The King-Devick test in an outpatient concussion clinic: Assessing the diagnostic and prognostic value of a vision test in conjunction with exercise testing among acutely concussed adolescents

Assessing Brain Processing Deficits Using Neuropsychological and Vision-Specific Tests for Concussion

INTRODUCTION

Since verbal memory and visual processing transpire within analogous cerebral regions, this study assessed (i) if a visual function can predict verbal memory performance. It also hypothesized whether neurocognitive (e.g., ImPACT) tests focusing on the Visual Memory and Cognitive Efficacy Index will predict Verbal Memory scores and (ii) if vision metrics and age can identify individuals with a history of concussion. Finally, it also hypothesized that King-Devick and near point of convergence scores alongside age considerations will identify candidates with a prior reported history of concussion.

MATERIALS AND METHODS

This observational cohort assessed 25 collegiate ice hockey players prior to the competitive season considering age (19.76 ± 1.42 years) and BMI (25.9 ± 3.0 kg/cm2). Hypothesis 1 was assessed using a hierarchical (sequential) multiple regression analysis, assessing the predictive capacity of Visual Memory and Cognitive Efficacy Index scores in relation to Verbal Memory scores. Hypothesis 2 utilized a binomial logistic regression to determine if King-Devick and near point of convergence scores predict those with a prior history of concussion.

RESULTS

Hypothesis 1 developed two models, where Model 1 included Visual Memory as the predictor, while Model 2 added the Cognitive Efficacy Index as a predictor for verbal memory scores. Model 1 significantly explained 41% of the variance. Results from Model 2 suggest that the Cognitive Efficacy Index explained an additional 24.4%. Thus, Model 2 was interpreted where only the Cognitive Efficacy Index was a significant predictor (p = 0.001). For every 1 unit increase in the Cognitive Efficacy Index, Verbal Memory increased by 41.16. Hypothesis 2's model was significant, accounting for 37.9% of the variance in those with a history of concussion. However, there were no significant unique predictors within the model as age (Wald = 1.26, p = 0.261), King-Devick (Wald = 2.31, p = 0.128), and near point of convergence (Wald = 2.43, p = 0.119) were not significant predictors individually.

CONCLUSIONS

The conflicting findings of this study indicate that baseline data for those with a history of concussion greater than one year may not be comparable to the same metrics during acute concussion episodes. Young athletes who sustain a concussion may be able to overcompensate via the visual system. Future prospective studies with larger sample sizes are required using the proposed model's objective metrics.

Multisystem recovery after sport-related concussion in adolescent rugby players: a prospective study protocol

INTRODUCTION

Sport-related concussion is one of the most common injuries in adolescent rugby players with evidence of prolonged recovery in some concussed athletes. Concussion is a complex pathophysiological process that can affect a variety of subsystems with multifactorial presentation. Most research on adolescents recovery after concussion focuses on neurocognitive functioning and symptom outcomes over the short term. There is a need to explore concussion recovery over time across multiple subsystems in adolescent rugby players.

METHODS AND ANALYSIS

This prospective study will use sensorimotor and oculomotor outcomes in adolescent male and female rugby players aged 16-18 years. Players will be recruited from school or club rugby teams across the province of Ulster. Baseline assessment will be undertaken at the start of the playing season and will include questionnaires, Quantified Y Balance Test and Pupillary Light Reflex. Players who sustain a concussive event will be reassessed on all outcomes at 3 days, 7 days, 14 days, 23 days, 90 days, 180 days and 365 days postconcussion. For serial outcome data, we will examine response curves for each participant and make comparisons between known groups. We will use logistic regression to explore any association between demographic variables and recovery. The strength of the predictive model will be determined using R2, p values and ORs, with 95% CIs.

ETHICS AND DISSEMINATION

Ethical approval has been granted for this study from Ulster University Research Ethics Committee (REC/14/0060). This study will be published in an open-access research journal on completion.

TRIAL REGISTRATION NUMBER

ACTRN12622000931774p.

Exercise-Induced Vision Dysfunction Early After Sport-Related Concussion Is Associated With Persistent Postconcussive Symptoms

OBJECTIVE

The purpose of this study was to determine if exercise-induced vision dysfunction [reduced performance and/or symptom exacerbation on a post-exercise King-Devick (KD) test] in adolescents early after sport-related concussion was associated with increased risk of persistent post-concussive symptoms (PPCS, recovery >28 days). We used exercise as a provocative maneuver before the KD test, hypothesizing that concussed adolescents with exercise-induced vision dysfunction would be more likely to develop PPCS.

