Modeling of Brain Shift Phenomenon for Different Craniotomies and Solid Models.

Journal of Applied Mathematics (Impact Factor: 0.72). 01/2012; 2012. DOI: 10.1155/2012/409127
Source: DBLP

ABSTRACT This study investigates the effects of different solid models on predictions of
brain shift for three craniotomies. We created a generic 3D brain model based on
healthy human brain and modeled the brain parenchyma as single continuum and
constrained by a practically rigid skull. We have used elastic model,
hyperelastic 1st, 2nd, and 3rd Ogden models, and hyperelastic Mooney-Rivlin with
2- and 5-parameter models. A pressure on the brain surface at craniotomy region
was applied to load the model. The models were solved with the finite elements
package ANSYS. The predictions on stress and displacements were compared for
three different craniotomies. The difference between the predictions of elastic
solid model and a hyperelastic Ogden solid model of maximum brain displacement
and maximum effective stress is relevant.

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    ABSTRACT: Pelvic floor injuries during vaginal delivery are considered a significant risk factor to develop pelvic floor dysfunction. The molding of the fetus head during vaginal delivery facilitates the labor progress, since it adjusts to the birth canal geometry. In this work, a finite element model was used to represent the effects induced by the passage of the fetus head on the pelvic floor. The numerical model used for this simulation included the pelvic floor muscles attached to the bones, and a fetus body. The model of the fetus head included the skin and soft tissues, the skull with sutures and fontanelles, and the brain. The fetus head movements during birth in vertex position were simulated: descent, internal rotation and extension. Two models of the fetus head were compared: a rigid and a deformable one, with the inclusion of the cranial sutures. The influence of the fetus head molding on the pelvic floor muscles was analyzed by evaluating their reaction forces, stretch, and stress and strain fields. Additionally, anatomical indices for the molding of the fetal skull were obtained and compared with clinical data. The passage of the deformable fetus head through the birth canal leads to a reduction of 17.3% on the reaction forces on the pelvic floor muscles when compared to the ones of a rigid head. Furthermore, the fetus head molding implies inferior resistance to rotation resulting in a reduction of 1.86% in muscle stretching. Quantitative evaluation of the fetus head molding showed good agreement with clinical experiments. Copyright © 2015 Elsevier Ltd. All rights reserved.
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    ABSTRACT: The fetus head is a sensible structure, subjected to high efforts, since it has to pass through the birth canal. During vaginal delivery the fetal head is subjected to high loads, which are caused by the pelvic floor. The sutures in the skull are called cranial sutures and lie between the bony plates and are responsible for protecting the brain. Due to the existence of these sutures, the skull bones can move as they go through all the diameters of the maternal pelvis. The objective of this study is to contribute to the clarification of the values of the strains and stresses caused in the fetal head, related to a vaginal delivery. In this work, the stretch on the pelvic floor and in the fetal skull were studied. The forces caused by the fetus on the pelvic floor, when the fetus moves down toward the vulva were also studied. In this work we simulated a vaginal delivery with a fetus considered rigid and a fetus considered deformable (presence of the flexible sutures), presenting in an occiput-anterior position and in an occiput-posterior position. The results obtained for the stretching of the pelvic floor and the fetus skull are higher when the fetus is considered a rigid structure and in an occiput-posterior position. When the skull is a rigid structure, the forces on the pelvic floor and the stretches caused by the fetus are greater in relation to the skull with a deformable structure (presence of the flexible sutures).
    Bioengineering (ENBENG), 2013 IEEE 3rd Portuguese Meeting in; 01/2013


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May 21, 2014