The spinal cord is a bundle of nerves that carries signals between the brain and the rest of the body. Acute spinal cord injury (SCI) is due to a traumatic injury. The injury may cause a bruise (contusion), compression (from blood or bones), a partial tear, or a complete tear (transection) in the spinal cord. SCI is more common in men and young adults.
SCI results in a decrease or loss of movement, feeling, and organ function below the level of the injury. The most common sites of injury are the cervical and thoracic areas. SCI is a common cause of lifelong (permanent) disability and death in children and adults.
The spine has 33 vertebrae. They are:
- 7 cervical (neck).
- 12 thoracic (upper back).
- 5 lumbar (lower back).
- 5 sacral* (sacrum, located in the pelvis).
- 4 coccygeal* (coccyx, located in the pelvis).
* By adulthood, the five sacral vertebrae fuse to form one bone. The four coccygeal vertebrae fuse to form one bone.
These vertebrae form the spine and protect the spinal cord. In general, the higher up the spine that the injury happens, the more severe the symptoms. Injury to the vertebrae does not always mean the spinal cord has been damaged. And damage to the spinal cord can happen without breaks or dislocations of the vertebrae.
SCI can be divided into two main types of injury:
- Complete injury. There is no function below the level of the injury. This means no feeling or movement. Both sides of the body are equally affected. Complete injuries can happen at any level of the spinal cord.
- Incomplete injury. There is some function below the level of the injury. This could be movement in one limb more than the other, feeling in parts of the body, or more function on one side of the body than the other. Incomplete injuries can happen at any level of the spinal cord.