| 1. Objective:1.1Glucocorticoids are a class of the most commonly used drugs in the caudal injection therapy, but also most vulnerable to be abused leading to many clinical accidents. Glucocorticoids have a role to save the sodium and excrete potassium, easily lead to sodium retention, as well as the adverse reactions such as liver swelling and asthma. And different hormones cause adverse reactions in varying degrees. With regards to this, investigating the safety of different glucocorticoids in caudal injection therapy is necessary. However, previous literatures were just reports of clinical cases or comparative study of the clinical efficacy in different hormones, lack of basic research. So our group designed experiment1in major to study the effects on adrenocortical function and morphology of Sprague-Dawley(SD) rats treating with epidural steroid injection by prednisone, dexamethasone(DXM), triamcinolone acetonide, commonly used in clinical, providing the experimental basis for normalization of hormone security selection and drug compatibility.1.2Caudal injection therapy developed from the basis of anesthesiology. And we generally considered that the mechanism of caudal injection in the treatment of lumbar disc herniation was due to glucocorticoids into the epidural space directly blocking the pain pathway,blocking stimulation of the nerve root by chemical-stimulating factor and inhibition of inflammation, elimination of edema as well as inhibition of adhesion. So that in clinical some people arbitrarily increased the amount of local anesthetic or glucocorticoid, in order to improve clinical efficacy. Security on the amount of local anesthetic has been related to in-depth study, and the attention of clinicians. But on the amount of hormones, because of some of its adverse effects not appearing immediately, such as glucose, lipids and electrolytes, usually a few days or even weeks before a certain change need to go through a few days or even weeks before a certain change, many physicians blindly increase the amount of hormones, even with two hormones used together. For the amount of hormone had not been strictly controlled. So our group designed experiment2in major to study the effects on glucose, lipids and morphology of the femoral head of Sprague-Dawley(SD) rats with epidural injection by different concentrations of prednisone, providing experimental evidence for the selection of concentration in epidural steroid injections.1.3At present, injection of compound drugs for the clinical treatment of various intractable pain has become a common method of pain treatment. And through testing and studying the patients’nerve, muscle function before and after caudal injection with EMG and other inspection methods, the caudal drug injection therapy has been further confirmed in the affirmative. And more generally from the view of blocking nerve root, eliminating inflammation, dilate blood vessels, peel adhesion and neurotrophic to consider the composition of the commonly used composite liquid, but there were also scholars from the point of changing the pH value of the sacral canal environment, by adding an appropriate amount of sodium bicarbonate in the treatment of liquid to raise the pH directly, by reducing local tissue acidosis, to reduce the generation of H+and substances that causing local pain, in order to enhance the therapeutic effect. According to the doctrine of the distribution of pH, if the pH value is the greater, the degree of dissociation will be smaller, the higher of the local anesthetic concentration of non-ionic state, and the local anesthetic of non-ionic playing a role in nerve cells increased significantly, and finally the onset time and completely block time of local anesthesia drug were much shorter. This alkalization solution therapy obtained good results from the clinical reports. But whether this alkaline liquid will be adverse to the tissue of epidural space or not, still lack the support from the basic experiments. So our group designed experiment3preliminary to study the effects on function and histology of nerve root in SD rats with epidural injection by alkaline solution, providing experimental evidence for epidural injection by alkaline solution.2. Methods:2.1A total of70male SD rats were randomly devided into6groups, and every group has12rats. First3groups are experimental groups, including group1, just prednisone group, epidural injection of prednisone acetate+lidocaine+saline, the ratio of1ml:2ml:17ml; group2, just dexamethasone group, epidural injection of dexamethasone+lidocaine+saline, the ratio of1ml:2ml:17ml; group3, just triamcinolone acetonide group, epidural injection of triamcinolone acetonide+lidocaine+saline, the ratio of1ml:2ml:17ml. Group4, just the control group, epidural injection of lidocaine+saline, the ratio of2ml:18ml, each liquid dosage is1ml/kg/time. Group5, just the normal group, only involved in anesthesia, without any other processing. Experimental group and control group were weekly treated with epidural injection, for three consecutive weeks. Injection and assessment methods referred to the epidural modeling and assessment methods described in literature, and liquid injected into the epidural space in rats by the5,6lumbar intervertebral space. The fourth week of a unified time to take the blood of rats, carefully collect the supernatant after centrifugation, and detect the serum cortisol levels by the rats cortisol (Cortisol) ELISA kit. And take the rats of bilateral adrenal glands fixed in10%neutral buffered formalin, conventional methods