MULES on the sidelines: A vision-based assessment tool for sports-related concussion

Optimal Diagnostic Strategies for Concussion-Related Vision Disorders: A Review

Concussions are a mild form of traumatic brain injury (TBI) that is typically self-limited and transient with a high prevalence within our communities. Due to the vast visual network interconnectivity, visual symptoms secondary to a concussion occur about 90% of the time. A gold standard to confirm concussion acutely has not been well established. Visual function testing based on symptoms remains the standard of care in off-site evaluation for diagnosis of oculomotor dysfunction. This review covers the current diagnostic strategies for vision based disorders post-concussion for sideline testing, off-site testing, and research driven testing.

An Examination of Visual Quality of Life and Functional Vision Among Collision and Non-Collision Athletes Over a Competitive Season

OBJECTIVE

Repetitive head impacts (RHIs) experienced during sports are gaining attention due to potential long-term neurological dysfunction, absent of a diagnosed concussion. One area susceptible to dysfunction is vision. The goal of this study was to evaluate changes in visual quality of life (VQOL) and functional vision scores from pre- to post-season among collision and non-collision athletes.

METHODS

The Visual Functioning Questionnaire-25 and Neuro-Ophthalmic Supplement (NOS), as well as functional vision testing (Mobile Universal Lexicon Evaluation System - MULES) were completed pre- and post-season by three groups: collision athletes, non-collision athletes, and minimally active controls (MACs).

RESULTS

There were 42 participants, with 41 (21 male, 20 female) completing both testing sessions, with a mean (standard deviation [SD]) age of 21 (2.46) years (collision group, n = 14; non-collision group, n = 13, MACs, n = 14). Baseline analyses revealed no significant differences between groups for VQOL or MULES scores. However, those with a family history of psychiatric disorder scored significantly worse on NOS. Post-season/follow-up testing revealed no significant differences between groups for VQOL scores. Non-collision athletes significantly improved on the MULES test by 2.46 ± 3.60 (SD) s (35.0 [95% confidence interval, 0.29-4.63]; p = .03). Change score results from pre- to post-season were not significant.

CONCLUSION

Although the groups were not significantly different from one another, non-collision athletes significantly improved MULES scores, whereas collision athletes performed the worst, suggesting exposure to RHIs may impact functional vision. Thus, further evaluation of RHIs and their impact on vision is warranted.

Rapid Automatized Picture Naming in an Outpatient Concussion Center: Quantitative Eye Movements during the Mobile Universal Lexicon Evaluation System (MULES) Test

Number and picture rapid automatized naming (RAN) tests are useful sideline diagnostic tools. The main outcome measure of these RAN tests is the completion time, which is prolonged with a concussion, yet yields no information about eye movement behavior. We investigated eye movements during a digitized Mobile Universal Lexicon Evaluation System (MULES) test of rapid picture naming. A total of 23 participants with a history of concussion and 50 control participants performed MULES testing with simultaneous eye tracking. The test times were longer in participants with a concussion (32.4 s [95% CI 30.4, 35.8] vs. 26.9 s [95% CI 25.9, 28.0], t=6.1). The participants with a concussion made more saccades per picture than the controls (3.6 [95% CI 3.3, 4.1] vs. 2.7 [95% CI 2.5, 3.0]), and this increase was correlated with longer MULES times (r = 0.46, p = 0.026). The inter-saccadic intervals (ISI) did not differ between the groups, nor did they correlate with the test times. Following a concussion, eye movement behavior differs during number versus picture RAN performance. Prior studies have shown that ISI prolongation is the key finding for a number-based RAN test, whereas this study shows a primary finding of an increased saccade number per picture with a picture-based RAN test. Number-based and picture-based RAN tests may be complimentary in concussion detection, as they may detect different injury effects or compensatory strategies.

An assessment of current concussion identification and diagnosis methods in sports settings: a systematic review

BACKGROUND

Concussion in sport is an ongoing global concern. The head injury assessment (HIA) by the field of play is acknowledged as the first step in recognising and identifying concussion. While previous systematic literature reviews have evaluated the sensitivity of side-line screening tools and assessment protocols, no systematic review has evaluated the research designs and assessments used in a field setting. This systematic review investigated existing screening and diagnostic tools used in research as part of the HIA protocol to identify concussion that are currently used in professional, semi-professional and amateur (club) sports settings.

