Pulsed radiofrequency: a review of the basic science as applied to the pathophysiology of radicular pain: a call for clinical translation

Safety outcomes and improvement in pain scores after radiologist-performed fluoroscopy-guided interlaminar cervical epidural steroid injection

INTRODUCTION

Image-guided spine injections are an important tool in the management of patients with a variety of spinal pathologies. Our practice offers radiologist-performed fluoroscopy-guided interlaminar cervical epidural steroid injection (ESI) routinely performed in the outpatient setting. The purpose of this study was to evaluate clinical outcomes and improvement in pain scores after radiologist-performed cervical ESI.

METHODS

An institutional database was used to retrospectively identify cervical injections performed between October 2016 and October 2022. All injections were performed at the C7-T1 level utilizing 1.0 mL of 10 mg/mL dexamethasone without epidural anesthetic. The Numerical Rating Scale (NRS) was used to assess pain improvement. Cervical MRI was reviewed to assess pre-injection cervical disease severity. Patient charts were reviewed for any post-injection complications.

RESULTS

A total of 251 cervical injections in 186 patients met our inclusion criteria with mean clinical follow up of 28.5 months (range 0.2 - 73.0 months). No patients experienced any major complications after injection. Post-injection pain scores were available for 218 of 251 injections (86.9%) with mean follow-up of 11.8 days (range 6 - 57 days). There was a significant improvement in pain scores from a mean pre-injection NRS score of 5.2/10 to 3.0/10 (p < .0001). 117 patients (53.7%) reported ≥ 50% improvement after injection. Patients who had prior injection were more likely to report ≥ 50% pain improvement after subsequent injection (p = .012).

CONCLUSION

Radiologist-performed fluoroscopy-guided interlaminar cervical ESI at the C7-T1 level is a safe and effective tool in the management of patients with cervical pathology.

Central Causation of Autism/ASDs via Excessive [Ca2+]i Impacting Six Mechanisms Controlling Synaptogenesis during the Perinatal Period: The Role of Electromagnetic Fields and Chemicals and the NO/ONOO(-) Cycle, as Well as Specific Mutations

The roles of perinatal development, intracellular calcium [Ca2+]i, and synaptogenesis disruption are not novel in the autism/ASD literature. The focus on six mechanisms controlling synaptogenesis, each regulated by [Ca2+]i, and each aberrant in ASDs is novel. The model presented here predicts that autism epidemic causation involves central roles of both electromagnetic fields (EMFs) and chemicals. EMFs act via voltage-gated calcium channel (VGCC) activation and [Ca2+]i elevation. A total of 15 autism-implicated chemical classes each act to produce [Ca2+]i elevation, 12 acting via NMDA receptor activation, and three acting via other mechanisms. The chronic nature of ASDs is explained via NO/ONOO(-) vicious cycle elevation and MeCP2 epigenetic dysfunction. Genetic causation often also involves [Ca2+]i elevation or other impacts on synaptogenesis. The literature examining each of these steps is systematically examined and found to be consistent with predictions. Approaches that may be sed for ASD prevention or treatment are discussed in connection with this special issue: The current situation and prospects for children with ASDs. Such approaches include EMF, chemical avoidance, and using nutrients and other agents to raise the levels of Nrf2. An enriched environment, vitamin D, magnesium, and omega-3s in fish oil may also be helpful.

6. Persistent spinal pain syndrome type 2

INTRODUCTION

Persistent Spinal Pain Syndrome (PSPS) refers to chronic axial pain and/or extremity pain. Two subtypes have been defined: PSPS-type 1 is chronic pain without previous spinal surgery and PSPS-type 2 is chronic pain, persisting after spine surgery, and is formerly known as Failed Back Surgery Syndrome (FBSS) or post-laminectomy syndrome. The etiology of PSPS-type 2 can be gleaned using elements from the patient history, physical examination, and additional medical imaging. Origins of persistent pain following spinal surgery may be categorized into an inappropriate procedure (eg a lumbar fusion at an incorrect level or for sacroiliac joint [SIJ] pain); technical failure (eg operation at non-affected levels, retained disk fragment, pseudoarthrosis), biomechanical sequelae of surgery (eg adjacent segment disease or SIJ pain after a fusion to the sacrum, muscle wasting, spinal instability); and complications (eg battered root syndrome, excessive epidural fibrosis, and arachnoiditis), or undetermined.

