title: Structural and mechanical characterisation of bridging veins: A review.
abstract: Bridging veins drain the venous blood from the cerebral cortex into the superior sagittal sinus (SSS) and doing so they bridge the subdural space. Despite their importance in head impact biomechanics, little is known about their properties with respect to histology, morphology and mechanical behaviour. Knowledge of these characteristics is essential for creating a biofidelic finite element model to study the biomechanics of head impact, ultimately leading to the improved design of protective devices by setting up tolerance criteria. This paper presents a comprehensive review of the state-of-the-art knowledge on bridging veins. Tolerance criteria to prevent head injury through impact have been set by a number of research groups, either directly through impact experiments or by means of finite element (FE) simulations. Current state-of-the-art FE head models still lack a biofidelic representation of the bridging veins. To achieve this, a thorough insight into their nature and behaviour is required. Therefore, an overview of the general morphology and histology is provided here, showing the clearly heterogeneous nature of the bridging vein complex, with its three different layers and distinct morphological and histological changes at the region of outflow into the superior sagittal sinus. Apart from a complex morphology, bridging veins also exhibit complex mechanical behaviour, being nonlinear, viscoelastic and prone to damage. Existing material models capable of capturing these properties, as well as methods for experimental characterisation, are discussed. Future work required in bridging vein research is firstly to achieve consensus on aspects regarding morphology and histology, especially in the outflow cuff segment. Secondly, the advised material models need to be populated with realistic parameters through biaxial mechanical experiments adapted to the dimensions of the bridging vein samples. Finally, updating the existing finite element head models with these parameters will render them truly biofidelic, allowing the establishment of accurate tolerance criteria and, ultimately, better head protection devices.
authors: Biomechanics Section, KU Leuven, Belgium. Electronic address: nele.famaey@kuleuven.be.
authors: Nele
authors: N
authors: Famaey
authors: Biomechanics Section, KU Leuven, Belgium.
authors: Zhao
authors: Z
authors: Ying Cui
authors: Department of Neurosurgery, University Hospital Gasthuisberg, KU Leuven, Belgium.
authors: Grace
authors: G
authors: Umuhire Musigazi
authors: Composite Materials Group, Department of Metallurgy and Materials Engineering, KU Leuven, Belgium.
authors: Jan
authors: J
authors: Ivens
authors: Department of Neurosurgery, University Hospital Gasthuisberg, KU Leuven, Belgium.
authors: Bart
authors: B
authors: Depreitere
authors: Translational Cell & Tissue Research, KU Leuven, Belgium.
authors: Erik
authors: E
authors: Verbeken
authors: Biomechanics Section, KU Leuven, Belgium.
authors: Jos
authors: J
authors: Vander Sloten
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D002540:Cerebral Cortex / Q000098:blood supply; D006801:Humans; D055595:Mechanical Phenomena; D054063:Superior Sagittal Sinus / Q000166:cytology
keywords: Anatomy; Bridging veins; Finite element modeling; Mechanical properties; Tolerance criteria