Maximum Principal Strain and Strain Rate Associated with Concussion Diagnosis Correlates with Changes in Corpus Callosum White Matter Indices

Abstract

On-field monitoring of head impacts, combined with finite element (FE) biomechanical simulation, allow for predictions of regional strain associated with a diagnosed concussion. However, attempts to correlate these predictions with in vivo measures of brain injury have not been published. This article reports an approach to and preliminary results from the correlation of subject-specific FE model-predicted regions of high strain associated with diagnosed concussion and diffusion tensor imaging to assess changes in white matter integrity in the corpus callosum (CC). Ten football and ice hockey players who wore instrumented helmets to record head impacts sustained during play completed high field magnetic resonance imaging preseason and within 10 days of a diagnosed concussion. The Dartmouth Subject-Specific FE Head model was used to generate regional predictions of strain and strain rate following each impact associated with concussion. Maps of change in fractional anisotropy (FA) and median diffusivity (MD) were generated for the CC of each athlete to correlate strain with change in FA and MD. Mean and maximum strain rate correlated with change in FA (Spearman ρ = 0.77, p = 0.01; 0.70, p = 0.031), and there was a similar trend for mean and maximum strain (0.56, p = 0.10; 0.6, p = 0.07), as well as for maximum strain with change in MD (−0.63, p = 0.07). Change in MD correlated with injury-to-imaging interval (ρ = −0.80, p = 0.006) but change in FA did not (ρ = 0.18, p = 0.62). These results provide preliminary confirmation that model-predicted strain and strain rate in the CC correlate with changes in indices of white matter integrity.

Head-Impact–Measurement Devices: A Systematic Review

“…Most research has involved male athletes, predominantly in football (n ¼ 40),* ice hockey (n ¼ 12), 16,[42][43][44][45]61,62,[76][77][78][79][80] soccer (n ¼ 4), 87,[93][94][95] and boxing (n ¼ 1). 89 Males sustained more impacts in ice hockey and boxing than females did.…”

“…7 g t o 145g, 16,17,47,58,61,62,70,72 with a 95th percentile of 7688 rad/ s 2 . 26 Among football injuries, acceleration and impact location increased the specificity of injury prediction.…”

“…40,72 A total of 6 collegiate ice hockey concussions were captured using the HITS. Linear values ranged from 30.7g to 31.7g in an all-male sample 61,62 (n ¼ 2) and 30.4g to 52.2g in an all-female sample 43 (n ¼ 4). Researchers have reported average rotational values of 4030 rad/s 2 for females 107 and values ranging from 1307 to 5419 rad/s 2 for males.…”

Age at First Exposure to Football Is Associated with Altered Corpus Callosum White Matter Microstructure in Former Professional Football Players

“…It is particularly vulnerable to diffuse axonal injury, with head impacts due to the density and orientation of fibers, the position of the dural reflections creating barriers to brain movement, and increased shear strain on the tract when external acceleration forces are applied. 56,57 The greatest shear strain occurs in the genu (anterior CC) and splenium (posterior CC), 57 and these regions are frequently damaged in TBI. 26,[56][57][58][59][60] Studies also report CC microstructural damage following prolonged exposure to RHI in football, 49 hockey, 50 and soccer players.…”

“…56,57 The greatest shear strain occurs in the genu (anterior CC) and splenium (posterior CC), 57 and these regions are frequently damaged in TBI. 26,[56][57][58][59][60] Studies also report CC microstructural damage following prolonged exposure to RHI in football, 49 hockey, 50 and soccer players. 5 Further, several neuroimaging studies in children demonstrate disrupted CC development following TBI of varying severity.…”