METHODS

The literature on the diagnosis and treatment of PSPS-type 2 was retrieved and summarized.

RESULTS

There is low-quality evidence for the efficacy of conservative treatments including exercise, rehabilitation, manipulation, and behavioral therapy, and very limited evidence for the pharmacological treatment of PSPS-type 2. Interventional treatments such as pulsed radiofrequency (PRF) of the dorsal root ganglia, epidural adhesiolysis, and spinal endoscopy (epiduroscopy) might be beneficial in patients with PSPS-type 2. Spinal cord stimulation (SCS) has been shown to be an effective treatment for chronic, intractable neuropathic limb pain, and possibly well-selected candidates with axial pain.

CONCLUSIONS

The diagnosis of PSPS-type 2 is based on patient history, clinical examination, and medical imaging. Low-quality evidence exists for conservative interventions. Pulsed radiofrequency, adhesiolysis and SCS have a higher level of evidence with a high safety margin and should be considered as interventional treatment options when conservative treatment fails.

Dorsal root ganglion-pulsed neuromodulation radiofrequency treatment has significant clinical efficacy in chronic spinal-origin pain, bringing noticeable improvement in symptoms and sleep quality for patients

BACKGROUND

Chronic spinal-origin pain poses a substantial clinical challenge, prompting the investigation of novel treatment modalities. This study aims to evaluate the potential application of spinal nerve dorsal root ganglion (DRG) radiofrequency treatment in addressing chronic spinal-origin pain.

METHODS

The study encompassed patients undergoing treatment for chronic spinal-origin pain, with a particular focus on those experiencing pain localized in specific regions. Inclusion criteria comprised patients with conditions such as a herniated intervertebral disc or foraminal stenosis leading to compression of descending or exiting nerve roots, accompanied by reported radicular pain in the lower limb.

RESULTS

There was no significant difference in comparability between the two groups (p > 0.05). The clinical effective rate in the study group was significantly higher than that in the control group (p < 0.05). The VAS scores of the study group at 2 weeks and 1 month after treatment were significantly lower than those of the control group (p < 0.05). The PSQI index of the study group after treatment was significantly lower than that of the control group (p < 0.05). There was no significant difference in the incidence of complications between the two groups (p > 0.05).

CONCLUSION

Spinal nerve DRG radiofrequency treatment has significant clinical efficacy in chronic spinal-origin pain, bringing noticeable improvement in symptoms and sleep quality for patients. The occurrence of complications is relatively low, and it can be reduced through strict operational standards and preoperative and postoperative management. However, caution should be exercised in its widespread application, but it is worthy of broad clinical use.

Efficacy of High-Voltage Pulsed Radiofrequency of the Dorsal Root Ganglion for Treatment of Chronic Lumbosacral Radicular Pain: A Randomized Clinical Trial

BACKGROUND

Pulsed radiofrequency (PRF) is an efficacious treatment for patients with lumbosacral radicular pain, but the optimal radiofrequency parameters are inadequately described. We hypothesized that high-voltage radiofrequency therapy around the dorsal root ganglion can be more effective and enduring than the standard voltage PRF therapy.

MATERIALS AND METHODS

This was a prospective and randomized study. Patients were divided into two groups. In group 1 (high-voltage group), PRF was applied at 60 V to the patients. Patients in group 2 (low-voltage group) received PRF treatment at 45 V. The patients were evaluated using a numeric rating scale (NRS) and the Oswestry Disability Index (ODI). Evaluation scales were repeated before the intervention and at the first and sixth months after the treatment.

RESULTS

The study included 41 analyzed patients. There was no statistically significant difference between the groups at the first-month NRS (p > 0.05). Sixth-month NRS scores were lower in the high-voltage group (p = 0.016). The groups showed no statistically significant differences in the one-month ODI scores (p > 0.05). When the NRS values were analyzed with linear regression, a positive correlation was found between the sixth-month NRS values and high-voltage PRF (odds ratio: 0.385; p = 0.013). Comparison of the treatment success in terms of time showed statistically significant results in both groups in the first and sixth months (p < 0.05).

CONCLUSIONS

The results of our study revealed that both low- and high-voltage PRF are effective. Because of the lower sixth-month NRS values in the high-voltage group and the similar complication rate, it was considered that high-voltage PRF can be a promising application.

