What is spinal cord injury?

Spinal cord injury is damage to the spinal cord as a result of a direct trauma to the spinal cord itself or as a result of indirect damage to the bones, soft tissues, and vessels surrounding the spinal cord. The spinal cord is the major bundle of nerves carrying nerve impulses to and from the brain to the rest of the body. Rings of bone called vertebrae surround the spinal cord. These bones constitute the spinal column (back bones).

Spinal cord damage results in a loss of function, such as mobility or feeling. In most people who have spinal cord injury, the spinal cord is not severed. Spinal cord injury is not the same as back injury, which might result from causes such as pinched nerves or ruptured disks. Even when a person sustains a break in a vertebra or vertebrae, there might not be any spinal cord injury if the spinal cord itself is not affected.

What happens in a spinal cord injury?

There are two kinds of spinal cord injury -- complete and incomplete. In a complete injury, there is no function below the level of the injury. There is no sensation or voluntary movement. In an incomplete injury, there is some functioning below the level of the injury.

How common is spinal cord injury?

Spinal cord injury occurs in various countries throughout the world with an annual incidence of 15 to 40 cases per million. For some of these people, the injury is the result of a disease, such as polio or spina bifida. However, for most, the spinal cord injury is the result of trauma. The leading traumatic cause of spinal cord injuries is automobile accidents, causing 44% of all injuries. Other causes of spinal cord injuries, in descending order of frequency, include violence (gunshot wounds, for example), falls, and sports. While sports only account for 8% of all spinal cord injuries, 60% of those sports-related injuries are a result of diving accidents. For spinal cord injuries occurring over age 45, falls overtake automobile accidents as the number one cause.

Males account for over 80% of patients with spinal cord injuries. The average patient age is 33, but the most frequent age of injury is 19.

What causes spinal cord injury?

Spinal cord injuries might result from falls, diseases such as polio or spina bifida (a disorder involving incomplete development of the brain, spinal cord, and/or their protective coverings), motor vehicle accidents, sports injuries, industrial accidents, and assaults, among other causes. If the spine is weak because of another condition, such as arthritis, apparently minor injuries can cause spinal cord trauma.

Partial and complete spinal cord injuries

There are two types of spinal cord injuries: complete and partial. If a spinal cord injury is complete, there is no function below the point of injury. This means the patient will experience no sensation or voluntary movement and that both sides of the body, for example have both arms, will usually be equally affected. A complete injury can result in the paralysis of all four limbs (quadriplegia) or the lower half of the body (paraplegia).

For partial injuries, a patient may be able to move one limb more than the other or be able to feel more with one side than the other. The level of incomplete injuries may vary from patient to patient, and can affect the body in different ways. For example, a C-6 injury may result in having no hand control but having wrist control. A C-5 injury may deprive a patient of wrist and hand control, but not arm and shoulder control.

Aside from having a loss of sensation and movement, patients with a spinal cord injury may also experience bladder and bowel complications. Spinal cord injuries often affect fertility in males. If the spinal cord injury is high (example, C-1 or C-2), the patient may need a respirator or diaphragmatic pacemaker to breathe properly.

Other complications that may result from a spinal cord injury are an inability to regulate blood pressure, low blood pressure, reduced control of body temperature, an inability to sweat that occurs below the level of injury, and chronic pain. Patients with spinal injuries also have an increased susceptibility to respiratory disease and autonomic dysreflexia. Autonomic dysreflexia is primarily the result of the body being unable to control the blood pressure. This is especially a concern for patients who have a spinal cord injury at T-6 or above. The signal responsible for "telling" the blood vessels to relax cannot be processed because of the injury. With autonomic dysreflexia, these blood vessels intermittently remain constricted, thus elevating the blood pressure and possibly leading to life-threatening complications such as stroke. External methods of lowering the blood pressure to a safe level are often necessary.

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