Abstract:

BACKGROUND: Resent studies demonstrate that sciatica is caused by inflammatory reaction of nucleus pulposus, and dorsal root ganglion (DRG) is in involved in this process; however, its pathophysiological changes remain poorly understood.
OBJECTIVE: To explore pathogenesis of sciatica related to nucleus pulposus protrusion without mechanical compression.

METHODS: Totally 24 male SD rats were randomly divided into the experimental group and control group, with 12 rats in each group. The coccygeal intervertebral discs of rats were opened to obtain 5 coccygeal nucleus pulposus, mixed with 50 μL physiological saline to prepare suspension. Rats in the experimental group were prepared non-compressive models by injecting suspension to the epidural cavum of rats. Meantime, the same volumes of physiological saline were injected into rats in the control group. The rat hind paw mechanical withdrawal thresholds were measured, pain-related behavior and dorsal root ganglion morphology were observed.
RESULTS AND CONCLUSION: In the absence of mechanical pressure, disappearance of the nucleolus, degeneration of the nuclear membrane and significant hyperalgesia derived by auto-transplantation of nucleus pulposus to the epidural cavum of rats were observed. Dorsal root ganglion cells often had hyperemia, edema and intracytoplasmic vacuoles, with large and irregular nuclei. Prominent Nissl bodies were not seen. The Inflammatory reaction derived by autograft nucleus pulposus is an important factor in DRG injury and sciatica.