Concussive Injuries Diagnosed by Measuring a Brain Protein in Blood

A simple blood test detects brain injury by measuring the levels of two brain proteins, which are released into the circulation following head trauma.

Elevated levels of both proteins are found in patients with nonconcussive head trauma, potentially signaling a subconcussive brain injury. To formalize a clinical role for these biomarkers, investigators at Orlando Health (FL, USA) evaluated the diagnostic accuracy of the serum glial and neuronal serum biomarkers glial fibrillary acidic protein (GFAP) and ubiquitin C-terminal hydrolase (UCH-L1). Levels of these proteins were determined both individually and in combination for their efficacy in detecting the presence of a concussion and for grading potential subconcussive and non-concussive brain injury in pediatric and adult trauma patients.

For the current study, blood samples were obtained from pediatric and adult trauma patients of all ages presenting with normal mental status within four hours of injury. Of 3462 trauma patients screened, 751 were enrolled for the study and 712 had relevant biomarker data. Repeated blood sampling was conducted at regular periods from four to 180 hours postinjury in adults.

For detection of concussion and gradients of injury in children versus adults, the investigators compared three groups of patients: (1) those with concussion; (2) those with head trauma without overt signs of concussion (non-concussive head trauma controls) and (3) those with peripheral (body) trauma without head trauma or concussion (non-concussive body trauma controls). A total of 1904 samples from 712 trauma patients were analyzed.

Results revealed that within four hours of injury, there were incremental increases in levels of both GFAP and UCH-L1 from non-concussive body trauma (lowest), to mild elevations in non-concussive head trauma, to highest levels in patients with concussion. In concussion patients, GFAP concentrations were significantly higher compared with body trauma controls and with head trauma controls in both children and adults. However, for UCH-L1, there were no significant differences between concussion patients and head trauma controls and between body trauma and head trauma controls in children.

The outcome of the study confirmed that GFAP outperformed UCH-L1 in detecting concussion in both children and adults. Blood levels of GFAP and UCH-L1 showed incremental elevations across three injury groups: from non-concussive body trauma, to non-concussive head trauma, to concussion. However, UCH-L1 was expressed at much higher levels than GFAP in those with non-concussive trauma, particularly in children.

"It is estimated that up to 3.8 million concussions occur in the U.S. annually from organized and recreational sports - and there are more than two million ER visits for traumatic brain injuries and concussions," said senior author Dr. Linda Papa, specialist in emergency medicine at Orlando Health. "It is a significant health problem in both athletes and non-athletes. This study includes an array of patients with different injury mechanisms, including car crashes, falls, and bicycle accidents in addition to recreational and sports injuries. It is not limited to just one group of injury types. A unique feature of this study is that it includes patients who hit their heads but have no symptoms. This group is rarely - if ever - included in biomarker studies."

The study was published in the August 25, 2019, online edition of the journal BMJ Paediatrics Open.

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