What is spinal cord injury (SCI)?
Spinal cord injury is damage to the spinal cord that results in a loss of function such as mobility or feeling. Frequent causes of damage are trauma (e.g. car accident, falls or diving) or disease (e.g. polio, spina bifida or Friedreich's Ataxia).
- Quadriplegia (also known as tetraplagia) is loss of function below the neck.
- Paraplegia is loss of function below the chest.
The spinal cord does not have to be severed in order for a loss of functioning to occur. In fact, in most people with spinal cord injury, the spinal cord is intact, but the damage due to compression or bruising to it results in loss of functioning. Spinal cord injury 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 if bone damage is treated correctly.
What is the spinal cord and the vertabrae?
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 carry messages 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 initiate 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 or tetraplegia).
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 nerves in the lumbar and sacral vertebrae generally results 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 spinal cord injury? What is the ASIA Impairment Scale?
The effects of spinal cord injury depend on the type and level of the injury.
Spinal cord injury is commonly referred to as either complete or incomplete. In a complete spinal cord injury there are no signals below the point of injury between the brain and the body— no sensation and no voluntary movement. 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 spinal cord injury, 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. There is a wide range of variation.
The degree of function after injury is measured according to the five-level ASIA Impairment Scale. They are:
- A - Complete: No motor or sensory function in the lowest sacral segment (S4-S5).
- B - Incomplete: Sensory function below neurologic level and in S4-S5, no motor function below neurologic level.
- C - Incomplete: Motor function is preserved below neurologic level and more than half of the key muscle groups below neurologic level have a muscle grade less than 3.
- D - Incomplete: Motor function is preserved below neurologic level and at least half of the key muscle groups below neurologic level have a muscle grade 3.
- E - Normal: Sensory and motor function is normal
Read more about the ASIA Scale.
A person with a spinal cord injury above C4 may require a ventilator to breathe. A 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, spinal cord injury produces other changes. There can be bowel and bladder dysfunction. Sexual functioning is also frequently affected. 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 spinal cord injury 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.
After spinal cord injury how much function can be restored?
At the time of injury, the spinal cord swells. As this swelling reduces, some function may return. This can take up to 18 months after the injury. However, only a very small fraction of people with a spinal cord injury recover all function.
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 a spinal cord injury 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 stop neurons from regrowing themselves, inserting new cells and bypassing the damaged area.
Intensive Activity Based exercise programs can assist in the improvement of independent functional abilities. Intensive exercise programs can:
- Increase muscle mass
- Increase muscle activity
- Increase blood circulation
- Improve sensation
- Prevent a decrease in bone mineral density
- Improve quality of life
- Increase independence in activities of daily living and occupational activities
- Decrease skin tissue breakdown and other health problems associated with spinal cord injury
Does everyone with a spinal cord injury use a wheelchair?
People with high injuries usually need a power wheelchair for independent mobility. People with low C spinal cord injuries and below may be able to use manual wheelchairs.
Manual chairs are more convenient as they cost and weigh less and are easy to fold for transport. However the independence provided by a power chair to the person who needs it outweighs any limitations.
Some people walk using crutches and leg braces. This does not mean they will never use a wheelchair, perhaps preferring them only for longer distances.
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