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

Abstract

Objective-This study investigated the diagnostic and prognostic value of the King-Devick (K-D) test in conjunction with treadmill testing in adolescents after sport-related concussion (SRC) in an outpatient concussion management clinic without baseline measures. Design-Prospective cohort.Methods-The K-D test was administered pre-and post-exercise on a graded treadmill test to acutely concussed (AC, <10 days from injury, n=46, 15.4±2.1 years) participants for 2 clinic visits (1 week apart) and to matched controls (MC, n= 30, 15.8±1.4 years) for 2 visits (1 week apart). Initial K-D test times were compared between MC and AC. Changes in times from pre-to postexercise during a treadmill test were compared for MC and AC and from Visit 1 to Visit 2. Smooth pursuits and repetitive saccades were compared with initial visit K-D test performance.Results-Comparison of pre-exercise K-D test times at Visit 1 distinguished MC from AC (46.1±9.2s vs. 53.7±13.0s, p=0.007). Comparison of pre-and post-exercise K-D test times revealed significant improvements for MC (46.1±9.2s vs. 43.1±8.5s, p<0.001) and AC who recovered by Visit 2 (Fast Recovery Group [FRG], n=23, 50.4±10.0s vs. 47.3±9.8s, p=0.002). No significant difference was seen in pre-and post-exercise K-D test times on Visit 1 for AC who took longer than 2 weeks to recover (Slow Recovery Group [SRG], n=23, 57.0±15.0s vs. 56.0±16.3s, p=0.478). At Visit 1, AC had more abnormal smooth pursuits than MC (17% vs. 3%, *

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

“…This study validates a previous finding 6 that participants who did not exhibit the typical improvement in KD test time after exertion took longer to recover from SRC than those whose postexertion time improved. In addition, participants who did not show the typical improvement reported more symptoms on the initial-visit PCSS, which was significantly associated with recovery.…”

“…Similarly, a previous study 6 demonstrated a mean reduction of 3.2 seconds in KD test time in healthy control individuals tested 1 week apart at rest (P , .001). The authors of 2 studies 6,25 have assessed the effect of systematic exercise on the KD test in healthy controls. Lawrence et al 6 found a mean reduction of 2.3 seconds (P , 0.001) after the BCTT, and Eddy et al 25 described a mean reduction of 1.7 seconds after a bout of moderate exertion.…”

“…The authors of 2 studies 6,25 have assessed the effect of systematic exercise on the KD test in healthy controls. Lawrence et al 6 found a mean reduction of 2.3 seconds (P , 0.001) after the BCTT, and Eddy et al 25 described a mean reduction of 1.7 seconds after a bout of moderate exertion. However, participants who did not perform any exercise still had a mean reduction of 1.5 seconds on repeated KD tests.…”

“…Hence, the KD test also evaluates cognitive domains, such as attention, spatial and temporal orientation, and working memory. 5 In a previous derivation study, 6 adolescents with acute concussions (within 1 week of injury) and healthy control participants performed the KD test twice before and once after a graded treadmill test for exercise tolerance after concussion, the Buffalo Concussion Treadmill Test (BCTT). Concussed patients and healthy control individuals who recovered normally (within 3 weeks) demonstrated the typical learning effect of reduced postexercise KD time (mean improvement of 3 6 4 seconds).…”

<p>On-field assessment of concussion: clinical utility of the King-Devick test</p>

“…The authors estimated that for every 1-point of worsening of overall SAC score, there was a 4.7-s increase in K-D total time score from baseline ( p =0.001), while every 1-point worsening of BESS had an estimated 1.6-point increase in K-D time score from baseline ( p =0.043). Lawrence and colleagues studied the diagnostic and prognostic value of the K-D test in an outpatient setting 20. They administered the K-D test pre- and post-treadmill test to both individuals who had a concussion recently (n=46) and matched controls (n=30) 20.…”