Concussions

Abstract

Objectives: To assess whether the King-Devick (K D) test is useful as a prognostic test for prolonged concussion symptoms by examining the relationship between a) change in performance on K D test from baseline to within two days post-injury and b) the absolute K D time at post-concussion testing, with an outcome of time to return to play (RTP).

Design: Prospective Cohort Study. Methods: Collegiate varsity athletes in the Concussion Assessment, Research, and Education (CARE) Consortium completed baseline and post-injury King-Devick tests from 2014 to 2018. Two exposures were evaluated: 1) change in K D score from baseline to within two days post-injury and 2) absolute K D score within two days post-injury, adjusted for baseline K D. We used Cox proportional hazards models to analyze the relationships between these exposures and time to RTP post-concussion.

Results: A total of 309 concussion injuries were included. Median baseline K D score was 40.0 s (IQR: 35.8, 45.2). Median post-injury K D score was 45.8 s (IQR: 39.8, 57.1). Median number of days until RTP in this cohort was 11 (IQR: 8, 17). Post-injury K D score adjusted for baseline K D had a stronger association with time to RTP duration (HR: 0.99 (0.98, 1.00), p = 0.03) than the difference in K D score from baseline to post-injury (HR: 0.99 (0.99, 1.00), p = 0.07).

Conclusion: Higher post-injury K D scores are associated with longer RTP. The association between K D post-concussion test and longer RTP warrants further investigation to assess the utility of the K D for prognostication in a clinical setting.

Summary Points:

• CARE Consortium funded by NCAA and Department of Defense (DOD).
• Actual post-injury K-D scores may be useful as a means for predicting likelihood of prolonged Return To Play, without the need for baseline value.
• The King-Devick test may be useful as an objective prognostic tool for predicting prolonged recovery following concussion.
• Identifying risk for prolonged post-concussion symptoms would provide an opportunity for targeted early intervention to improve recovery time.
• K-D takes only minutes to administer and can be completed by an individual without complex training.

Abstract

The popularity trend of mixed martial arts (MMA) is steeply increasing, especially in the very young population. Unfortunately, MMA carries an enormous risk of head trauma. The aim of this article is to provide review of studies on the association between head injuries and cognitive functions in MMA fighters. A systematic literature review was performed. Web of Science, PubMed, Springer, and Scopus databases were used. A total of 30 studies were identified. The inclusion criteria were as follows: studies with MMA fighters and head injuries and/or TKO/KO and/or reduction of cognitive functions in these fighters. The results indicate that the incidence of head traumas ranges between 58% and 78% of all injuries. The King-Devick test seems to be a suitable rapid tool used in the studies to assess the extent of cognitive impairment. Among the detected studies, the post-fighting scores were significantly worse for fighters with head trauma during the match. We also found anomalies in MMA fighters in different brain structures, but it seems that the thalamus and caudate are the most affected. The impaired performance in processing speed, verbal memory and psychomotor speed is regularly confirmed in studies with MMA fighters. In addition, head traumatization seems to be a risk factor for the development of neurodegenerative disorders and it may be one of the possible causes of chronic traumatic encephalopathy (CTE). Several global medical societies have identified MMA as a violent and dangerous sport and have called for its ban – but unsuccessfully. Therefore, possible recommendations should include increased medical supervision of the fighter (during his career, but also after it) and the introduction of practical safety instructions for fighters to reduce the risk of developing CTE. With the increasing popularity of MMA, the risk of CTE should not be underestimated.

Abstract

Background: Sideline diagnostic tests for concussion are vulnerable to volitional poor performance (“sandbagging”) on baseline assessments, motivated by desire to subvert concussion detection and potential removal from play. We investigated eye movements during sandbagging versus best effort on the King-Devick (KD) test, a rapid automatized naming (RAN) task.

Methods: Participants performed KD testing during oculography following instructions to sandbag or give best effort.

