Key points

Introduction

Neuropsychological assessment has a long history of being one of the key components in a comprehensive evaluation of a head injury. A sport-related concussion (SRC) has been labeled one of the most complex injuries in sports medicine to diagnose, assess, and manage. An SRC is understood to be a complex pathophysiological rather than neurostructural process, induced by a biomechanical force. ^, As such, changes are not readily observed with traditional neuroimaging and for some, deficits can still be present even when physical symptoms have resolved. Therefore, neuropsychological testing plays an integral role in providing a standardized, methodological approach in a comprehensive evaluation. This article reviews the history of neuropsychological assessment in SRC, as well as the role of neuropsychologists in a multifaceted assessment. This article also includes a case study demonstrating the practical use of computerized neurocognitive testing in a comprehensive neuropsychological assessment of an SRC.

History of neuropsychological assessment and concussion

Clinical neuropsychology as a field emerged during the beginning of the twentieth century, with the growing interest in the behavioral expression of brain dysfunction. Clinical neuropsychologists have used neuropsychological assessment as a means by which to detect and characterize neurocognitive impairment. Initially, most of the field focused on assessing moderate to severe brain injuries. It was not until 1974, in New Zealand, with the work of Gronwall and Wrightson on mild head injuries, that the subspecialty of Sport Neuropsychology emerged.

In the 1980s research from Barth and colleagues, along with studies from the University of Virginia, served as springboards for others to supply empirical evidence of the neurocognitive impact after an SRC and the timeframe for resolution of cognitive symptoms. Neurocognitive characteristic deficits following an SRC are typically seen in the areas of memory, attentional processes, reaction time, and processing speed. Barth and colleagues introduced the Sports Laboratory Assessment Model approach where athletes complete a neuropsychological assessment before their competitive seasons and test again following concussion with the same assessment to compare baseline scores to postinjury scores. This approach not only provided a starting point for research and generalizations regarding concussions but allowed for clinicians to take an individualistic approach with treatment management.

The modality of neurocognitive assessments has transformed over the years. In the early 1980s, assessments used traditional neuropsychological measures. The development of computerized assessment in the 1990s has guided a shift in neurocognitive assessments. It has now become standard practice for neuropsychologists to use computerized neurocognitive test protocols as part of the evaluation and for baselines. Each approach has its strengths and weaknesses. Traditional paper-pencil testing is reasonably reliable and valid ; however, it lacks feasibility in a sport setting, particularly when there is a need to acquire large numbers of baseline assessments. Computerized testing on the other hand allows for efficient administration, storage, and access to large numbers of baseline assessments. Computerized testing also has minimal practice effects, given that it allows for multiple versions and randomization of stimuli. Furthermore, computerized testing allows for better accuracy and increased validity when assessing reaction time to within one-hundredth of a second and changes or deficits in cognitive speed. This approach is not without its limitations in that it does not allow for direct observation, only provides a brief snapshot of limited cognitive domains, and if not interpreted by the appropriate individuals may be used incorrectly. Taking these strengths and limitations into consideration, there is support for a hybrid approach of using both paper-pencil and computerized modalities. However, there is a paucity of research regarding the clinical utility of this approach. Regardless of the modality of administration, a comprehensive neuropsychological assessment of SRC is multifaceted in nature. Currently, a complete neuropsychological evaluation of SRC not only includes neurocognitive testing but also a clinical evaluation, symptom inventory, postural/vestibular screen, as well as assessment of emotional functioning.

Baseline testing

As previously discussed, the seminal study by Barth and colleagues set the stage for including baseline testing in SRC management. SRC is a clinical diagnosis that has been primarily based on the subjective assessment of a variety of symptoms including somatic, cognitive, emotional, and/or sleep disturbances. It is often evaluated in the absence of loss of consciousness or other neurologic markers. Therefore, using preinjury baseline assessments helps to control for individual differences such as ADHD, various learning delays, cultural/linguistic differences, age, education, and the possible influence of psychiatric issues, ^, by increasing diagnostic accuracy. There is no universal or standard clinical profile, trajectory of recovery, or type of dysfunction that is always observed. ^{, ,} Each injury is unique to the individual considering preexisting history. Opponents of baseline testing contend that it does not provide any added value beyond normative data and raise concerns related to invalid administration. Baseline assessments are currently instituted as part of a concussion management program in professional sports, colleges, and high schools. However, when baseline data are unavailable, neuropsychologists typically rely on normative-based comparison scores corrected for age, sex, and education to determine any declines.

Symptom inventories

The assessment and measurement of symptoms is an important component in a comprehensive neuropsychological evaluation of SRC. Perhaps the most commonly used symptom inventory is the Postconcussion Symptom Scale (PCSS). The PCSS is a battery of concussion-related symptoms rated on a severity scale from 0 to 6 with 0 being none and 6 being severe. It has a reported sensitivity of 40.81%, specificity of 79.31%, a positive predictive value of 62.50%, and a negative predictive value of 61.33%. Limitations of the PCSS include the intrinsic subjective nature of a self-reported questionnaire, as well as research revealing a wide range of variability among concussed individuals.