DESIGN

Secondary analysis of data from a multi-center, randomized clinical trial comparing KD test performance before and after the Buffalo Concussion Treadmill Test in adolescents within 10 days of sport-related concussion who were randomized to aerobic exercise or placebo stretching program.

SETTING

Three university-associated sports medicine clinical programs.

PARTICIPANTS

Ninety-nine adolescents with sport-related concussion (exercise group: n = 50, 15.3 ± 1 years, 60% M, 22% with PPCS; stretching group: n = 49, 15.9 ± 1 years, 65% M, 35% with PPCS) tested a mean of 6 ± 2 days from injury.

INDEPENDENT VARIABLE

King-Devick test performed immediately before and 2 minutes after Buffalo Concussion Treadmill Test.

MAIN OUTCOME MEASURE

Persistent post-concussive symptoms.

RESULTS

Adolescents who demonstrated exercise-induced vision dysfunction upon initial evaluation developed PPCS at a significantly greater rate when compared with adolescents who did not (71% vs 34%, P < 0.001). Exercise-induced vision dysfunction corresponded to a relative risk of 3.13 for PPCS.

CONCLUSIONS

Adolescents with exercise-induced vision dysfunction had a 3-fold greater relative risk of developing PPCS than those without exercise-induced vision dysfunction.

Norm-Based Cutoffs as Predictors of Prolonged Recovery After Adolescent Sport-Related Concussion

OBJECTIVES

To identify predictors of prolonged recovery (ie, >28 days) using patient demographic factors and healthy, norm-based cutoffs on a multimodal test battery in adolescents after sport-related concussions (SRCs).

DESIGN

Retrospective cohort. Patients were deemed recovered after successful completion of return-to-play/school protocols and received medical clearance.

SETTING

Community concussion clinic.

PATIENTS

Male and female adolescent student athletes diagnosed with a SRC and evaluated within 1 week of injury.

INDEPENDENT VARIABLES

Patient demographics, medical history, injury description, computerized neurocognitive testing, vestibular/ocular testing, and symptoms at initial clinical visit.

MAIN OUTCOME MEASURES

Performance on clinical testing to predict recovery duration, classified as normal (<28 days) or prolonged (>28 days).

RESULTS

A total of 201 adolescent student athletes (age = 15.3 ± 1.4 years) were included (female 35%). Average recovery duration for the entire cohort was 22.3 ± 13.3 days, with 22% (n = 45) of adolescent student athletes taking >28 days to recover. The final model was 88.3% accurate in classifying normal and prolonged recovery. Predictor variables included sex, loss of consciousness, history of ocular disorder, history of concussion, performance on visual motor speed composite, visual motion sensitivity symptom provocation and near point of convergence distance, number-naming total time, and symptom count.

CONCLUSIONS

These findings suggest that using norm-based cutoffs from cognitive, oculomotor, and vestibulo-ocular testing and symptom reporting, clinicians can accurately predict a prolonged recovery (sensitivity = 81%) and normal recovery (specificity = 83%) in an adolescent, SRC cohort.

Clinical Outcome Following Sport-Related Concussion Among Children and Adolescents with a History of Prior Concussion: A Systematic Review

Authoritative sources advise clinicians and parents that a history of prior concussion confers increased risk for worse outcome from a future concussion. However, the strength of the evidence supporting such pronouncements and thus the extent to which clinicians should incorporate this information into their care and management of pediatric concussion is unclear. This systematic review critically analyzed and synthesized the literature on the association between a history of prior concussion and prognosis/clinical outcome following a subsequent sport-related concussion among children and adolescents. The online databases PubMed, MEDLINE®, PsycINFO®, CINAHL, Cochrane Library, EMBASE, SPORTDiscus, Scopus, and Web of Science were searched from inception to May 15, 2021. From 5,118 total records screened, 51 studies (46 cohort studies and 5 case-control studies) met inclusion criteria, reporting concussion recovery or outcome for 26,643 youth. A median of 36% had a prior history of concussion. Across all studies and outcomes, the majority (k=37, 72.5%) did not find a statistically significant association between lifetime history of concussion and outcome from a subsequent concussion. Important methodological limitations in the literature were identified. Available studies do not provide consistent or compelling evidence that children and adolescents with a history of concussions are at increased risk for worse clinical outcome following a subsequent sport-related concussion-although methodological limitations temper the strength of this conclusion. Clinicians are cautioned against routinely treating children and adolescents with one or more prior injuries differently, and more conservatively, because doing so, in some cases, might be counterproductive.