Results: Twenty healthy participants without concussion history were included (mean age 27 ± 8 years). Sandbagging resulted in longer test times (89.6 ± 39.2 s vs 48.2 ± 8.5 s, p < .001), longer inter-saccadic intervals (459.5 ± 125.4 ms vs 311.2 ± 79.1 ms, p < .001) and greater numbers of saccades (171.4 ± 47 vs 138 ± 24.2, p < .001) and reverse saccades (wrong direction for reading) (21.2% vs 11.3%, p < .001). Sandbagging was detectable using a logistic model with KD times as the only predictor, though more robustly detectable using eye movement metrics. Conclusions: KD sandbagging results in eye movement differences that are detectable by eye movement recordings and suggest an invalid test score. Objective eye movement recording during the KD test shows promise for distinguishing between best effort and post-injury performance, as well as for identifying sandbagging red flags.

Sport concussion (SC) has emerged as a major health concern in the medical community and general public owing to increased research and media attention, which has primarily focused on male athletes. Female athletes have an equal, if not increased, susceptibility to SC. An ever-growing body of research continues to compare male and female athletes in terms of SC before and after an injury. Clinicians must be cognizant of this literature to make evidence-based clinical decision when providing care to female athletes and discern between dated and/or unsupported claims in terms of SC.

Summary Points:

• Clinical measures based on visual tasks, most notably the King-Devick (K-D) Test, have been introduced as viable sideline measures of sport concussion (SC)
• The K-D test is a rapid visual screening tool that assesses the speed and accuracy of an athlete reading numbers from left to right in increasingly complex patterns provided on alternative cards, which requires the use of saccades and concentration to complete.
• The K-D test has been demonstrated to have evidence of high test–retest reliability, sensitivity, and specificity with variable test–retest intervals across a wide range of age, sport, and non-sport groups.
• Additionally, preliminary evidence suggests sex does not seem to influence K-D test performance. The evidence remains promising for the K-D test as a sideline measure of SC.

Sports-related concussion has emerged as a public health crisis due to increased diagnosis of the condition and increased participation in organized and recreational athletics worldwide. Under-recognition of concussions can lead to premature clearance for athletic participation, leaving athletes vulnerable to repeat injury and subsequent short- and long-term complications. There is overwhelming evidence that assessment and management of sports-related concussions should involve a multifaceted approach. A number of assessment criteria have been developed for this purpose. It is important to understand the available and emerging diagnostic testing modalities for sports-related concussions. The most commonly used tools for evaluating individuals with concussion are the Post-Concussion Symptom Scale (PCSS), Standard Assessment of Concussion (SAC), Standard Concussion Assessment Tool (SCAT3), and the most recognized computerized neurocognitive test, the Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT). The strengths and limitations of each of these tools, and the Concussion Resolution Index (CRI), CogSport, and King-Devick tests were evaluated. Based on the data, it appears that the most sensitive and specific of these is the ImPACT test. Additionally, the King-Devick test is an effective adjunct due to its ability to test eye movements and brainstem function.

Summary Points:

• This study identified the benefits of the K-D Test that are unique to concussion assessment tools.
• The K-D Test is easy to administer, tests eye movement and brainstem functions that other tests do not and is able to identify events in athletes without symptoms of concussion (unrecognized concussions).
• The K-D Test is an effective addition to the concussion screening protocol.

Background: Disruption of the visual and vestibular systems is commonly observed following concussion. Researchers have explored the utility of screening tools to identify deficits in these systems in concussed patients, but it is unclear if these tests are measuring similar or distinct phenomena.

Purpose: To determine the relationships between common vestibular tests including the King-Devick (K-D) test, Sensory Organization Test (SOT), Head Shake-Sensory Organization Test (HS-SOT), and Dynamic Visual Acuity (DVA) test, when administered contiguously, to healthy recreational athletes aged 14 to 24 years.

Study Design: This study used a prospective design to evaluate relationships between the K-D, SOT, HSSOT, and DVA tests in 60 healthy individuals.

Methods: Sixty participants (30 males, 30 females; mean age, 19.9±3.74 years) completed the four tests in a single testing session.

Results: Results did not support a relationship between any pair of the K-D, SOT, HS-SOT, and DVA tests. Pearson correlations between tests were poor, ranging from 0.14 to 0.20. As expected the relationship between condition 2 of the SOT and HS-SOT fixed was strong (ICC=0.81) as well as condition 5 of the SOT with HS-SOT sway (ICC=0.78). The test-retest reliability of all 4 tests was evaluated to ensure the relationships of the 4 tests were consistent between test trials and reliability was excellent with intraclass correlations ranging from 0.79 to 0.97.

