title: Finite element analysis for normal pressure hydrocephalus: The effects of the integration of sulci.
abstract: Finite element analysis (FEA) is increasingly used to investigate the brain under various pathological changes. Although FEA has been used to study hydrocephalus for decades, previous studies have primarily focused on ventriculomegaly. The present study aimed to investigate the pathologic changes regarding sulcal deformation in normal pressure hydrocephalus (NPH). Two finite element (FE) models-an anatomical brain geometric (ABG) model and the conventional simplified brain geometric (SBG) model-of NPH were constructed. The models were constructed with identical boundary conditions but with different geometries. The ABG model contained details of the sulci geometry, whereas these details were omitted from the SBG model. The resulting pathologic changes were assessed via four biomechanical parameters: pore pressure, von Mises stress, pressure, and void ratio. NPH was induced by increasing the transmantle pressure gradient (TPG) from 0 to a maximum of 2.0 mmHg. Both models successfully simulated the major features of NPH (i.e., ventriculomegaly and periventricular lucency). The changes in the biomechanical parameters with increasing TPG were similar between the models. However, the SBG model underestimated the degree of stress across the cerebral mantle by 150% compared with the ABG model. The SBG model also overestimates the degree of ventriculomegaly (increases of 194.5% and 154.1% at TPG = 2.0 mmHg for the SBG and ABG models, respectively). Including the sulci geometry in a FEA for NPH clearly affects the overall results. The conventional SBG model is inferior to the ABG model, which accurately simulated sulcal deformation and the consequent effects on cortical or subcortical structures. The inclusion of sulci in future FEA for the brain is strongly advised, especially for models used to investigate space-occupying lesions.
authors.affiliation: Department of Brain and Cognitive Engineering, Korea University, Seoul, South Korea.
authors.forename: Hakseung
authors.initials: H
authors.lastname: Kim
authors.affiliation: Department of Brain and Cognitive Engineering, Korea University, Seoul, South Korea.
authors.forename: Dae-Hyeon
authors.initials: DH
authors.lastname: Park
authors.affiliation: Department of Brain and Cognitive Engineering, Korea University, Seoul, South Korea; Department of Neurosurgery, Yonsei University College of Medicine, Seoul, South Korea.
authors.forename: Seong
authors.initials: S
authors.lastname: Yi
authors.affiliation: Department of Brain and Cognitive Engineering, Korea University, Seoul, South Korea.
authors.forename: Eun-Jin
authors.initials: EJ
authors.lastname: Jeong
authors.affiliation: Department of Neurosurgery, Stanford University School of Medicine, Stanford, California, USA.
authors.forename: Byung C
authors.initials: BC
authors.lastname: Yoon
authors.affiliation: Department of Neurosurgery, Addenbrooke's Hospital, University of Cambridge, Cambridge, United Kingdom.
authors.forename: Marek
authors.initials: M
authors.lastname: Czosnyka
authors.affiliation: Department of Engineering, University of Cambridge, Cambridge, United Kingdom.
authors.forename: Michael P F
authors.initials: MPF
authors.lastname: Sutcliffe
authors.affiliation: Department of Brain and Cognitive Engineering, Korea University, Seoul, South Korea; Department of Neurosurgery, Addenbrooke's Hospital, University of Cambridge, Cambridge, United Kingdom. Electronic address: dongjookim@korea.ac.kr.
authors.forename: Dong-Joo
authors.initials: DJ
authors.lastname: Kim
mesh_terms: D002540:Cerebral Cortex / Q000473:pathology* / Q000503:physiopathology*; D003198:Computer Simulation; D055119:Elastic Modulus; D020342:Finite Element Analysis; D006801:Humans; D006850:Hydrocephalus, Normal Pressure / Q000473:pathology* / Q000503:physiopathology*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D007427:Intracranial Pressure; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008959:Models, Neurological; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013314:Stress, Mechanical
keywords: Bi-phase; Biomechanics; Finite element model; Normal pressure hydrocephalus; Transmantle pressure gradient