Study of an infant brain subjected to periodic motion via a custom experimental apparatus design and finite element modelling
Introduction
Shaken baby syndrome (SBS) is a form of child abuse caused by violent shaking. Almost 200 babies in the UK die annually from injuries related to SBS, whereas twice that number of babies survive with permanent brain damage or visual impairment.
An early biomechanical study of SBS focused on measuring the shaking acceleration by using either a dynamic rigid anthropomorphic shaking dummy (Duhaime et al., 1987, Prange et al., 2003, Cory and Jones, 2003) or mathematical dynamic modelling (Wolfson et al., 2005). However, the results are contradictory to pathological evidence. The explanation of the mechanism of injury remains unknown (Goldsmith and Plunkett, 2004, Shannon and Becker, 2001, Ommaya et al., 2002).
Meanwhile, a considerable number of experimental studies was performed related to impact head injuries. Margulies et al. (1990, 1992) constructed mid-sagittal plane skull models that were excited by traffic collision whiplash to study the diffused axonal injury (DAI). Ivarsson et al. (2000) constructed a physical model of a parasagittal human head to establish whether cerebral ventricles could relieve the shearing deformation to protect the brain from rotational injury. Bradshaw et al. (2001) created a model of a coronal plane to investigate the DAI induced by coronal impacts. Finite element (FE) methods were also used to model head injury. Kleiven and Holst (2002) studied the size of the head and intracranial response under impact loading by using a 3D FE model. Margulies and Thibault (2000), Lapeer and Prager (2001) and Cheng, et al. (2005) used an FE model to demonstrate that an infant’s skull with fontanelle shows a significantly larger cranial deformation and stress distribution to the brain. Additionally, an FE study by Omori et al. (2000) indicated that the protruded vasculature tissue inside of the CSF affected the stress distribution on the brain surface during rotational loading. However, a combination of the experimental testing and FE modelling has not been previously reported for the study of SBS.
The aim of the present study is to investigate an innovative test apparatus and to compare reliable test data to FE models for the study of SBS. The motion of an infant brain is explored with and without anterior fontanelle (Fig. 1) and its protrusion into the fluid. The FE modelling of the brain–skull interface was compared to the traditional Lagrangian algorithm and the fluid–structure–interaction (FSI).
Section snippets
Description of method
Fig. 2 shows the configuration of the experiment and the numerical simulation. The method consisted of the design of the experimental apparatus and the anthropomorphic infant head models with an open circle covered with membrane, which is used to simulate the anterior fontanelle. The FE models were used to validate the test results, and the experimental output (displacement vs. time) was used as input to the models.
Table 1 shows the results from the experiment and the FE models. For simplicity,
Test rig vs. shaking test
The TRL test data using a soft-neck dummy were compared to the output of the apparatus (Fig. 9). For a period of 3.5 s, AL1 represents three shakings, and AL2 represents a continuous shake. The rig produced a repetitive displacement similar to (lying between) that of AL1 and AL2. This demonstrates that the rig is capable of reproducing the shaking profile.
The FE model was excited by using the experimental output (Fig. 9) for a 4 s interval.
Experimental model M1 vs. M2
Fig. 10 shows the field of displacements of the paper
Discussion
The test results demonstrate that the rig produced a repetitive displacement between that of the AL1 and AL2 TRL tests. The rig velocity was comparable to the TRL values. Because a similar horizontal movement was observed in the gelatine sphere between M1 and M2, the experimental results indicate that the open model with a built-in stiffening factor was identical to the fully closed model.
The Lagrangian analysis (with the advantage of the smallest computational cost) of the open dome predicted
Conclusion
A set of experiments to study the mechanics of SBS was performed using a custom adjustable pneumatic apparatus that mimicked the motion observed in volunteer tests of the shaking of an automotive dummy. Three techniques (Lagrangian, ALE and Eulerian) are available for conducting the FSI in FE analyses.
The results indicate that the FSI in FE models with interacting brain, CSF and skull components is more accurately and realistically assessed by using a Eulerian method for a shaking injury
Conflict of interest statement
I declare that there are no financial and personal relationships with other people or organisations that could inappropriately influence (bias) my work.