Physical Activity Following Sport-Related Concussion in Adolescents: A Systematic Review

OBJECTIVE

To evaluate the evidence related to how physical activity (PA) affects recovery following a sport-related concussion (SRC) in adolescents.

DESIGN

Systematic review Data Source: PUBMED, MEDLINE, and SPORTDiscus Eligibility criteria for selecting study:(1) original research article (e.g., randomized controlled trials (RCT), quasi-experimental designs, cohort, case-control studies), (2) 66% or greater of the sample has to have a SRC diagnosed by a clinician, (4) human research, (5) evaluate the effect of a SRC on PA in adolescents only (<18 years). Participants were seen within 1-2 weeks post-SRC for acute studies and 4 weeks post-SRC for studies focused on prolonged recoveries.

RESULTS

Twenty-two studies met the inclusion criteria (i.e., 8 regarding PA (PA-daily aerobic activity including light-moderate intensities), 8 evaluating active rehabilitation/exercise programs (20 minutes of daily aerobic exercise below symptom threshold), 6 examining a single bout of exertion). The methodological quality of the literature was assessed using the Downs and Black risk of bias (ROB) checklist. The ROB scores ranged from 7-24, with only two RCTs included. Studies demonstrated single bouts of exertion testing were safe and feasible. Daily PA or active rehabilitation/exercise programs led to a reduction in symptoms present and a decrease in number of days to medical clearance.

CONCLUSION

Following a brief period of rest (24-48 hours), individuals can gradually and safely return to PA below their physical symptom exacerbation thresholds. Further research is warranted to delineate how to optimize the timing, intensity, duration, and modality of PA impacts symptom resolution and physiological recovery following SRC.

The acute, systemic effects of aerobic exercise in recently concussed adolescent student-athletes: preliminary findings

OBJECTIVES

Examine the acute effects (pre-, during, post-intervention) of two different intensities of aerobic exercise or rest on autonomic, oculomotor, and vestibular function and symptom burden in patients with a recent sport-related concussion (SRC) and compare their responses to sex-matched, age-stratified, non-concussed (HEALTHY) student-athletes.

METHODS

Student-athletes between the ages of 13 and 18 that presented to the sports medicine clinic within Day 3-7 post-SRC and from local schools were recruited for a randomized controlled trial (RCT). The participants were administered the Vestibular/Ocular Motor Screening (VOMS), King-Devick (K-D), and Post-Concussion Symptom Scale (PCSS) before and after the intervention. Heart rate variability (HRV) and mean arterial pressure (MAP) were collected before, during, and after the intervention. The intervention was either a single, 20-min session of treadmill walking at 40% (40HR) or 60% of age-predicted max heart rate (60HR), or seated, rest (NOEX).

RESULTS

30 participants completed the intervention with the SRC group treated 4.5 ± 1.3 days post-injury. Pre-exercise HRV and MAP were significantly different (p's < 0.001) during treatment but returned to pre-exercise values within 5 min of recovery in both the SRC and HEALTHY groups. Both the SRC and HEALTHY groups exhibited similar reductions pre- to post-intervention for symptom severity and count (p's < 0.05), three VOMS items (p's < 0.05) but not K-D time.

CONCLUSIONS

To date, this is the first adolescent RCT to report the acute, systemic effects of aerobic exercise on recently concussed adolescent athletes. The interventions appeared safe in SRC participants, were well-tolerated, and provided brief therapeutic benefit.

TRIAL REGISTRATION

Clinicaltrials.gov Identifier NCT03575455.

An investigation into the measurement properties of the King-Devick Eye Tracking system

Objectives

Eye tracking has been gaining increasing attention as a possible assessment and monitoring tool for concussion. The King-Devick test (K-DT) was expanded to include an infrared video-oculography-based eye tracker (K-D ET). Therefore, the aim was to provide evidence on the reliability of the K-D ET system under an exercise condition.

Methods

Participants (N = 61; 26 male, 35 female; age range 19-25) were allocated to an exercise or sedentary group. Both groups completed a baseline K-D ET measurement and then either two 10-min exercise or sedentary interventions with repeated K-D ET measurements between interventions.

Results

The test-retest reliability of the K-D ET ranged from good to excellent for the different variables measured. The mean ± SD of the differences for the total number of saccades was 1.04 ± 4.01 and there was an observable difference (p = 0.005) in the trial number. There were no observable differences for the intervention (p = 0.768), gender (p = 0.121) and trial (p = 0.777) for average saccade’s velocity. The mean ± SD of the difference of the total fixations before and after intervention across both trials was 1.04 ± 3.63 and there was an observable difference in the trial number (p = 0.025). The mean ± SD of the differences for the Inter-Saccadic Interval and the fixation polyarea before and after intervention across both trials were 1.86 ± 22.99 msec and 0.51 ± 59.11 mm2 and no observable differences for the intervention, gender and trial.

