To that end, researchers offered new insights into the sensitivity of onsite tests that could enable earlier detection of concussion and treatment.
In one paper, investigators, led by Thomas Buckley, EdD, associate professor of kinesiology and applied physiology at the University of Delaware, assessed the reliability of the King Devick test, a rapid number-naming test that measures the efficiency of athletes' eye movements as they read numbers on cards or screens from left to right or top to bottom. They enrolled 830 National Collegiate Athletic Association (NCAA) athletes, who were all participating in the joint NCAA/United States Department of Defense Grand Alliance Concussion Assessment, Research and Education Consortium, which is designed to study and prevent concussion.
To determine the year-to-year reliability of the King Devick test, researchers performed the test annually for two years in the summers of 2015 and 2016. The researchers' endpoint measure was the athletes' fastest time to complete the test without errors each year.
They found a significant positive correlation between year one and year two of the test (year 1: 40.8 ±7.4 seconds; year 2: 38.75±7.7 seconds, r=0.827, p<0.001), suggesting high year-to-year reliability. The mean improvement was 2.02 seconds and the median improvement was 2.2 seconds, suggesting that coaches should expect a modest improvement in performance of about 2 seconds from year to year.
“We found high reliability across the board,” Dr. Buckley said in an interview with Neurology Today. “This is one of the first accurate, easily administrated visual tests for cognition after concussion. This shows that an ocular-motor assessment has an important role in the overall multifaceted concussion assessment.”
However, the test does not represent a thorough post-injury evaluation of cognitive function, Dr. Buckley said. “These tests are supportive of, but should not replace, the physician evaluation.”
Dr. Buckley noted that 27 percent of the athletes were found to perform worse at year two than year one, which shows the test has some normal variability and also supports the need for supplemental physical exams.
“This study had a huge number of collegiate athletes who performed the test, and the researchers correlated over the course of two years what the difference was in times,” said Amaal Starling, MD, assistant professor of neurology at the Mayo Clinic in Scottsdale, AZ, who was not involved with the study. “The results are very reassuring, although not surprising, that it is a very reliable tool to use from year to year. The small mean improvement of about two seconds emphasizes the fact that this test needs to be given for a baseline every single year to be accurately used as a screening tool for concussion.”
“There don't seem to be significant age-related changes, at least within a time frame of one year,” Dr. Vargas added. “That would suggest that there's enough consistency within the test that if we're looking at a one-year time frame, you can be pretty confident that any changes are real differences – that they are due to acute injuries and not worsening in performance related to age-related changes. So that's the value added. The test is not just sensitive, but consisten
In another paper, researchers explored the possible association between persistent post-concussion syndrome (PPCS), which includes problems with balance, headache, fatigue, inability to concentrate, and blurry vision and dysfunction in the autonomic nervous system.
Researchers, led by Melissa Cortez, DO, a neurologist at University of Utah Health, enrolled 29 athletes — seven of whom had sustained acute concussions, 11 had PPCS, and 11 served as controls.
They administered the Concussion Symptom Severity scale and the Standardized Assessment of Concussion to all participants. Those with PPCS and acute concussion groups (p=0.91 and p=0.32, respectively), and both concussion groups' scores were significantly higher than those of participants in the control group (p=0.003/0.002 and p=0.01/0.008, respectively).
However, they found that participants in the PPCS group had significantly elevated markers of autonomic dysfunction, such as dizziness, fatigue, and orthostatic hypotension, compared to both athletes in the acute concussion group and non-concussed controls. These included a higher heart rate increment on a five-minute head-up tilt test (p=0.02), reduced heart rate variability (p=0.03), and increased scores on the COMPASS-31 scale of autonomic symptoms (p>0.001).
The findings, the researchers wrote, are “suggestive of a relative hyperadrenergic pattern in [PPCS], which is not present during the acute phase of concussion.” These changes, they noted, may “explain sustained symptoms of dizziness and fatigue associated with orthostatic intolerance [in PPCS], and importantly, could provide potential treatment opportunities.”
Dr. Starling agreed. “For athletes who have PPCS and are dizzy, clinicians should have a high degree of suspicion for autonomic dysfunction, and if autonomic testing is available, they should send patients for that testing.”
She noted that autonomic dysfunction is treatable. “Treatment may start with conservative measures – lifestyle modifications like fluid intake, fluids with lots of electrolytes, increasing salt, wearing compression stockings, not eating large meals but multiple small meals, and elevating the head of the bed during sleep, which reduces sympathetic drive. And if autonomic dysfunction is persistent despite lifestyle modifications, there are medications we can use for treatment. However, starting with those conservative measures can be quite helpful.”
Going forward, Dr. Starling said: “We need to continue working on biomarkers. That will play a huge role in future research. Until we have those, it makes it hard to have research with consistent outcome measures. Now, it's still quite subjective and everyone is using different outcome measures, which makes it hard to take a finding from one study and compare it to another study. We need more standardization, gold standard assessment tools, and biomarkers.”
Dr. Vargas agreed. “The diversity and breadth of research presented at the AAN Sports Concussion Conference is a testament to the fact that there are so many aspects of concussion that we don't fully understand, and which are in need of further research.”