Conclusions: The lack of relationships in these tests is clinically important because it suggests that the tests evaluate different aspects of visual and vestibular function. Further, these results suggest that a comprehensive assessment of visual and vestibular deficits following concussion may require a multifaceted approach.

Summary Points:

• K-D Test, an easily-administered oculomotor assessment tool, also incorporates the cognitive domain because it identifies impairment of eye movements, attention, language, and other symptoms that are associated with suboptimal brain function.
• The results of the current study are clinically important because knowing that there were no relationships between the K-D, SOT, HS-SOT, and DVA tests may encourage healthcare professionals to appreciate the complexity of impairments in visual-vestibular function.
• Each of these tests seem to measure a specific and seemingly independent aspect of the visual or vestibular system.

Purpose: To explore relationships between KDT and other concussion tests at baseline.

Methods and Study Design: Baseline concussion test scores were obtained from the Concussion Awareness, Research, and Education (CARE) Consortium for the KDT (mean=41.1seconds, standard-deviation(SD)=6.9, range=24.0-112.0); SCAT3 Symptom Evaluation [total, severity]; Brief Symptom Inventory-18 [anxiety, depression, somatization]; Balance Error Scoring System [firm-surface, foam-surface]; Standardized Assessment of Concussion (SAC) [orientation, immediate-memory, concentration, delayed-memory]; Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) [verbal-memory, visual-memory, visual-motor speed, reaction-time]; and the Vestibular-Ocular Motor Screening tool [Δ-score, dichotomized>2, mean-convergence]. Data were analyzed from athletes’ first year in CARE (n=2,331, mean-age=20.0yrs, SD=1.5, range=17.3-30.1). Fifty-five subjects were excluded as outliers on KDT and ImPACT. Pearson bivariate correlations were used to assess relationships between KDT and the other tests. SAC-immediate-memory (r=-.069, p=.002), SAC-concentration (r=-.219, p<.001), ImPACT-verbal memory (r=-.049, p=.028), ImPACT-visual-motor speed (r=-.271, p<.001) and ImPACT-reaction-time (r=.169, p<.001) significantly correlated with baseline KDT times. These were used as predictors in a hierarchical regression model (n=1,962).

Results: The regression model explained 10.5% (r2=.105, small effect size) of the variance in KDT baseline times with SAC-concentration (β=-.168, p<.001), ImPACT-visual-motor speed (β=-.221, p<.001), ImPACT-reaction-time (β=.054, p=.029) and ImPACT-verbal-memory (β=.056, p=.014) being significant predictors of baseline KDT times.

Conclusions: Better baseline SAC-concentration, ImPACT-visual-motor speed and ImPACT-reaction-time predicted better baseline KDT times. Conversely, better ImPACT-verbal-memory predicted worse KDT times. However, the effect sizes for these relationships were small.

Significance of Findings: Results demonstrate small associations at baseline between KDT and other concussion tests, but significant variance in KDT performance (almost 90%) was not explained by any of these associations, suggesting KDT may contribute unique information to baseline concussion assessments.

Summary Points:

• K-D Test performance was significantly correlated with SAC concentration, ImPACT visual motor speed and ImPACT reaction time.
• Regression models only explained 10% of the variability in KD baselines. Therefore, findings suggest that K-D measures a construct not related to other commonly used concussion assessments at baseline.
• K-D Test should be used in conjunction with other measures as part of a comprehensive assessment battery.

Objective: To evaluate the between trial reliability of the King-Devick (KD) test.

Background: The KD test is a reading efficiency test meant to provide an assessment of cognitive visual processing. Administration of the test requires two trials; however the reliability of trial one to trial two is unknown.

