Pulsed Radiofrequency Attenuates Complete Freund's Adjuvant-Induced Epigenetic Suppression of Potassium Chloride Cotransporter 2 Expression

Clinical Radiofrequency Ablation Outcomes of Combined Sensory Nerve Branch and Dorsal Entry Root Zone Complex Lesions for Sacroiliac Joint Complex Pain

BACKGROUND

Chronic lower back pain (LBP) with or without leg pain (LP) is the most commonly reported anatomical site of pain among Canadian adults with chronic pain. A common cause for LBP and LP arises from dysfunction of the sacroiliac joint (SIJ) complex. When conventional medical management or rehabilitative efforts for SIJ-related LBP and LP fail to provide analgesia, pulsed radiofrequency (PRF) and/or radiofrequency ablation (RFA) of the dorsal entry root zone complex lesions (DREZC) and/or their more peripheral branches can also be a suitable means for treatment. Both PRF and RFA are interventional techniques that utilize heat to attenuate or ablate transmission of painful signals, respectively. The purpose of this chart review is to explore the clinical outcomes of patients experiencing SIJ-related pain who have undergone procedures with combined sensory nerve branch RFA and DREZC PRF lesions targeting the SIJ complex.

METHODS

Following institutional review board approval, a retrospective chart review was performed from June 2018 to February 2021 for patients with LBP and/or LP refractory to physical rehabilitative efforts and medical management that underwent combined PRF and RF treatments for a diagnosis of SIJ complex pain. RF and PRF procedures were anatomically guided with the addition of sensory stimulation to ensure appropriate needle placement. Charts were reviewed for percentage of analgesia at final follow-up, duration of effect, degree of analgesia, patients' functional improvements, and changes in medication use patterns.

RESULTS

Data was reviewed from 180 patients with LBP or LP who underwent combined PRF and RF treatments for a diagnosis of SIJ complex pain. The group consisted of 69 men and 111 women with a mean age of 59 years. All patients had lesions to their dorsal roots and/or branches (lumbar medial and sacral lateral), as determined using their pain profile as well as sensory stimulation. In the sample of 180 patients a total of 276 SIJs were treated over the period of data collection. Overall, 85.0% (n = 234) of procedures were considered successful with more than 50% analgesic relief at final follow-up. Of 234 successful outcomes, 110 reported ongoing analgesia (mean = 80.3% pain relief, SD ± 18.0) on the last date of follow up (mean = 53.2 days, SD ± 41.8) prior to being lost to follow-up. For patients not lost to follow-up, the mean amount of analgesia was reported to be 83.9% with an average duration of 86.3 days. Among all treatments, 6.9% (n = 19) provided no analgesic effect. Among the successful procedure outcomes, 54.4% (n = 150) reported increased activity/mobility, 24.3% (n = 67) reported improved sleep, 49.3% (n = 136) reported improved mood, and 11.6% (n = 32) reported decreased medication usage. Nine patients reported complications following the procedure. Complications included transient soreness, bruising, tenderness, myofascial pain, and two mild vagal responses without lasting sequelae.

CONCLUSION

This review suggests that combined sensory nerve branch RFA and DREZC PRF lesions targeting the SIJ complex is a suitable intervention to treat SIJ-related LBP and/or LP refractory to physical rehabilitative efforts and medical management. Approximately 85% of these cases were successfully treated with the majority of patients report lasting analgesic effects with minimal complications, supporting the use of sensory stimulation-guided combined RF and PRF lesions for treatment of refractory SIJ complex pain.

SNI and CFA induce similar changes in TRPV1 and P2X3 expressions in the acute phase but not in the chronic phase of pain

