Intervertebral disc fenestration is among the recommended surgical procedures in the management of intervertebral disc disease. It was designated this study, to evaluate the potential for damage to the spinal cord during ventral cervical and lateral thoracolumbar fenestration procedures. Fourty five cadavers of stray dogs of both sexes and various breeds, were used. All dogs were young adults, neurologically normal and with body weight ranging from 7 to 13kg. From 25 dogs, the cervical spinal segment comprehending C1-C7 was freshly collected after death, while from the remaining 20 dogs, the thoracolumbar segment T11-L4 was equally freshly harvest. The spinal canal was opened (all the dogs were free of intervertebral disc disease) and a dorsal incision was performed through the annulus fibrosus of the intervertebral disc until the nucleus pulposus was reached. A either ventral or lateral fenestration, with and without window openening was immediately performed. From a total of 100 fenestrated cervical intervertebral discs, 78 dorsal extrusions of disc material were observed, being 55% in the window group and 45% in the non-windowed group. From the 120 thoracolumbar fenestrated discs, 68 (56.6%) presented dorsal extrusion of nucleus pulposus material into the spinal canal. Fourty-seven of these occurred in the window group, whereas 53% of the extrusions occurred in the non-window group. It was verified that intervertebral disc fenestration, with or without the opening of a window in the annulus fibrosus can result in disc material extrusion towards the vertebral canal. The incidence of extrusion was significantly higher in the cervical region when compared to the thoracolumbar area (p< 0.01), but there were no differences in disc extrusion rates between the window and non-window techniques in either cervical or thoracolumbar areas.
spinal surgery; intervertebral disc extrusion; disc fenestration; dogs
