Experimental Spinal Epidural Abscess: A Pathophysiological Model in the Rabbit

Abstract

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.

Paraplegia Caused by Intratumoral Hemorrhage Within Thoracic Epidural Granuloma -Case Report-

“…The developmental mechanism of symptoms of spinal epidural abscess may involve mechanical spinal cord compression 6,7) and spinal circulatory disorder. 10,15,16) Mechanical compression by abscess is considered to be directly involved in the remission of neurological manifestations after spinal decompression.…”

The indications and timing for operative management of spinal epidural abscess: literature review and treatment algorithm

“…33,35,51,54 The pathogenesis by which infection in the epidural space leads to neurological deficit remains a controversial topic, with evidence for both direct compression and vascular occlusion caused by septic thrombophlebitis as the offending mechanism. 8,23,24,30,55,66 The direct-inoculation rabbit model studied by Feldenzer et al along with the clinical improvement seen after surgically addressing mass effect caused by SEA, support the direct compression model. 13,23,24 However, instances of rapid clinical deterioration in the absence of radiographic compression and postmortem examinations showing venous and arterial thrombosis lend credence to a vascular etiology.…”

“…17 This condition is defined by a pyogenic infection of the potential space between the vertebral body and dura mater of the spine. 23,51,58 The epidural space can be seeded with infection by a variety of mechanisms including hematogenous spread (50%), direct extension from adjacent infection (33%), inoculation from spinal procedures (15%), or unknown mechanisms. 17,53,57 Although Staphylococcus aureus causes approximately two-thirds of spinal abscesses, other infecting pathogens including gram-positive and -negative bacteria, anaerobic bacteria, mycobacteria, fungi, and parasites have also been implicated.…”

Retropharyngeal abscess with secondary osteomyelitis and epidural abscess: proposed pathophysiological mechanism of an underrecognized complication of unstable craniocervical injuries: case report

“…4,5,14,28,30 This condition is defined as a pyogenic infection between the vertebral body and dura mater covering the spinal cord. 8,30,40 The epidural space can be seeded with infection by a variety of mechanisms, including hematogenous spread (50%), direct extension from adjacent infection (33%), inoculation from spinal procedures (15%), and other mechanisms. 5,32,39 Although Staphylococcus aureus causes approximately two-thirds of spinal abscesses, other infecting pathogens, including gram-positive and -negative bacteria and anaerobic bacteria, are possible causative agents.…”

“…Studies in the literature decades ago demonstrated in rabbits that diffuse thrombosis of the underlying vasculature is the probable cause of neurological decline in this condition. 8,9 Although surgical treatment of neurologically intact patients with vertebral osteomyelitis alone or minimal epidural abscess is quite controversial, vertebral osteomyelitis and epidural abscess associated with neurological deficits are considered surgical emergencies. 1,6,24,42,53 Since local inflammation leading to thrombophlebitis or venous congestion is thought to be a possible mechanism of neurological injury, surgical debridement is useful to remove the inciting organisms and factors to reduce the risk of vascular-related neurological complications.…”