Portable EEG Makes 'Real Time' Call on Sports Concussions

Damian McNamara

January 29, 2019

Keeping track of a cognitive score based on EEG "brain vital signs" may help detect the impact of overt, and subtler, concussive events in individual athletes over a season of play, new research suggests.

During the study, 12 of 47 Tier III Junior-A competitive ice hockey players experienced at least one concussion. This group showed significant differences in cognitive latency scores in the immediate post-concussion period, and when cleared to return to play, compared with unaffected players.

The automated EEG strategy allows the measurement of six responses involved in auditory sensation, basic attention, and cognitive processing — and it yields numerical scores in 10 minutes. Importantly, the system creates a characteristic EEG "fingerprint" specific to the effects of concussion.

"We have determined [that] using the brain vital signs framework allows for rapid and readily accessible objective measures of brain function at the frontlines," senior author Ryan C.N. D'Arcy, PhD, Simon Fraser University, Vancouver, Canada, told Medscape Medical News.

"The brain vital signs method is more sensitive to the subtle impacts of concussion and can detect physiological impairments that the current concussion protocols cannot," he added.

The study was published online January 16 in Brain.

Objective, Real Time Measure

Results of traditional behavior-based measures of concussion can be subjective, the investigators note. Therefore, they turned to EEG to develop an objective measure of cognitive deficits in real time, with the aim of creating an approach that could be "rapidly and easily deployable in both sport and clinical settings."

The investigators’ brain vital sign system centers on EEG event-related potentials (ERPs), which measure quantitative changes in EEG wavelength amplitudes and latencies that reflect sensory processing.

Applying ERP changes to concussion has been well studied but has not yet been practically adapted to widespread implementation in sport or clinical venues.

In addition, few longitudinal studies have evaluated ERPs immediately post-concussion. "To date, most of the literature has focused on longer-term effects of injury," the researchers write.

To learn more, they measured brain vital signs for each participant before the ice hockey season. The investigators assessed players who experienced a suspected concussion within 24 hours rink-side or at a local medical center, and again when medical staff cleared them to return to play.

The players (mean age, 18 years) all received routine clinical concussion management during the study. The investigators collected brain vital signs data for research purposes only — not to guide clinical decisions.

When asked about previous concussions at baseline, 17 participants reported having received none, 24 had between one and five, and six did not give a report. Each participant played a mean of 27 games during the season.

The EEG system and consumables all fit in a portable carrying case measuring less than 14 inches x 12 inches x 4 inches in size.

Brain Scores

Of the 12 players who experienced a concussion, researchers diagnosed 10 with one concussion, one with two concussions, and one with three concussions. They only included the first concussion for each player in their analysis.

Table. Significant Changes in Brain Scores at Concussion vs Baseline

 

t (11) Scorea

P Value

Auditory Sensation Amplitude

+3.36

.006

Auditory Sensation Latency

–2.90

.014

Basic Attention Amplitude

+3.32

.007

Basic Attention Latency

–3.32

.007

Cognitive Processing Amplitude

+2.54

.028

Cognitive Processing Latency

–2.28

.044

aResults based on post hoc t-tests.

Time from concussion to returning to play was a mean of 17 days (range, 4 to 70 days).

Four brain vital signs differed significantly from time of concussion to return to play: a decrease in auditory sensation amplitude [t(11) –3.23; P = .008], an increase in auditory sensation latency [t(11), 2.65; P = .02], an increase in basic attention latency [t(11), 2.63; P = .02], and a decrease in cognitive processing amplitude [t(11), –2.29; P = .04].

In addition, there was a significant increase from baseline to return-to-play in basic attention amplitude [t(11), 2.24; P = .0466].

"The continued impairment in basic attention suggests that concussed players who were cleared for return-to-play still had objective, physiological deficits as detected by brain vital sign assessment, with persistent attention impairments being a common symptom related to concussion," the researchers write.

