The King-Devick test of rapid number naming for concussion detection: meta-analysis and systematic review of the literature

Vision encompasses a large component of the brain’s pathways, yet is not represented in current sideline testing.

We performed a meta-analysis of published data for a vision-based test of rapid number naming (King-Devick [K-D] test).

Studies & Methods
Pooled and meta-analysis of 15 studies estimated preseason baseline K-D scores and sensitivity/specificity for identifying concussed versus non-concussed control athletes.

Baseline K-D (n = 1419) showed a weighted estimate of 43.8 s (95% CI: 40.2, 47.5; I2 = 0.0%; p = 0.85 – indicating very little heterogeneity). Sensitivity was 86% (96/112 concussed athletes had K-D worsening; 95% CI: 78%, 92%); specificity was 90% (181/202 controls had no worsening; 95% CI: 85%, 93%).

Rapid number naming adds to sideline assessment and contributes a critical dimension of vision to sports-related concussion testing.

Further Reading: Read the whole study at Concussion

Concussion in Ice Hockey: Current Gaps and Future Directions in an Objective Diagnosis


This review provides an update on sport-related concussion (SRC) in ice hockey and makes a case for changes in clinical concussion evaluation. Standard practice should require that concussions be objectively diagnosed and provide quantitative measures of the concussion injury that will serve as a platform for future evidence-based treatment.


The literature was surveyed to address several concussion-related topics: research in ice hockey-related head trauma, current subjective diagnosis, promising components of an objective diagnosis, and current and potential treatments.

Main Results:

Sport-related head trauma has marked physiologic, pathologic, and psychological consequences for athletes. Although animal models have been used to simulate head trauma for pharmacologic testing, the current diagnosis and subsequent treatment in athletes still rely on an athlete’s motivation to report or deny
symptoms. Bias-free, objective diagnostic measures are needed to guide quantification of concussion severity and assessment of treatment effects. Most of the knowledge and management guidelines of
concussion in ice hockey are generalizable to other contact sports.


There is a need for an objective diagnosis of SRC that will quantify severity, establish a prognosis, and provide effective evidence-based treatment. Potential methods to improve concussion diagnosis by health care providers include a standardized concussion survey, the King–Devick test, a quantified electroencephalogram and blood analysis for brain cell-specific biomarkers.

Further Reading: Read the whole study at Clinical Journal Of Sport Medicine

The Concussion Toolbox: The Role of Vision in the Assessment of Concussion

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.

Further Reading: Read the whole study at Seminars in Neurology

Use of the King-Devick Test for sideline concussion screening in junior rugby league

To determine whether the King-Devick (K-D) test used as a sideline test in junior rugby league players over 12
matches in a domestic competition season could identify witnessed and incidentally identified episodes of concussion

A prospective observational cohort study of a club level junior rugby league team (n=19) during the 2014 New
Zealand competition season involved every player completing two pre-competition season baseline trials of the K-D test.
Players removed from match participation, or who reported any signs or symptoms of concussion were assessed on the
sideline with the K-D test and referred for further medical assessment. Players with a pre- to post-match K-D test
difference >3 s were referred for physician evaluation.

The baseline test-retest reliability of the K-D test was high (rs=0.86; p<0.0001). Seven concussions were
medically identified in six players who recorded pre to post-match K-D test times greater than 3 s (mean change of 7.4 s).
Post-season testing of players demonstrated improvement of K-D time scores consistent with learning effects of using the
K-D test (67.7 s vs 62.2 s).

Although no witnessed concussions occurred during rugby play, six players recorded pre to post-match
changes with a mean delay of 4 s resulting in seven concussions being subsequently confirmed post-match by health
practitioners. All players were medically managed for a return to sports participation.

The K-D test was quickly and easily administered making it a practical sideline tool as part of the continuum
of concussion assessment tools for junior rugby league players.

