A Multifaceted Approach to Interpreting Reaction Time Deficits After Adolescent Concussion

Abstract

Context: Reaction time (RT) is a critical element of return to participation (RTP), and impairments have been linked to subsequent injury after a concussion. Current RT assessments have limitations in clinical feasibility and in the identification of subtle deficits after concussion symptom resolution. Objectives: To examine the utility of RT measurements (clinical drop stick, simple stimulus-response, single-task Stroop, and dual-task Stroop) to differentiate between adolescents with concussion and uninjured control individuals at initial assessment and RTP. Design: Prospective cohort study. Setting: A pediatric sports medicine center associated with a regional tertiary care hospital. Patients or Other Participants: Twenty-seven adolescents with a concussion (mean age ¼ 14.8 6 2.1 years; 52% female; tested 7.0 6 3.3 days postconcussion) and 21 uninjured control individuals (mean age ¼ 15.5 6 1.6 years; 48% female). Main Outcome Measure(s): Participants completed the Post-Concussion Symptoms Inventory (PCSI) and a battery of RT tests: clinical drop stick, simple stimulus-response, single-task Stroop, and dual-task Stroop. Results: The concussion group demonstrated slower clinical drop stick (b ¼ 58.8; 95% CI ¼ 29.2, 88.3; P, .001) and dual-task Stroop (b ¼ 464.2; 95% CI ¼ 318.4, 610.0; P, .001) RT measures at the initial assessment than the uninjured control group. At 1-month follow up, the concussion group displayed slower clinical drop stick (238.9 6 25.9 versus 188.1 6 21.7 milliseconds; P, .001; d ¼ 2.10), single-task Stroop (1527.8 6 204.5 versus 1319.8 6 133.5 milliseconds; P ¼ .001; d ¼ 1.20), and dual-task Stroop (1549.9 6 264.7 versus 1341.5 6 114.7 milliseconds; P ¼ .002; d ¼ 1.04) RT than the control group, respectively, while symptom severity was similar between groups (7.4 6 11.2 versus 5.3 6 6.5; P ¼ .44; d ¼ 0.24). Classification accuracy and area under the curve (AUC) values were highest for the clinical drop stick (85.1% accuracy, AUC ¼ 0.86, P, .001) and dual-task Stroop (87.2% accuracy, AUC ¼ 0.92, P, .002) RT variables at initial evaluation. Conclusions: Adolescents recovering from concussion may have initial RT deficits that persist despite symptom recovery. The clinical drop stick and dual-task Stroop RT measures demonstrated high clinical utility given high classification accuracy, sensitivity, and specificity to detect postconcussion RT deficits and may be considered for initial and RTP assessment.