Concussion patients with a normal head CT scan may believe they are free of brain injury, but CT scans often miss damage at the molecular level, warns a University of Rochester Medical Center study.
In fact, when doctors examine the nerve cells of concussion patients the pattern of brain injury is identical for mild and severe concussions, said lead author Jeffrey J. Bazarian, M.D., a brain injury expert and an attending physician in the Emergency Department at Strong Memorial Hospital, of the University of Rochester Medical Center.
In an article in the February Academic Emergency Medicine journal, Bazarian and colleagues said that a more accurate and rapid diagnostic test for concussion could lead to better treatment in the short term and might also prevent long-term neurological problems.
"Unfortunately, the widespread use of the CT scan as the primary tool for diagnosing head injuries has biased the way we think about concussions," Bazarian said. "For many people, a more significant axonal injury has occurred, and this underlies the problems they have with motor skills and memory, and may also be a risk factor for later development of Alzheimer's and Parkinson's diseases."
More than 1.2 million Americans seek emergency room care annually for mild head injuries. Doctors routinely use a Computed Tomography (CT) scan of the head to rule out bleeding on the brain or other symptoms of a brain injury. Many patients with a normal CT test go home. But an estimated 320,000 individuals, or one-quarter of those patients, continue to suffer from symptoms such as forgetfulness, headaches and other cognitive defects that persist beyond one year.
Bazarian and colleagues reviewed the medical literature to look for ways to improve the care of brain-injured patients. Their findings show:
n Although the CT scan is used most often in the United States to diagnose head injuries, other tests such as the Magnetic Resonance Imaging (MRI), Functional MRI, Single Photon Emission Computed Tomography (SPECT) scans or Positron Emission Tomography (PET) scans are more precise tools.
n Testing a patient's verbal skills, memory and coordination after a head injury is useful. The literature shows that athletes with head injuries consistently perform worse on tests for memory, listening skills, and reaction time, even when the concussion was mild and the CT scan was normal.
n After a blow to the head, doctors can sometimes diagnose a brain injury by detecting brain-specific proteins in the blood. Yet currently available brain biomarkers are poor predictors of patient outcome after concussion. Better blood tests are needed for use on athletic fields, in clinics, or at the scene of a mass casualty incident, the authors said.
"Among coalition forces in Iraq, where brain injury has been called the signature wound of the war, undiagnosed brain injury in combat leaders may expose them and their troops to increased risk on the battlefield," Bazarian added. "This has given the development of an accurate and portable means of diagnosing brain injury a new sense of urgency."
Co-authors on the study were Brian Blyth, M.D., and Lynn Cimpello, M.D., both Emergency Department physicians at the University of Rochester Medical Center, The National Institutes of Health and the Society for Academic Emergency Medicine funded the research.
(Note: Concussion is defined as loss of consciousness of less than 30 minutes, or as amnesia lasting less than 24 hours, or any period of altered mental status at the time of injury. Most concussions are the result of either a direct blow to the head, or rapid deceleration from a motor vehicle collision or fall.)
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