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Every year, 1.4 million people are treated in U.S. emergency departments for traumatic brain injury. In the military, 15 to 25 percent of all injuries sustained in 20th century conflicts were to the head.1,2
Traditionally, evaluation of traumatic brain injury (TBI) begins by history from the patient, family or emergency medical services personnel about mechanism of injury and loss of consciousness. This is followed by a physical examination and thorough neurological examination (including the Glascow Coma Scale [GCS] Score). Neuroimaging techniques such as computed tomography (CT scanning) and magnetic resonance Imaging (MRI) may also be necessary.
 "The severity of TBI can be difficult to determine during the first hours after injury because neurological examinations have restricted value," says Linda Papa, MD, MSc, director of Academic Clinical Research, Orlando Health, Graduate Medical Education, attending emergency physician, Orlando Regional Medical Center, Orlando, FL. The exam can be influenced by intoxication from drugs or alcohol and sedative medications. Neuroimaging techniques are used to provide objective information; however, CT scanning has low sensitivity to diffuse brain damage, and the availability and utility of MRI acutely is limited.
But now there is a blood test for traumatic brain injury that shows potential for reducing CT scans in emergency departments. A study3 showed that patients with traumatic brain injuries had significantly higher blood levels of glial fibrillary acidic protein (GFAP) than patients without such injuries. This is a promising first step in reducing the number of CT scans performed in emergency departments.
"This test has the potential for determining injury severity soon after injury, helping emergency physicians make decisions about performing CT scans, seeking neurological consultations and transferring patients to other facilities," says lead study author Dr. Papa. "We can now perform blood tests for heart attack, and hope to be able to do the same for traumatic brain injury. While it is not a substitute for all CT scans, it could possibly rule out patients who do not need them, as well as ensure that patients at risk get the CT scans they need."
Details
The potential blood test detects a serum biomarker for TBI. Samples are transported to a central laboratory and are analyzed in batches using a sandwich enzyme-linked immunosorbent assay. Assay results are sent after the lab has received a given quota. Therefore, patient management is not altered by the test. Turnaround time is expected to be about same timeframe as a complete blood count or basic metabolic panel. The development of both a point-of-care and core lab test is in the works.
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Benefits
Ultimately, the potential test provides an objective marker to enhance current clinical evaluation, even in patients with mild TBI. Such acute elevations of this biomarker could make it a potentially useful clinical tool for determining injury severity very early in the course after injury. Potential applications could include influencing the decision to image patients who are intoxicated or sedated, determining the degree of brain injury in a multiple trauma victim and making transport decisions regarding transfer to a neurosurgical facility.
The test would provide a non-invasive method of detecting TBI. Repeated tests could be performed without risk of radiation exposure. Biomarkers could provide additional information about prognosis and could be added to guidelines for return to duty, work or sports activities. The test would also allow for enhanced triaging of patients based on serum levels.
Looking Ahead
"The GFAP blood test seems to have greater specificity than other blood tests that have been studied for their predictive value in TBI," Dr. Papa says. "Ultimately, our goal is to ensure that all patients get the most accurate screening possible in the least invasive way possible. Further tests are needed to validate our findings."
Once the data is collected to demonstrate the safety and efficacy of use of this marker, the test should be immediately available, says Salvatore Silvestri, MD, FACEP, program director, Emergency Medicine Residency, Orlando Regional Medical Center, associate EMS medical director, Orlando, FL, who worked on Dr. Papa's study. Dr. Papa believes this could occur within five years.
"The availability of a serum biomarker for decision making in TBI patients is a practice changing event," Dr. Silvestri says. "It is wonderful to be on the ground floor of this tremendous project."
Karen Appold is a medical freelance writer. Visit www.WriteNowServices.com.
References
1. Faul M, Xu L, Wald MM, et al. Traumatic Brain Injury in the United States. Emergency Department Visits, Hospitalizations and Deaths 2002-2006. Atlanta, GA: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention; 2010. Available at: http://www.cdc.gov/traumaticbraininjury/pdf/blue_book.pdf.
2. Okie S. Traumatic brain injury in the war zone. N Engl J Med. May 19 2005;352(20):2043-2047.
3. "Elevated Levels of Serum Glial Fibrillary Acidic Protein Breakdown Products in Mild and Moderate Traumatic Brain Injury Are Associated with Intracranial Lesions and Neurosurgical Intervention." Annals of Emergency Medicine.
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