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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

Relative displacement at five mark locations (M1–M5) along the brain/skull interface.
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fig7: Relative displacement at five mark locations (M1–M5) along the brain/skull interface.

Mentions: Impact position is found to be crucial in determining the extent and location of tissue injury in rat brain. Our results (Table 3) show that lateral impact induced higher peak MPS in all three brain regions compared to the central impact. Moreover, the high strains induced by the lateral impact were mainly focused on the ipsilateral side of the brain, while those induced by the central impact were more diffusely located on both sides (Figure 5, Cases  1 and 8). This is consistent with the clinical observation that lateral impact inflicts primarily unilateral cortical damage, whereas central impact causes bilateral cortical alterations [3, 7]. Furthermore, the lateral impact is able to induce a larger relative movement between the brain and skull, which contributes to the subarachnoid hemorrhage (SAH), a common cerebrovascular event following CHI [5, 6]. The relative displacement at five marked locations (M1–M5) along the brain/skull interface was compared between central and lateral impacts (Figure 7). The maximum relative displacement was 0.43 mm at location M1 subjected to lateral impact and 0.20 mm at location M2 subjected to central impact. This indicates that SAH is more likely to occur on the ipsilateral side of the brain. However, the relative displacement induced by the lateral impact was minimal at location M2. This is due to the fact that this location is along the midline of the lateral impactor, which constrained the relative motion between the brain and skull. A similar observation existed at location M3, along the midline of the central impactor, which limited the relative skull/brain displacement. This implies that a properly designed impact position is able to guide SAH to target a specific region of interest.


Characterization of Closed Head Impact Injury in Rat.

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

Relative displacement at five mark locations (M1–M5) along the brain/skull interface.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

fig7: Relative displacement at five mark locations (M1–M5) along the brain/skull interface.
Mentions: Impact position is found to be crucial in determining the extent and location of tissue injury in rat brain. Our results (Table 3) show that lateral impact induced higher peak MPS in all three brain regions compared to the central impact. Moreover, the high strains induced by the lateral impact were mainly focused on the ipsilateral side of the brain, while those induced by the central impact were more diffusely located on both sides (Figure 5, Cases  1 and 8). This is consistent with the clinical observation that lateral impact inflicts primarily unilateral cortical damage, whereas central impact causes bilateral cortical alterations [3, 7]. Furthermore, the lateral impact is able to induce a larger relative movement between the brain and skull, which contributes to the subarachnoid hemorrhage (SAH), a common cerebrovascular event following CHI [5, 6]. The relative displacement at five marked locations (M1–M5) along the brain/skull interface was compared between central and lateral impacts (Figure 7). The maximum relative displacement was 0.43 mm at location M1 subjected to lateral impact and 0.20 mm at location M2 subjected to central impact. This indicates that SAH is more likely to occur on the ipsilateral side of the brain. However, the relative displacement induced by the lateral impact was minimal at location M2. This is due to the fact that this location is along the midline of the lateral impactor, which constrained the relative motion between the brain and skull. A similar observation existed at location M3, along the midline of the central impactor, which limited the relative skull/brain displacement. This implies that a properly designed impact position is able to guide SAH to target a specific region of interest.

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