Value of Quantitative Electroencephalography in Diagnosis and Management of Mild to Moderate Traumatic Brain Injury: Case Series of 150 Football Players with Multiple Concussions

Abstract

Multiple sports-related concussions have been associated with neurocognitive impairments ranging from a mild dementia to full Alzheimer’s disease. Quantifying injuries and associated impairments is important to a diagnosis and management strategy. In addition to a necessary history and physical exam, other testing is always needed to confirm clinical suspicions. Radiology and imaging is often added, but they are often insensitive and nonspecific. An often neglected alternative or addition is electrophysiological assessment. Quantitative EEG, such as eVox, (which we call functional EEG) is one such readily available, objective electrophysiological system that has a large database with which to refer. In our clinic we evaluated a case series of 150 retired former professional American Football players who presented with histories of concussion and persistent symptoms of cognitive impairments. Their evaluations included comprehensive examinations, brain MRI (concussion protocol,) neurocognitive testing, and quantitative electroencephalography (Evoke NeuroScience.). Males, ages 32 to 65 years with professional football careers ranging from 1 to 18 years. Physical exams included ataxia of speech and gait, word finding impairments, nystagmus, pendular reflexes, and abnormal affect. Neurocognitive testing revealed impairments in up to five cognitive domains. MRI (concussion protocol) were positive findings in only 34%. Evoke EEG findings included delayed P300a and P300b, reduced EEG power in regions associated with working memory, and information processing and alterations in heart rate variability. The physical-neurological exam provided some objective findings, but they were often subtle. Brain MRIs were abnormal in only 34%. Neurocognitive testing identified abnormalities in all cases. The Evoke EEG provided electrophysiological abnormalities in all cases. Evoke EEG is sensitive and objective, and adds confirmatory neurophysiological data that correlate tightly with formal neurocognitive impairments and symptoms. Additionally, specific abnormal patterns provided objective rationale for targeted treatment regimens, including neurofeedback and neurocognitive training.

1. Introduction

The recognition and diagnosis of mild to moderate traumatic brain injury, mTBI, continues to be challenging, even in a world with advanced and expensive technology. Even nomenclature can be perplexing and further confusion occurs when terms like concussion, or post-concussion state are intermixed. The American Congress of Rehabilitation and the World Health Organization have defined clinical criteria but clear diagnoses continue to be elusive and the incidence varies from 200/100,000 to over 700/100,000 [1]. Diagnostic tools are initially associated with radiology. But x-rays and CT scans are overwhelmingly insensitive and MRI and Spect scans are most often negative or nonspecific. A high index of suspicion and neuro-psychological testing are keys, but the latter is often delayed, arduous, complicated by potential tester bias and with much delayed results.

Here we focus on the value of electrophysiological testing in the diagnosis of mTBI, using a readily available system that can be performed in an outpatient clinical setting, The eVox system by Evoke NeuroScience.

Quantitative Electroencephalography, which we call Functional EEG due to its ability to quantify brain waves loci while active physiological functions are underway, has been available in university research settings for over 30 years [2, 3, 4, 5, 6]. It was, however, introduced into outpatient clinical settings by commercial entities 12 years ago, such as Evoke Neuroscience of New York, which we used in this study. These commercial systems have standardized the protocols and all results are uploaded to a central processing mainframe system which contains thousands of tests, for age, gender specified reference for comparisons [7].

We added Evoke NeuroScience EEG testing to our clinical testing protocol seven years ago and have found that it’s availability in the clinical setting was practical, useful, and provided timely confirmatory electrophysiological data which could aid in the diagnosis, when combined with history, physical examination, and neurocognitive testing. Although our clinical population includes brain injury cases from multiple causes, motor vehicle accidents, falls, infections, hypoxia, here we report the results of a case series of 150 professional football players, with histories of multiple sports-related concussions.

2. Methodology

The system consists of an initial, short subjective neurocognitive screener, then application of an individually sized electrode cap with 22 electrodes attached to a laptop computer with the Evoke software. Continuous EEG recordings are made during 5 minutes of rest, with eyes open, followed by 5 minutes rest, with eyes closed, and then 10 minute of continuous recordings as the patient performs tasks from the computer screen. This task includes identifying by pressing a button when a large blue ball appears on the screen during a series of other items appearing on the screen and in one’s earpieces. An electrode on the chest over the heart records an EKG rhythm strip during the testing.

Photos examples during testing.

See (Figures 1 and 2).

Figure 1.

A subject during testing.

Figure 2.

Another subject during testing.

Objective neurophysiology components obtained from the testing consists of:

Heart-Rate Variability (HRV).

Event-Related Potentials (ERPs).