Dual-neuromodulation strategy in pain management of herpes zoster ophthalmicus: retrospective cohort study and literature review

BACKGROUND

Effective pain control of herpes zoster ophthalmicus (HZO) is not only essential to attenuate the clinical symptoms but to reduce the risk of postherpetic neuralgia development. Recently, neuromodulation therapy has been one promising option for neuropathic pain and increasingly applied in management of zoster-related pain. One key factor of neuromodulation treatment is the therapeutic site for the impaired nerves. In this study we aim to investigate one novel dual-neuromodulation strategy, targeting the level of the peripheral branch and trigeminal ganglion, in the pain management of HZO.

METHODS

Dual neuromodulation strategy combining short-term peripheral nerve stimulation (PNS) with pulsed radiofrequency (PRF) of trigeminal ganglion was compared with single PNS treatment for HZO-related pain. Clinical recordings of patients were retrospectively reviewed. The primary outcome was the pain severity, assessed by the visual analogue scale (VAS) before and after neuromodulation therapy.

RESULTS

PNS achieved significant relief of pain with or without PRF treatment before discharge, which provided enduring therapeutic effect up to 12-month follow-up. The mean reduction of VAS was 6.7 ± 1.4 in dual modulation therapy (n = 13) at last follow-up and 5.4 ± 1.5 in PNS subgroup (n = 20), respectively. Moreover, dual modulation strategy provided better control of pain compared with PNS therapy alone at each time point.

CONCLUSION

It is feasible and effective to combine the PNS and PRF in pain management of HZO. This novel dual modulation strategy of trigeminal pathway may provide additional therapeutic effects of pain symptoms in HZO population.

Efficacy of conditioned autologous serum therapy (Orthokine®) on the dorsal root ganglion in patients with chronic radiculalgia: study protocol for a prospective randomized placebo-controlled double-blind clinical trial (RADISAC trial)

BACKGROUND

Pulsed radiofrequency (PRF) treatment on the dorsal root ganglion (DRG) has been proposed as a good option for the treatment of persistent radicular pain based on its effect of neuromodulation on neuropathic pain. Autologous conditioned serum (ACS) therapy is a conservative treatment based on the patient's own blood. The aim of this manuscript is to develop a study protocol using ACS on the DRG as a target for its molecular modulation.

METHODS

We plan to conduct a randomized controlled study to compare the efficacy of PRF therapy plus ACS versus PRF therapy plus physiological saline 0.9% (PhS) on the DRG to reduce neuropathic pain in patients with persistent lower limb radiculalgia (LLR) and to contribute to the functional improvement and quality of life of these patients. Study participants will include patients who meet study the inclusion/exclusion criteria. Eligible patients will be randomized in a 1:1 ratio to one of treatment with PRF plus ACS (experimental group) or PRF plus PhS (placebo group). The study group will consist of 70 patients (35 per group) who have experienced radicular pain symptoms for ≥ 6 months' duration who have failed to respond to any therapy. Both groups will receive PRF on the DRG treatment before the injection of the sample (control or placebo). Patient assessments will occur at baseline, 1 month, 3 months, 6 months, and 12 months after therapy. The primary efficacy outcome measure is Numeric Pain Rating Scale (NPRS) responders from baseline to 12 months of follow-up using validated minimal important change (MIC) thresholds. A reduction of ≥ 2 points in NPRS is considered a clinically significant pain relief. The secondary efficacy outcome measure is the proportion of Oswestry Low Back Pain Disability Scale (ODS) responders from baseline to 12 months of follow-up in the experimental group (PRF plus ACS) versus the placebo group (PRF plus PhS). ODS responders are defined as those patients achieving the validated MIC of ≥ 10-point improvement in ODS from baseline to 12 months of follow-up as a clinically significant efficacy threshold.

DISCUSSION

This prospective, double-blind, randomized placebo-controlled study will provide level I evidence of the safety and effectiveness of ACS on neuropathic symptoms in LLR patients. TRIAL REGISTRATION {2A}{2B}: EUDRACT number: 2021-005124-38. Validation date: 13 November 2021. Protocol version {3}: This manuscript presents the 2nd protocol version.

