Hybrid simulation of brain–skull growth

Abstract

This paper describes a hybrid model that includes both a standard finite element model and also volume-preserving structural modeling for a clinical application involving skull development in infants, with particular application to craniostosis modeling. To accommodate the growing brain, the skull needs to grow quickly in the first few months of life, and most of the growth of the skull at that time occurs at the sutures. Craniosynostosis, which is a developmental abnormality, occurs when one or more sutures are fused early in life (even in utero) while the skull is growing, resulting in an abnormal skull shape. To study normal brain-skull growth and to develop a model of craniosynostosis, we have developed a hybrid computational model to simulate the relationship between the growing deformable brain and the rigid skull. Our model is composed of the nine segmented skull plates as rigid surfaces, deformable sutures, and a volumetrically controllable deformable brain. The Cranial Index (ratio of biparietal width to fronto-occipital length) is measured during the simulation, showing a characteristic peak during development. Measures of linear growth along each dimension show characteristic increases over time. The hybrid simulation framework shows promise to support further investigations into abnormal skull development. By varying the properties of the sutures in our model, we can now simulate different craniosynostosis models, such as scaphocephaly and trigonocephaly. In this paper, we show results on the evolution of the Cranial Index as calculated using standard landmarks and compare to the normal index, and thereby evaluate our model by comparing it with patient data.

Mechanical Properties of Calvarial Bones in a Mouse Model for Craniosynostosis

“…Coronal sutures in the wild type mouse appear to be close (while never fully fused)at about postnatal day thirty (P30) while in the Crouzon mouse overlapping of the frontal and parietal bone at this suture begins at embryonic stages (E18.5) with full closure at typically about P10 [ 15 ]. This model provides an invaluable resource with which to understand the biomechanics of normal and craniosynostotic skulls during postnatal development and to improve surgical reconstruction of this condition in the long term [ 19 – 21 ].…”

An Overview of Modelling Craniosynostosis Using the Finite Element Method

“…It does not, however, explain how the growing brain interacts with different calvarial reconstructions during the development. In this respect, intracranial volume or brain soft tissue can be modelled and expanded based on the changes in the intracranial volume to take into account the loading arising from the growing brain [Jin et al, 2014;Libby et al, 2017;Marghoub et al, 2018]; (2) modelling the sutures -it is well established that the sutures can release the local mechanical strain [e.g., Moss,80 1954; Jaslow and Biewner, 1995;Moazen et al, 2013]. It is important to include the sutures to develop more realistic models of the craniofacial system [Jin et al, 2013;Libby et al, 2017;Weickenmeier et al, 2017;Marghoub et al, 2018].…”

“…At the same time in the past 20 years, evolutionary biologists and functional morphologists have widely used this technique to understand the form and function of craniofacial systems in an evolutionary context [e.g., Rayfield, 2007;Moazen et al, 2009;Wang et al, 2010;O'Higgins et al, 2011;Prado et al, 2016]. More recently, this technique has been used to understand the biomechanics of craniofacial development and its associated congenital diseases such as cleft lip/palate and craniosynostosis [e.g., Remmler et al, 1998;Pan et al, 2007;Khonsari et al, 2013;Jin et al, 2014;Lee et al, 2017;Marghoub et al, 2018].…”

Skull Development Simulation Model for Craniosynostosis Surgery Planning

“…Previously, we developed a simpler pressure-based model to simulate both normal and abnormal head development [4]. The results of normal head development, scaphocephaly, and trigonocephaly were acceptable models, but the result for anterior plagiocephaly did not match well the clinical datasets.…”