P300a, P300b, N100

Brain Mapping: Head Maps.

EEG Source Localization: LORETA.

Theta: Beta Ratio.

Peak Alpha Frequency (PAF).

Examples of these items are illustrated below: inFigures 3–7.

Figure 3.

Neuropsychological screener.

Figure 4.

Heart metrics.

Figure 5.

Event-related potentials (ERPs).

Figure 6.

EEG head maps.

Figure 7.

EEG: Source localization (LORETA).

As in this Evoke NeuroReport example, objective electrophysiological data is reported after analysis compared to the central mainframe database of over 60,000 examinations.

The Neuropsychological Screener is indeed subjective and repetitive of separate clinical and neuropsychological testings.

The remaining data are objective.

Heart-Rate Variability (HRV) is an objective evaluation of the autonomic nervous system, which, we remind ourselves, is a brain-controlled process, which is reflected in the variability of the heart rate during the testing. The balance between sympathetic and parasympathetic power in this case shows a high sympathetic dominance. This can be the basis for home-based HRV neuro-biofeedback training, utilizing readily available home-based systems, which can be monitored remotely by the clinician.

Event-Related Potentials (ERPs) document the time elapsed through identified neural circuits related to attention (P300a), information processing (P300b), and visual (N100.) This documents conduction speed through this well described circuit. In this case there is significant prolonged latencies for P300a and P300b, but normal in N100 [8, 9, 10, 11].

EEG Head Maps provide important visual overview of EEG power from brain waves of 2 Hz to 30 Hz, including delta, theta, alpha 1, alpha 2, and beta 1 and beta 2 frequencies, with localization of power over the entire brain, from a top looking down perspective. Deviations in EEG power is illustrated in normal, 1, 2 and 3 standard deviations from normal. In the case illustrated here, there are regional EEG power deviations that can be correlated with regional brain physiology and processes. This information can be optimized by neurobiofeedback training toward specific regions of abnormal EEG power [12].

EEG: Source Localization (LORETA) provides localization of abnormal (excessive high, excessive low) EEG power by localizing to specific Brodmann areas. These anatomical gyri and loci and be then clinically correlated with known neurocognitive functions of these brain regions.

3. Results

As expected in American Football alumni all patients were male. Their ages ranged from 32 years to 65 years, with professional football careers ranging from 1 to 18 years, in addition to their college and high school careers. At the time of examination all were ambulatory and 75% were currently employed. Common findings on physical examinations included ataxia of speech and gait ataxia, word finding impairments, nystagmus, pendular reflexes, and abnormal affect. Neurocognitive testing in all cases revealed impairments from mild to marked impairments in up to five cognitive domains. Previously obtained MRI studies (concussion protocol) revealed positive findings in only 34%, with some with scattered areas of gliosis, hemosiderin deposition and focal and global atrophy. Most MRI studies, 66%, even using a concussion protocol, were negative.

Evoke functional EEG findings, however, showed electrophysiological abnormalities in all cases. These included delayed P300a latency under visual attention tasks at the vertex, delayed P300b latency under go-no-go conditions, and slowed response times to visual and cognitive stimuli. There was also commonly low localized frontal and parietal EEG power, reduced neuronal capacity in regions associated with cognition and working memory, abnormal theta/beta ratios, abnormalities in visual, auditory processing, information processing and working memory tracts. Alterations in heart rate variability with reduced vagal activity, sympathetic dominance and baroreflexive activity were prevalent.

4. Conclusions

In evaluation of mTBI the physical and neurological examination provides objective findings that are subtle, and significant in only a minority of cases. Brain MRIs with concussion protocol provide positive finding in less than a third of cases and are often non-specific. Formal neurocognitive testing identified abnormalities in all cases, but this may be delayed and remote to busy clinical determinations. In this case series of known concussions, we found that the functional EEG (Evoke Neuroscience) provides valuable, objective electrophysiological data that is without evaluator bias. We note that other, similar systems are also available to practicing brain injury medicine physicians in clinical settings and are not endorsing a specific system, only reporting on our finding with this system. We conclude that such in office electrophysiological technology is currently available and can add confirmatory objective electrophysiological findings that provide meaningful data which correlate with clinical examinations of neurocognitive impairments for mild/moderate traumatic brain injury in a clinical setting. We are currently studying this technology and other technologies in other brain disorders. Additionally, it should be emphasized that even beyond a confirmed diagnosis, identifying abnormal electrophysiological functions also provides specific scientific rationale for targeted treatments and treatment monitoring regimens [13].

The author has no financial or fiscal relationship with any quantitative EEG provider. This study was funded solely by RehabMed South, Inc., Tampa, Florida.