Design/Methods: 3193 KD test scores were evaluated from 2,373 NCAA athletes (1,110 female, 1,263 male, 20.22±2.32 years old, 70.28±4.51 inches,177.72 ±76.36 lbs.) from five institutions that underwent baseline KD testing over a two-year period as part of the NCAA/DoD CARE protocol. All testing was completed prior to their athletic season. Subjects were instructed to read aloud numbers from three cards as quickly as possible without making errors. The cumulative time from all three cards was the score for that trial with two trials being conducted. The outcome measures were the times for trial one and trial two. A Pearson correlation and reliable change index (RCI) were calculated.

Results: There was a significant positive correlation between trial one (43.05±7.97 seconds, range 23.84 – 103.8 seconds) and trial two (40.7 sec ± 7.46, range 22.38 – 86.55 seconds) with an r of 0.882, p<0.001. A majority of subjects improved on the second trial (n=2452, 77%) with 25 subjects receiving the same score and 716 (22%) scoring worse on the second trial. The mean improvement was 2.35 seconds with a median of 2.2 seconds. The RCI was calculated at 7.59 seconds with 219 (7%) of the subjects exceeding the RCI.

Conclusions: The results of the study suggest that the KD test is stable across both trials at baseline. However, a modest learning effect of approximately 2.3 seconds should be expected on the second trial suggesting the second trial is necessary for an accurate baseline score.

Summary Points:

• K-D Test is stable across both trials at baseline with a modest learning effect of approximately 2.3 seconds should be expected on the second trial suggesting that the second trial is necessary for an accurate baseline score.

Objective: The purpose of this article is to synthesize and appraise the evidence regarding the use of oculomotor-based vision assessment to identify and monitor recovery from mild traumatic brain injury (mTBI). Specific objectives are to (1) identify changes in oculomotor-based vision following mTBI; (2) distinguish methods of assessment; (3) appraise the level and quality of evidence; and, if warranted, (4) determine clinical recommendations for assessment.

Methods: A systematic review was undertaken to identify and appraise relevant literature. A search was conducted of 7 databases of peer-reviewed literature from January 1990 to January 2015. Articles were included if study populations were clearly identified as having mTBI and used an assessment of oculomotor-based vision. Articles with pooled data (eg, mTBI and stroke), addressing afferent visual function (eg, visual field deficits) or using single case designs, were excluded.

Results: Twenty articles were selected for inclusion. Exploratory findings suggest that measurements of saccades, smooth pursuit, and vergence are useful in detecting changes associated with mTBI. Assessment methods included eye tracker protocols, optometric assessment, and the King-Devick test.

Conclusion: The strength of this evidence is not yet sufficient to warrant clinical recommendations. Research using rigorous methods is required to develop reliable, valid, and clinically useful assessment protocols.

Summary Points:

• Changes in saccadic eye movements are reported in individuals with mTBI.
• Saccadic eye movements are the most investigated eye movement in sports-related concussion literature where the need for a sideline tool to objectively detect impairment due to mTBI has been recognized.
• Studies used the King-Devick (K-D) Test to examine the effect of mTBI on saccadic eye movements.
• The K-D Test requires very minimal setup or administrator training and is typically administered in less than 2 minutes.
• A high degree of test-retest reliability using inter-class correlation is reported with the K-D Test in relation to investigating head trauma.
• The K-D Test measures saccadic reaction time which has been shown to be slowed following mTBI (as compared with controls) in eye tracking studies.
• Results from all sports-related studies reviewed indicate that performance on the K-D Test was significantly slowed following concussion compared with preinjury baseline performance.
• Test scores improved to baseline levels (pre-concussion) within 2 to 3 weeks post-injury.
• Multiple oculomotor and cognitive skills are used to complete the K-D Test. Abnormalities in test performance are not specific to saccades and may be reflective of impairment in other oculomotor (eg. vergence, accommodation) and cognitive functions (eg. attention).

Sports-related concussion is a change in brain function following a direct or an indirect force to the head, identified in awake individuals and accounting for a considerable proportion of mild traumatic brain injury. Although the neurological signs and symptoms of concussion can be subtle and transient, there can be persistent sequelae, such as impaired attention and balance that make affected patients particularly vulnerable to further injury. Currently, there is no accepted definition or diagnostic criteria for concussion, and there is no single assessment that is accepted as capable of identifying all patients with concussion. In this paper, the authors review the available screening tools for concussion, with particular emphasis on the role of visual function testing. In particular, they discuss the oculomotor assessment tools that are being investigated in the setting of concussion screening.

