A simple blood test may predict the severity of a concussion as accurately as an invasive spinal tap, researchers report.
They focused on a biomarker called neurofilament light chain. This nerve protein can be detected in the blood and cerebrospinal fluid when nerve cells are injured or die, according to the study.
"When your brain is injured, neurofilament light chain levels are higher in both your blood and your spinal fluid," said study author Dr. Pashtun Shahim, of the U.S. National Institutes of Health Clinical Center.
"Measuring this biomarker in your blood with a simple blood draw is faster and easier than measuring it in your spinal fluid, which requires a more invasive spinal tap. Our findings are exciting because they show that the simple test may also be just as accurate for determining how severe the injury is and predicting how you might do long term," Shahim said.
The study was published online July 8 in the journal Neurology.
The researchers looked at 104 professional Swedish hockey players, median age 27, and a control group of 14 healthy non-athletes.
Of the hockey players, 45 had suffered a concussion within the past week, 31 had had multiple concussions, and 28 had no recent concussion or symptoms.
The players with multiple concussions had a median of 18 picograms/milliliter (pg/mL) of the protein biomarker their blood. Those with recent concussions had 12 pg/mL, and those with no recent concussions or symptoms had 10 pg/mL. The control group had 9 pg/mL. These levels correlated with the levels in the participants' spinal fluid.
The researchers also found that the levels in the hockey players' blood were strongly associated with more concussions and more severe concussions, even a year after the injury.
The study also included 162 people with brain injuries, average age 43, and a control group of 68 healthy people.
People with head injuries had a median of 12.8 pg/mL of the biomarker in their blood, while the control group had 6.3 pg/mL. Those levels were similar to levels detected by more sophisticated tests such as brain imaging.
The level of biomarker in the blood accurately distinguished among mild, moderate and severe concussions. The difference in biomarker levels between people with concussions and the control group was evident up to five years after concussion, according to the researchers.
"In both of our studies, the same idea came through: Neurofilament light chain shows great promise as a biomarker in the blood," Shahim said in a journal news release.
"This is notable because the test may help us identify people whose concussions might give them debilitating symptoms for years after the injury. And that may help doctors treat their patients more specifically for the type of concussion they have," he said.
However, the test isn't yet ready for prime time. "In order to implement these results into clinical practice, larger studies will be needed to determine how neurofilament light chain changes across the spectrum of traumatic brain injury and in different populations," Shahim noted.
The American Academy of Family Physicians has more on concussion.
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