Biomechanical Aspects of a Fluid Percussion Model of Brain Injury

Abstract

The fluid percussion model is in widespread use for the study of brain injury. However, the tissue deformation characteristics of the model have not been determined. Studies have suggested that at high levels of fluid percussion, the fluid percussion model is primarily a model of brainstem injury. It was proposed that this occurs as a direct result of the volume influx to the cranial vault at the moment of impact. This study examines the biomechanical deformation produced by the fluid percussion model. The purpose of this investigation was to describe the regional strain distribution in brain tissue at the moment of impact and to determine the effect of volume efflux produced by the percussion device. A cat skull was sectioned parasagittally and filled with an optically transparent gel. A grid pattern was painted in the midsagittal plane and was used to record the surrogate brain tissue deformation in response to fluid percussion loading. Motion of the grid pattern at low and high levels of fluid percussion loading was recorded using a high-speed camera, and a series of photographs developed from the high-speed film were analyzed to determine the intracranial strain distribution at these loading levels. The results of these studies indicated that the maximum site of strain was located in the region of the lower brainstem and that deformations were negligible in other regions of the brain. These studies provide an explanation for the pathophysiologic results obtained in a parallel series of experiments from which it was concluded that high-level fluid percussion is predominantly a model of lower brainstem injury.

Vulnerability of Central Neurons to Secondary Insults afterIn VitroMechanical Stretch

“…Rather, our focus here was on mechanisms that can lead to neuronal damage in mild in vitro stretch injury . The strain rates experienced by the neurons in our injury model are considerably less than those in previously published reports, because most of these used models that reproduced strains experienced during severe TBI in vivo (Thibault et al, 1992;Ellis et al, 1995;Zhang et al, 1996;Laplaca et al, 1997). Thus, our findings in a milder traumatic insult are significant in several respects.…”

The Mechanics of Traumatic Brain Injury: A Review of What We Know and What We Need to Know for Reducing Its Societal Burden

“…Direct visualization of grid patterns or embedded markers within a transparent silicone gel also provided direct evidence for the unique patterns of deformations that occur with accelerations imposed in different directions and the influence that different skull/gel boundary conditions and ventricular structures have on intracranial strains, showing that the ventricles can redistribute and, in some regions, reduce the strains appearing within the brain after impact [99][100][101][102]. In some instances, these models have been used to assess the effectiveness of different animal models to recreate the deformation patterns that appear during impact and have led to a redesign of animal models to produce deformation patterns that more closely resemble the strains within the hemispheres during injury [103][104][105]. These same techniques are now extended to blast loading conditions [102][103][104][105][106][107][108][109], where the efforts will yield significant information on the manner that external blast waves transfer to the brain simulant, how these pressures are distributed throughout the surrogate, and how these pressures dissipate over time.…”

“…In some instances, these models have been used to assess the effectiveness of different animal models to recreate the deformation patterns that appear during impact and have led to a redesign of animal models to produce deformation patterns that more closely resemble the strains within the hemispheres during injury [103][104][105]. These same techniques are now extended to blast loading conditions [102][103][104][105][106][107][108][109], where the efforts will yield significant information on the manner that external blast waves transfer to the brain simulant, how these pressures are distributed throughout the surrogate, and how these pressures dissipate over time. Although providing a direct window into the possible response of the brain to any external mechanical loading condition, it is worth noting that the highly elastic material properties of brain tissue surrogates will need to be considered in extending or interpreting these results for the viscoelastic, nonlinear brain tissue.…”

Modelos experimentales de traumatismo craneoencefálico

“…En el otro extremo del cilindro se coloca un péndulo que generará un pulso de presión sobre el fluido contenido dentro del tubo y que deformará el cerebro inmediatamente bajo la duramadre expuesta (Figura 3). La intensidad del trauma causado dependerá de la presión ejercida con el pulso de fluido 79,113 .…”