Subconcussive injuries may be detected with a blood test

Written by Sharon Salt, Editor

Researchers at Orlando Health (FL, USA) have recently reported that they are making progress in developing a blood test that could detect subconcussive injuries.

People who receive a subconcussive injury often display no symptoms or immediate effects. However, these injuries can cause wear and tear on the brain over time if the injuries are repeated. Very few studies have also addressed the impact of subconcussive injuries following head trauma in the general population, as opposed to military members or athletes.

What is a subconcussive injury?

A subconcussive injury is a term that refers to a potential brain injury that does not meet the threshold for a concussion.

In this recent study, which has been published in BMJ Paediatrics Open, over 700 emergency room patients – both children and adults – were included. The study participants included patients with concussions, those with head trauma without overt signs of concussion and those with body trauma without head trauma or concussion.

The researchers conducted blood tests in the study participants and specifically examined the presence of two proteins (GFAP and UCH-L1). These proteins are found in our brains and are released into the blood after an injury occurs, and higher levels of these proteins are reported to be indicators of a concussion or subconcussive injury.

Within this study, elevated levels of both of these biomarkers were found in the patients with nonconcussive head trauma, which the research team believes could potentially signal a subconcussive brain injury.

Previous studies examining these two biomarkers have focused on detecting brain lesions, however, subconcussive injuries do not necessarily result in lesions, and even the vast majority of patients with concussions tend to have normal CT scans.

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In a quote request, lead author Linda Papa (Orlanda Health) stated that GFAP and UCH-L1 were approved in 2018 by the US FDA in adults to detect abnormalities on CT scans in mild-to-moderate traumatic brain injury. However, they have not been approved to detect concussion and the vast majority of patients with concussions have a normal CT scan of the brain. Furthermore, these markers have not been approved for use in children.

Papa explaind that: “This study addresses these two limitations. Firstly, it focuses on patients with concussion who have a normal mental status after their trauma (and have normal CT scans of the brain) and secondly, it includes patients of all ages. Patients who don’t have symptoms are the most challenging to diagnose because they look fine when they are being evaluated. Therefore, having an objective measure of concussion (such as a blood test) would be very helpful.”

Speaking of the study in more detail, Papa mentioned that GFAP performed better than 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 body trauma, to head trauma without concussion, to concussion. GFAP was detectible in blood for up to a week post-injury in patients with concussion.”

In terms of the practicality of the test, Papa noted that it takes several hours and specialized equipment to receive a result. Thus, it is not practical for clinical use. However, companies are now working on a benchtop device for the hospital lab and a point-of-care handheld device that could be used on site. According to Papa, “the technology is only a year or two away.”

“Next steps will include examining these patients over time to see how they recover from their injuries and validating these results in a larger group of patients, particularly children and youth,” Papa concluded.

Sources: Papa L, Zonfrillo MR, Welch RD et al. Evaluating glial and neuronal blood biomarkers GFAP and UCH-L1 as gradients of brain injury in concussive, subconcussive and non-concussive trauma: a prospective cohort study. BMJ Paediatr. Open 3, e000473 (2019);