In Vivo Pressure Responses of the Cervical Cerebrospinal Fluid in a Porcine Model of Extension and Flexion Whiplash Exposures

Purpose The mechanisms of whiplash injury remain poorly understood. One theory suggests that the characteristic inertial loading of the head and neck in motor vehicle collisions can produce injurious cerebrospinal fluid (CSF) pressure transients in the cervical spine. However, these in vivo CSF pressure responses have not yet been adequately characterized. Methods This study used a pig model to characterize the cervical CSF pressure responses to head kinematic inputs in extension (simulating low-speed rear-end collisions with no head restraint) and flexion (simulating low-speed frontal collisions). We also compared the pressure and pressure impulses at three spinal levels to determine if the pressure transient responses differ spatially. Four anesthetized pigs were instrumented with intrathecal pressure transducers placed at the C2, C5, and C7 levels. A servomotor system was programmed to actuate the head through specific trajectories to model two extension, and two flexion, whiplash exposures. Results During the extension tests, mean peak pressure transients ranged from - 31.2 to 148.7 mmHg, whereas during the flexion tests, mean peak pressure transients ranged from - 50.8 to 126.9 mmHg. Peak individual responses ranged from - 71.1 to 244.8 mmHg across all tests. Pressure impulses reached a maximum of 6.77 mmHg<middle dot>s. Peak pressure and pressure impulses were largest at the C5 and C7 levels during extension exposures and at the C2 level in flexion exposures. Conclusion The reported pressure and pressure impulse responses could be used to determine neural tissue tolerances relevant to whiplash injury and contribute to the development and validation of computational models of whiplash.