Acupuncture Relieves Cervical Spondylosis Radiculopathy by Regulating Spinal Microglia Activation Through MAPK Signaling Pathway in Rats

Purpose

Local acupuncture has been found to have a good analgesic effect in rats with cervical spondylosis radiculopathy (CSR), but it lacks a regulatory effect on traditional Chinese medicine syndrome types of CSR. We proposed "Invigorating Qi and activating Blood" (IQAB) acupuncture, compared with Fenbid, and local electroacupuncture (LEA), to observe whether it has advantages in the protection of the CSR rat model and to elucidate its mechanism through the MAPK (mitogen-activated protein kinase) signaling pathway.

Materials and Methods

Male Sprague-Dawley rats were randomly divided into six groups: control, sham, model, Fenbid, LEA, and IQAB. The CSR model was induced by inserting nylon sutures to compress the C4-T1 nerve root. The Fenbid group was treated with ibuprofen sustained-release capsules (15 mg/kg·d, ig). The LEA group received electroacupuncture at both C5 and C7 EX-B2 once a day. The IQAB group received acupuncture at both ST36 and BL17 based on the LEA group's intervention. Mechanical allodynia and gait, morphological changes in the spinal cord, IL-6 and TNF-α levels, MAPKs phosphorylation ratio, monocyte chemoattractant protein-1 (MCP-1) levels in the spinal cord, and the expression of p-p38 in the spinal cord and its colocalization with neurons and glial cell activation markers were detected.

Results

Mechanical allodynia, gait disorder, edema, reduced Nissl-positive cell numbers, and increased IL-6 and TNF-α levels in the spinal cord were observed in CSR rats. IQAB significantly alleviated these changes, and the effects were generally comparable to those of Fenbid. Meanwhile, the phosphorylation ratios of p38 and extracellular regulated protein kinase (ERK), co-expression of p-p38 with neuron/microglia, and MCP-1 levels in the spinal cord were markedly down-regulated by IQAB compared with those in CSR model rats.

Conclusion

IQAB reduced p38-activation-related microglia activation and MCP-1 levels, thus alleviating pathological changes, inflammation levels in the local spinal cord, and pain behavior of CSR.

The treatment of persistent spinal pain syndrome with epidural pulsed radiofrequency: improvement of the technique

Background

In Persistent Spinal Pain Syndrome (PSPS), Pulsed Radiofrequency (PRF) is a used procedure. The results of PRF in PSPS performed with an electrode placed through the sacral hiatus were reported to be successful on pain in only 32% of patients. We have tried to improve the results by applying a new system to PRF.

Methods

Ten patients were treated with PRF application through a steerable epidural catheter with a reference electrode outside the foramen. This method was named "Optimization Current Flow" (OCF). The duty cycle of PRF was 2 × 10 msec and total exposure time was 150 s. Follow up was planned for 1, 3, and 6 months. The NRS score was considered to be the primary outcome.

Results

In the first 10 patients treatment was successful (69% of the patients) at 6 months follow-up.

Conclusion

This new modality of PRF in patients with PSPS seems to be superior to procedures done with a needle. Further prospective double-blind randomized long-term studies with a significant number of patients are required to validate this technique as there is a need to improve PRF results in PSPS.

Elucidating the Mechanisms of Pulsed Radiofrequency for Pain Treatment

Pulsed radiofrequency is a well-documented treatment option for multiple painful conditions where pulses of energy are delivered close to neural elements. Since its earliest adoption, this technique has gained increasing acceptance as a minimally invasive procedure, and new applications are evolving. Studies have shown microscopic and biochemical changes that reflect beneficial effects; however, the exact mechanism of action is not yet completely understood. To redress this paucity, 11,476 articles of scientific relevance published between 1980 and November 2022 were mined through a search of the PubMed database, arriving at 49 studies both in animals and humans. In general, the experimental studies examined have shown that pulsed radiofrequency induces multiple changes with antinociceptive and neuromodulatory effects. These modifications include changes in neural and glial cells, synaptic transmission, and perineural space. Studies also reveal that pulsed radiofrequency regulates inflammatory responses, cellular signaling proteins, and the expression of genes related to pain transmission, acting in biological processes in structures such as myelin, mitochondria, axons, glial cells, connective tissue, regulation of proteins, ion channels, and neurotransmitters.

