Analysis of Concussions with Persisting Symptoms Caused by Motor Vehicle Crashes in 136 Vehicle Occupants Shows that Females Are Vulnerable Road Users.

At the Canadian Concussion Centre, we treated 136 patients from 2000 to 2020 who sustained concussion plus persisting concussion symptoms (C+PCS) as motor vehicle occupants involved in motor vehicle crashes (MVCs). This center specializes in the treatment of patients with C+PCS. The objective of the present study was to identify strategies for preventing concussion among vehicle occupants involved in MVC.

Region-Dependent Mechanical Properties of Human Brain Tissue Under Large Deformations Using Inverse Finite Element Modeling.

This study aims to facilitate intracranial simulation of traumatic events by determining the mechanical properties of different anatomical structures of the brain. Our experimental indentation paradigm used fresh, post-operative human tissue, which is highly advantageous in determining mechanical properties without being affected by postmortem time. This study employed an inverse finite element approach coupled with experimental indentation data to characterize mechanical properties of the human hippocampus (CA1, CA3, dentate gyrus), cortex white matter, and cortex grey matter.

Contaminant film thickness affects walkway friction measurements.

Walkway tribometers are used to measure available friction for evaluating walkway safety and pedestrian slip risk. Numerous variables can affect tribometer measurements, including the type and distribution of contaminants on the surface. Here, we quantified the effect of application method on contaminant film thickness, and the effect of film thickness on tribometer measurements on the four reference walkway surfaces used in ASTM F2508-16e.

Region-Dependent Viscoelastic Properties of Human Brain Tissue Under Large Deformations.

This study characterizes the mechanical properties of human brain tissue resected during the course of surgery under multistep indentation loading up to 30% strain. The experimental characterization using fresh, post-operative, human brain tissue is highly advantageous since postmortem times can affect its biomechanical behavior. Although the quasilinear theory of viscoelasticity (QLV) approach has been widely used to model brain tissue mechanical properties, our analysis concluded that the linear viscoelastic approach provided a better fit to the experimental data overall.

Quantifying the uncertainty in tribometer measurements on walkway surfaces.

Properly estimating and reporting the uncertainty of walkway surface friction is key to ensuring pedestrian safety. Here we quantified the amount and sources of uncertainty in friction measurements by having four users of four units of each of two walkway tribometer models (Slip-Test Mark IIIB, English XL) perform 12 measurements on four samples of four different surfaces that ranged from slippery to slip-resistant. We found that 51-82% of the total variance in the measurements was explained by the user, unit, sample and a user-unit interaction, which means that the variance a single user calculates from their own data does not capture most of the uncertainty in their measurements.

Brain tissue strains vary with head impact location: A possible explanation for increased concussion risk in struck versus striking football players.

Background: On-field football helmet impacts over a large range of severities have caused concussions in some players but not in other players. One possible explanation for this variability is the struck player's helmet impact location.

Methods: We examined the effect of impact location on regional brain tissue strain when input energy was held constant.

Regional mechanical properties of human brain tissue for computational models of traumatic brain injury.

Unlabelled: To determine viscoelastic shear moduli, stress relaxation indentation tests were performed on samples of human brain tissue resected in the course of epilepsy surgery. Through the use of a 500µm diameter indenter, regional mechanical properties were measured in cortical grey and white matter and subregions of the hippocampus. All regions were highly viscoelastic.

Whiplash Injury or Concussion? A Possible Biomechanical Explanation for Concussion Symptoms in Some Individuals Following a Rear-End Collision.

Study Design Finite element modeling of experimental data. Background The clinical presentations of whiplash injury and concussion have considerable overlap. Both diagnoses are generally based on presenting signs and symptoms, and a history of neck or head trauma.

Strong Correlation of Genome-Wide Expression after Traumatic Brain Injury In Vitro and In Vivo Implicates a Role for SORLA.

The utility of in vitro models of traumatic brain injury (TBI) depends on their ability to recapitulate the in vivo TBI cascade. In this study, we used a genome-wide approach to compare changes in gene expression at several time points post-injury in both an in vitro model and an in vivo model of TBI. We found a total of 2073 differentially expressed genes in our in vitro model and 877 differentially expressed genes in our in vivo model when compared to noninjured controls.

Viscoelastic properties of the P17 and adult rat brain from indentation in the coronal plane.

This technical brief serves as an update to our previous work characterizing the region-dependence of viscoelastic mechanical properties of the P17 and adult rat brain in the coronal plane (Elkin et al., 2011, "A Detailed Viscoelastic Characterization of the P17 and Adult Rat Brain," J. Neurotrauma, 28, pp.