of dehydration, paraffin-embedded sections, HE staining and measure adrenal cortex thickness and the proportion of fascicular zone. All data were used to mean±standard deviation (x±s), using SPSS13.0statistical software for analysis of variance (One-way ANOVA of LSD method) for statistical processing, comparing each group of rats’ serum cortisol levels, adrenal cortex thickness and the proportion of the fascicular zone.2.2A total of60male SD rats were randomly devided into5groups, and every group has12rats. First3groups were experimental groups, including groups with low, medium and high concentrations of prednisone, and the drugs of low concentration group of prednisone combined as prednisone acetate+lidocaine+saline, medication ratio of1ml:2ml:17ml; the drugs of medium concentration group of prednisone combined as prednisone acetate+lidocaine+saline, medication ratio of2ml:2ml:16ml; the drugs of high concentration group of prednisone combined as prednisone acetate+lidocaine+saline, the ratio4ml:2ml:14ml. group4and group5were the control group and the normal group. The control group, epidural injection of lidocaine+saline, the ratio of2ml:18ml, each liquid dosage is1ml/kg/time. Group5, just the normal group, only involved in anesthesia, without any other processing. Experimental group and control group were weekly treated with epidural injection, for three consecutive weeks, and were bleeded before the first treatment and one week after each treatment. Compare the continuous changes of glucose(GLU), total cholesterol(CHO), triglyceride (TG) in each group. All experimental rats were sacrificed with10%excess chloral hydrate anesthesia at the4th week, the femoral head were fixed in formalin, decalcified, soaked in water overnight, dehydrated, transparent, dip wax embedded, sectioned, HE staining and observed under the microscope. All data were used to mean±standard deviation (x±s), using Analysis of variance of the data for analyzing with SPSS13.0software. Within group at different time points were compared using Post Hoc Multiple comparisons (LSD method). Between the different groups before treatment were compared using One-Way ANOVA variance; the same point in time between the different groups after treatment, because of the need to consider the factors before treatment, the use of Analysis of Covariance was necessary. P<0.05indicated that the difference was statistically significance.2.3A total of36male SD rats were randomly devided into3groups, and every group has12rats. There were experimental group-just alkaline solution group, control group-just without alkaline solution, and the normal group. Alkalization solution group of drugs combined as dexamethasone+lidocaine+saline+sodium bicarbonate, medication ratio of1ml:2ml:12ml:5ml, the control group drugs combined dexamethasone+lidocaine+saline, medication ratio of1ml:2ml:17ml, the liquid dosage are1ml/kg/time. Normal group involved in anesthesia, without any other processing. Experimental group and control group were weekly treated with epidural injection, for three consecutive weeks. Measure paw withdrawal threshold to mechanical stimulation and cauda equina nerve conduction velocity of the rats before experiment and the forth week. By electrophysiological testing was completed in the forth week, take the rats spina cord and nerve roots fixed in10%neutral buffered formalin, conventional methods of dehydration, paraffin-embedded sections, HE staining, observed by optical microscope. Using SPSS13.0statistical software for statistical analysis, and measurement results were used to mean±standard deviation (x±s). Whingroup before and after treatment were compared using Paired-Samples T Test. Between the different groups before treatment were compared using One-Way ANOVA variance; comparison between the different groups after treatment, because of the need to consider the factors before treatment, the use of Analysis of Covariance was necessary. P<0.05indicated that the difference was statistically significance.3. Results:3.1There is statistical significance difference in serum cortisol between group1,4,5and group2,3(P<0.05). Adrenal gland in each group of HE staining showed that group2and group3the proportion of fascicular zone in cortex comparing with1,4,5decreased significantly (P<0.01). Animals died during the experiment:the third week(just after the second treatment), prednisone group had died1rat, dexamethasone group and triamcinolone acetonide group had died2rats, all with distended abdomen. Autopsy revealed massive abdominal ascites, intestinal flatulence, with speculating for heart failure death be caused by sodium and water retention. The control group and normal group both also had died1rat due to narcotic drugs overdose during experiment. 