A new minimally invasive experimental spinal cord injury model in rabbits

The aim of this experimental study was to evaluate the effectivity of epidural microballoon inflation into the unroofed spinal column for the creation of a new experimental spinal cord injury model in rabbits. 10 New Zealand white rabbits were used for this study. Before operation and after anasthesia with 50 mg/kg ketamine and 8 mg/kg xylazine, spinal evoked potentials (SEP) were recorded in all rabbits. A midline skin incision was done on the lomber skin at the level of L1-L4. Paravertebral muscles were dissected bilaterally. A microhemilaminotomy was done in the right L3 lamina close to the midline by using Midas-rex micro-diamond drill instruments. The ligamentum flavum was opened and removed with microscissors. A microballoon was inserted into the spinal column between the bone and dura mater to the level of T12. The microballoon was inflated by using a pressure- and volume-controlled microballoon inflation device. Pre-injury and post-injury SEPs were recorded. The microballoon was deflated 15 minutes later and removed completely from the epidural space. 24 hours later the SEP study was repeated. Following microballoon inflation the SEP waves dropped to the basal level. All rabbits were paraplegic after the operation. In conclusion, this experimental study demonstrated that the microballoon inflation technique is a very successful method for the evaluation of spinal cord injury in rabbits. Unroofing of the spinal column is extremely important because decompression may be an effective treatment in spinal cord injury. Also the traumatic effect of aneurysm clips represents a different type of injury to the spinal cord. This new model may be used in experimental studies of spinal cord injury in rabbits.