UBC Theses and Dissertations
Cervical cerebrospinal fluid pressure in an in-vivo porcine model of simulated whiplash loading Soltan Mohammadzadeh, Nikoo
Whiplash is a common automotive injury and can cause debilitating symptoms including neck stiffness and pain, headaches, and other cognitive/psychological symptoms. The diagnosis, treatment, and prevention of whiplash is challenged by the lack of scientific consensus on the mechanism of injury and source of symptoms. One theorized whiplash injury mechanism postulates that the rapid head/neck motion during a rear-end collision causes pressure transients in the spinal cerebrospinal fluid (CSF) which strain the sensory nerve cells in the cervical dorsal root ganglia. This study aimed to improve understanding of this potential injury mechanism by 1. Developing an in-vivo whiplash injury model to produce controlled and repeatable whiplash exposures, and 2. Correlating the head kinematics in simulated whiplash exposures with the cervical CSF pressure response. A custom test apparatus consisting of programmable servo-motors was developed that could simulate specific programmed whiplash exposures in a porcine model. An in-vivo porcine model was selected due to the gross anatomical and scale similarities to humans, and to enable measuring live spinal CSF pressure. Four anaesthetized Yorkshire pigs underwent surgery to implant three fiber-optic pressure transducers in the cervical intrathecal space. Cranial surgery was also performed to rigidly attach accelerometers and angular rate sensors for measuring head kinematics. Each instrumented animal experienced multiple whiplash exposures where the severity and shape of the whiplash exposure was altered. Relevant head kinematic parameters were extracted and correlated with the cervical CSF pressure response. Qualitatively, all whiplash exposures across the different subjects produced similar patterns of local and global maxima in CSF pressure. Maximum angular rate of the head and Neck Injury Criterion (relates the relative motion of the head and torso) were positively correlated with local pressure maxima, while delay in extension onset was negatively correlated with the local pressure maxima. Additionally, maximum head extension and time to maximum extension were positively, and negatively, correlated with global pressure maxima, respectively. These findings can be used to inform the design of automotive safety systems such as active anti-whiplash seats to reduce the pressure amplitudes in the cervical spine and risk of injury during whiplash exposures.
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