Clinical Trials within U.S.: Traumatic Brain Injury

TRAUMATIC BRAIN INJURY refers to bram damage caused by an external mechanical force. It is a relatively common event, with 1.5 million people in the United States incurring some sort of head trauma annually. Fortunately, 75 percent of the cases turn out to be mild, with little or no consequences. However, survivors in the remaining 25 percent suffer from moderate to severe functional deficits, which greatly decrease quality of life as well as life expectancy. Although there has been much work dedicated to helping patients with this condition, the complexity of the brain has rendered it extremely difficult to develop a successful regenerative or restorative treatment. Despite over a decade of stem cell research, it is [Page 134]only just recently that the first clinical trial in the United States was approved by the U.S. Food and Drug Administration for using stem cells to treat brain injuries.

The full extent of damage from a traumatic brain injury arises from the combination of multiple processes. Obviously, destruction would be incurred by direct external force. “Contrecoup” injuries, in which a moving brain is slammed into the skull opposing the impact side (e.g., in a car accident), are also direct causes of cerebral wounding. However, following that, the injured organ and surrounding tissues undergo subsequent waves of damage caused by secondary structural, biochemical, and inflammatory mechanisms. Pressure within the brain increases (generally as a result of fluid accumulation, be it blood or invasion of inflammatory components), neurotransmitters are inappropriately released in toxic quantities, or integrity of vasculature is lost. The end result is the death of other neurons not initially involved with the original injury.

Because of how the brain is organized, injuries to the organ can give rise to drastically different clinical manifestations, based on location and severity of the lesion. For survivors, injuries are classified according to the Glasgow Coma Scale as “mild,” “moderate,” or “severe,” based on eye, verbal, and motor abilities. Although 75 percent of cases are mild, approximately 50,000 people die per year (about half of all traumatic deaths) because of severe head trauma.

In terms of treatment for individuals with head injuries, acute care is limited to minimizing the secondary wave of damage. The most important part of this care is reducing intracranial pressure and maintaining adequate blood perfusion through the use of pharmacologie or surgical interventions. Poststabilization, supportive management of symptoms, physical therapy, and cognitive therapy make up the basis of chronic care because no restorative treatments exist as of yet.