Summary Points:

• K-D Test is an assessment of visual function and integrity of attention.
• Healthy athletes tend to improve on K-D Test performance with repeated testing and following exercise.
• Any decline in performance (an increase in score time) compared with baseline testing is indicative of a concussion.
• K-D Test is an ideal sideline test since it takes less than 1–2 minutes to complete and can be administered by nonmedical personnel such as parents or coaches.
• Current evidence suggests that the K-D Test can serve as a complementary test to sideline concussion testing to increase the sensitivity.
• Ideally, a sideline screening assessment should be standardized, cost-effective, and able to be administered by nonmedical personnel, so that it is practical in both youth and high-school athletics, as well as collegiate and professional sports.

Mild head injury such as concussions and subconcussive repetitive impact may lead to subtle changes in brain function and it is imperative to find sensitive and reliable tests to detect such changes. Tests involving the visual system, in particular eye movements, can incorporate higher cortical functioning and involve diffuse pathways in the brain, including many areas susceptible to head impact. With concussions, the clinical neuro-ophthalmic exam is important for detecting abnormalities in vergence, saccades, pursuit, and visual fixation. On the sidelines, the King–Devick test has been used as a visual performance measure that incorporates eye movements and increases the sensitivity in detecting possible concussions in conjunction with standard sideline tests of cognition, symptom checklists, and balance. Much promise lies in the eye movement laboratory to quantitate changes in saccades and pursuit with concussions using video-oculography. A combination of eye movement tasks coupled with neuroimaging techniques and other objective biomarkers may lead to a better understanding of the anatomical and physiological consequences of concussion and to better understand the natural history of this condition.

Summary Points:

• The K-D Test provides a rapid, reliable, and objective assessment.
• Performing the K–D Test involves saccades, attention, and language, and therefore evaluates diffuse networks in the brain, including the networks for saccade generation in the brainstem, cerebellum, and areas of the cerebral cortex such as the DLPC, frontal eye fields, supplementary motor area, and parietal lobes.
• Worsening from baseline is consistent with the diagnosis of concussion, since in healthy athletes the scores typically improve with practice and are not adversely affected by physical activity.
• In a meta-analysis of 15 studies evaluating the ability of the K–D Test to detect concussions in a variety of sports including hockey, lacrosse, football, basketball, soccer, boxing, and rugby, the K–D Test was found to have a sensitivity of 86% and a specificity of 90%.
• Multiple lines of evidence have emerged to show that the K–D Test, is sensitive and specific in detecting concussions on the sidelines and complements tests of balance and the SAC.

Objective: The objective of this paper is to review existing literature surrounding the utility of the King-Devick Test which is a commonly used sideline assessment tool for sport-related concussions.

Methods: A review of the literature was performed using MEDLINE, CINHAL, and SportDiscus databases. The search was performed from the beginning of the record through November 16th, 2015.

Results: This search strategy yielded 27 articles from aforementioned databases. Further searching in The Cochrane Library with King-Devick AND Concuss* search terms yielded one additional article, summing a total of 28 articles. After removal of duplicates and implementation of the inclusion/exclusion criteria, 8 articles for extensively reviewed.

Conclusion: This narrative review suggests that the King-Devick test is an efficient sideline assessment tool for sport-related concussions. However, we recommend that the King-Devick should be used as a sideline screening tool, not a concussion diagnosis tool at this time. A proper baseline time including multiple tests may be recommended to negate the learning affect and to have a reliable baseline in which to measure from for future reference. A three second difference appears appropriate to identify the possibility of concussion and to remove an athlete from play. At this time, the athlete should be monitored and further evaluated as symptoms are sometimes delayed. We suggest that further research may be useful to better determine the efficacy of the K-D test in detecting concussions across a broader range of athletes and sports. We also suggest further research may investigate the K-D test a potential return-to-play tool for clinicians and medical personnel.

