Effect of epidural polydeoxyribonucleotide in a rat model of lumbar foraminal stenosis

Therapeutic effect of epidural dexamethasone palmitate in a rat model of lumbar spinal stenosis

BACKGROUND

Dexamethasone palmitate (DEP), a prodrug of dexamethasone (DEX), is a synthetic corticosteroid medication distinguished by the inclusion of a fatty acid component known as palmitate. This study introduces DEP as a novel therapeutic option for spinal epidural injection, aiming to provide safer and longer-lasting pain relief as an alternative to for patients with spinal stenosis.

METHODS

40 rats were randomly divided into four groups: those receiving epidural administration of normal saline (NS), and DEP in the lumbar spinal stenosis (LSS) model, and non-model rats receiving epidural NS administration. Paw withdrawal thresholds to mechanical stimulation and motor function (neurogenic intermittent claudication) were observed for up to 21 days. Hematology and blood chemistry analyses were performed 1 week after drug therapy. Tissue samples were collected for steroid pathology examination to evaluate adhesion degree, perineural area inflammation, and chromatolysis in the dorsal root ganglion (DRG), and adrenal gland.

RESULTS

The DEX and DEP groups demonstrated significant recovery from mechanical allodynia and motor dysfunction after 2 weeks of drug therapy (p<0.001). However, by the third week, the effect of DEX started to diminish while the effect of DEP persisted. Furthermore, the DEP group exhibited reduced fibrosis and less chromatolysis than the NS group. No steroid overdose or toxin was observed in any group.

CONCLUSION

The epidural administration of DEP demonstrated therapeutic efficacy in reducing allodynia and hyperalgesia resulting from chronic DRG compression, thus offering prolonged pain relief. These findings underscore the potential of DEP as a promising treatment alternative for pain associated with LSS, serving as a viable substitute for .

Repeated epidural delivery of Shinbaro2: effects on neural recovery, inflammation, and pain modulation in a rat model of lumbar spinal stenosis

The choice of treatment for lumbar spinal stenosis (LSS) depends on symptom severity. When severe motor issues with urinary dysfunction are not present, conservative treatment is often considered to be the priority. One such conservative treatment is epidural injection, which is effective in alleviating inflammation and the pain caused by LSS-affected nerves. In this study, Shinbaro2 (Sh2), pharmacopuncture using natural herbal medicines for patients with disc diseases, is introduced as an epidural to treat LSS in a rat model. The treatment of primary sensory neurons from the rats' dorsal root ganglion (DRG) neurons with Sh2 at various concentrations (0.5, 1, and 2 mg/mL) was found to be safe and non-toxic. Furthermore, it remarkably stimulated axonal outgrowth even under H2O2-treated conditions, indicating its potential for stimulating nerve regeneration. When LSS rats received epidural injections of two different concentrations of Sh2 (1 and 2 mg/kg) once daily for 4 weeks, a significant reduction was seen in ED1+ macrophages surrounding the silicone block used for LSS induction. Moreover, epidural injection of Sh2 in the DRG led to a significant suppression of pain-related factors. Notably, Sh2 treatment resulted in improved locomotor recovery, as evaluated by the Basso, Beattie, and Bresnahan scale and the horizontal ladder test. Additionally, hind paw hypersensitivity, assessed using the Von Frey test, was reduced, and normal gait was restored. Our findings demonstrate that epidural Sh2 injection not only reduced inflammation but also improved locomotor function and pain in LSS model rats. Thus, Sh2 delivery via epidural injection has potential as an effective treatment option for LSS.

Development of a Deep Learning Model for the Analysis of Dorsal Root Ganglion Chromatolysis in Rat Spinal Stenosis

Objective

To create a deep learning (DL) model that can accurately detect and classify three distinct types of rat dorsal root ganglion neurons: normal, segmental chromatolysis, and central chromatolysis. The DL model has the potential to improve the efficiency and precision of neuron classification in research related to spinal injuries and diseases.

