Unit #

Topics Covered

About SCI
Secondary Damage
Applied Regeneration
Current Interventions

Spinal Cord Injury (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, gunshot, falls, 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 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 after the bones are stabilized (Spinal Cord Injury resource center, 2006).

The effects of SCI depend on the type of injury and the level of the injury. SCI can be divided into two types of injury - complete and incomplete. A complete injury means that there is no function below the level of the injury; no sensation and no voluntary movement. Both sides of the body are equally affected. An incomplete injury means that there is some functioning below the primary level of the injury. 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.
Cervical (neck) injuries usually result in quadriplegia. spinal map

Injuries above the C-4 level may require a ventilator for the person to breathe. C-5 injuries often result in shoulder and biceps control, but no control at the wrist or hand. C-6 injuries generally yield wrist control, but no hand function. Individuals with C-7 and T-1 injuries can straighten their arms but still may have dexterity problems with the hand and fingers. Injuries at the thoracic level and below result in paraplegia, with the hands not affected. At T-1 to T-8 there is most often control of the hands, but poor trunk control as the result of lack of abdominal muscle control. Lower T-injuries (T-9 to T-12) allow good truck control and good abdominal muscle control. Sitting balance is very good. Lumbar and Sacral injuries yield decreasing control of the hip flexors and legs.
Besides a loss of sensation or motor functioning, individuals with SCI also experience other changes. For example, they may experience dysfunction of the bowel and bladder,. Sexual functioning in men may affect their fertility resulting in a low sperm count, while women's fertility is generally not affected. Very high injuries (C-1, C-2) 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 (Spinal cord injury resource center, 2006).

Approximately 450,000 people live with SCI in the US. There are about 10,000 new SCI's every year; the majority of them (82%) involve males between the ages of 16-30. These injuries result from motor vehicle accidents (36%), violence (28.9%), or falls (21.2%).Quadriplegia is slightly more common than paraplegia (Spinal cord injury resource center, 2006).

Complications following a SCI
Secondary complications can develop following a spinal cord injury and necessary steps should be taken to prevent these complications. Following is a list of possible complications, please be sure and read all the material on each of the websites to get a clear understanding of the complications that can arise following a SCI.

Researchers studying spinal cords obtained from autopsy have identified several different types of spinal cord injuries. The most common types of spinal cord injuries found in one large study were contusions (bruising of the spinal cord) and compression injuries (caused by pressure on the spinal cord). Other types of injury included lacerations, caused by a bullet or other object, and central cord syndrome.

In contusion injuries, a cavity, or hole, often forms in the center of the spinal cord. Myelinated axons typically survive in a ring along the inside edge of the cord. Some axons may survive in the center cavity, but they usually lose their myelin covering. This demyelination greatly slows the speed of nerve transmission. Slowing of nerve impulses can be measured by a diagnostic technique called transcranial magnetic stimulation (TMS).

Another example of a spinal cord injury is central cord syndrome, which affects the cervical (neck) region of the cord and results from focused damage to a group of nerve fibers called the corticospinal tract. The corticospinal tract controls movement by carrying signals between the brain and the spinal cord. Patients with central cord syndrome typically have relatively mild impairment, and they often spontaneously recover many of their abilities. Patients usually recover substantially by 6 weeks after injury, despite continued loss of axons and myelin. Delays in motor responses persist, but permanent impairment is usually confined to the hands.

Complete severing of the spinal cord is rare in humans, but even axons that survive the initial injury often lose their ability to function. Secondary damage, which continues for hours, can cause loss of myelin, degeneration of axons, and nerve cell death. Patients with their spinal cords completely severed often show abnormal reflexes that emerge more than 8 months after injury. These reflexes, such as twitching of muscles in the arm and hand in response to sensory stimulation of the legs and feet, may result from "sprouting" of new branches from sensory fibers just below the lesion. They may also result from activation of nerve pathways that are normally suppressed. Other abnormal responses, such as sweating in response to movement of a hair, may be due to sprouting of nerves in the autonomic nervous system. The autonomic nervous system is the part of the PNS that controls involuntary body functions such as sweating and heart rate.

Article pertaining to damage and recovery

SECONDARY DAMAGE

1. Immune System Reactions

2. Calcium and Excitotoxicity

3. Necrosis and Apoptosis

4. Axon Damage

APPLIED REGENERATION

A combination of therapeutic approaches are being applied in order to facilitate regeneration following a spinal cord injury. The following links will provide you with information that will further your understanding about the possibilities of recovery following a SCI.

1. Transplantation

2. Trophic Factors

3. Combination Factors

CURRENT INTERVENTIONS

1. Drug therapy

2. Neural prostheses

3. Rehabilitation