METHODS

A systematic searching of relevant databases was undertaken for peer-reviewed literature between 2015 and 2020.

RESULTS

Twenty-six studies met the inclusion criteria. Studies were of moderate to good quality, reporting a variety of designs. The majority of studies were undertaken in professional/elite environments with medical doctors and allied health practitioners (e.g., physical therapists) involved in 88% of concussion assessments. While gender was reported in 24 of the 26 studies, the majority of participants were male (77%). There was also a variety of concussion assessments (n = 20) with the sports concussion assessment tool (SCAT) used in less than half of the included studies.

CONCLUSION

The majority of studies investigating concussion HIAs are focused on professional/elite sport. With concussion an issue at all levels of sport, future research should be directed at non-elite sport. Further, for research purposes, the SCAT assessment should also be used more widely to allow for consistency across studies.

The MICK (Mobile integrated cognitive kit) app: Digital rapid automatized naming for visual assessment across the spectrum of neurological disorders

OBJECTIVE

Rapid automatized naming (RAN) tasks have been utilized for decades to evaluate neurological conditions. Time scores for the Mobile Universal Lexicon Evaluation System (MULES, rapid picture naming) and Staggered Uneven Number (SUN, rapid number naming) are prolonged (worse) with concussion, mild cognitive impairment, multiple sclerosis and Parkinson's disease. The purpose of this investigation was to compare paper/pencil versions of MULES and SUN with a new digitized format, the MICK app.

METHODS

Participants (healthy office-based volunteers, professional women's hockey players), completed two trials of the MULES and SUN tests on both platforms (tablet, paper/pencil). The order of presentation of the testing platforms was randomized. Between-platform variability was calculated using the two-way random-effects intraclass correlation coefficient (ICC).

RESULTS

Among 59 participants (median age 32, range 22-83), no significant differences were observed for comparisons of mean best scores for the paper/pencil versus MICK app platforms, counterbalanced for order of administration (P = 0.45 for MULES, P = 0.50 for SUN, linear regression). ICCs for agreement between the MICK and paper/pencil tests were 0.92 (95% CI 0.86, 0.95) for MULES and 0.94 (95% CI 0.89, 0.96) for SUN, representing excellent levels of agreement. Inter-platform differences did not vary systematically across the range of average best time score for either test.

CONCLUSION

The MICK app for digital administration of MULES and SUN demonstrates excellent agreement of time scores with paper/pencil testing. The computerized app allows for greater accessibility and scalability in neurological diseases, inclusive of remote monitoring. Sideline testing for sports-related concussion may also benefit from this technology.

King-Devick Test Performance and Cognitive Dysfunction after Concussion: A Pilot Eye Movement Study

(1) Background: The King-Devick (KD) rapid number naming test is sensitive for concussion diagnosis, with increased test time from baseline as the outcome measure. Eye tracking during KD performance in concussed individuals shows an association between inter-saccadic interval (ISI) (the time between saccades) prolongation and prolonged testing time. This pilot study retrospectively assesses the relation between ISI prolongation during KD testing and cognitive performance in persistently-symptomatic individuals post-concussion. (2) Results: Fourteen participants (median age 34 years; 6 women) with prior neuropsychological assessment and KD testing with eye tracking were included. KD test times (72.6 ± 20.7 s) and median ISI (379.1 ± 199.1 msec) were prolonged compared to published normative values. Greater ISI prolongation was associated with lower scores for processing speed (WAIS-IV Coding, r = 0.72, p = 0.0017), attention/working memory (Trails Making A, r = −0.65, p = 0.006) (Digit Span Forward, r = 0.57, p = −0.017) (Digit Span Backward, r= −0.55, p = 0.021) (Digit Span Total, r = −0.74, p = 0.001), and executive function (Stroop Color Word Interference, r = −0.8, p = 0.0003). (3) Conclusions: This pilot study provides preliminary evidence suggesting that cognitive dysfunction may be associated with prolonged ISI and KD test times in concussion.

How sandbag-able are concussion sideline assessments? A close look at eye movements to uncover strategies

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.