Comparison of Two Different Pulsed Radiofrequency Modes for Prevention of Postherpetic Neuralgia in Elderly Patients With Acute/Subacute Trigeminal Herpes Zoster

OBJECTIVE

Trigeminal postherpetic neuralgia (PHN) is often refractory to treatment. Pulsed radiofrequency (PRF) neuromodulation can help in preventing PHN after herpes zoster. This study aimed to compare the efficacy and safety of two different PRF modes on gasserian ganglion neuromodulation in elderly patients with acute/subacute trigeminal herpes zoster.

MATERIALS AND METHODS

A total of 120 elderly patients with acute or subacute (within past three months) trigeminal herpes zoster were randomized to receive either a single cycle of high-voltage, long-duration PRF (HL-PRF group; N = 60) or three cycles of standard PRF (S-PRF group; N = 60). Patients were followed up for six months after treatment. Visual analog scale (VAS) pain score, 36-Item Short Form Health Survey (SF-36) score, and pregabalin at baseline and at different time points during follow-up were recorded.

RESULTS

VAS and SF-36 scores declined significantly from baseline levels in both groups (p < 0.001). The scores were significantly lower in the HL-PRF group than in the S-PRF group at some time points (p < 0.05). The mean dose of pregabalin was significantly lower in the HL-PRF group than in the S-PRF group on days 3, 14, and 28 after treatment (p < 0.05). No serious adverse events occurred in either group.

CONCLUSION

HL-PRF neuromodulation of the gasserian ganglion appears to be more effective than S-PRF for preventing PHN in the elderly.

CLINICAL TRIAL REGISTRATION

ChiCTR2000038775.

The Clinical Efficacy of High-Voltage Long-Duration Pulsed Radiofrequency Treatment in Pudendal Neuralgia: A Retrospective Study

BACKGROUND

Patients with pudendal neuralgia (PN) experience long-lasting chronic pain, hyperalgesia, and comorbid emotional disorders, such as depression and anxiety. Treatment via conventional pulsed radiofrequency (PRF) current carries a significantly high rate of failure.

OBJECTIVE

To determine the safety and clinical efficacy of high-voltage, long-duration PRF application to the pudendal nerve in patients with PN.

STUDY DESIGN

Observational retrospective design, self before-after controlled clinical trial.

MATERIALS AND METHODS

We analyzed the records of 70 patients of our hospital with diagnosed PN. Treatment consisted of PRF application to the pudendal nerve, using computed tomography guidance to target the pudendal nerve at the level of the ischial spine or ischial tuberosity of the affected side. PRF was applied with the following parameters: temperature 42 °C, frequency 2 Hz, pulse width 20 ms, field intensity ramped gradually from 40 to 90 V, duration 900 sec. The therapeutic effect was evaluated by collecting patient scores for the visual analog scale (VAS), SF-36 health survey questionnaire (SF-36), and patient health questionnaire (PHQ-9) before treatment and at 1-, 4-, and 12-week follow-ups after PRF treatment. Data were analyzed by paired t-test with p < 0.05 considered to be statistically significant.

RESULTS

VAS, SF-36, and PHQ-9 scores at 1, 4, and 12 weeks after high-voltage long-duration PRF treatment were significantly improved relative to their respective pretreatment baseline scores (p < 0.05 for all). The effective rate at 12 weeks after high-voltage long-duration PRF was up to 88.6%.

LIMITATIONS

A small sample size and lack of a control group.

CONCLUSIONS

High-voltage long-duration PRF provided significant short-term (at least 12 weeks) pain relief to most patients with PN; it also improved subjective measures of depression and quality of life over the same duration of time.

Knowledge Areas and New Trends in Lumbar Disc Herniation Research: Bibliometrics and Knowledge Mapping Analysis

OBJECTIVE

To determine the coalitions and impact of authors, countries, institutions, and journals, evaluate the knowledge base, find the hotspot trends, and identify the emerging topics in lumbar disc herniation (LDH).

METHOD

The articles related to LDH were obtained from the Web of Science Core Collection on August 21, 2021. Two scientometric software (CiteSpace 5.8.R.1 and VOSviewer 1.6.17) were used to perform bibliometric and knowledge-map analysis.

