Spinal Cord Injury 101
Spinal cord injury is usually the result of forceful trauma related to motor vehicle accidents, sports injuries, falls, or acts of violence. SCI is sudden and dramatic, and happens to an estimated 17,000 people a year in the United States. Most injuries occur to men (about 80 percent) and mostly to people in their 20s. In recent years higher numbers of people 60 and older are becoming spinal cord injured, the result, apparently, of more active lifestyles across the lifespan.
More than half of spinal cord injuries occur in the cervical area (neck), a third occur in the thoracic area (mid-chest), and the remainder occur mostly in the lumbar area (the lower back). Except in cases of gunshot or knife wound, the spinal cord is not usually cut, it is pinched, or bruised.
The spinal cord is an extension of the brain; it’s a thin bundle of nerve -fibers that extends from the base of the brain down to the tailbone. It is made up of long nerve fibers, some extending the length of the back, plus numerous nerve networks up and down the cord. The spinal cord coordinates movement and activity of arms and legs and torso; the cord also transmits messages for sensation, such as touch, heat, or pain.
Until the 1940s, long-term survival after SCI was very poor. People often died of infections to the urinary tract, lungs, or skin. The era of antibiotic drugs, beginning around World War II, made it possible for people living with spinal cord injury to stay healthy and to closely match life expectancy with the general public.
Spinal cord injury is much more than a single event. The initial trauma wipes out an essential population of spinal nerve cells. In the hours and days after injury, however, a new wave of events continues the damage. These events include swelling, immune response, loss of oxygen and the release of chemicals that poison surviving nerve cells. In theory, this secondary damage might be controlled, thus saving precious nerve tissue and function. Indeed, there have over the years been dozens of drugs and procedures that have been tested for this. At this time, however, there is no recommended treatment to prevent secondary spinal cord damage.
Levels of Injury
The backbone is made up of 33 vertebrae segments. In the neck, or cervical region, the segments are labeled C1 through C8, and correspond to nerves that control function in the neck, arms, hands, and diaphragm. Injuries to this area result in tetraplegia (the medical term) or quadriplegia (as it is more commonly called).
C1 – C3: A high cervical injury, such as that of the late actor Christopher Reeve (C2) affects breathing and requires mechanical ventilation.
C4 generally means loss of movement and sensation in all four extremities; C5 injuries usually spare the shoulders and biceps, but not so much the wrists or hands. C5s can handle many activities of daily living on their own, including feeding. C6 injuries have sufficient wrist control to drive an adaptive vehicle, but not much power in the hands. C7 and T1 injuries can handle most of their own self-care but hands and fingers still won’t be 100 percent.
In the thoracic, or upper back -region, T1 to T8 segments affect control of the upper torso and trunk. This is the result of abdominal muscle loss but arms and fingers are OK. Lower thoracic injuries (T9 to T12) allow better trunk control.
Lumbar, or mid-back region segments (L1 through L5) affect hips and legs. A person with an L4 injury can often extend the knees. The sacral segments (S1 through S5) in the lower back affect groin, toes, and legs.
It’s important to note that no two spinal cord injuries are exactly alike. Other than level of injury, the major factor that determines level of function and potential for recovery is how badly the spinal cord was bruised.
Just about all segments of spinal cord injury affect the legs and feet, as well as bladder, bowel and sexual function. A number of other complications may accompany SCI: low blood pressure, autonomic dysreflexia (for injuries above T6), spasticity, and chronic pain. Then there are the secondary issues related to paralysis: pressure ulcers, respiratory issues, urinary tract infections, pain, and depression.
Complete vs. Incomplete
There are several tests doctors use to measure level of injury and -degree of paralysis. The most common is the American Spinal Injury Association (ASIA) Impairment Score (AIS), which assigns a letter grade to general levels.
ASIA A means no motor or sensory function is detected below the level of injury.
ASIA B means there is some sensory function, no motor function.
ASIA C indicates some motor function and some sensory function have been preserved.
ASIA D means more than half of muscle and sensory function remains.
ASIA E is normal.
One of the key aspects of the AISA score is completeness vs. incompleteness. In simple terms, a person with an incomplete injury has some ability to move muscles, or to feel touch or pinprick below the level of injury. That means there is spared sensory or motor function below the level of injury.
It is true in most cases of SCI that people improve beyond their initial diagnosis. Many people get quite a bit better over the first few months but generally, improvement plateaus after six months to a year. The important thing about complete vs. incomplete is that historically, incomplete patients stand a better chance of recovering some degree of function than those labeled complete.
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