- Annually results
in over 500,000 hospitalizations.
- Costs society
an estimated $25 billion each year.
- Is the leading
cause of death and disability in children and young adults.
- Causes 75,000
to 100,000 deaths each year.
PROGRESS
IN MEDICAL RESEARCH
Each year 400,000
to 500,000 Americans are admitted to a hospital with a head
injury. Many of these injuries cause permanent, often devastating
disability: loss of memory, emotional instability, learning
problems, and epilepsy. The injured individual is often left
unable to work. As recently as the late 1970's, it was widely
believed that all damage occurred at the time of head injury
and that little could be done medically to affect outcome.
Today's brain injured patient receives immediate, aggressive
medical intervention in addition to surgery. The result is
significantly improved recovery.
How
has animal research helped people who have a head injury?
Experimental studies
of brain injury in animals made it clear that delayed brain
injury was much more significant than had been thought. Most
important, the development of delayed tissue damage could
be interrupted. Scientists identified metabolic changes, brain
swelling, and biochemical events which caused tissue damage
and loss of function. With increased understanding of pathophysiologic
mechanisms, standards of treatment changed to minimize delayed
brain injury. Clinical trials were developed based on solid
scientific hypothesis. A number of these trials are currently
underway. A recent multi-center spinal cord injury study demonstrated
improved outcome after treatment with methylprednisolone.
Previous studies were inconclusive, but animal studies pointed
the way to the higher dose required for effectiveness.
Is
animal research still needed to improve treatment?
Although medical
beliefs and treatment have been revolutionized in the last
fifteen years, much work remains. Scientists only partly understand
the physiologic mechanisms for secondary brain injury. The
relative contributions of immediate (primary) and delayed
(secondary) injury mechanisms are unclear. Research is now
beginning to consider interaction treatment strategies. Tissue
culture studies are limited to nerve cell responses, while
in human injury the vascular system and physiologic response
are critical in determining outcome. Only through carefully
controlled experimental studies including the humane use of
animal models can we continue to expand our understanding
of head injury physiology and develop improved treatment(s).
What
is the future for people with a head injury?
As experimental
scientists expand our understanding of head injury pathology
and recovery, hypotheses will be developed for science-based
clinical trials. Aggressive management of the head-injured
has already improved care and expected outcome. Multi-center
trials of specific medical interventions can be expected to
lead to further changes in patient management with improved
recovery, just as in the recent successful clinical trial
for spinal cord injury.
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