RESULTS

From the set parameters, 4642 articles were included in the literature. Although the total number of publications fluctuated between 2001 and 2020, a general trend toward increase was observed. Respectively, the most productive country and institution in the field were the United States and Wooridul Spine Hospital. The most active and cited authors were Lee and Weinstein. Spine was the most impactful and cited journal. Weinstein (JAMA 296:2441-2450, 2006) had the highest number of co-citations and Weinstein(N Engl J Med 358:794-810, 2008) had the highest number of citations. The keyword "low back pain" was ranked first for frequency and total link strength, whereas "risk factor" was ranked first for centrality. Topics including pathogenesis (disc herniation), examination methods (MRI), treatment methods (non-surgical treatment, surgical treatment), surgical options (laminectomy, discectomy), clinical observations (double-blind, efficacy, outcome, learning curve), and evaluation of efficacy (meta-analysis) of LDH have been the focus of leading-edge research in 2001-2020.

CONCLUSION

Using bibliometric methods, this study mapped the knowledge map of LDH research in the past 20 years. The study identifies existing trends to provide a framework for further research.

Case report: Baxter's nerve radiofrequency in patient with plantar fasciitis nonresponsive to conventional treatment

Plantar fasciitis is recognized as the leading cause of talalgia worldwide. In the vast majority of cases it can be controlled with the use of appropriate footwear, stretching exercises and changes in the sport activity, while a few cases require infiltrations or surgical interventions. The latter puts the patient at greater risk, and is reserved for the most severe cases. We propose using pulsed radiofrequency ablation of Baxter's nerve to treat this painful symptom in patients who do not respond adequately to conventional treatment. We present the case of a patient with refractory plantar fasciitis in whom surgery had been ruled out. The patient underwent pulsed radiofrequency treatment with satisfactory results in the short and medium term.

High-voltage long-duration pulsed radiofrequency attenuates neuropathic pain in CCI rats by inhibiting Cav2.2 in spinal dorsal horn and dorsal root ganglion

Inclinicalpractice, high-voltage, long-duration pulsed radiofrequency (HL-PRF) is effective for several types of intractable neuropathic pain (NP), but the mechanisms have not been well explored. Cav2.2 channels could increase neuronal excitability and neurotransmission accompanying NP. This study investigated the relationship of the efficacy of HL-PRF on NP with the levels of Cav2.2 in the spinal dorsal horn (SDH) and dorsal root ganglions (DRGs) of chronic constriction injury (CCI) in rats. Sham HL-PRF, GVIA (a specific Cav2.2 channel blocker), HL-PRF, or GVIA + HL-PRF was applied to CCI rats. The results showed: compared with the sham group, the PWT and PWL of CCI rats decreased significantly (P < 0.05), and Cav2.2 expression was elevated significantly in the SDH and DRGs (P < 0.05). Compared with the CCI group, both HL-PRF and ω-conotoxin GVIA treatment reversed the increased PWT and PWL (P < 0.05) and downregulated the overexpression of Cav2.2 in the SDH and DRGs (P < 0.05). Furthermore, PWT, PWL, and the expression of Cav2.2 in the SDH and DRGs were not significantly different among the 3 treatment groups. HL-PRF on L₅ DRG reversed the hyperalgesia behavior of NP and reduced the levels of Cav2.2 in the ipsilateral SDH and DRGs in CCI rats. Moreover, the underlying mechanism may be related to the downregulation of CaV2.2 protein levels in both SDH and DRG.

Case report: Baxteŕs nerve radiofrequency in patient with plantar fasciitis nonresponsive to conventional treatment

Plantar fasciitis is recognized as the leading cause of talalgia worldwide. In the vast majority of cases it can be controlled with the use of appropriate footwear, stretching exercises and changes in the sport activity, while a few cases require infiltrations or surgical interventions. The latter puts the patient at greater risk, and is reserved for the most severe cases. We propose using pulsed radiofrequency ablation of Baxter's nerve to treat this painful symptom in patients who do not respond adequately to conventional treatment. We present the case of a patient with refractory plantar fasciitis in whom surgery had been ruled out. The patient underwent pulsed radiofrequency treatment with satisfactory results in the short and medium term.

Herniated discs: when is surgery necessary?

In all levels of disc herniations the absolute surgical indications include deteriorating neurological deficits with myelopathy or cauda equina syndrome. However, this review summarized the relative indications for surgery in each level.

In cervical disc herniation (CDH), the indications for surgery consist of six months of persisting symptoms, not responding to conservative treatment. However, high-quality studies are lacking, and a randomized controlled trial is now underway to clarify the indications.

