Neck Strength Does Not Predict Time To Concussion Symptom Resolution Among Adolescents

PURPOSE: Neck strength is proposed as a modifiable risk factor for sustaining a sport-related concussion, with lower concussion risk in those with higher neck strength. Post-injury measures of neck strength as a prognostic indicator for concussion recovery has not been explored. METHODS: We prospectively examined adolescents ages 13-18 years enrolled within 18 days of concussion and monitored them until symptom resolution. Our primary outcome was time from concussion to symptom resolution (days). At the initial post-injury visit, participants underwent isometric neck strength testing using hand-held dynamometry for: extension, flexion, right/left lateral flexion (LF), and right/left sternocleidomastoid (SCM). We used Kaplan-Meier plots and univariable Cox proportional hazards (PH) models for each muscle group, and multivariable Cox PH models to examine neck strength and recovery time, adjusting for covariates. RESULTS: We examined 38 adolescents with concussion (age = 15.9 +/-1.4 years, 63% female, 11.6 +/-3.7 days post-injury). Upon univariable examination, extension, flexion, right and left LF, and right and left SCM strength were not associated with symptom resolution time (Figure). After adjusting for age and sex, there were no associations between symptom resolution time and overall neck strength (hazard ratio[HR] = 1.02, 95%CI = 0.95, 1.09, p = 0.66), extension, flexion, right LF, left LF, right SCM, or left SCM strength (Figure). CONCLUSIONS: In adolescents with concussion, neck strength measured soon after injury was not associated with duration of concussion symptoms. Although neck strength is related to risk of concussion, our results suggest that concussion recovery does not share a similar relationship. We obtained post-injury neck strength measures, which could be impacted by deficits in neck motion or proprioception occurring at the time of concussion, so future studies may investigate how these factors relate to recovery trajectory.The authors gratefully acknowledge funding from the Tai Foundation and NIH (R01HD108133 & T32AR080630).