New, Clinically more Relevant Model for Nerve Root Injury in the Rat.
Spine (Phila Pa 1976). 2013 Sep 15;38(20):1744-8
Authors: Finskas O, Blixt A, Fujioka Y, Olmarker K
STRUCTURED ABSTRACT: Study Design. Exposure to nucleus pulposus and displacement of intra spinal nervous structures with assessment of spontaneous behavior changes in rats.Objective. To develop a controlled, experimental model for nerve root injury.Summary of Background Data. There are a number of experimental models presented for studies on radiculopathies. One often utilized model is based on exposure to nucleus pulposus and displacement of the dorsal root ganglion (DRG). However, it is clinically more common that the nerve roots are displaced/compressed than the DRG. In the present study, we developed a model for displacement of the nerve root by modifying the DRG model.Methods. After removing the left L3-4 facet joint the underlying disc was punctured and the L4 nerve root was displaced laterally by an injection needle (n = 10). In sham experiments the same procedure was performed without disc puncture and displacement (n = 10). In ten rats, the left L4-5 facet joint was removed. The underlying disc was punctured and the L4 DRG was displaced medially by an injection needle. Assessment of spontaneous behavior changes were performed at days 1, 3, 7, 14 and 21 post surgery.Results. There was a clear increase in duration of the behavior Unloading of the paw following displacement of the DRG that was most pronounced at day 1 and then gradually declined. There was a similar patter for this behavior induced by nerve root displacement although the duration was higher than for the DRG displacement. No apparent trends in behavior changes were observed for the other behaviors studied.Conclusion. Displacement of the nerve root induced more changes in pain behavior than displacement of the DRG but only for the behavior Unloading of the paw. Since nerve root injury is more common than DRG injury, this model may be more clinically relevant than the DRG model.
PMID: 24042709 [PubMed – in process]