Despite concentrated research efforts there is currently no treatment for spinal cord injury (SCI). Several researchers have identified that cerebrospinal fluid (CSF) may have a role in the biomechanics of the injury event and in the secondary physiologic response, but this has not been closely examined. The aim of this thesis was to develop a large animal model and a benchtop model of human SCI, and to use these to characterise (1) the pressure response of the CSF during the SCI event, (2) the effect of CSF thickness on mechanical indicators of injury severity, and (3) the pressure differentials and cord morphology associated with thecal occlusion and decompression.

Study 1 presented the large animal model and provided preliminary CSF pressure transient data that indicated further investigation was warranted. In Study 2, the CSF pressure transients from medium and high severity human-like SCIs were characterised. The peak pressures at 30 mm from the impact were within the range associated with experimental traumatic brain injury, but the wave was damped to peak pressures associated with noninjurious everyday fluctuations by 100 mm. In Study 3, results from the bench-top model demonstrated that the thickness of the CSF layer is directly proportional to the resultant peak CSF pressure, cord compression and impact load.

In Study 4, the cranial-caudal CSF pressure differential increased gradually over eight hours of thecal occlusion. Decompression eliminated or reduced the differential, after which it did not change significantly. These results indicate that lumbar CSF pressure measured prior to decompression may not be representative of CSF pressure cranial to an injury. In Study 5, the change in spinal cord and thecal sac morphology after surgical decompression was assessed with ultrasound. Moderate SCI was associated with a residual cord deformation and then gradual swelling, while high severity SCIs exhibited immediate swelling which occluded the thecal sac within five hours.

The different aspects of CSF response to SCI demonstrated in this thesis can potentially be used to assess and validate current and future models of SCI, and to guide future studies of clinical management strategies such as CSF drainage and early decompression.