Conclusion

The results provide evidence on the reliability of the K-D ET, and the eye-tracking components and demonstrate the relationship between completion time and other variables of the K-D ET system. This is vital as the use of the K-DT may be increasing and the combination of the K-DT and eye tracking as one single package highlights the need to specifically measure the reliability of this combined unit.

Spotlight on the Developmental Eye Movement (DEM) Test

The developmental eye movement (DEM) test is a practical and simple method for assessing and quantifying ocular motor skills in children. In this review, a summary of the literature relevant to the DEM test has been made, its psychometric properties and its pros and cons have also been considered. The DEM test provides clinicians with a simple method of measuring eye movement using a psychometric test. Over the years, many studies have enabled the identification of the strengthens and weaknesses of this test apart from outlining the psychometric properties. The validity of the test has been checked and expanded over time and studies have shown that the DEM test measures an aspect of eye movement related to reading, rather than purely parameters associated with eye-movement. Some reservations have emerged regarding the repeatability of the test because a degree of learning effect emerges over multiple sessions. Being aware of this point allows correct clinical application and interpretation of the test. Normative data in children were available for nine languages and countries. So far, DEM test could be applied clinically in each case when a rapid test of eye movement was required, such as in testing for vision-related visual problems.

Rehabilitation of Sport-Related Concussion

This article provides a summary of clinical assessment methods and nonpharmacologic rehabilitation techniques used for concussed patients. It describes concussion-relevant physical examination methods to identify underlying symptom generators. This approach allows practitioners to prescribe targeted rehabilitation therapies to treat postconcussion symptoms. Evidence-based rehabilitation approaches include cervical rehabilitation, vestibulo-ocular rehabilitation, and sub-symptom threshold aerobic exercise.

Postexercise Slowing on the King-Devick Test and Longer Recovery From Sport-Related Concussion in Adolescents: A Validation Study

CONTEXT

The King-Devick (KD) test is a rapid number-reading test that has emerging use in the assessment of sport-related concussion (SRC). Previous research suggested that healthy individuals and patients with acute concussions who had shorter recovery times (<3 weeks) demonstrated a learning effect on the KD test after mild to moderate exertion, whereas patients with longer recovery times did not.

OBJECTIVE

To assess if the absence of postexertional improvement on the KD test within 10 days of concussive head injury was associated with a longer duration of recovery.

DESIGN

Prospective cohort study.

SETTING

University concussion-management clinics.

PATIENTS OR OTHER PARTICIPANTS

Male and female adolescent athletes (n = 99, aged 13-18 years) presenting within 10 days of SRC.

MAIN OUTCOME MEASURE(S)

The KD test was administered before and after the Buffalo Concussion Treadmill Test (BCTT). Days from injury to recovery, with recovery defined as being asymptomatic, confirmed by the assessment of a physician who was blinded to the treatment group, and the return of normal exercise tolerance on the BCTT were recorded.

RESULTS

Participants with postexertional slowing (PES group, n = 33) had a longer duration of recovery (17 days versus 13.5 days, P = .033) than participants without PES (no-PES group, n = 66). At any clinic visit, PES was also associated with a relative risk of 2.36 (95% confidence interval = 1.55, 3.61; P < .001) of not recovering within the following week.

CONCLUSIONS

The current study validates our prior work showing that acutely concussed adolescents who did not display the typical learning effect on the KD test after the BCTT took longer to recover from SRC than those who exhibited the typical learning effect.

On-field assessment of concussion: clinical utility of the King-Devick test

Sport-related concussion (SRC) is an important public health concern with up to 3.8 million SRCs occurring each year. As the incidence and rate of SRC increases, reliable and valid tools for diagnosis and management are needed. The King-Devick (K-D) test assesses a patient’s visual function based on reading a series of numbers as well as counting both time to completion and errors. Its rapid administration time and simplicity make the K-D test a potentially useful SRC diagnostic tool, though limitations exist in baseline testing and what constitutes an abnormal score. Additionally, the K-D tests should never be used in isolation to diagnose a concussion, but rather as one test in conjunction with additional clinical measures, as part of an individualized approach to each patient. The current review examines the clinical utility of the K-D test.