3.2Just one week after treatment, GLU in the high concentration and the medium concentration group of prednisone was significantly higher than other groups;(2) Just one week after treatment, the increasing trend of serum CHO, TG in the high concentration group was significantly higher than other groups, peaked in2weeks after treatment, the increasing trend of serum CHO, TG in the medium concentration group, after2weeks of treatment, was higher than low concentration group, control group and normal group. While serum TG was also slightly elevated in the low concentration group compare to the control group and normal group;(3) the situation of empty lacunae in femoral head, and disorder, Shorter, thinner of bone trabecula in the high concentration group was more common and more serious than other groups. During the experiment, the low concentration group and high concentration group of prednisone both had died1rats caused by sodium and water retention. The control group and normal group both also had died1rat due to narcotic drugs overdose. Rats with Sodium and water retention all showed distended abdomen, the autopsy found that the abdomen with massive ascites, intestinal flatulence.3.3Before and after the experiment, there was no statistically significant differences in the posterior limb’s retracting threshold for mechanical stimulation of rats among each group, also was the cauda equina’conduction velocity in each group. There was no obvious damage change in pathological section of each group’nerve root. During the experiment, the rate of sodium and water retention in alkaline solution group was higher than other groups, and4rats appeared to sodium and water retention, of which3died, while the control group2rats appeared to sodium and water retention and all died. The normal group had died1rat due to narcotic drugs overdose. Rats with Sodium and water retention all showed distended abdomen, the autopsy found that the abdomen with massive ascites, intestinal flatulence, with speculating for heart failure death be caused by sodium and water retention.4. Conclusions:4.1Epidural injection of long-term hormone with systemic impact, such as dexamethasone and triamcinolone acetonide, might cause adrenal insufficiency and adrenal atrophy morphological changes in male SD rats, but middle-term hormones with less systemic impact as prednisone did not cause such similar changes. May be due to the longer half-life time of the long-term hormone, high accumulation of the drug concentration caused by continuous administration, and long-term inhibition of the normal function of the adrenal gland, may also be caused by different potency due to different hormone kinds. And prednisone acetate caused the lower risk of sodium and water retention. Therefore, in epidural steroid injection therapy, selection of middle-term hormones with mainly local effects as prednisone acetate was safer than long-term hormone with more systemic impact, such as dexamethasone and triamcinolone acetonide.In epidural steroid injection, there is a rare, potentially, even serious complications of the nervous system, the surrounding tissue, organs and other systems, etc., such as brain and spinal cord infarct, epidural hematoma, disc space infection, menstrual disorders, allergies and so on. The mechanism of some complications remains unclear and needs further study. Faced with the above factors of insecurity, we should develop a standard and reasonable operating procedures to guide the clinical application as soon as possible. Concerned about basic research of the epidural injection in the later practice of scientific research. And use of a unified, standard treatment monitoring indicators and time of assessment endpoints in future clinical trials, with long-term observation of the clinical response to the relevant factors, and comparing the effect of the difference between the different groups. It is recommended that multiple clinical centers together to study, collection of valid data to evidence-medical analysis, using the scientific conclusions to guide the clinical application.4.2Epidural injection of high concentrations of prednisone has a negative impact on glucose, lipids, and made the pathological changes of similar necrosis on the femoral head. Therefore, we should strictly control indications of epidural steroid injection in treatment of pain-related diseases. For patients with diabetes, obesity or hyperlipemia, as well as severe osteoporosis, mainly relying on the unilateral femoral head to load, with more concentrated stress should be used with caution in epidural steroid therapy, and prohibited to multiple injections. In other patients with repeated epidural injection, should pay attention to the routine monitoring of blood glucose, blood lipids, platelets and plasma viscosity, as convenient indicators of important reference value for the prevention and treatment of femoral head necrosis. Concerned about the results of the present study, the less low concentrations of steroid using in the epidural space is a much safer choice.4.3In alkaline solution group, and the routine epidural injection liquid of normal control group, the nerve root function did not occur significantly sensitive or slow changes, and there was not obvious histological damage of nerve root before and after experiment. Showed that drug composition of the experimental group and control group did not cause significant damage to nerve root function and histology, which was a relatively safe drug of choice. Namely the alkaline solution of caudal injection will not cause the harmful effects of nerve root function and histology, this formula can be used as a safe choice. However, due to long-term hormone maybe easily leading to sodium and water retention, if we join the alkalization of the solution will more easily lead to balance disorders in electrolyte and acid-base of the body, causing sodium and water retention or aggravating circumstances. Taking into account the existence of the risk of sodium and water retention, I believe that by reducing the current clinical practical dosage of5%bicarbonate5ml can reduce the occurrence of such risks. As for the ideal amount, we need further basic experimental and clinical research as guidance, in order to better play its clinical value under the premise of safety. |
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