Experimental spinal epidural abscess: a pathophysiological model in the rabbit.

To define the pathophysiology of spinal cord dysfunction associated with spinal epidural abscess formation, we developed an experimental model. Spinal epidural abscesses were produced in rabbits by injecting Staphylococcus aureus into the posterior thoracolumbar epidural space under direct vision. Progressive neurological deficits were detected in 18 of 20 animals; severe paraparesis or paraplegia occurred in 75%, and sphincter dysfunction occurred in 55%. Clinical data, including the results of plain spine roentgenography, myelography, and biochemical and bacteriological examination of the cerebrospinal fluid, were recorded. Epidural abscesses with varying degrees of spinal cord compression were confirmed pathologically in 95% of the experimental group. Spinal cord white matter changes included vacuolization, loss of myelin, and axonal swelling. The gray matter of the spinal cords was relatively preserved. There was no microscopic evidence of thrombosis or vasculitis in the major blood vessels supplying the spinal cords. Histopathological changes detected in the spinal cords were more consistent with direct compression of neural tissue than with infarction. The progressive clinical course and the histopathological changes in the spinal cord after compression by abscess closely resembled those of experimental compression of the spinal cord by epidural neoplasm.