EEG For Sports Concussion Assessment

Concussion is an important and significant risk for young athletes

Long gone are the days when athletes were encouraged to shake off a concussion and get back to play as soon as possible. With so many children and teens playing contact sports, concussion has rightfully become an important public health issue. The American Academy of Neurology (AAN) describes concussion as “a form of mild traumatic brain injury (TBI)” and that it “is a common consequence of trauma to the head in contact sports.” The number of concussions per year in the US is estimated to be between 1.6 to 3.8 million.¹ While most concussions are mild and self-limiting, a minority produce long-term cognitive, physical, and psychosocial sequelae. Indeed the risk of long-term complications from concussion increases as the number of concussive episodes in a given patient increase. Unfortunately, it is not always immediately clear which concussions will be minor and of little lasting consequence, and which are a harbinger of chronic problems. Could EEG allow us to reliably assess the severity and prognosis of concussion?

Numerous diagnostic tools exist, but few are portable or cost-effective

Many investigative options have been proposed to diagnose and characterize concussion. CT is the most commonly used imaging modality—mainly because it is quick,widely available and relatively inexpensive. While CT can rule out significant trauma, it does little to help the provider in a concussion workup. MRI and neuropsychologic testing get us a bit closer, but are much more time-consuming, especially the latter. Newer work positron emission tomography (PET) , functional MRIs (fMRIs), and certain biomarkers (e.g., GFAP, UCH-L1) is intriguing but not ready for prime time.

Rethinking electroencephalography (EEG) in concussion: The power of QEEG.

Perhaps surprisingly, EEG was used as early as the 1940s to establish a qualitative link between TBI and abnormal brain function. Despite decades of research, standard EEG never emerged as a first line diagnostic tool for concussion. This has perhaps changed with the advent of more sophisticated technologies such as QEEG (quantitative EEG) and advanced EEG diagnostic algorithms. In broad-ranging 2017 literature review 460 articles from between 1996 and 2016, Authors Ianof and Anghinah concluded that conventional EEG is only useful in the evaluation of post-concussion epilepsy, but “not useful as a routine screening measure among individuals with mTBI or postconcussive symptoms.” Their assessment of QEEG, however, was just the opposite. In concussed individuals, QEEG showed immediate reduction in mean alpha frequency, with increased theta, increased delta, or increased theta:alpha ratio.² While the authors highlighted the fact that no clear EEG of QEEG features are unique to mTBI, their research revealed patterns of QEEG abnormality that correlated with acute, subacute and chronic concussion. From these results, the authors conclude QEEG “appears promising as a diagnostic assessment for mTBI and post-concussive symptoms.”²

Theta patterns may hold the key to determining severity of concussion

In a systematic literature review of studies examining resting state EEG (rsEEG) following concussion, Conley et al. found that concussed athletes rather consistently exhibit abnormal theta oscillations.³ The authors also noted that compared to pre-injury baseline or controls, concussed players had lower theta power, increased theta coherence, or increased frontotemporal theta power.³ Importantly, abnormalities in theta oscillations are associated with difficulties in attention goal directed cognition, decision-making, athletic performance, memory and sleep. They are also associated with anxiety and suicidal ideation. Larger studies will be required to determine if there are consistent pathognomonic features on rsEEG to determine the severity of concussion and predict outcome and risk of recurrence.

QEEG as a tool for pre-season screening, post-concussion assessment, and long-term follow up

The Committee on Sports-Related Concussions in Youth writes in Sports-Related Concussions in Youth: Improving the Science, Changing the Culture, that QEEG “can detect differences in performance and neural responses in concussed versus non-concussed student athletes in high school and college even when behavior measures fail to do so… Such results suggest that QEEG techniques could provide a more effective means to identify athletes with impairments following concussion and to predict when they might more safely return to play.”⁴ While it remains difficult to elucidate any EEG or even QEEG changes that reliably occur in individuals with concussion and that are absent in healthy controls, the power to detect meaningful changes may lie in pre-and post-concussion comparisons. Since portable QEEG—reusable EEG electrode caps and mobile-phone based acquisition applications—is now affordable, one could envision QEEG screening for athletes as part of their preseason health physicals. This data would be an invaluable comparator for sideline based concussion assessment to help identify theta wave changes and other indictors consistent with acute TBI and concussion.