Peripheral inflammation and nerve injury usually accompany each other. However, whether inflammatory and neuropathic pain share similar mechanisms at all stages is unknown. TRPV1 and P2X3 are two major ion channels in dorsal root ganglia (DRGs) and are involved in chronic pain. Here, their function and expression in DRGs at different phases of the two types of pain were investigated. Both the paw withdrawal threshold (PWT) and paw withdrawal latency were decreased in rats injected with complete Freud's adjuvant (CFA). However, only the PWT was decreased in rats with spared nerve injury (SNI). CFA increased the magnitude of the TRPV1-mediated Ca²⁺ response but not the P2X3-mediated Ca²⁺ response 14 days after injection. Consistent with this result, the P2X3 expression level in CFA rats was increased only at 3 days after injection. SNI surgery increased the magnitudes of the TRPV1- and P2X3-mediated Ca²⁺ responses and upregulated both TRPV1 and P2X3 expression in lumbar DRGs. The distributions of TRPV1 and P2X3 in DRGs after modeling were observed, and TRPV1 was found to be highly expressed mainly in the L4-L5 DRGs in CFA rats and in the L5-L6 DRGs in SNI rats. P2X3 was highly expressed in the L4-L6 DRGs in CFA rats 3 days after injection but was only highly expressed in the L4 DRG 14 days after modeling. On the other hand, SNI promoted the P2X3 expression L4-L5 DRGs 3 days after surgery, but only L6 DRG 14 days after modeling. All the results indicate that P2X3 and TPRV1 are involved in inflammatory and neuropathic pain by different expression levels and distributions in the lumbar DRG in the chronic stage.

The etiological contribution of GABAergic plasticity to the pathogenesis of neuropathic pain

Neuropathic pain developing after peripheral or central nerve injury is the result of pathological changes generated through complex mechanisms. Disruption in the homeostasis of excitatory and inhibitory neurons within the central nervous system is a crucial factor in the formation of hyperalgesia or allodynia occurring with neuropathic pain. The central GABAergic pathway has received attention for its extensive distribution and function in neural circuits, including the generation and development of neuropathic pain. GABAergic inhibitory changes that occur in the interneurons along descending modulatory and nociceptive pathways in the central nervous system are believed to generate neuronal plasticity, such as synaptic plasticity or functional plasticity of the related genes or proteins, that is the foundation of persistent neuropathic pain. The primary GABAergic plasticity observed in neuropathic pain includes GABAergic synapse homo- and heterosynaptic plasticity, decreased synthesis of GABA, down-expression of glutamic acid decarboxylase and GABA transporter, abnormal expression of NKCC1 or KCC2, and disturbed function of GABA receptors. In this review, we describe possible mechanisms associated with GABAergic plasticity, such as central sensitization and GABAergic interneuron apoptosis, and the epigenetic etiologies of GABAergic plasticity in neuropathic pain. Moreover, we summarize potential therapeutic targets of GABAergic plasticity that may allow for successful relief of hyperalgesia from nerve injury. Finally, we compare the effects of the GABAergic system in neuropathic pain to other types of chronic pain to understand the contribution of GABAergic plasticity to neuropathic pain.

Efficacy of Pulsed Radiofrequency to Cervical Nerve Root for Postherpetic Neuralgia in Upper Extremity

Background

Postherpetic neuralgia (PHN) seriously affects a patient’s quality of life, and it is urgent to find a method that can effectively alleviate the PHN of the upper extremity.

Objective

To observe the Efficacy of pulsed radiofrequency (PRF) to cervical nerve root for PHN in upper extremity under CT guidance.

Study Design

Retrospective comparative study.

Setting

Shengjing Hospital of China Medical University.

Methods

Fifty patients with PHN in upper extremity were enrolled in Pain Management. Patients were randomized into two groups: cervical nerve root block (A group, n = 25) and cervical nerve root PRF (B group, n = 25). At each observation time, the general characteristics, visual analog scale (VAS), quality of life scores assessment (SF-36), the total efficacy rate, dosage of antiepileptic and narcotic analgesics, and the incidence of complications were followed up.

Results

Compared with the preoperative, the postoperative VAS decreased, the physical component summary (PCS) and the mental component summary (MCS) increased in both groups (P < 0.05). The differences between group B and group A were statistically significant after 1 month, which could be maintained for 1 year (P < 0.05). The total efficacy rate of group A and group B was 52.0% and 80.0% at 1 Year, respectively. The total efficacy rate of group B was higher than that of group A (P < 0.05). The dosage of antiepileptic and narcotic analgesics in group B decreased significantly, and the decline was significant compared with group A (P < 0.05). The incidence of complications between the two groups were similar (P > 0.05).

Conclusion

CT-guided PRF to cervical nerve root for the treatment of PHN in the upper extremity is safe and effective. PRF can replicate the location of pain, precise positioning, reduce trauma, and increased pain relief rate.

