Comparison and utility of King-Devick and ImPACT® composite scores in adolescent concussion patients

The King-Devick (KD) oculomotor test has recently been advocated for sideline diagnosis of concussion. Although visual processing and performance are often impaired in concussion patients, the utility of KD as a concussion diagnostic tool is not validated. Purpose To examine the diagnostic value of KD, by comparing KD with post-concussion symptom scale (PCSS) and ImPACT® composite scores. We hypothesized that KD would be correlated with visual motor speed/memory (VMS, VIS) and reaction time (RT), because all require cognitive visual processing. We also expected parallel changes in KD and PCSS across recovery. Methods Thirty-five concussed individuals (12-19 y; 18 females, 17 males) were evaluated with PCSS, ImPACT® composite and KD scores over four clinical visits (V). Results KD times improved with each visit (ΔV1-V2: 7.86 ± 11.82; ΔV2-V3: 9.17 ± 11.07; ΔV3-V4: 5.30 ± 7.87 s) and paralleled improvements in PCSS (ΔV1-V2: 8.97 ± 20.27; ΔV2-V3: 8.69 ± 14.70; ΔV3-V4: 6.31 ± 7.71), RT (ΔV1-V2: 0.05 ± 0.21; ΔV2-V3: 0.09 ± 0.19; ΔV3-V4 0.03 ± 0.07) and VMS (ΔV1-V2: - 5.27 ± 6.98; ΔV2-V3: - 2.61 ± 6.48; ΔV3-V4: - 2.35 ± 5.22). Longer KD times were associated with slower RT (r = 0.67; P < 0.0001) and lower VMS (r = - 0.70; P < 0.0001), respectively. Conclusion Cognitive visual performance testing using KD has utility in concussion evaluation. Validation would further establish KD as an effective ancillary tool in longitudinal concussion management and research.