Primary Study Of Extracorporeal Shock Wave Effect On The Thoracic Segments Spinal Cord In Rats

Background:With the development of society, the production and living manner of people has changed a great deal; mental labor is gradually taking the place of physical labor. As the result, more and more people suffer from neck-shoulder-lumbodorsal pain and the incidence rate is rising year by year, while no especially effective treatment is found. In recent years, the curative effect of extracorporeal shock wave (ESW) for bone-anadesma disease has been generally accepted and it has been widely applied in clinic. Now, the nerves and the great vessels are usually regarded as the restricted zone of ESW, because the position of neck-shoulder-lumbodorsal pain tightly adjoins to spinal cord, whether ESW cause injury to the spinal cord as the pain treated by it, there is no definite world or national literature.Objective:To discuss if ESW causes injury to the spinal cord of the rat and whether vertebral plate can protect the spinal cord; to study the safety of ESW with therapeutic dosage in treating the diseases of spinal column according to the effect of ESW on spinal cord. If ESW with therapeutic dose doesn't cause injury on spinal cord according to the study, it would prove the safety of ESW used on the neck-shoulder-lumbodorsal pain, and bring gospel to the patients sufferring from the pain; if it causes injury on spinal cord, which would warn us that it should be cautious when treating the disease by ESW.Methods:The model of ESW was set up taking rats as the research object. 126 male Sprague Dawley (SD) rats were randomly divided into 4 groups: Group DS (directly shocked group, n=48), Group OS (shocked after operation group, n=48), Group US (unshocked after operation group, n=24) and Group NC (normal control group, n=24). The rats in Group DS received no operation to unclose vertebral plate and ESW therapeutic machine focused directly on the spinal cord; the rats in Group OS were operated to unclose the thoracic vertebral plate from No. 7 to No. 10 and were shocked on the spinal cord by ESW therapeutic machine after the skin healed; the rats in Group US were operated to unclose the thoracic vertebral plate from No. 7 to No. 10 but not shocked on the spinal cord after the skin healed; the rats in Group NC received no operation and no shock. 12 rats from Group DS and 12 from Group OS were killed 4h, 8h, 24h and 72h respectively after the disposal, and 6 rats from Group US were killed at the same time points. After perfusion, the spinal tissue specimens (T7~10) were collects from the rats of the 4 groups for routine pathological section Haematoxylin-Eosin (HE) to observe the injury of the spinal cord; immunohistochemistry was employed to examine C-fos protein expression in spinal cord; Terminal-deoxynucleotidyl transferase mediated d-UTP nick end labeling (TUNEL) was used to observe the apoptosis of spinal cord cell; semiquatitative analysis was made; the motor function of hind limbs was evaluated in each group according to BBB (Basso-Beattie-Breanahan) Score 8h, 24h and 72h after disposal, the results were statistically analyzed with ANOVA, statisticed by the t test.Results:1. The routine HE images showed the spinal cord with hemorrhage, edema, neuronal degeneration and necrosis in Group DS and Group OS after shock, the injury in Group OS was much more severe than that in Group DS. No obvious injury of spinal cord was found in Group US and Group NC.2. The expression of C-fos protein in spinal cord in Group OS was most obvious, and then was that in Group DS; the expression of 24h after shock was most obvious out of all the time points in both groups; no obvious expression was found in Group US and Group NC, the difference of average optical density (AOD) from those in Group OS and Group DS was significant (P<0.01).3. TUNEL showed the apoptotic index (AI) of Group OS was the highest, the next was that of Group DS; AI of Group US and NC were close to each other, and much lower than those of Group OS and Group DS, the difference was significant (P<0.01).4. The BBB scores of Group OS and Group DS decreased, and that of Group OS decreased most greatly; the scores of Group US and Group NC were higher and close to each other, the difference from those of the above 2 groups was significant (P<0.01).Conclusion:1. The direct focus of ESW on the spinal cord may cause hemorrhage, edema, degeneration even partial necrosis of neuron, the motor function of hind limbs may descend;2. The vertebral plate of the spinal column can partly protect the spinal cord in the shock by ESW, however it can not completely remove the affect of ESW on spinal cord which may cause certain injury.3. On the base of present theory and the experiment results, because the rat is lower animal, it's anatomy and physiology is greatly different from human, the effect of ESW on higher animal or human spinal cord and whether applied to clinic therapy or not, which should be further studied. We should be cautious when applying ESW to treat the disease on the spinal column, at least, the shock focus should not be direct on the spinal cord to avoid spinal cord injury.