Summary Points:

• This review supports the use of the King-Devick test as an efficient sideline assessment tool for sport-related concussions
• Successful identification of concussions and appropriate subsequent management will lead to a reduced risk of a secondary concussion and long-term neurological complications

Sports-related concussions are an increasingly recognized public health problem and may have serious neurologic implications for athletes. The vision-based King-Devick (K-D) test of rapid number naming has become an important tool to screen for concussion in athletes on the sidelines. In recent years there has been a shift towards using a computerized tablet version of the K-D and although there are several studies demonstrating its utility in screening for concussion, there is limited data directly comparing the two versions. Therefore, the purpose of this investigation was to measure levels of agreement and quantify the relative differences in baseline scores between the spiral-bound and computerized tablet versions of the K-D test. We recruited 85 participants into the study and administered both K-D test versions to each participant. There was excellent agreement (ICC=0.92, 95% CI: 0.82, 0.96) and strong linear correlation(r=0.94) between the two versions. However, the tablet version had a significantly longer mean pre-season baseline time compared to the spiral version (52.3 seconds vs. 48.6 seconds, p<0.001, paired t-test). A difference of 3.7 seconds between the two test modalities may be clinically significant since acutely concussed athletes in published studies and meta-analyses show average increases of 4 to 6 seconds in the K-D test time from baseline. Therefore, the two K-D test versions have excellent agreement suggesting that the tablet version should also be good predictor of concussion. However, alternating between the tablet and spiral versions of the K-D test may be inaccurate when screening for concussion during sideline testing.

Summary Points:

• The tablet and spiral bound K-D Test showed excellent agreement.
• The tablet version of the K-D Test is good predictor of concussion.

Users should not alternate between tablet and spiral versions of the K-D test.

Concussion may lead to subtle changes in brain function, and tests involving the visual system probe higher cortical functioning and increase our sensitivity in detecting these changes. Concussions are acutely and sometimes more persistently associated with abnormalities in balance, cognition, and vision. The visual system involves roughly half of the brain’s circuits, including many regions susceptible to head impacts. After a concussion, the neuro-ophthalmologic exam commonly detects abnormalities in convergence, accommodation, the vestibulo-ocular reflex, ocular muscle balance, saccades, and pursuit. The King-Devick (K-D) test is a visual performance measure that may increase the sensitivity of detecting concussions on the sideline when used in combination with tests of cognition and balance that are part of the Sports Concussion Assessment Tool (3rd ed.; SCAT3). Portable eye movement trackers and pupillometry may in the future improve our neuro-ophthalmic assessment after concussions. Combining visual tasks with neuroimaging and neurophysiology has allowed subtle changes to be detected, may refine our ability to make appropriate return-to-play decisions, and could potentially determine susceptibility to long-term sequelae of concussion.

Summary Points:

• Given that about half the brain’s circuits are involved in vision, it is not surprising that concussions often involve injury to visual pathways. Additionally, post-concussive visual symptoms are common.
• The K-D Test is a measure of eye movement performance that provides an objective outcome.
• Rapid number naming requires saccades, attention, and language, as well as other areas of the brain required for reading. Therefore the K-D Test evaluates brainstem, cerebellum, and cerebral cortex functioning.
• The K-D Test has been studied in youth, collegiate, and professional sports and tested among concussed and non-concussed athletes. It has been found that there is a 5- to 7-second increase in post-injury K-D Test scores compared with the individual’s baseline.
• The most commonly used sideline tests such as the SAC and BESS do not assess eye movements. The K-D Test provides a visual assessment post-injury and, when used in combination with the SAC and BESS, increases the sensitivity for identifying potential concussions.
• The K-D Test has the greatest capacity to distinguish those who sustained concussion versus controls when compared with a timed tandem-gait test and the SAC.

Tests involving the visual system can probe higher cognitive functioning and can increase our ability to detect subtle changes associated with brain injury.

Background: Concussion, particularly in relation to sports and combat activities, is increasingly recognized as a potential cause of both short- and long-term neurologic sequelae. This review will focus on the neuro-ophthalmologic findings associated with concussion, the current tests for concussion, and the potential for visual performance measures to improve our detection and assessment of concussions.

Evidence Acquisition: A PubMed search using the specific key words “concussion,” “mild traumatic brain injury,” “neuro-ophthalmological findings,” and “diagnostic and management tests” was performed. An emphasis was placed on articles published during the past 5 years, but additional articles referenced within recent publications were obtained.

