Objective testing for sports-related concussion

Aug. 30, 2019

Despite increased awareness of the dangers of sports-related concussion, most young athletes aren't routinely evaluated for that traumatic brain injury. The Mayo Clinic Concussion Check Protocol can be used by parents or other adults on the sidelines to quickly assess whether a young athlete should be removed from play.

"In less than four minutes, these tests can help detect whether an individual has been concussed," says David W. Dodick, M.D., a neurologist and the director of the concussion program at Mayo Clinic in Phoenix/Scottsdale, Arizona. "We know it's not practical or feasible at this time to put a health care provider on the sidelines of every youth game and practice. But there are objective tests, which can be done by a trained adult, that can consistently and reliably detect whether a concussion may have occurred."

More than half of concussions aren't reported. Athletes may not recognize the symptoms or may be reluctant to speak up and risk removal from play. Even when an athlete is taken out of play after a big hit, a standard sidelines evaluation can miss a concussion.

"The exam has to be concussion focused and objective," Dr. Dodick says. "A lot of sidelines evaluations are very subjective. In addition, even in the best of circumstances when a trained health care professional is examining the athlete, he or she may interpret a test differently than the person who performed a baseline examination. And some of the signs considered typical — such as the ability to stand on one leg — may not be abnormal even if there is a concussion, or may be abnormal when there isn't a concussion."

Mayo Clinic's Concussion Check Protocol is printed on a small card. The three basic steps are:

  • Recognize and remove — Watch for concerning hits or signs of concussion, and remove the player.
  • Memory assessment — Ask the athlete the orientation questions listed on the back of the card.
  • King-Devick test — Give the athlete this two-minute test of eye movement.

Athletes who fail any of these steps should be removed from play until cleared by a medical professional.

The concussion check protocol requires testing each athlete at the start of the season to provide a baseline for comparing subsequent sidelines testing. A Mayo Clinic study comparing the results of preseason and postseason King-Devick tests found that concussion hadn't been recognized in 10% of the athletes whose test results were abnormal at the end of the season.

"These athletes either weren't reporting symptoms, or they didn't have symptoms. But they still very likely had brain injury from head impacts," Dr. Dodick says.

Children's structurally immature brains put them at higher risk of concussion and of prolonged symptoms afterward. Up to 40% of children who have concussions will continue to experience three or more symptoms a year after the injury. Those symptoms include cognitive disturbances such as memory defects and difficulties with concentrating, processing information, and learning new information. Balance impairment, problems with depth perception and spatial disorientation brought on by movement also can occur. About one-third of people with concussion experience post-traumatic headaches that persist for more than three months.

"Even a single concussion can have profound consequences," Dr. Dodick says. "Also, concussion is really the tip of the iceberg. What's under the iceberg is silent concussions — the effects of repetitive head hits that may occur more commonly than symptomatic concussion. We have experts sitting on the sidelines of professional sports but nobody watching over kids. The most vulnerable among us are the least protected."

Seeking biomarkers to aid treatment

In addition to validating concussion check protocols in young athletes, Mayo Clinic is investigating potential biomarkers for traumatic brain injury and the long-term consequences of repeated head injuries. One effort involves discovering genetic, imaging, blood, symptom or spinal fluid markers for individuals at risk of, or who have developed, chronic traumatic encephalopathy (CTE), currently detectable only post-mortem. "We feel we are making strong progress toward that goal," Dr. Dodick says.

Another project is a multiphase study of post-traumatic headache, conducted in collaboration with other institutions and with funding from the Department of Defense. That project includes:

  • A preclinical study to determine the precise molecular mechanisms that lead to post-traumatic headache after concussion
  • Research to uncover potential genetic risk factors to help identify individuals likely to experience persistent post-traumatic headache
  • A placebo-controlled clinical trial aimed at determining whether quick intervention after concussion can prevent persistent headaches
  • Imaging studies conducted immediately after concussion and at subsequent intervals to determine whether imaging changes can predict prognosis and response to treatment

"When the head suffers an impact, a series of injurious cascades is set in motion in the brain that can lead to progressive damage. Ultimately, we believe one of the single most important areas of concussion research needs to determine how to disrupt these cascades and prevent or minimize brain injury from a concussion," Dr. Dodick says. "Preventing these cascades would be better than the current watching and waiting to see what remains, and then trying to treat the cognitive, balance, sleep, emotional and headache symptoms that plague up to 20% of individuals after a concussion, for months or years."

For more information

Email Dr. Dodick via concussion@mayo.edu for more information.