Methods

H&E slide images were divided into an internal training set (80%) and a test set (20%). The training dataset was labeled by two pathologists using pre-defined grades. Using this dataset, a two-component DL model was developed with the first component being a convolutional neural network (CNN) that was trained to detect the region of interest (ROI) and the second component being another CNN used for classification.

Results

A total of 240 lumbar dorsal root ganglion (DRG) pathology slide images from rats were analyzed. The internal testing results showed an accuracy of 93.13%, and the external dataset testing demonstrated an accuracy of 93.44%.

Conclusion

The DL model demonstrated a level of agreement comparable to that of pathologists in detecting and classifying normal and segmental chromatolysis neurons, although its agreement was slightly lower for central chromatolysis neurons. Significance: DL in improving the accuracy and efficiency of pathological analysis suggests that it may have a role in enhancing medical decision-making.

Epidural Injection of Harpagoside for the Recovery of Rats with Lumbar Spinal Stenosis

Epidural administration is the leading therapeutic option for the management of pain associated with lumbar spinal stenosis (LSS), which is characterized by compression of the nerve root due to narrowing of the spinal canal. Corticosteroids are effective in alleviating LSS-related pain but can lead to complications with long-term use. Recent studies have focused on identifying promising medications administered epidurally to affected spinal regions. In this study, we aimed to investigate the effectiveness of harpagoside (HAS) as an epidural medication in rats with LSS. HAS at various concentrations was effective for neuroprotection against ferrous sulfate damage and consequent promotion of axonal outgrowth in primary spinal cord neurons. When two concentrations of HAS (100 and 200 μg/kg) were administered to the rat LSS model via the epidural space once a day for 4 weeks, the inflammatory responses around the silicone block used for LSS were substantially reduced. Consistently, pain-related factors were significantly suppressed by the epidural administration of HAS. The motor functions of rats with LSS significantly improved. These findings suggest that targeted delivery of HAS directly to the affected area via epidural injection holds promise as a potential treatment option for the recovery of patients with LSS.

Comparison of ligamentum flavum thickness between central and lateral lesions in a patient with central lumbar spinal canal stenosis

Thickened ligamentum flavum has been considered as a major cause of central lumbar spinal canal stenosis (CLSCS). Previous studies have demonstrated that ligamentum flavum thickness (LFT) is correlated with aging, degenerative spinal stenosis, and disc degeneration. Thus, hypertrophy of the ligamentum flavum is a major cause of CLSCS, and measurement of LFT has been considered a morphologic parameter in the diagnosis of CLSCS. To our knowledge, comparison of LFT between central and lateral lesions has not been reported. In addition, no research has analyzed best clinical cutoff values of central ligament flavum thickness (CLFT) and lateral ligament flavum thickness (LLFT). This study aimed to compare CLFT with LLFT in patients with CLSCS and further compare the CLFT and LLFT findings between the 2 groups to analyze LFT variation. Both CLFT and LLFT samples were collected from 101 participants with CLSCS and from 103 participants in the control group who underwent lumbar magnetic resonance imaging without evidence of CLSCS. Axial T2-weighted lumbar magnetic resonance scans were acquired at the L4 to 5 facet joint level from each participant. Average CLFT value was 2.25 ± 0.51 mm in the control group and 4.02 ± 0.74 mm in the CLSCS group. Average LLFT value was 2.50 ± 0.51 mm in the control group and 3.38 ± 0.66 mm in the CLSCS group. CLSCS patients had significantly higher CLFT and LLFT (both P < .001). Regarding the validity of both CLFT and LLFT as predictors of CLSCS, a receiver operating characteristic estimation revealed that the most suitable cutoff value for CLFT was 3.10 mm, with sensitivity of 95.0%, specificity of 94.2%, and an area under the curve of 0.97. The best cut-off value of LLFT was 2.92 mm, with sensitivity of 78.2%, specificity of 77.7%, and area under the curve of 0.87. We have 4 important new findings: The mean CLFT is significantly lower than that of the mean LLFT in the normal control group; CLFT and LLFT are both significantly associated with CLSCS; Increase rate of CLFT is faster than that of LLFT in the CLSCS group; and CLFT is a more sensitive measurement parameter to predict CLSCS than LLFT.

