? Do you have any recommended rehabilitation centres?

Handling a Spinal Cord Injury

Most people feel incredibly confused and out of their depth when handling a spinal cord injury. It usually takes a few days to a few weeks for the shock of the injury to set in. Before reality has settled, patients usually are in denial of their injury.

While it is important to take time to grieve for your lost abilities, setting new goals for future development is crucial for proper coping. As soon as spinal shock subsides, physicians are able to get a deeper understanding of the completeness of your injury. Be sure to discuss a future prognosis for rehabilitation. Be open and honest with your doctor about the way you are feeling and your concerns.

Many spinal cord injury patients are able to move with the use of a motorised wheelchair. With time, patients may be able to learn how to drive a modified car to further regain autonomy. While patients may to do some tasks on their own, it is important to understand that you will need help in day to day life. Coping with this dependency is an important step in emotional recovery.

We strongly encourage arming yourself with as much knowledge of spinal cord injuries as possible. Read other patient’s stories online and speak with your doctor about the level of independence you may realistically be able to recover. Local, state, and national support groups are great resources for learning how to cope with your new condition and there are also some useful spinal cord injury mobile applications that may help with day to day tasks.