Spinal Cord Injury 101
What is the spinal cord? How is it different from the spine (backbone)?
The spinal cord is made of nerve cells which connect to each other, sending signals back and forth from the brain to end-organs like skin and muscle. It runs from the base of the brain and extends down the back. It is encased and protected by the bony spinal column (also known as the spine or backbone) made of stacked vertebrae. The spinal cord runs through a canal (the vertebral canal) formed by these vertebrae.
What is spinal cord injury (SCI)?
SCI occurs when the spinal cord is damaged, and signals from the brain cannot be properly transmitted to the rest of the body. This results in some loss of function: the loss of sensation (feeling) and/or muscle control (movement). The spinal cord does not have to be severed in SCI, for even compression or bruising of the spinal cord can cause this loss of function.
SCI is very different from back injuries such as ruptured disks, spinal stenosis or pinched nerves. It is possible for a person to "break their back” or “break their neck" yet not sustain an SCI if only the bones (the vertebrae) around the spinal cord are damaged, but the spinal cord itself is not affected.
How many people have SCI?
Spinal cord injury (SCI) is a leading cause of disability in the United States and worldwide. On average, 300,000 people sustain an SCI each year and a total of about 4 to 5 million people live with an SCI in the United States.
What are the common causes of SCI?
Causes of SCI can be classified into traumatic or non-traumatic.
The most common causes of traumatic injury are:
- Motor vehicle accidents
- Acts of violence like gunshot and stab wounds
- Sports-related accidents (diving, gymnastics and football are particularly high-risk activities)
Non-traumatic causes of SCI include:
- Spinal metastasis from cancer
- Spinal tumors arising from the cord itself or the vertebral column (primary tumors)
- Ischemia or infarcts (lack of blood flow to the spinal cord)
- Complications from surgery or other medical treatment
- Birth defects, such as spina bifida
What is a complete injury? How is it different from an incomplete injury?
The effects of SCI depend on the type of injury and the level of the injury. SCI can be divided into two types of injury - complete and incomplete.
A complete injury is when there is no sensation and no voluntary movement below the level of injury. Generally both sides of the body are equally affected.
An incomplete injury means that there is some functioning below the primary level of the injury. A person with an incomplete injury may be able to move one limb more than another, may be able to feel parts of the body that cannot be moved, or may have more functioning on one side of the body than the other. People with incomplete injuries can be expected to recover more motor control and sensation as the body recovers and heals itself. They generally have better outcomes than persons with complete injuries.
What is Tetraplegia (Quadriplegia)? How about Paraplegia?
The extent of a spinal cord injury depends upon the injury location:
- The segment of the spinal column found in the neck region (cervical vertebrae) directly supports the head. Injuries at this level cause weakness or total paralysis of all four limbs, also known as tetraplegia.
- Injuries at the thoracic level (vertebrae that connect with the ribs) and the lumbar level (the part of the spine found in the small of the back) spare the arms but affect both lower limbs; this is also known as paraplegia.
- Persons with injuries in the sacral part of the spinal column (the segments connected to the pelvis) usually do not have impaired movement but have problems with controlling bowel movements and urination.