Epidural and Intrathecal Drug Delivery in Rats and Mice for Experimental Research: Fundamental Concepts, Techniques, Precaution, and Application

Epidural and intrathecal routes are the most effective drug administration methods for pain management in clinical and experimental medicine to achieve quick results, reduce required drug dosages, and overcome the adverse effects associated with the oral and parenteral routes. Beyond pain management with analgesics, the intrathecal route is more widely used for stem cell therapy, gene therapy, insulin delivery, protein therapy, and drug therapy with agonist, antagonist, or antibiotic drugs in experimental medicine. However, clear information regarding intrathecal and epidural drug delivery in rats and mice is lacking, despite differences from human medicine in terms of anatomical space and proximity to the route of entry. In this study, we discussed and compared the anatomical locations of the epidural and intrathecal spaces, cerebrospinal fluid volume, dorsal root ganglion, techniques and challenges of epidural and intrathecal injections, dosage and volume of drugs, needle and catheter sizes, and the purpose and applications of these two routes in different disease models in rats and mice. We also described intrathecal injection in relation to the dorsal root ganglion. The accumulated information about the epidural and intrathecal delivery routes could contribute to better safety, quality, and reliability in experimental research.

Epidural Injection Method for Long-Term Pain Management in Rats with Spinal Stenosis

Epidural injection is one of the most common nonsurgical treatment options for long-term pain relief in lumbar spinal stenosis. Recently, various nerve block injections have been used for pain management. Among them, nerve block through epidural injection is a safe and effective method for the clinical treatment of low back or lower extremity pain. Although the epidural injection method has a long history, the effectiveness of long-term epidural injections in disc diseases has not been scientifically proven. In particular, to verify the safety and efficacy of drugs in preclinical studies, the route and method of drug administration in terms of the clinical application method and duration of use must be established. However, there is no standardized method for long-term epidural injections in a rat model of stenosis to identify the precise efficacy and safety of epidural injections. Therefore, standardizing the epidural injection method is very important for evaluating the efficacy and safety of drugs used for back or lower extremity pain. We describe the first standardized long-term epidural injection method for evaluating the efficacy and safety of drugs according to their route of administration in rats with lumbar spinal stenosis.

The mechanism of action of pulsed radiofrequency in reducing pain: a narrative review

Pain from nervous or musculoskeletal disorders is one of the most common complaints in clinical practice. Corticosteroids have a high pain-reducing effect, and their injection is generally used to control various types of pain. However, they have various adverse effects including flushing, hyperglycemia, allergic reactions, menstrual changes, immunosuppression, and adrenal suppression. Pulsed radiofrequency (PRF) is known to have a pain-reducing effect similar to that of corticosteroid injection, with nearly no major side effects. Therefore, it has been widely used to treat various types of pain, such as neuropathic, joint, discogenic, and muscle pain. In the current review, we outlined the pain-reducing mechanisms of PRF by reviewing previous studies. When PRF was first introduced, it was supposed to reduce pain by long-term depression of pain signaling from the peripheral nerve to the central nervous system. In addition, deactivation of microglia at the level of the spinal dorsal horn, reduction of proinflammatory cytokines, increased endogenous opioid precursor messenger ribonucleic acid, enhancement of noradrenergic and serotonergic descending pain inhibitory pathways, suppression of excitation of C-afferent fibers, and microscopic damage of nociceptive C- and A-delta fibers have been found to contribute to pain reduction after PRF application. However, the pain-reducing mechanism of PRF has not been clearly and definitely elucidated. Further studies are warranted to clarify the pain-reducing mechanism of PRF.