A recently developed symptom inventory, the Concussion Clinical Profile Screening tool (CP Screen), was developed to evaluate concussion-specific symptoms that may reflect established concussion profiles and minimize overlap with other health conditions. A preliminary analysis of the CP Screen revealed high internal consistency of the CP Screen in the control (Cronbach’s alpha = .87) and concussed (Cronbach’s alpha = .93). Moderate to high correlations among the CP Screen factors and PCSS factors and Vestibular/Ocular Motor Screening (VOMS) items, support concurrent validity. The receiver operating characteristic curve analysis for identifying concussed from controls was also significant ( P <.001) for all CP Screen factor and modifier scores with excellent areas under the curve (AUCs) for migraine (.93), ocular (.88), vestibular (.85), and cognitive (.81) factors, demonstrating predictive validity. More research is needed to demonstrate the generalizability of these findings.

Computerized neuropsychological assessment

A vast amount of studies has found that both traditional and computerized versions of neuropsychological batteries are sensitive to the acute effects of a concussion. ^{, ,} Computerized assessments have gained increasing popularity given that they allow for group administration, are scored automatically, and limit the effects of human variability. ^,

The Immediate Post-concussion Assessment and Cognitive Test (ImPACT ) is a 20- to 25-minute computerized baseline and postconcussion testing battery that has well established reliability and validity for the assessment of symptoms and cognitive functions associated with SRC. ^{, ,} It is regarded as the most commonly used measure in the neurocognitive assessment of SRC. ImPACT is composed of 6 modules, which produce 4 output scores, including verbal memory, reaction time, visual-motor speed, and visual-memory composites. ImPACT has been found to be sensitive to the acute effects of concussion, revealing substantial changes in functioning in the first few days postinjury. ^, Pearson test-retest correlation coefficients for the verbal memory, visual memory, reaction time, and processing speed composite scores ranged from 0.65 to 0.86. These coefficients are comparable to or even higher than many other paper-pencil neuropsychological measures. The battery also contains criteria that identifies invalid performances, and the overall sensitivity and specificity have been determined to be 81.9% to 91.4% and 69.1% to 89.4%, respectively. Currently, ImPACT is the most widely used computerized neurocognitive assessment ; it is the only neurocognitive assessment that has garnered Food and Drug Administration approval for marketing and is commonly used in high school, collegiate (NCAA), and professional sports (NFL, NBA, MLB, Auto-Racing & USOC) nationally. ^,

Other less-widely used computerized neurocognitive assessments for SRC and their limitations include:

HeadMinder, Inc.’s Concussion Resolution Index (CRI) is an online neurocognitive and neurobehavioral assessment tool. The test includes 6 subtests that evaluate the speed of information processing, visual recognition, and reaction time. Past research has observed it to be sensitive (88%) in identifying postconcussion symptoms and resistant to retest effects. ^, Limitations include false positives recorded in the protracted phases of recovery ^, and no explicit assessment for memory impairment.

CogSport/Axon is composed of series of 7 card tasks measuring 5 composite cognitive domains. These domains are reaction time, decision-making, matching, working memory, and attention. Collie and colleagues found that CogSport reliably measures psychomotor function, decision-making, working memory, and learning. Despite high correlations to paper-pencil neuropsychological tests, there has been considerable variability reported in the specificity and sensitivity of the composite scores.

C3 Logix is composed of 4 neuropsychological tests: Simple Reaction Time, Choice Reaction Time, Trail-Making Difference (Trails A subtracted from Trails B), and Symbol-Digit Modalities. Throughout the literature there has been considerable debate surrounding the tests used in this assessment. Research is limited regarding the psychometric properties of this assessment, and test-retest reliability has only been founded in 2 of the neuropsychological tests used.

Central Nervous System Vital Signs (CNS-VS) , initially developed as a routine clinical screening instrument, is composed of 7 tests: visual and verbal memory, finger-tapping, symbol digit coding, the Stroop, continuous performance test, and a test of shifting attention. Its psychometric characteristics are similar to the paper-pencil version of the neurocognitive measures that it is composed of. However, one limitation of CNS-VS is the practice effects, as it has been proved that individuals score significantly better on the second and/or third session when compared with the first on 6 out of the 9 domains.

Brief sideline cognitive assessments

Apart from the aforementioned neuropsychological measures, rapid cognitive screening tests have been developed to assess the immediate effects of a head injury. ^, One example of a rapid cognitive screening test is the Standardized Assessment of Concussion (SAC). The SAC is a tool developed to identify the effects of mild traumatic brain injury on the sideline and does not require specific training in neuropsychology for the purposes of administration or interpretation. The test assesses orientation, immediate recall, concentration, and delayed recall. The SAC has been shown to have a sensitivity and specificity of 80% to 94% and 76%–91%, respectively. This measure is embedded in the Sport Concussion Assessment Tool (SCAT-5), the most recent revision of a sideline evaluation screening tool. The SCAT-5 includes indications for emergent management, signs of concussion, Glasgow Coma Score, Maddocks questions, rapid neurologic screen, medical health history questions, symptom evaluation, cognitive screen, neck evaluation, balance evaluation, coordination evaluation, and considerations for management and advice. These abbreviated testing paradigms are not to be in replacement of a comprehensive neuropsychological evaluation or used as a standalone measure, it is more appropriately used as a rapid screen for SRC on the sidelines.

