Case: Extruded disc material located centrally at L5-6
2nd August 2014
Intervertebral discs are the soft tissue structures separating the bones of the vertebral column. There are 7 cervical, 13 thoracic, and 7 lumbar vertebrae. Most clinically significant disc disease affects the thoracolumbar discs between T10 and L3. Degenerate discs can rupture and spill their central contents (disc extrusion) or bulge out (disc protrusion). The extrusion or protrusion puts pressure on the spinal cord and/or the spinal nerve roots causing pain (which can be severe) and/or neurological signs (anything between mild wobbliness to complete paraplegia and complete loss of “down stream” sensation).
Honey, a 5 year Cocker spaniel presented with significant pain, present for a few weeks. She was a bit wobbly on his back legs, but she was getting around.
Plain x-rays often aren’t enough to conclusively diagnose disc disease because the disc is soft tissue density, not bone density. But if any extruded disc material is adequately mineralised which is sometimes the case, then the extrusion may show up on standard x-rays. This was the case with Honey and an L5-6 disc (the disc between the 5th and 6th vertebrae) extrusion was apparent.
Myelography was performed where a contrast agent is added to the fluid that surrounds the spinal cord to highlight area(s) of compression. Most times, disc material extrudes to the left or to the right. But the myelogram suggested that the extruded material was very centrally positioned under the spinal cord. This made it harder to get at. The pain that Honey was in will have related to extruded material pressing on spinal nerve roots.
The nerve roots coming out between the vertebrae at the L5-6 level are important because they comprise part of the nerve supply to the back legs. In addition the end of the spinal cord is located at that level within the spinal canal, and nerve roots going further down the back within the spinal canal to give further supply to the back legs and the bladder pass this level.
To access the extruded disc material we ended up doing hemilaminectomy procedures on both sides of the spinal column.
Honey made an excellent recovery and pain was rapidly resolved with surgery. We were a bit shocked to see just how comfortable and mobile she was at a routine post-op check 2-3 weeks post-op. While we were going over with the owner what we’d done in detail, using a spine visual aid, she thought she’d put her feet up on the table and get involved …