Further Reading: Read the whole study at Journal of the Neurological Sciences

Evaluation of the King-Devick Test as a concussion screening tool in high school football players

Concussion is the most common type of traumatic brain injury, and results from impact or impulsive forces to
the head, neck or face. Due to the variability and subtlety of symptoms, concussions may go unrecognized or be ignored,
especially with the pressure placed on athletes to return to competition. The King-Devick (KD) test, an oculomotor test
originally designed for reading evaluation, was recently validated as a concussion screening tool in collegiate athletes. A
prospective study was performed using high school football players in an attempt to study the KD as a concussion
screening tool in this younger population.

343 athletes from four local high school football teams were recruited to participate. These athletes were given
baseline KD tests prior to competition. Individual demographic information was collected on the subjects. Standard team
protocol was employed to determine if a concussion had occurred during competition. Immediately after diagnosis, the
KD test was re-administered to the concussed athlete for comparison to baseline. Post-season testing was also performed
in non-concussed individuals.

Of the 343 athletes, nine were diagnosed with concussions. In all concussed players, cumulative read times for
the KD test were significantly increased (p < 0.001). Post-season testing of non-concussed athletes revealed minimal
change in read times relative to baseline. Univariate analysis revealed that history of concussion was the only
demographic factor predictive of concussion in this cohort.

The KD test is an accurate and easily administered sideline screening tool for concussion in adolescent
football players.

Further Reading: Read the whole study at Journal of the Neurological Sciences

Gender and age predict outcomes of cognitive, balance and vision testing in a multidisciplinary concussion center

This study examined components of the Sports Concussion Assessment Tool, 3rd Edition (SCAT3) and a vision-based test of rapid number naming (King–Devick [K-D]) to evaluate sports and non-sports concussion patients in an outpatient, multidisciplinary concussion center. While the Symptom Evaluation, Standardized Assessment of Concussion (SAC), modified Balance Error Scoring System (BESS), and K-D are used typically for sideline assessment, their use in an outpatient clinical setting following concussion has not been widely investigated.

K-D, BESS, SAC, and SCAT3 Symptom Evaluation scores were analyzed for 206 patients who received concussion care at the Concussion Center at NYU Langone Medical Center. Patient age, gender, referral data, mechanism of injury, time between concussive event and first concussion center appointment, and the first specialty service to evaluate each patient were also analyzed.

In this cohort, Symptom Evaluation scores showed a higher severity and a greater number of symptoms to be associated with older age (r = 0.31, P = 0.002), female gender (P = 0.002, t-test), and longer time between the concussion event and first appointment at the concussion center (r = 0.34, P = 0.008). Performance measures of K-D and BESS also showed associations of worse scores with increasing patient age (r = 0.32–0.54, P ≤ 0.001), but were similar among males and females and across the spectrum of duration since the concussion event. Patients with greater Symptom Severity Scores also had the greatest numbers of referrals to specialty services in the concussion center (r = 0.33, P = 0.0008). Worse Immediate Memory scores on SAC testing correlated with slower K-D times, potentially implicating the dorsolateral prefrontal cortex as a commonly involved brain structure.

This study demonstrates a novel use of sideline concussion assessment tools for evaluation in the outpatient setting, and implicates age and gender as predictors of outcomes for these tests.

Further Reading: Read the whole study at Journal of the Neurological Sciences

Adding vision to concussion testing: A prospective study of sideline testing in youth and collegiate athletes

Sports-related concussion commonly affects the visual pathways. Current sideline protocols test cognition and balance, but do not include assessments of visual performance. We investigated how adding a vision-based test of rapid number naming could increase our ability to identify concussed athletes on the sideline at youth and collegiate levels.

Participants in this prospective study included members of a youth ice hockey and lacrosse league and collegiate athletes from New York University (NYU) and Long Island University (LIU). Athletes underwent pre-season baseline assessments using 1) the King-Devick (K-D) test, a <2-minute visual performance measure of rapid number naming; 2) the Standardized Assessment of Concussion (SAC), a test of cognition; 3) a timed tandem-gait test of balance. The SAC and timed tandem-gait are components of the currently used Sport-Concussion Assessment Tool, 3rd Edition (SCAT3 and Child-SCAT3). In the event of a concussion during the athletic season, injured athletes were re-tested on the sideline/ rink-side. Non-concussed athletes were also assessed as control participants under the same testing conditions.

