Spine, cord, injury

What is spinal cord injury (SCI)?

SCI is damage to the spinal cord that results in a loss of function such as mobility or feeling. Frequent causes of damage are trauma (car accident, falls, diving etc.) or disease (polio, spina bifida, Friedreich's Ataxia etc.).

The spinal cord does not have to be severed in order for a loss of functioning to occur. In fact, in most people with SCI, the spinal cord is intact, but the damage due to compression or bruising to it results in loss of functioning. SCI is very different from back injuries such as ruptured disks, spinal stenosis or pinched nerves.

A person can "break their back or neck" yet not sustain a spinal cord injury if only the bones around the spinal cord (the vertebrae) are damaged, but the spinal cord is not affected. In these situations, the individual may not experience paralysis once the bones are stabilised.

What are the spinal cord and the vertebrae?

The adult spinal cord is about 50 centimetres long and extends from the base of the brain to about the waist. It is the major bundle of nerves that Vertebra cross sectioncarry nerve impulses between the brain and the rest of the body. Nerves within the spinal cord (upper motor neurons) carry messages back and forth from the brain to the spinal nerves along the spinal tract. Lower motor neurons branch out from the spinal cord to the other parts of the body, carrying sensations (from the skin and other body parts and organs to the brain) and instructions (to the various body parts to Digaram of vertebrainitiate actions such as muscle movement).

Injury to the spinal cord causes loss of function of the nerves, limbs and organs below the site of the injury.

The spinal cord lies within vertebrae. These rings of bones are together called the spinal column or back bone. In general, the higher in the spinal column an injury occurs, the more dysfunction a person will experience. There are seven vertebrae in the neck—the Cervical Vertebrae—C1 (at the top) to C7. Injury in this region usually causes loss of function to the arms and legs (quadriplegia).

There are twelve Thoracic Vertebrae. The highest (T1) is where the top rib attaches. Injury to the thoracic region affects the chest and the legs.

Between the thoracic vertebrae and the pelvis lie the 5 Lumbar Vertebrae. The 5 Sacral Vertebrae run from the pelvis to the end of the spinal column. Injury to the lumbar and sacral vertebrae generally result in loss of functioning in the hips and legs.

Loss of function in the chest, hips and legs is Paraplegia.

What are the effects of SCI?

The effects of SCI depend on the type and level of the injury.

Vertebra diagramThere are two types of injury - complete and incomplete. A complete SCI is one that at the point of injury has totally cut the passage of signals between the brain and the body. There is no function below the level of the Spinal columninjury - no sensation and no voluntary movement. Both sides of the body are equally affected. 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. With the advances in acute treatment of SCI, incomplete injuries are becoming more common.

The level of injury is very helpful in predicting what parts of the body might be affected by paralysis and loss of function. Remember that in incomplete injuries there will be some variation in these prognoses.

A person with an SCI above C4 may require a ventilator to breathe. C5 injury often leaves shoulder and biceps control, but no control at the wrist or hand. C6 injury leaves control of the wrist, but not the hand. C7 and T1 injuries leave the ability to straighten the arms, but have only limited hand and finger dexterity.

Injuries below T1 result in paraplegia. At T1 to T8 there is most often control of the hands, but lack of abdominal muscle control leaves poor trunk control. Lower T injuries leave good control of the trunk and abdominal muscles. Injuries at the Lumbar and Sacral vertebra reduce control of the hip flexors and legs.

Besides a loss of sensation or motor functioning, SCI produces other changes. There can be bowel and bladder dysfunction. Sexual functioning is also frequently affected by SCI. Men may have their fertility affected, while women's fertility is generally not affected. Very high injuries (C1, C2) can result in a loss of many involuntary functions including the ability to breathe, necessitating breathing aids such as mechanical ventilators or diaphragmatic pacemakers. Other effects of SCI may include low blood pressure, inability to regulate blood pressure effectively, reduced control of body temperature, inability to sweat below the level of injury, and chronic pain.

Do people with SCI ever get better?

At the time of injury, the spinal cord swells. When the swelling goes down, some functioning may return. Especially in incomplete injuries, functioning may return as late as 18 months after the injury. However, only a very small fraction of people with SCIs recover all functioning.

Is there a cure?

Most body parts and organs can repair themselves after they are injured. However the central nervous system cannot. Attempting to repair the damage caused by a brain or spinal cord injury is a puzzle that has not yet been solved.

Nevertheless the damage caused by an SCI can be reduced by limiting immediate cell death and reducing the inflammation of the injured cord.

Attempts to regenerate function in the damaged area are focusing on regrowing nerves, blocking the mechanism that stops neurons from regrowing themselves, inserting new cells and bypassing the damaged area.

Information on these strategies is available @ www.christopherreeve.org. See also Making Connections.

What is life expectancy after SCI?

Before World War II, most people who sustained SCI died within weeks of their injury due to urinary dysfunction, respiratory infection or bedsores. However modern antibiotics and materials such as plastics and latex, and better procedures for dealing with the everyday issues of living with SCI, mean many people approach the lifespan of the general population. Most who survive the first 24 hours are still alive 10 years later.