On February 14, 2018, the Food and Drug Administration (FDA) cleared the first blood test that can help healthcare practitioners assess the severity of concussions in adults. The test is only approved for use in adults, but clinical trials for evaluating head injuries in children are expected to start soon.
Concussions, also called mild traumatic brain injury (mTBI), can be caused by a bump, blow or piercing injury to the head and can result in abnormal brain function—for example, loss of consciousness, memory loss, sensitivity to noise or light, or loss of balance. Damage to the brain can range from relatively mild to more severe. The severity of a concussion is often difficult to determine because signs and symptoms can occur within hours or several days after the injury and can also vary from person to person.
People who are screened for concussions are usually first assessed using a neurological exam that evaluates factors such as headache, neck pain, dizziness, nausea and vomiting. Next, a computed tomography (CT) scan may be taken of the head to see if there is bleeding on the brain or tissue damage that would require treatment or intervention, such as surgery. Most people who receive CT scans have no detectible bleeding or damage.
The newly approved blood test, called the Brain Trauma Indicator (BTI), helps determine whether a CT scan is needed in people with suspected concussion. The test measures two brain-specific proteins, ubiquitin C-terminal hydrolase (UCH-L1) and glial fibrillary acidic protein (GFAP), that are rapidly released by the brain into the blood within 12 hours of serious brain injury. Test results can be available within three to four hours. Low blood levels of these proteins indicate that, if the person has damage, it is likely too small to be seen on a CT scan. If these protein levels are high, healthcare practitioners could rule out mild concussion and order a CT scan to look for bleeding and damage that would require intervention.
BTI developers say that use of their blood test could improve the accuracy of distinguishing between mild concussions and more serious brain injury in adults. They also say BTI could reduce the number of unnecessary CT scans by 33% in people suspected of having brain injury. CT scans can be expensive and time-consuming, and unnecessary scans expose patients to potentially harmful radiation.
The FDA evaluated data and product performance from a study of 1,947 blood samples from adults suspected of having a concussion. When compared to CT scan results, the FDA found that BTI correctly identified the presence of damaged brain tissue in 97.5% of the individuals and correctly identified the absence of damage in 99.6% individuals. The FDA's review and approval of BTI took fewer than six months because it was part of the administration's Breakthrough Devices Program.
BTI is only approved for use in adults, but plans are in the works to start a clinical trial to evaluate its use in children. Developers of the test are also working on a smaller, hand-held testing device that would be of interest to healthcare practitioners working in sports medicine, low-resource settings, or military installations.
Some experts caution that head injuries can be complicated, and BTI does not replace CT scans in all cases. Also, CT scans, which were used to evaluate the effectiveness of BTI, do not detect all severe injuries. Thus, BTI does not eliminate the need for a full evaluation by a healthcare practitioner, including observation of the patient, neurological exam, and diagnosis.
And while BTI has promise for evaluating concussions, it cannot be used to address the cumulative damage done by repeated head injuries. These repetitive traumas have been linked to degenerative brain disease—a condition that has received a lot of press because of its prevalence in football players who experience many hits to the head over the span of their careers.