Neuropsychological assessment of youth sport–related concussion

There are unique challenges present when assessing and managing SRC in children. When considering neuropsychological assessment in a younger population, children’s cognitive, emotional, and physical development must be regarded. Three computerized batteries used in children, are CogSport, The Pediatric ImPACT, and CNS-VS. This modality of assessment works well with this age group, but each test has its strengths and weaknesses.

The Pediatric ImPACT is a computerized assessment battery used in children aged 5 to 12 years. It is one of the few that incorporates developmentally appropriate stimuli and task instructions, factor-derived composite scores, empirically based clinical algorithms, and comprehensive normative data sets. The 6 Pediatric ImPACT neurocognitive subtests are consistent with the original measure with adaptations of instructions, cognitive demands, and stimuli, made to be more appropriate for a younger age range.

Assessing visual-motor deficits

A comprehensive neuropsychological assessment of symptoms often includes the evaluation of visual-motor and vestibular deficits. Dysfunction of the vestibular system, including dizziness, balance difficulties, and visual deficits, is commonly seen after concussion. In fact, poor oculomotor function has been reported as one of the most robust discriminators for the identification of mild traumatic brain injury. The visual-motor deficits often reported by such patients include difficulty with saccades, accommodation, smooth pursuit, fixation, reading, and photosensitivity.

The VOMS assessment consists of 5 domains: (1) smooth pursuit, (2) horizontal and vertical saccades, (3) convergence (NPC), (4) horizontal vestibular ocular reflex (VOR), and (5) visual motion sensitivity (VMS). The VOMS has demonstrated internal consistency in identifying concussed patients with a high predicated probability of AUC (0.89) with VOR, VMS, and NPC distance.

Another measure, the King-Devick test, was initially created in 1976 to evaluate horizontal-saccade performance and reading performance and in 2011 became adapted in concussion screening. The assessment takes approximately 2 minutes to administer and is sensitive to vestibulo-ocular changes secondary to concussion (sensitivity = 86%; specificity = 90%). ^,

Role of neuropsychologists

Neuropsychologists are key members in a multidisciplinary team in the treatment and management of SRCs. Interpretation of test scores following a neuropsychological evaluation is intricate and requires specialized knowledge about the psychometric properties of assessment (eg, validity, reliability, normative data, base rates, and reliable change). ^{, ,} Additional factors such as culture, preexisting (eg, LD or ADHD), or co-occurring diagnoses (eg, mood symptoms) can influence test performance and the interpretive process of any neuropsychological assessment. Furthermore, the most recent consensus statement highlights the growing body of literature reporting that psychological factors play a significant role in symptom recovery and presentation. A clinical neuropsychologist is specifically trained in conceptualizing the psychological, cognitive, behavioral, physiologic as well as neurologic principals when treating and managing SRCs. Given these multiple factors, it is clear that neuropsychologists are uniquely qualified to interpret assessments and incorporate the data in the treatment and management of concussions. ^,

Case study

John Smith is a 15-year-old high school male football player running back that sustained a frontal, helmet-to-helmet hit during the third quarter of a regular season game. Acutely, the athlete reported experiencing dizziness, blurred vision, and an immediate headache. He got up independently, and while attempting to return to the huddle, displayed balance difficulties and confusion (ie, did not comprehend the plays that were being called). He was immediately pulled off the field by the certified athletic trainer (ATC), where the SCAT-5 was completed on the sideline. The rapid screener identified a high likelihood of an SRC. John Smith was removed from the game and recommended to follow with a sport neuropsychologist.

John Smith presented to his initial neuropsychological clinic visit 2 days after the injury. A clinical interview was completed that revealed no prior history of concussion, a personal and family history of motion sickness, as well as a family history of migraines. During this initial visit the athlete reported experiencing constant, daily headaches that worsened during the bus ride to and from school. He also reported dizziness with quick movements, photosensitivity, and mild nausea. During school, he experienced cognitive difficulties particularly with attention, processing speed, and short-term memory. Emotionally, the athlete and his parents endorsed increased irritability. Neurocognitive testing with ImPACT revealed statistically significant deficits in memory (visual and verbal), reaction time, and visual motor speed in comparison to his baseline performance ( Table 1 ). The neuropsychologist also completed the VOMS, which revealed deficits; specifically, it was provocative for dizziness. His clinical profile was primarily a vestibular and secondarily a posttraumatic migraine profile.

Table 1

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