Spinal cord injury (SCI) is damage to the spinal cord, the bundle of nerves running from the base of the brain (brainstem) to the upper part of the lumbar spine. SCI disrupts communication between the brain and the rest of the body below the level of the injury, and depending on the severity resulting in the inability to move limbs, loss of sensation, bowel and bladder function. Depending on the underlying mechanism of injury, SCI can be divided into traumatic and non-traumatic causes. It can be further classified by the level of injury: tetraplegia involving all four limbs or paraplegia involving legs only; and the severity of injury: complete vs incomplete, with incomplete tetraplegia being most common.

Traumatic Spinal Cord Injury

Significant trauma to the vertebral column encasing the spinal cord can result in spinal cord injury. In a person with a vulnerable bony spine, for example someone with osteoporosis or ankylosing spondylitis, weakness in the supporting structure, such as with rheumatoid arthritis or Down's syndrome, or narrowing of the spinal canal due to spinal stenosis, a minor trauma or injury can result in spinal cord injury. The common underlying cause of injuries include motor vehicle accidents, followed by falls, violence such as gunshot wounds or assault, sports injuries, and industrial accidents. The American Spinal Injury Association (ASIA) scoring system is widely utilized by healthcare providers for further classification of SCI based on the injury level and severity.  

Non-traumatic spinal cord injury

Spinal cord injury also can be secondary to multiple sclerosis (MS), inflammatory conditions, compression by bony spurs or herniated discs, and metastatic cancer, all disrupting spinal cord function. MS is a central nervous system (brain and spinal cord) disorder that damages the myelin sheath surrounding the nerve cells and fibers, and can presents with symptoms of spinal cord dysfunction, as well as disruption of vision, speech or cognitive function. A condition known as transverse myelitis is an inflammation across both sides of one level, or segment, of the spinal cord resulting in temporary or permanent symptoms that include paralysis and loss of sensation, bowel and bladder control. The segment of the spinal cord where the damage occurs determines the parts of the body affected, much like with a traumatic SCI.