Evidence supporting their findings include the directional changes in brain vital signs, which were closely associated with the diagnosis of injury as well as clinical recovery and resolution of symptoms.

Post hoc t-tests revealed a significant decrease in the cognitive processing index for latency [t(22), –2.788; P = .01] between baseline and post-season testing. At the same time, the total score also significantly decreased [t(22), –3.611; P = .002].

"The decrease in the cognitive processing index scores suggests that cognitive semantic processing may be a particularly sensitive indicator of concussion-related changes in neurophysiological processing," the investigators write.

Standard Sports Tool?

"We were particularly surprised at the changes in measures of cognitive processing over the course of the season in hockey players that had not been diagnosed with a concussion, raising further concerns around the emerging concept of 'subconcussive' impacts," said D'Arcy.

"Importantly, this is a result that we also since observed in youth football players, in a completely different study," he added.

There is no known objective assessment designed specifically to measure the effects of subconcussive impacts, the researchers note.

However, "the brain vital sign changes from baseline to post-season are consistent with MRI assessments of subconcussive accumulation in athletes," they write.

"Current evidence has primarily focused on effects of diagnosed concussion, and not on potential subconcussive impacts. Our current findings suggest we have much more to understand about the short- and long-term effects of repetitive subclinical/subconcussive impacts on the brain," D'Arcy said.

"Now that we can more accurately detect and measure the associated functional changes using brain vital signs, we can then begin to evaluate prevention and early interventions that would help protect people from potential long-term harmful effects of concussion," he added.

A lack of a healthy controls group to help determine normal ranges for the brain vital signs is a limitation of the study. In addition, the researchers were unable to demonstrate that accumulated subconcussive impacts among the non-concussed players were the only contributing factor to the changes they observed.

The research is ongoing, and the investigators hope that evaluating more participants will confirm their results. They also plan to collect additional time points to learn more about recovery patterns and timelines.

"We envision brain vital signs to be a standard, simple, and accessible tool in any sports setting or clinical setting, such as your local doctor's office or sporting venues," D'Arcy said. The potential of this strategy could "significantly change how concussions are detected and managed."

Using advances in artificial intelligence, the investigators also plan to monitor and predict cognitive changes related to dementia and other long-term negative impacts to brain health, he added.

A "Good First Step"

Commenting on the findings for Medscape Medical News, Kathryn Van Pelt, PhD, a post-doctoral fellow at the University of Kentucky, noted that the study "is a good first step" toward finding a new concussion diagnostic tool.

"The concussion field is pushing and striving to find better diagnostic tools, and [current study authors] Fickling et al. propose brain vital signs might be a possible tool," she said.

"The authors demonstrate that brain vital signs change over the course of the season among a subset of concussed male ice hockey players in a good preliminary study."

However, as the authors point out, there are some critical next steps needed before reaching a conclusion on the diagnostic utility of brain vital signs, added Van Pelt, who was not affiliated with the current study.

A larger sample size, inclusion of female athletes, and a more diverse study sample overall "would help ensure their results are generalizable [and] create a better normative profile," she said.

Interestingly, in research from Van Pelt on more than 10,000 military cadets published online January 14 in Injury Epidemiology, female sex and previous concussion were the most consistent estimators of concussion risk across a number of settings.

In addition, the current research could benefit from addition of a metric to track the number of impacts experienced by a player, Van Pelt said. This data would enable researchers to test for a dose-response relationship between the number of impacts and changes in brain vital signs, for example.

"Establishing a dose-response relationship between the number of impacts and brain vital signs would provide stronger evidence for a subconcussive effect," she said.

The study was funded by Mathematics of Information Technology and Complex Systems, Natural Sciences and Engineering Council Canada, and Canadian Institutes for Health Research (CIHR). D'Arcy is affiliated with HealthTech Connex Inc, a company working on commercialization of a platform to measure brain vital signs. Van Pelt has disclosed no relevant financial relationships.

Brain. Published online January 16, 2019. Full text

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