Simulation is an invaluable tool in mechanical engineering. According to researchers from Stanford, Oxford and Exeter Universities, simulation may also prove an invaluable tool in saving lives.
The researchers turned to simulation to address the many problems with a neurosurgical procedure known as a decompressive craniectomy. In this procedure, surgeons remove a part of the skull to alleviate the swelling of an injured brain. This controversial procedure is both invasive and unreliable, with some patients suffering long-term disabilities as a result. Because of this, it is often turned to only as a last resort.
One of the main problems with decompressive craniectomies is that there are no clear criteria for who should receive the procedure, when it should be administered, where the skull opening should be made, or how big the opening should be. Traditionally, these are judgment calls made by experienced surgeons, as there is no more reliable method for evaluating the procedure’s options. But that may be changing, thanks to simulation.
A Personalized Brain Model
In order to study the effect of altering these surgical variables, researchers developed a 3D model of a human brain. To create the model, the researchers first took magnetic resonance images of an adult female brain. Using Simpleware ScanIP, Synopsys’ 3D image reconstruction and model generation software, the researchers then combined 190 two-dimensional slices of the brain to create the 3D, simulation-ready model.
3D model in hand, the researchers then turned to simulation to quantify the mechanical stress that brains experience due to decompressive craniectomies. The brain model was imported into Abaqus, Dassault Systèmes’ finite element analysis (FEA) software, where the team prescribed boundary conditions, material models and interaction constraints.
The researchers then simulated skull openings of varying sizes and locations to determine which would cause the least amount of stress. They semi-manually removed skull elements to create the opening, and prescribed a local volumetric expansion in a region of the white matter to simulate the brain swelling.
The simulations revealed many interesting properties of decompressive craniectomies. For example, the research suggests that opening the skull on the same side of the swelling is better for the brain than opening it on the side opposite to the swelling. The researchers also identified three potential failure mechanisms of the procedure: axonal stretch in the center of the brain bulge, axonal compression at the edge of the craniectomy, and axonal shear around the skull opening.
Ultimately, the research suggests that simulating brains could provide surgeons with an invaluable tool in determining which patients are fit for decompressive craniectomies, where the skull opening should be located, and how big the opening should be.
“The recent development of new tools for bridging between medical imaging data and simulation opens up exciting new opportunities for gaining a better understanding of current clinical procedures and for the development of new, more effective, patient specific therapies,” says Professor Philippe Young of the Simpleware Product Group at Synopsys.
So, go ahead and leave your helmet at home—if anything happens to your brain, simulation has your back. (Note: do not take this advice.)
You can learn more about this research by reading the original paper: The mechanics of decompressive craniectomy: Personalized simulations. Lead author J. Weickenmeier is the Principal Investigator of Weickenmeier Lab at Stevens Institute of Technology.