A comparison of head dynamic response and brain tissue stress and strain using accident reconstructions for concussion, concussion with persistent postconcussive symptoms, and subdural hematoma

Abstract

Objective:Concussions typically resolve within a few days however in a few cases the symptoms last for a month or longer and are termed persistent post-concussive symptoms (PPCS) with more serious brain trauma resulting in bleeds, such as subdural hematoma (SDH). Dynamic response and brain tissue deformation characteristics may provide a means of distinguishing between these three types of injuries. Methods:Reconstruction cases were recruited from sports medicine clinics and hospitals along with medical reports, video footage, and medical imaging. All subjects received a direct blow to the head resulting in head trauma symptoms, those that resolved in 9 days were termed concussions, those with symptoms longer than 18 months were PPCS and those presenting with subdural hematoma (SDH). An anthropometric dummy headform was dropped onto various impact surfaces using a monorail drop rig. Headform dynamic response data was collected and used as input into the University College Dublin Brain Trauma Model to obtain maximum principal strain and von Mises stress. Results:Both linear and rotational acceleration of the head increased in magnitude with an increase in injury severity (from concussion, to PPCS, and SDH). The PPCS group had peak resultant rotational accelerations similar to SDH and significantly higher than concussions. There were no significant differences for peak resultant linear accelerations between the two concussion groups however they were both significantly lower than the SDH group. Brain tissue deformation measures however, did not follow the same trend as dynamic response and resulted with SDH having the lowest values of stress and strain. PPCS had significantly higher values of strain than the SDH group, where both the concussion and PPCS groups had significantly higher stress values than the SDH group. Conclusion:This study supports the notion that there is a positive relationship between an increase in the dynamic response and the risk for more serious brain injury. Peak resultant linear acceleration may be more related to SDH meanwhile rotational acceleration may be more related to severity of concussion. Despite SDH being the more severe brain injury, on average this group 4 had the lowest values for stress and strain as compared to concussion and PPCS. Finite element analysis of the SDH injuries examined brain tissue values for the group of elements in the model than corresponded to the location of the bleed which may not be reflective of the highest values if the entire cerebrum was considered. More importantly, SDH injuries are vascular injuries and may not necessarily result in damage to the brain. In summary, this study found that the dynamic response of an impact is reflective of injury severity. Understanding the relationship between the dynamic response and the nature of the injury provides important information for developing strategies for injury prevention. 5 DefinitionsBulk Modulus -is a measure of the compressibility of a material in Pascal Decay Constant -a rate constant t...

Proceedings from the Ice Hockey Summit III: Action on Concussion

“…Impact types dictate how energy is transferred to brain tissue [29]. The high linear (g) and rotational (rad/sec 2 ) accelerations listed in Table 1 must be avoided [28,29,[35][36][37][38].…”

A comparison in a youth population between those with and without a history of concussion using biomechanical reconstruction

“…10,38,39,44,43 It has been used by researchers to determine magnitudes of response and biomechanical vulnerability that may exist for different TBI lesions 10,39,43 and to establish the range of brain tissue deformation that is associated with PCS in adults. 38,44 As a result, this method has been found to have sufficient sensitivity to investigate the biomechanics of impacts for falling events, although this research would be the first to attempt to use this method for a pediatric population. In terms of accuracy, while there is no current state data on strain available for known impact loading conditions of a living human brain, this method has been found to produce similar magnitudes of brain strain response as has been described in anatomical tissue injury research.…”

The effect of acceleration signal processing for head impact numeric simulations

“…Brain injury research often involves linear and rotational acceleration signals to quantify the risk of incurring an injury, be it a traumatic brain injury (TBI) or concussion (mTBI) [1][2][3][4].…”

“…However, while some research in the literature follow the SAE J211 convention [2][3][4]10], several use more aggressive filters [11,12] and in some cases signals are filtered twice [5]. In addition to these inconsistencies in data treatment, the SAE J211 convention was developed for car crash analyses and not for processing data for sporting impacts.…”

“…Other researchers have published extensively using accelerometers installed in a Hybrid III headform [2][3][4]13] both for brain injury research and helmet testing and report using a lowpass filter with a 1650 Hz cutoff, which is a higher cutoff frequency than the SAE J211 convention.…”