Acknowledgements
The authors are grateful to Arup for providing the LS-DYNA software that is essential to performing the FSI analyses of this work. They also wish to thank:—Dr A. M. Parsons for leading the TRL experimental shaking work; Dr P. Lawford of the Department of Medical Physics and Clinical Engineering, the University of Sheffield, for considerable assistance with the paediatric medical background; and Dr S. Cirovic of the Centre for Biomedical Engineering, University of Surrey and Dr. Alaster Yoxall,
References (25)
Simulation of acute subdural hematoma and diffuse axonal injury in coronal head impact
Journal of Biomechanics
(2001)Strain relief from the cerebral ventricles during head impact: experimental studies on natural protection of the brain
Journal of Biomechanics
(2000)- et al.
Consequences of head size following trauma to the human head
Journal of Biomechanics
(2002) - et al.
Physical model simulations of brain injury in the primate
Journal of Biomechanics
(1990) - et al.
Mechanisms of brain injury in infantile child abuse
The Lancet
(2001) - et al.
Study on the influence of different interface conditions on the response of finite element human head models under occipital impact loading
JSME international Journal Series C – Mechanical Systems, Machine Elements and Manufacturing
(2003) - et al.
A Text Book of Head and Neck Anatomy
(1988) - Cheng, J., Cirovic, S. et al., 2005. Can shaking alone damage an infant’s brain? A new hypothesis for the vulnerability...
- Cheng, J., 2008. Shaken baby syndrome: simulation via computational and physical modelling. PhD thesis. University of...
- et al.
Can shaking alone cause fatal brain injury?-A biomechanical assessment of the Duhaime shaken baby syndrome model
Medicine, Science and the Law
(2003)
The shaken baby syndrome—A clinical, pathological, and biomechanical study
Journal of Neurosurgery
A biomechanical analysis of the causes of traumatic brain injury in infants and children
The American Journal of Forensic Medicine and Pathology
Cited by (19)
A coupled physical-computational methodology for the investigation of short fall related infant head impact injury
2019, Forensic Science InternationalCitation Excerpt :Thus, the FE tissue response properties must be consistent with those of the corresponding areas of physical-surrogate. The cranial bone material orientation in the FE-head, compared to reality, is shown in Fig. 3a, b, c and further replicating the fibrous appearance of the cranial bones in the physical-surrogate, see Fig. 3d, e. To model the brain, a surrogate brain material, gelatin was used in the 3D printed head [16,17], in accordance with a previous study by Cheng et al. [19], which conducted a dynamic tensile test and modelled the gelatin as a brain surrogate material. A latex rubber and polyamide micro fleece scalp, representing the elastic and frictional properties [20] of the scalp, was modelled and applied to the outer contact surface of the skull, whilst leaving the skull surface uncovered to permit the application of random speckle pattern for Digital Image Correlation analysis of the physical model for subsequent derivation of local/regional response data [16,17].
Development and validation of a physical model to investigate the biomechanics of infant head impact
2017, Forensic Science InternationalCitation Excerpt :The infant skull, comprising the cranial bones and sutures were printed in polypropylene polymers using Stratsys RGD835 Vero White Plus for the frontal and parietal bones, RGD8510 DM Rigid Light Grey 25 for the occipital bone and FLX9870 DM for the sutures To model the brain, a surrogate brain material, gelatin (10% gelatin: 90% water) was injected into a rubber balloon in the brain cavity through the foramen magnum of the 3D printed head model, in accordance with a previous study [15]. Once the liquid gelatin had set, the foramen was sealed.
Biomechanics of Periventricular Injury
2020, Journal of NeurotraumaModeling of inflicted head injury by shaking trauma in children: what can we learn?: Part II: A systematic review of mathematical and physical models
2019, Forensic Science, Medicine, and PathologyBiomechanics of Acute Subdural Hematoma in the Elderly: A Fluid-Structure Interaction Study
2019, Journal of Neurotrauma