Analysis of HIC and Hydrostatic Pressure in the Human Head during NOCSAE Tests of American Football Helmets.

Brain damage is a serious economic and social burden. Contact sports such as American football, are one of the most common sources of concussions. The biomechanical response of the head-helmet system caused by dynamic loading plays a major role. The literature has focused on measuring the resultant kinematics that act on the head and helmet during tackles. However, few studies have focused on helmet validation tests, supported by recent findings and emerging numerical approaches. The future of helmet standards could benefit from insights at the level of injury mechanisms, using numerical tools to assess the helmets. Therefore, in this work, a numerical approach is employed to investigate the influence of intracranial pressure (ICP) on brain pathophysiology during and after helmeted impacts, which are common in American football. The helmeted impacts were performed at several impact locations according to the NOCSAE standard (configurations A, AP, B, C, D, F, R, UT). In order to evaluate the ICP levels, the αHEAD finite element head and brain model was combined with a Hybrid III-neck structure and then coupled with an American football helmet to simulate the NOCSAE impacts. In addition, the ICP level was analyzed together with the resulting HIC value, since the latter is commonly used, in this application and others, as the injury criterion. The obtained results indicate that ICP values exceed the common threshold of head injury criteria and do not correlate with HIC values. Thus, this work raises concern about applying the HIC to predict brain injury in American football direct head impacts, since it does not correlate with ICP predicted with the FE head model.

Material and Structural Modeling Aspects of Brain Tissue Deformation under Dynamic Loads.

The aim of this work was to assess the numerous approaches to structural and material modeling of brain tissue under dynamic loading conditions. The current technological improvements in material modeling have led to various approaches described in the literature. However, the methods used for the determination of the brain's characteristics have not always been stated or clearly defined and material data are even more scattered. Thus, the research described in this paper explicitly underlines directions for the development of numerical brain models. An important element of this research is the development of a numerical model of the brain based on medical imaging methods. This approach allowed the authors to assess the changes in the mechanical and geometrical parameters of brain tissue caused by the impact of mechanical loads. The developed model was verified through comparison with experimental studies on post-mortem human subjects described in the literature, as well as through numerical tests. Based on the current research, the authors identified important aspects of the modeling of brain tissue that influence the assessment of the actual biomechanical response of the brain for dynamic analyses.

Investigation of biomechanics of skull structures damages caused by dynamic loads.

PURPOSE: The aim of the study was to examine the influence of cranial sutures on the crack behaviour of a human skull after the impact. The authors focused on the assessment of skull breaking nature, based on a real-world vehicle-to-bicyclist accident. In the state of the art, there is still no consensus about sutures mechanical properties. Currently, most of the numerical head models do not have distinguished cranial sutures. METHODS: The authors compared different elastic properties for cranial sutures and their influence on the nature of the skull fracture. The mathematical and numerical modelling have been applied to mimic the nature of the skull fracture. The LS-DYNA explicit code with material models featuring the erosion of finite elements was used. The models of the skull with different cranial sutures properties were impacted against a validated front-end of a vehicle. RESULTS: Various fracture patterns were obtained for different material properties of the sutures and the results were compared to a model without the cranial sutures. Based on the results, a graph was plotted to indicate differences in sutures energy absorption capabilities. The numerical results were supported by the mathematical modelling. The developed diagram may enable better understanding of the complex mechanical phenomena on the suture interface. CONCLUSIONS: Biomechanical evidence was provided for the important role of the sutures in numerical models as well as their significant influence on the biomechanics of skull fractures caused by dynamic loads.

An analysis of the effect of impact loading on the destruction of vascular structures in the brain.

Subdural hematomas are one of the frequent complications of head injuries. Such hematomas result from exceeding the border strength values of bridging veins. Subdural haemorrhages are life-threatening and are a frequent cause of considerable pathologies. Traffic participants and also soldiers who participate in armed conflicts are the most vulnerable to head injuries. Although hematomas have been studied for many years the mechanism of hematoma formation has not been fully clarified as yet. In the paper, the effort of brain tissue structures due to the propagation of shock wave was analyzed. Particular attention was paid to the deformation ability and changes in the energy of bridging veins. This research was concerned with changes in mechanical properties of these veins in the frontal, parietal and occipital regions of the brain. For the present research the authors have constructed finite element models of brain tissue fragments and conducted numerical studies taking into account the boundary conditions arising from violent overloads that result from combat operations. As a result of the numerical analysis conducted, critical values of strain and stress have been obtained. The analysis showed high diversity in the properties of the different regions of the brain tissue. The studies carried out by the authors rendered it possible to assess the effort of the tissue structures of veins in connection with mechanical parameters, including geometrical parameters, in particular in relation to the likelihood of hematoma formation.

Misuse of OTC drugs in Poland.

INTRODUCTION: The misuse of over-the-counter (OTC) drugs became a global public health concern. Although abuse with dextrometorphan (DXM), pseudoefedrine (PSD), codeine (COD) or benzydamine (BND) may lead even to psychosis, drugs containing these substances are relatively cheap and freely available. In Poland the Act on Counteracting Drug Addiction was amended in 2015, however it seems that there are still some points which could be improved. METHODS: Study was conducted between October 2014 and June 2015 using a specially designed questionnaire delivered to pharmacists from the Greater Poland region. Questionnaire consisting of 11 closed questions was distributed by direct contact and via the Internet. From over 2500 distributed questionnaires, we received 761 sheets and 680 were included. RESULTS: The misuse of OTC drugs is increasing in Poland from pharmacists point of view. The most popular substance was PSD followed by COD and DXM. The main reason of misuse of these drugs could be related to the use of Internet and free access to these medications. In respondents (58.2%) opinion OTC drugs containing analyzed substances should be moved into the prescription status. CONCLUSIONS: The misuse of OTC drugs should be considered as a very dangerous phenomenon. Although the Act on Counteracting Drug Addiction was amended in Poland in 2015, there are some facets requiring improvement. Social education may play a key role in the limitation of misuse of OTC drugs.