CT-Guided Stellate Ganglion Pulsed Radiofrequency Stimulation for Facial and Upper Limb Postherpetic Neuralgia

Objective: Postherpetic neuralgia (PHN) is the most common complication of herpes zoster, manifesting as a persistent, spontaneous, knife-like pain or paroxysmal burning that seriously affects a patient’s quality of life. An effective treatment of PHN is lacking. This retrospective study examined the efficacy and safety of stellate ganglion (SG) pulsed radiofrequency (PRF) on facial and upper limb PHN.

Methods: Eighty-four patients with PHN on the face or upper limbs were enrolled for the study. Patients were randomly divided into two surgical groups according to the order of enrollment; one group underwent SG block (SG-B group, n = 42) and the other underwent SG pulsed radiofrequency (SG-P group, n = 42). After surgery, patients were followed at 1 week, 2 weeks, 1 month, 3 months, and 6 months. Observation at each follow-up included basic patient characteristics, visual analog scale (VAS), quality of life (QOL) using Physical Component Summary (PCS), and Mental Component Summary (MCS) to assess, total effective rate, complications and side effects.

Results: Compared with preoperative values, VAS decreased in both groups after surgery (P < 0.05). In the SG-B group, VAS increased after 1 month, while in the SG-P group, VAS gradually decreased at later follow-up time points. VAS decreased more significantly in the SG-P group after 1 month (P < 0.05). PCS and MCS increased in both groups after the operation, and the difference was significant compared with preoperative values (P < 0.05). The total effective rates of the SG-B and SG-P groups were 64.3 and 83.3%, respectively. The total effective rate of the SG-P group was higher than that of the SG-B group (P < 0.05). The incidence of complications and side effects in the SG-B group was higher than that in the SG-P group (P < 0.05).

Conclusion: SG pulsed radiofrequency treatment of facial and upper limb PHN is safe and effective. It is a treatment method worth promoting.

Pulsed Radiofrequency Applied to the Sciatic Nerve Improves Neuropathic Pain by Down-regulating The Expression of Calcitonin Gene-related Peptide in the Dorsal Root Ganglion

Background: Clinical studies have shown that applying pulsed radiofrequency (PRF) to the neural stem could relieve neuropathic pain (NP), albeit through an unclear analgesic mechanism. And animal experiments have indicated that calcitonin gene-related peptide (CGRP) expressed in the dorsal root ganglion (DRG) is involved in generating and maintaining NP. In this case, it is uncertain whether PRF plays an analgesic role by affecting CGRP expression in DRG. Methods: Rats were randomly divided into four groups: Groups A, B, C, and D. In Groups C and D, the right sciatic nerve was ligated to establish the CCI model, while in Groups A and B, the sciatic nerve was isolated without ligation. After 14 days, the right sciatic nerve in Groups B and D re-exposed and was treated with PRF on the ligation site. Thermal withdrawal latency (TWL) and hindpaw withdrawal threshold (HWT) were measured before PRF treatment (Day 0) as well as after 2, 4, 8, and 14 days of treatment. At the same time points of the behavioral tests, the right L4-L6 DRG was sampled and analyzed for CGRP expression using RT-qPCR and an enzyme-linked immunosorbent assay (ELISA). Results: Fourteen days after sciatic nerve ligation, rats in Groups C and D had a shortened TWL (P<0.001) and a reduced HWT (P<0.001) compared to those in Groups A and B. After PRF treatment, the TWL of the rats in Group D gradually extended with HWT increasing progressively. Prior to PRF treatment (Day 0), CGRP mRNA expressions in the L4-L6 DRG of Groups C and D increased significantly (P<0.001) and were 2.7 and 2.6 times that of Group A respectively. ELISA results showed that the CGRP content of Groups C and D significantly increased in comparison with that of Groups A and B (P<0.01). After PRF treatment, the mRNA expression in the DRG of Group D gradually decreased and the mRNA expression was 1.7 times that of Group A on the 4th day(P> 0.05). On the 8^th and 14^th days, the mRNA levels in Group D were restored to those of Groups A and B. Meanwhile, the CGRP content of Group D gradually dropped over time, from 76.4 pg/mg (Day 0) to 57.5 pg/mg (Day 14). Conclusions: In this study, we found that, after sciatic nerve ligation, rats exhibited apparent hyperalgesia and allodynia, and CGRP mRNA and CGRP contents in the L4-L6 DRG increased significantly. Through lowering CGRP expression in the DRG, PRF treatment might relieve the pain behaviors of NP.