Results: Concussion is frequently associated with abnormalities of saccades, pursuit eye movements, convergence, accommodation, and the vestibular-ocular reflex. Current sideline testing for athletes includes the Sports Concussion Assessment Tool, Third Edition (SCAT3) incorporates cognitive and balance testing. The King-Devick (K-D) test is a rapid visual performance measures that can be used on sidelines by nonmedical personnel, including parents of youth athletes. The K-D test complements components of the SCAT3 and improves the detection of concussions. Other vision-based tools for diagnosing and for managing concussion include eye movement tracking devices, pupillary assessment, computerized testing, imaging modalities, and eletrophysiologic testing. Many of the imaging modalities and electrophysiological studies have been combined with vision-based tests.

Conclusions: Concussion is associated with many neuro-ophthalmologic signs and symptoms. Visual performance measures enhance the detection and management of concussion, and future studies are under way to further incorporate vision-based testing into sideline diagnosis and long-term clinical assessments.

Summary Points:

• Patients with post-concussion syndrome demonstrate saccadic dysfunction.
• 60% of patients with a mild traumatic brain injury (mTBI) have abnormal pursuits or smooth eye movements.
• Studies of MMA fighters, boxers, collegiate athletes, professional hockey players, and rugby players score an average 5 to 7 seconds longer on the K-D Test of rapid number naming immediately after a concussive event compared to their baseline scores (pre-season or pre-fight scores).
• Adding the K-D Test to concussion screening, along with BESS and SAC, detected 100% of athletes with concussions, whereas BESS and SAC alone failed to flag 10% of the concussed athletes.

Traumatic brain injury (TBI) is a major cause of morbidity and mortality. Concussion, a form of mild TBI, might be associated with long-term neurological symptoms. The effects of TBI and concussion are not restricted to cognition and balance. TBI can also affect multiple aspects of vision; mild TBI frequently leads to disruptions in visual functioning, while moderate or severe TBI often causes structural lesions. In patients with mild TBI, there might be abnormalities in saccades, pursuit, convergence, accommodation, and vestibulo-ocular reflex. Moderate and severe TBI might additionally lead to ocular motor palsies, optic neuropathies, and orbital pathologies. Vision-based testing is vital in the management of all forms of TBI and provides a sensitive approach for sideline or post-injury concussion screening. One sideline test, the King-Devick test, uses rapid number naming and has been tested in multiple athlete cohorts.

Summary Points:

• Areas of the brain that control eye movements are vulnerable to trauma, therefore, mild TBI (or concussions) often lead to visual symptoms and clinical signs, which need specific evaluation.
• Common consequences of mild TBI include deficits in eye movements, executive function, visual attention, and visual memory.
• The K-D Test evaluates eye movements (saccades), attention, and language and provides a sensitive test for concussion screenings.

Background: Sport-related concussions are a subset of mild traumatic brain injuries and are a concern for many sporting activities worldwide.

Objective: To review and update the literature in regard to the history, pathophysiology, recognition, assessment, management and knowledge of concussion.

Methods: Searches of electronic literature databases were performed to identify studies published up until April 2013.

Results: 292 publications focusing on concussion met the inclusion criteria, and so they were quality rated and reviewed.

Conclusion: Concussion is hard to recognize and diagnose. Initial sideline assessment via the Sports Concussion Assessment Tool 3 (SCAT3), Child-SCAT3 or King-Devick Test should be undertaken to identify athletes with concussion as part of a continuum of assessment modalities and athlete management. Sports medicine practitioners should be cognizant of the definition, extent and nature of concussion, and should work with coaches, athletes and trainers to identify and manage concussions. The most common reason for variations in management of concussion is lack of awareness of—and confusion about—the many available published guidelines for concussion. Future research should focus on better systems and tools for recognition, assessment and management of concussion. Sport participants’ knowledge of concussion should be evaluated more rigorously, with interventions for sports where there is little knowledge of recognition, assessment and appropriate management of concussion.

