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Levels of Spinal Cord Injury (SCI)

If you or a loved one has an SCI, you likely want to know how severe it is.

Without knowledge about the spinal cord, it may be hard to understand the terms doctors use to describe the level of your injury.

Doctors rank SCIs on a "level of injury" scale. This scale looks at the site of the damage and how "complete" the injury is.

The parts of the body affected depend on the site of the injury. The completeness of the injury can give an idea of how drastically the injury will impact function.

How Doctors Decide the Level of a Spinal Cord Injury

The extent of an SCI varies from person to person.

But there are a few essential details that help doctors define the level of SCI damage:

  • The point of the SCI.
  • The injured parts of the spinal cord.
  • The completeness of the injury.

Spine anatomy

The damaged vertebrae determine the level of an SCI.

The vertebrae are the bones that make up your spine. The numbered vertebrae start with one at the top of the spine.

Location determines the vertebrae names:

  • Cervical = in the neck. Damage to these vertebrae leads to SCIs classified as C1 through C8.
  • Thoracic = in the chest. Damage to these vertebrae results in SCIs labeled T1 through T12.
  • Lumbar = in the lower back. Damage to these bones leads to SCIs called L1 through L5.
  • Sacral = from the pelvis to the tailbone. Damage to these vertebrae causes SCIs classified S1 through S5.

Each vertebra marks a border because of how the spine functions. Damage above one vertebra means all of the nerves below it stop working.

Incomplete and complete spine injuries

Whether your SCI is complete or incomplete can tell what function you retain after healing and rehabilitation.

Each vertebra has one set of two spinal nerves. Those that pass from the spinal cord to the body send signals creating movement. The other nerves send signals to the brain that it interprets as pain and touch.

Incomplete SCIs leave some nerve connections between the brain and the end of the spinal cord. People with incomplete injuries have a better chance of recovering feeling and movement than those with complete injuries.

With an incomplete spinal injury, it's possible to lose some function but keep others. Some people might feel light touch or pinpricks but can't move their limbs.

Incomplete injuries may also result in the opposite outcome. Some people might regain the ability to move their limbs but lose all feeling.

Complete SCIs sever the connections between the brain and the spinal cord past the damage. This injury is more likely to lead to no sensation or movement.

Spinal Cord Injury Tests: ASIA spinal assessment

Your doctor may perform an American Spinal Injury Association (ASIA) assessment. This standard test is an extensive exam of the whole body.

It helps doctors find out:

  • The level of your SCI.
  • What parts of the body your SCI affects.
  • How you might recover.

How the Level of Spinal Cord Injury Affects Prognosis

Your SCI level can affect your abilities after healing and rehab.

Cervical spine injuries

T1 is the first thoracic vertebrae. It is right below the cervical vertebrae. Injuries in this region impact the entire body. The prognosis for injuries to T1 and the cervical vertebrae depends on the location of the damage.

Thoracic spine injuries

Spinal cord injuries to the thoracic vertebrae (T2 through T12) mainly damage the connection between the brain and the legs.

This type of injury typically results in paraplegia. Paraplegia is the loss of sensation and movement in the legs and the lower body. These injuries can also lead to loss of bowel and bladder control.

Lumbar spine injuries

Injuries that damage the lumbar region (L1 through L5) usually affect the control of the legs, bowel, and bladder.

Sacral spine injuries

Injuries that primarily damage the vertebrae and nerves in the sacral region (S1 through S5) typically only affect the feet. But they can also affect bowel and bladder control.

Above T1

Spinal cord injuries at or above T1 result in the loss of movement and sensation in all four limbs.

This prognosis is often called quadriplegia or tetraplegia. These terms refer to the same condition — the loss of voluntary movement of both the upper and lower parts of the body.

Quadriplegia affects the neck and both arms and legs. It will likely impact the functioning of other internal organs like the bladder or bowels.

Above C4

Spinal cord injuries at the C4 level and above, including C1, C2, and C3, usually result in total paralysis. Injuries to this area often cause the loss of the use of the chest, arms, and legs.

These types of injuries affect the motor signals that control the diaphragm. This muscle makes the lungs expand when breathing in. Damage to the spine above c4 may compromise the ability to breathe independently and require a mechanical ventilator to help you breathe.