Monday, August 23, 2004
New Study Reveals That Mild Head Injury Has Major Consequences on Brain Metabolism
Date: May 22, 2000
Contact: Roxanne Moster ( ([email protected]) )
Phone: (310) 794-2264
A new Positron Emission Tomography (PET) study of the brain provides the first tangible evidence that what many doctors traditionally diagnose as mild head injury - or concussion - may not be so mild after all, according to UCLA research.
UCLA researchers report in the May issue of the Journal of Neurotrauma that no matter what range of brain injury a person sustains - from a concussion to severe head trauma - the human brain goes into a prolonged altered metabolic state.
What does this mean for a tackled football player with a mild concussion, a child who has fallen and hit his head while skating or a passenger who has sustained a mild head injury from a car accident?
"This new evidence challenges the conventional neurological wisdom regarding cerebral concussion. Even though a person may appear normal, alert and able to talk, what occurs inside the person's brain is anything but normal," said researcher David Hovda, director of the UCLA Brain Injury Research Center and the study's senior author. "PET scan evidence will change the way brain-injured patients are currently diagnosed and managed."
When a mild concussion occurs, most physicians assess recovery based on the subject's ability to answer simple questions. MRI and CT scans, which display structure of the brain, are usually completely normal after a concussion. A PET scan, which instead reveals how the brain is functioning, can be very abnormal. In this study, the PET scans showed how much glucose (a fuel for brain cells) the brain utilized.
The researchers studied 42 patients within 30 days of sustained head injuries by using PET. The study compared post-traumatic levels of brain glucose utilization with the level of consciousness at the time of the PET study. Researchers found, surprisingly, that glucose metabolism in severely brain-injured coma patients resembled that of patients who suffered only mild concussions. In normal healthy persons, the quantity of glucose that the brain uses is closely tied to the level of brain activity. The brain of a patient who loses consciousness under anesthesia, for instance, uses only half the amount of glucose compared to the brain of a person who is fully awake.
"We were shocked to learn that the brain of a head-injured patient who walked up to the PET scanner could use the same amount of glucose as a deeply comatose patient wheeled in on a gurney," said UCLA neurosurgeon Marvin Bergsneider, the study's principal author. Interestingly, the reduced brain metabolism may continue for days to weeks after the injury.
Although this study did not look at the significance of reduced metabolism following head injury in humans, other research at UCLA's Brain Injury Research laboratory suggests that reduced brain metabolism may indicate a state of increased vulnerability to further injury.
"A second concussion too soon after the first can have devastating consequences to brain cells. Sending a football quarterback who got knocked unconscious back into the same game may be playing Russian roulette," said Bergsneider.
The UCLA findings add new insight into the physiology of concussion and mild head injury. "Although the reduction of glucose likely has one or more origins, the level of consciousness appears to have little influence among brain-injured patients early after injury," said Hovda.
Future studies will be required to further characterize and understand post-traumatic glucose reduction so that doctors can improve patient management and recovery from traumatic brain injury.
In addition to Bergsneider and Hovda, the following UCLA researchers contributed to the study: Stefan M. Lee, Ph.D.; Dr. Daniel F. Kelly; David L. McArthur, Ph.D.; Dr. Paul M. Vespa; Dr. Jae Hong Lee; Sung-Cheng Huang, D.Sc.; Dr. Neil Martin; Michael E. Phelps, Ph.D.; and Dr. Donald Becker.
Support for the study was funded by the National Institute of Neurological Disorders and Stroke, the Lind Lawrence Foundation, the MacDonald Family Foundation and the Rathman Foundation.
For more information on the UCLA Brain Injury Research Center, log on to (www.neurosurgery.medsch.ucla.edu).