Summary Points:

• Review of literature exploring concussion history, pathophysiology, recognition, assessment, and management.
• Signs of concussion including loss of consciousness, amnesia, focal neurological abnormalities are often not present, which is why sideline tests including the SCAT3 and King-Devick Test should be used to identify athletes with concussion who have less obvious signs and symptoms.
• Oculomotor function incorporates multiple sensory areas and frequently affected in mild concussion cases.
• Multiple individual measures should be used to determine when an athlete may return to play. Symptom assessment, neurocognitive function, and oculomotor testing may be used to monitor recovery and progress.

The King-Devick Test is designed to assess saccadic eye movements, measuring the speed of rapid number naming as well as errors made by the athlete, with the goal of detecting impairments of eye movement, attention, and language as well as impairments in other areas that would be indicative of suboptimal brain function (Galetta et al. 2011). The King-Devick Test includes a demonstration and three test cards with rows of single-digit numbers that are read aloud from left to right. The participant is asked to read the numbers as quickly as possible without making any errors. The administrator records the total time to complete the three cards and the total number of errors made during the test. The results are compared to a personal baseline. The King-Devick Test usually takes approximately 2 minutes to complete and can be administered on either an iPad or hardcopy (King-Devick, 2013). Such tools as well as balance tests may be used either by trained responders as part of an acute sideline or in-field assessment or by health care providers during subsequent clinical evaluation.

Summary Points:

• The K-D Test is a clinical tool in concussion management that is easy to administer in less than 2 minutes.
• K-D Test assesses oculomotor ability, rapid number naming, visual attention, and language, which gives insight into neurological pathways controlling these skills, which are often negatively impacted following a head trauma.
• K-D Test can be used by trained responders during an acute sideline assessment and healthcare providers in clinical evaluation.

The need for sideline rapid assessment of mild head injury is fundamental to limiting the deleterious effects of repeated impacts to the head. The great majority of athletes are at the youth sports level and not in collegiate or professional sports, which leaves many important decisions to be made by parents and coaches on the sideline. This structural element of sport is unlikely to change since allocating medically trained people to youth sports will require unavailable financial resources. Accordingly, empowering adults to administer a simple, rapid, yet effective test is paramount to preventing repeated head injury. As increasing evidence suggests that even mild impact to the head can lead to accruing neuropathology, it may be prudent to routinely perform sideline testing for players involved in even modest collisions. This could help avoid return to play of athletes with sub-concussive impacts as knowledge about head injury continues to evolve.

Summary Points:

• Sideline tools are necessary in order to detect concussions in amateur league and youth sports.
• 37 rugby players were administered the K-D Test prior to the start of the matches, after each match, and instances of any head trauma during a match. There were 5 witnessed concussions and 17 unrecognized concussions, which were all identified with poorer performance on the post-injury K-D Test.
• Physical fatigue did not worsen K-D scores therefore it is a reliable test to administer after intense physical exercise.
• The K-D Test is a reliable, repeatable, rapid sideline tool that may be administered by lay persons.

Due to the recent focus on concussion in sports, a number of tests have been developed to diagnose and manage concussion. While each test measures different brain functions, no single test has been shown to quickly and reliably assess concussion in all cases. In addition, most of the current concussion tests have not been validated by scientific investigation. This review identifies the pros and cons of the most commonly used noninvasive tests for concussion in order to provide a more complete picture of the resources that are available for concussion testing. The potential utility of research tools such as the head impact telemetry system, advanced magnetic resonance imaging protocols, and biomarkers are discussed in the context of the currently employed tools.

“The King–Devick (K–D) Test is a rapid number naming test that captures impaired eye movements and saccades, attention, and language. These involve integration of functions of the brainstem, cerebellum, and cerebral cortex. Impaired eye movements and saccades have been shown to correlate with suboptimal brain function, particularly in patients following concussion. Because the K–D test does not require a medical professional and can be administered in 1–2 min, it is practical for sideline use at all levels of sports.”

Summary Points:

• The K-D Test is a fast, easy to administer, sideline screening tool which assesses > 50% of brain pathways in 1-2 minutes.
• K-D Test involves integration of multiple areas of the brain including the brainstem, cerebellum, and cerebral cortex.
• K-D Test can be administered by non-medical professionals.