Among 243 youth (mean age 11±3 years, range 5-17) and 89 collegiate athletes (age 20±1 years, range 18-23), baseline time scores for the K-D test were lower (better) with increasing participant age (p<0.001, linear regression models). Among 12 athletes who sustained concussions during their athletic season, K-D scores worsened from baseline by an average of 5.2 seconds; improvement by 6.4 seconds was noted for the non-concussed controls (n=14). The vision- based K-D test showed the greatest capacity to distinguish concussed vs. control athletes based on changes from pre- season baseline to post-injury (ROC curve areas from logistic regression models, accounting for age=0.92 for K-D, 0.87 for timed tandem gait, and 0.68 for SAC; p=0.0004 for comparison of ROC curve areas).

Adding a vision-based performance measure to cognitive and balance testing enhances the detection capabilities of current sideline concussion assessment. This observation in mild traumatic brain injury patients reflects the common involvement and widespread distribution of the brain pathways dedicated to vision.

Further Reading: Read the whole study at The Journal of Neuro-Ophthalmology

The King-Devick test was useful in management of concussion in amateur rugby union and rugby league in New Zealand

To use the King-Devick (K-D) test in senior amateur rugby union and rugby league players over a domestic competition season to see if it could identify witnessed and unwitnessed episodes of concussion that occurred from participation in competition matches over three years.

A prospective observational cohort study was conducted on a club level senior amateur rugby union team (n=36 players in 2012 and 35 players in 2013) and a rugby league team (n=33 players in 2014) during competition seasons in New Zealand. All 104 players completed two trials 10 minutes apart of the K-D at the beginning of their competition season. Concussions (witnessed or unwitnessed) were only recorded if they were formally diagnosed by a health practitioner.

A total of 52 (8 witnessed; 44 unwitnessed) concussive events were identified over the duration of the study resulting in a concussion injury incidence of 44 (95% CI: 32 to 56) per 1,000 match participation hours. There was a six-fold difference between witnessed and unwitnessed concussions recorded. There were observable learning effects observed between the first and second K-D test baseline testing (50 vs. 45 s; z=-8.81; p<0.001). For every 1 point reduction in each of the post-injury SAC components there was a corresponding increase (worsening) of K-D test times post-match for changes in orientation (2.9 s), immediate memory (1.8 s) concentration (2.8 s), delayed recall (2.0 s) and SAC total score (1.7 s).

The rate of undetected concussion was higher than detected concussions by using the K-D test routinely following matches. Worsening of the K-D test post-match was associated with reduction in components of the SAC. The appeal of the K-D test is in the rapid, easy manner of its administration and the reliable, objective results it provides to the administrator. The K-D test helped identify cognitive impairment in players without clinically observable symptoms.

Further Reading: Read the whole study at Journal of the Neurological Sciences

Diagnostic tests for concussion: is vision part of the puzzle?

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.

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.

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.

Further Reading: Read the whole study at The Journal of Neuro-Ophthalmology

The Neuro-ophthalmology of Head Trauma

Lancet Neurol. 2014 Oct;13(10):1006-1016. doi: 10.1016/S1474-4422(14)70111-5.

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.

Further Reading:
Read the Whole Study at The Lancet Neurology

King-Devick Test® (K-D Test®) All rights reserved. Copyrighted. ©1983, 2010-2017, Patents-Pending. Mayo and Mayo Clinic are registered trademarks owned by Mayo Foundation for Medical Education and Research. Two Mid America Plaza, Suite 110, Oakbrook Terrace, IL 60181. King-Devick Test is for screening purposes only and any suspicion or indication of head trauma should be evaluated by a licensed professional.