The gold standard for diagnosing a concussion is a CT scan of the head. This is expensive and adds to lifetime radiation exposure, which could have adverse effects later in life. A new blood test looks for blood biomarkers that could determine whether or not someone has sustained a concussion.
More than 50 million people around the world suffer from traumatic brain injury (TBI) every year. Mild TBIs are called concussions, and they result in more than 2.5 million emergency visits and 20 million CT scans annually. Patients with possible concussions usually have recent head trauma, and may have symptoms such as headache, nausea, dizziness, confusion and changes in sleep. Symptoms may appear immediately, or be delayed for hours or days after an injury. Concussion symptoms typically ease within 72 hours and most resolve within 10 days, but some cases can persist.
Because of the cost and limitations of CT scans, researchers have long been searching for biomarkers that could indicate the presence or absence of a concussion. Many molecules have been examined and a protein called S100B has been studied the most. Although some have recommended using S100B as a biomarker for more serious TBIs that could be detected on CT, the evidence for its use in concussions is not as well established. For patients with concussions, two other proteins have been identified that could serve as biomarkers: ubiquitin C-terminal hydrolase-L1 (UCH-L1) and glial fibrillary acidic protein (GFAP).
Between 2012 and 2014, nearly 2,000 participants who sustained a TBI were enrolled in a study to measure their levels of UCH-L1 and GFAP after sustaining a suspected TBI. The study involved blood tests in addition to conventional TBI care, including CT scans. Blood samples were sent to three different labs whose personnel didn’t know the patient’s status. The treating physicians weren’t told of their blood test results. Patient CT scans were analyzed by two separate neuroradiologists who weren’t part of the testing sites and were also not aware of the blood test results. If both radiologists didn’t agree, a third radiologist reviewed the CT scans. The third radiologist was necessary in only 3 percent of the scans. CT scans were positive for TBI if they fulfilled defined criteria, for example, if there was any evidence of bleeding in the brain or skull fractures. The severity of the TBI was determined based on each CT scan.
The results of this study showed that all patients who had CT scans positive for a TBI had elevated levels of both UCH-L1 and GFAP. The blood test accurately predicted the presence of a TBI 95 percent of the time. The U.S. Food and Drug Administration approved the test for commercial use in 2018. Now physicians have another tool to determine if a patient has experienced a TBI that warrants a CT scan. The blood test can also produce a faster diagnosis, even before all the symptoms appear. This test would also reduce the number of unnecessary, expensive CT scans and the radiation exposure patients receive.