Spinal cord injuries: types and causes

Your spinal cord is 15 to 17 inches long. It starts at the base of the brain, and runs to your waist. It consists of long nerve fibers that carry information to and from the brain. The cord runs down through in the vertebrae like a string running through a stack of spools. The 33 vertebrae, the bones of the spinal column, surround the cord and protect it.

Injuries to the spinal cord are termed either partial or total, referring to the degree of damage to the cord, and its ability to transmit nerve impulses. Total injuries, in which the cord is entirely severed or otherwise so damaged that no nerve transmissions can move past the site of the injury, are relatively rare. Most injuries to the spinal cord are partial, in which the cord is damaged, but some degree of nerve transmission remains, leaving the person with some sensation or capacity for movement below the site of the injury to the cord.

Most injuries to the spinal column and cord result from trauma, some form of assault to the spine that fractures, crushes, compresses or dislocates one or more of your vertebrae. Damage occurs immediately, and is then usually compounded in the next days or weeks because of inflammation, bleeding, swelling and fluid accumulation that accompany the injury and create more pressure on the spinal cord.

More than 85% of new spinal cord injuries in the United States each year result from three kinds of trauma:

Motor vehicle crashes

Car, truck, motorcycle, and off-road vehicle injuries account for 42% of spinal cord injuries, about 6000 every year.

Interpersonal violence

About 15 percent of spinal cord injuries result from violent encounters, such as gunshot and knife wounds and brute force assaults.

Falls

Approximately 27 % of spinal cord injuries are caused by a fall. Among people over 65, falls are the major cause of spinal cord injuries.

Sports and recreation injuries

Contact sports, diving in shallow water, and other athletic activities account for 8% of spinal cord injuries. Sports with high risk of SCI include football, gymnastics, surfing, rugby, downhill skiing, diving, ice hockey and wrestling.

Non-traumatic injuries

Some spinal cord injuries are non-traumatic, in which the damage is slower-acting and cumulative, but the end result is the same. SCI can result from arthritis, cancer, other tumors, blood vessel problems or bleeding, spinal inflammation or infections. Degenerative disease of the intervertebral discs, the pads of tissue that separate and cushion the vertebrae can also cause pressure on the spinal cord severe enough to cause injury.

Who is at risk for SCI?

Although an unexpected trauma like a motor vehicle collision can happen to anyone, the numbers for SCI are skewed toward men. About 80% of spinal cord injury victims are men. The age group most at risk is young adults, ages 16-30. Participation in the high risk sports named above increases risk.

The other group at risk is people over 65, for whom falls are the most frequent cause of spinal injury. People with predisposing conditions such as arthritis and osteoporosis can develop a spinal column injury from a relatively minor injury.

Location of a Spinal Cord Injury and Affected Voluntary Muscles

This chart shows the Spinal Cord Level and the voluntary muscle functions associated with the vertebrae.