Why is CA3 more vulnerable than CA1 in experimental models of controlled cortical impact-induced brain injury?

One interesting finding of controlled cortical impact (CCI) experiments is that the CA3 region of the hippocampus, which is positioned further from the impact than the CA1 region, is reported as being more injured. The current literature has suggested a positive correlation between brain tissue stretch and neuronal cell loss. However, it is counterintuitive to assume that CA3 is stretched more during CCI injury.

Viscoelastic properties of the rat brain in the sagittal plane: effects of anatomical structure and age.

Rat is the most commonly used animal model for the study of traumatic brain injury. Recent advances in imaging and computational modeling technology offer the promise of biomechanical models capable of resolving individual brain structures and offering greater insight into the causes and consequences of brain injury. However, there is insufficient data on the mechanical properties of brain structures available to populate these models.

Dynamic, regional mechanical properties of the porcine brain: indentation in the coronal plane.

Stress relaxation tests using a custom designed microindentation device were performed on ten anatomic regions of fresh porcine brain (postmortem time <3 h). Using linear viscoelastic theory, a Prony series representation was used to describe the shear relaxation modulus for each anatomic region tested. Prony series parameters fit to load data from indentations performed to ∼10% strain differed significantly by anatomic region.

In vitro models of traumatic brain injury.

In vitro models of traumatic brain injury (TBI) are helping elucidate the pathobiological mechanisms responsible for dysfunction and delayed cell death after mechanical stimulation of the brain. Researchers have identified compounds that have the potential to break the chain of molecular events set in motion by traumatic injury. Ultimately, the utility of in vitro models in identifying novel therapeutics will be determined by how closely the in vitro cascades recapitulate the sequence of cellular events that play out in vivo after TBI.

Chondroitinase ABC reduces brain tissue swelling in vitro.

Increased intracranial pressure (ICP) caused by edema following severe traumatic brain injury (TBI) or stroke contributes to high rates of mortality and morbidity. The search continues for more effective treatments that target the edema that contributes to increased ICP. We previously described the effect of the fixed charge density (FCD) of brain on its swelling behavior according to the Donnan effect.

A detailed viscoelastic characterization of the P17 and adult rat brain.

Brain is a morphologically and mechanically heterogeneous organ. Although rat brain is commonly used as an experimental neurophysiological model for various in vivo biomechanical studies, little is known about its regional viscoelastic properties. To address this issue, we have generated viscoelastic mechanical property data for specific anatomical regions of the P17 and adult rat brain.

Age-dependent regional mechanical properties of the rat hippocampus and cortex.

Age-dependent outcomes following traumatic brain injury motivate the study of brain injury biomechanics in experimental animal models at different stages of development. Finite element models of the rat brain are used to better understand the mechanical mechanisms behind these age-dependent outcomes; however, age- and region-specific rat brain tissue mechanical properties are required for biofidelity in modeling. Here, we have used the atomic force microscope (AFM) to measure region-dependent mechanical properties for subregions of the cortex and hippocampus in P10, P17, and adult rats.

Fixed negative charge and the Donnan effect: a description of the driving forces associated with brain tissue swelling and oedema.

Cerebral oedema or brain tissue swelling is a significant complication following traumatic brain injury or stroke that can increase the intracranial pressure (ICP) and impair blood flow. Here, we have identified a potential driver of oedema: the negatively charged molecules fixed within cells. This fixed charge density (FCD), once exposed, could increase ICP through the Donnan effect.

Quantification of functional alterations after in vitro traumatic brain injury.

Traumatic brain injury (TBI) is caused by mechanical forces, producing tissue deformation at the moment of injury. Complex cellular, neurochemical and metabolic alterations are initiated by the deformation and result in delayed cell death and dysfunction. Using an in vitro model of TBI based on organotypic brain slice cultures, we have quantitatively studied the relationship between tissue deformation and functional outcome.

Region-specific tolerance criteria for the living brain.

Computational models of traumatic brain injury (TBI) can predict injury-induced brain deformation. However, predicting the biological consequences (i.e.

Mechanical heterogeneity of the rat hippocampus measured by atomic force microscope indentation.

Knowledge of brain tissue mechanical properties may be critical for formulating hypotheses about traumatic brain injury (TBI) mechanisms and for accurate TBI simulations. To determine the local mechanical properties of anatomical subregions within the rat hippocampus, the atomic force microscope (AFM) was adapted for use on living brain tissue. The AFM provided advantages over alternative methods for measuring local mechanical properties of brain because of its high spatial resolution, high sensitivity, and ability to measure live samples under physiologic conditions.