Excerpts from “Spinal Cord Injury: Emerging Concepts” from the National Institute of Neurological Disorders and Stroke.
Among the most exciting frontiers in medicine is the repair of traumatic injuries to the central nervous system (CNS), including the spinal cord. Improvements in treatment are helping many more people survive spinal cord injury, and the time survivors must spend in the hospital is half what it was 20 years ago. Yet most spinal cord injuries still cause lifelong disability, and further research is critically needed.
The normal spinal cord coordinates movement and sensation in the body. It is a complex organ containing nerve cells, supporting cells, segments, with higher segments controlling movement and sensation in upper parts of the body and lower segments controlling the lower parts of the body.
The types of disability associated with spinal cord injury vary greatly depending on the type of severity of the injury, the level of the cord at which the injury occurs, and the nerve fiber pathways that are damaged. Severe injury to the spinal cord causes paralysis and complete loss of sensation to the parts of the body controlled by the spinal cord segments below the point of injury. Spinal cord injuries also can lead to many complications, including pressure sores and increased susceptibility to respiratory diseases.
Clinical management of spinal cord injury has advanced greatly in the last 50 years. Recent advances include improved imaging of damage to the spinal cord and vertebrae and development of the first effective drug therapy for use in the hours just after injury. Once a patient is stabilized, supportive care and rehabilitation strategies promote long-term recovery.
Spinal cord injury research has now come of age. Because of general progress in neuroscience, as well as specific advances in spinal cord injury research, researchers can now test new ideas about how changes in molecules, cells, and their complex interactions in the living body determine the outcome of spinal cord injury. One of the most exciting messages from the workshop was the confirmation that findings from other fields, such as development, immunology and stroke research, can be applied to the study of spinal cord injury.
The functions of an undamaged spinal cord (return to top)
The spinal cord and the brain together make up the central nervous system (CNS). The spinal cord coordinates the body’s movement and sensation. Unlike nerve cells of the peripheral nervous system (PNS), which carry signals to the limbs, torso, and other parts of the body, neurons of the CNS do not regenerate after injury.
The spinal cord includes nerve cells, or neurons, and long nerve fibers called axons. Axons in the spinal cord carry messages to and from the brain. The spinal cord is organized into segments along its length. Nerves from each segment connect to specific regions of the body. The segments in the neck, or cervical region, control signals to the neck, arms and hands. Those in the upper back or thoracic region relay signals to the torso and some parts of the arms. Those in the upper lumbar or mid-back region just below the ribs control signals to the hips and legs. Finally, the sacral segments control signals to the groin, toes and some parts of the legs. The effects of spinal cord injury at different segments reflect this organization.
Changes to the spinal cord after injury (return to top)
The types of disability associated with spinal cord injury vary greatly depending on the severity of the injury, the segment of the spinal cord at which the injury occurs and which nerve fibers are damaged. In spinal cord injury, the destruction of nerve fibers that carry motor signals from the brain to the torso and limbs leads to muscle paralysis. Destruction of sensory nerve fibers can lead to loss of sensations such as touch, pressure and temperature; it sometimes also causes pain. Other serious consequences can include exaggerated reflexes, loss of bladder and bowel control, lost or decreased breathing capacity, impaired cough reflexes and spasticity (abnormally strong muscle contractions).
Since even a small number of nerve fibers can support significant nervous system function, measures that reduce damage could allow much greater function than would otherwise be expected. Devising interventions that will achieve this goal is one of the major challenges in spinal cord injury research today.
Facts (return to top)
- There are about 1,000,000 people in the world with spinal cord injuries (250,000 in the United States). Of these, thousands are war veterans, and over 5,000 are Indiana Hoosiers.
- Each year, over 10,000 new spinal cord injuries occur in the United States. The most common cause of new injuries (36%) are from motor vehicle accidents, and the second largest contributor (29%) are from acts of violence (gunshots and stabbings). The average age at the time of injury is 33.4 years old.
- The average length of hospital stay for a spinal cord injury is 79 days. The average cost for this hospital stay is over $200,000. The ongoing medical costs to maintain a spinal cord injured person is $134,000 per year. Costing about $5 million dollars over their lifetime.
- Fifty-six percent of people with a spinal cord injury are covered by Medicare or Medicaid. This costs taxpayers over $12 billion a year in medical costs alone.
- Most of the money raised for spinal cord injury research comes from private organizations like the Emily Hunt Foundation.
- Within the past two years, several major breakthroughs in spinal cord injury research have discovered a potential solution to permanent paralysis from a spinal cord injury. Research groups estimate with proper funding, a treatment will be developed in the next 5 to 10 years.
- Spinal cord injury primarily affects young adults. Fifty-five percent of spinal cord injuries occur among persons in the 16 to 30 year age group.
- Life expectancy for a spinal cord injured person is the average remaining years of life for an individual. Life expectancies for persons with spinal cord injury continue to increase, but are still somewhat below life expectancies for those with no spinal cord injury. Mortality rates are significantly higher during the first year after injury than during subsequent years, particularly for severely injured persons.
- If every spinal cord injured person in the US would help raise $100 per year, all of the current research facilities would be fully funded.
Facts drawn from the Spinal Cord Injury Information Network, May 2001 (www.spinalcord.uab.edu)
Current News in SCI and progress
In January 2000, scientists at Yale University found the human gene that emits a protein, which stops spinal nerves from regenerating. This is significant because three years ago scientists found a similar gene in laboratory mice, and created a drug that neutralizes the protein when spinal nerves are damaged. Now researchers are confident that they will be able to create a drug that neutralizes the effects of the protein. This creates a fertile environment for nerve cell growth. The strategy is now clear. First, stop the damage created by the gene protein found naturally in our bodies, then create a fertile environment where stem like cells will flourish and cause the nerves to regenerate.
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