Detection of Persisting Concussion Effects on Measures of Neuromechanical Responsiveness

Abstract

Abstract INTRODUCTION Numerous investigations have documented elevated risk for musculoskeletal injury following sport-related concussion, which suggests that an unrecognized vulnerability persists beyond the resolution of symptoms and return to sport participation. Improved clinical testing methods are needed to better assess the interrelated neurocognitive and neuromuscular capabilities of athletes who may have elevated susceptibility to MSK injury, and possible risk for long- term alterations in brain function, despite resolution of overt concussion symptoms. The term “neuromechanics” refers to the study of interactions between neural, biomechanical, and environmental dynamics We use the term “neuromechanical responsiveness” (NMR) to designate the ability to optimally integrate neurocognitive and neuromuscular processes during participation in sport-related activities. NMR testing may play an critical role in optimizing safe return to play circumstances. METHODS A cohort of 48 elite athletes (34 males: 23.8 ± 4.4 yr; 14 females: 25.4 ± 4.5 yr) performed visuomotor reaction time (VMRT) tests involving rapid manual contact with illuminated target buttons that included 2 dual-task conditions: 1) simultaneous oral recitation of scrolling text (VMRT + ST) and 2) simultaneous verbal responses to identify the right or left direction indicated by the center arrow of the Eriksen flanker test (VMRT + FT). A whole-body reactive agility (WBRA) test requiring side-shuffle movements in response to visual targets was used to assess reaction time, speed, acceleration, and deceleration. RESULTS Concussion occurrence at 2.0 ± 2.3 yr prior to testing was reported by 21 athletes. Strong univariable associations were found for VMRT + FT left minus right difference = 15 ms (OR = 7.14), VMRT + ST outer 2-ring to inner 3-ring ratio = 1.28 (OR = 4.58), and WBRA speed asymmetry = 7.7% (OR = 4.67). A large VMRT + FT X VMRT + ST interaction effect was identified (OR = 25.00). Recursive partitioning identified a 3-way VMRT + FT X VMRT + ST X WBRA interaction that had 100% positive predictive value for identification of athletes with concussion history, whereas negative status on all 3 factors provided 90% negative predictive value. CONCLUSION Performance on dual-task VMRT tests and the WBRA test identified NMR deficiencies among elite athletes who reported a history of concussion.