Abstract:

BACKGROUND: Studies have shown that sacral nerve-root stimulation based on anodes block technique can effectively reconstruct the bladder voiding function of the rabbits with spinal cord injury. But the corresponding technology of stimulating electrode has not been reported so far.
OBJECTIVE: To design and develop the stimulating electrodes matching with both rabbit sacral nerve roots and anodal blocking technique, to observe the ultrastructure and morphological change of rabbit sacral nerve roots which implanted in electrode stimulation for a long-term and to assess the safety of stimulating electrodes.
METHODS: Thirty New Zealand rabbits were included, 10 rabbits were randomly selected from them and sacrificed after anesthesia, and then cut the anterior roots of bilateral S2 and S3 immediately; after measuring the diameter under the light microscope, the sleeve type stimulation electrode matched with the diameter was made. The remaining 20 rabbits were randomly divided into control group and implantation group, with 10 rabbits in each group. In the implantation group, the stimulating electrodes were implanted into the forepart of S2 and S3 nerve roots after anesthesia, and then sacrificed after fed for half a year for collecting the samples. Then ultrastructure change of sacral nerve roots with the implantation was observed. 
RESULTS AND CONCLUSION: Structure of nerve cells of sacral nerve roots remained in good condition under a light microscope after long-term implantation of the stimulating electrodes. No obvious degeneration of axons, no inflammatory infiltration and glial scar formation were observed. In the implantation group, myelins arranged closely without demyelination phenomenon, and there was no atrophy of neuronal nuclear, no nuclear sag, no increased nuclear decompression and heterochromatin in neurons under the light microscope. Immunohistochemical analysis showed, compared with the control group, there were no significant differences in the expressions of glial fibrillary acidic protein, Bax, Bcl-2 and Caspase-3 proteins of nerve roots in the implantation group. The stimulation electrode of rabbit sacral nerve root is developed successfully, that is, the implantation is simple and safe as it can be used for long-term implantation without histopathological changes and apoptosis.

Key words: peripheral nervous system diseases, electric stimulation, electrodes, spinal nerve roots, sacrum