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Characterization of Closed Head Impact Injury in Rat.

Hua Y, Akula P, Kelso M, Gu L - Biomed Res Int (2015)

Bottom Line: Results revealed that impact depth and impactor shape were the two leading factors affecting intracranial responses.An indentation depth instead of impact depth would be appropriate to characterize the influence of a large deformed rubber impactor.This work could be used to better design or compare CHI experiments.

View Article: PubMed Central - PubMed

Affiliation: Department of Mechanical and Materials Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588-0656, USA.

ABSTRACT
The closed head impact (CHI) rat models are commonly used for studying the traumatic brain injury. The impact parameters vary considerably among different laboratories, making the comparison of research findings difficult. In this work, numerical CHI experiments were conducted to investigate the sensitivities of intracranial responses to various impact parameters (e.g., impact depth, velocity, and position; impactor diameter, material, and shape). A three-dimensional finite element rat head model with anatomical details was subjected to impact loadings. Results revealed that impact depth and impactor shape were the two leading factors affecting intracranial responses. The influence of impactor diameter was region-specific and an increase in impactor diameter could substantially increase tissue strains in the region which located directly beneath the impactor. The lateral impact could induce higher strains in the brain than the central impact. An indentation depth instead of impact depth would be appropriate to characterize the influence of a large deformed rubber impactor. The experimentally observed velocity-dependent injury severity could be attributed to the "overshoot" phenomenon. This work could be used to better design or compare CHI experiments.

No MeSH data available.


Related in: MedlinePlus

A coronal view of skull deformation for (a) flat impactor and (b) convex impactor.
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fig6: A coronal view of skull deformation for (a) flat impactor and (b) convex impactor.

Mentions: Under the same boundary constrains, the convex impactor reduced the intracranial peak MPS compared to the flat one: that is, K2 < K1 (column F in Table 3). However, it induced strain concentration within the brain (Figure 5, Cases  1 and 7), associated with the severity of TBI, and a stress concentration in the skull, leading to higher incidence of skull fracture (Figure 6). This is why flat impactors were commonly used in documented studies to induce the diffuse injury within the brain and to reduce the skull fracture [3, 5–7, 9]. In addition, the impactor diameter in the CHI tests is generally larger than 6 mm [3, 6, 7, 9], whereas it is less than 5 mm in the CCI tests [11, 15]. An increase in impactor diameter could substantially increase tissue strains in the cerebrum, located directly beneath the impactor; however, the strains in the hippocampus and cerebellum seem to be not sensitive to this impact parameter.


Characterization of Closed Head Impact Injury in Rat.

Hua Y, Akula P, Kelso M, Gu L - Biomed Res Int (2015)

A coronal view of skull deformation for (a) flat impactor and (b) convex impactor.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4588353&req=5

fig6: A coronal view of skull deformation for (a) flat impactor and (b) convex impactor.
Mentions: Under the same boundary constrains, the convex impactor reduced the intracranial peak MPS compared to the flat one: that is, K2 < K1 (column F in Table 3). However, it induced strain concentration within the brain (Figure 5, Cases  1 and 7), associated with the severity of TBI, and a stress concentration in the skull, leading to higher incidence of skull fracture (Figure 6). This is why flat impactors were commonly used in documented studies to induce the diffuse injury within the brain and to reduce the skull fracture [3, 5–7, 9]. In addition, the impactor diameter in the CHI tests is generally larger than 6 mm [3, 6, 7, 9], whereas it is less than 5 mm in the CCI tests [11, 15]. An increase in impactor diameter could substantially increase tissue strains in the cerebrum, located directly beneath the impactor; however, the strains in the hippocampus and cerebellum seem to be not sensitive to this impact parameter.

Bottom Line: Results revealed that impact depth and impactor shape were the two leading factors affecting intracranial responses.An indentation depth instead of impact depth would be appropriate to characterize the influence of a large deformed rubber impactor.This work could be used to better design or compare CHI experiments.

View Article: PubMed Central - PubMed

Affiliation: Department of Mechanical and Materials Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588-0656, USA.

ABSTRACT
The closed head impact (CHI) rat models are commonly used for studying the traumatic brain injury. The impact parameters vary considerably among different laboratories, making the comparison of research findings difficult. In this work, numerical CHI experiments were conducted to investigate the sensitivities of intracranial responses to various impact parameters (e.g., impact depth, velocity, and position; impactor diameter, material, and shape). A three-dimensional finite element rat head model with anatomical details was subjected to impact loadings. Results revealed that impact depth and impactor shape were the two leading factors affecting intracranial responses. The influence of impactor diameter was region-specific and an increase in impactor diameter could substantially increase tissue strains in the region which located directly beneath the impactor. The lateral impact could induce higher strains in the brain than the central impact. An indentation depth instead of impact depth would be appropriate to characterize the influence of a large deformed rubber impactor. The experimentally observed velocity-dependent injury severity could be attributed to the "overshoot" phenomenon. This work could be used to better design or compare CHI experiments.

No MeSH data available.


Related in: MedlinePlus