In thoracic disc herniation (TDH), the indications for surgery comprise failure of conservative measures and/or worsening neurological symptoms. Moreover, giant calcified thoracic disc herniations or myelopathy signs on magnetic resonance imaging, even in the absence of neurological symptoms, may benefit from surgical treatment as a preventive measure.

In lumbar disc herniation (LDH), the indications for surgery include imaging confirmation of LDH, consistent with clinical findings, and failure to improve after six weeks of conservative care.

Cite this article: EFORT Open Rev 2021;6:526-530. DOI: 10.1302/2058-5241.6.210020

Diagnosis and Treatment of Sciatica in the Netherlands: A Survey among Neurologists and Anesthesiologists

BACKGROUND

This study aimed to assess how Dutch neurologists and anesthesiologists diagnose and treat people with sciatica in secondary care and to evaluate their adherence to the newest guidelines.

METHODS

We conducted a cross-sectional survey. Respondents were asked about their current clinical practice related to sciatica. Three authors rated the respondents' adherence to the guidelines on a three-point Likert scale.

RESULTS

Eighty neurologists and 44 anesthesiologists completed the questionnaire. Neurologists diagnose their sciatica patients primarily using a magnetic resonance imaging (89%). Selective diagnostic nerve blocks are considered useful by 81% of the neurologists. Neurologists primarily treat patients with pain medication, and 40% of them think epidural steroid injections are effective in 40-60% of injected patients. Twenty-nine percent of neurologists refer patients to a neurosurgeon after 4 months. Anesthesiologists consider a selective diagnostic nerve root block to have a higher diagnostic value than mapping. The most reported side effect of epidural injections is exacerbation of pain (82%). Pulse radiofrequency is applied in 9-11% of acute cases. The results also indicate that Dutch neurologists and anesthesiologists follow an evidence-based approach that is strictly or broadly in line with the guideline.

CONCLUSIONS

Neurologists treat sciatica patients initially with pain medication and physiotherapy, followed by epidural steroid injections and referral for surgery. Anesthesiologists treat sciatica patients with one or more steroid injections or may perform a selective nerve root block. Imaging, selective nerve root blocks, medication, physiotherapy, and pulse radiofrequency are topics of further research.

Transforaminal epidural steroid injection combined with radio frequency for the treatment of lumbar disc herniation: a 2-year follow-up

Background

To assess the therapeutic efficacy of transforaminal epidural steroid injection (TFESI) combined with radio frequency (RF) for the treatment of lumbar disc herniation (LDH).

Methods

A total of 230 patients participated in the study: TFESI (Group T, n = 110), TFESI combined with RF (Group TR, n = 120). Visual analogue scale (VAS), Oswestry disability index (ODI) and Global perceived effect (GPE) scale were measured pre-operation, 1, 3, 6, 12 and 24 months after the operation. Hospitalization time, treatment time, complications, and recurrence were compared between the two groups.

Results

The VAS and ODI at each observation point of the post-operation were significantly decreased compared with the pre-operation in both groups (P < 0.05). There was no statistically difference of VAS and ODI between the two groups at 1 and 3 months of the post-operation (P > 0.05). However, The VAS and ODI scores in Group TR were significantly lower than that in Group T at 6, 12 and 24 months of the post-operation (P < 0.05). The GPE in group TR was high in the early days, while that at 1 and 3 months after treatment was significantly higher than that in group T (P < 0.05). The recurrence rate in Group TR was lower than that in Group T (P = 0.002). There was no significant difference in hospitalization time, complications, VAS and ODI score at the pre-operation between the two groups (P > 0.05).

Conclusion

These findings suggest that TFESI combined with RF could effectively improve the pain and function, and had a long-term satisfactory effect for the treatment of LDH.

A Literature Review of Dorsal Root Entry Zone Complex (DREZC) Lesions: Integration of Translational Data for an Evolution to More Accurate Nomenclature

The purpose of this translational review was to provide evidence to support the natural evolution of the nomenclature of neuromodulatory and neuroablative radiofrequency lesions for pain management from lesions of individualized components of the linear dorsal afferent pathway to “Dorsal Root Entry Zone Complex (DREZC) lesions.” Literature review was performed to collate anatomic and procedural data and correlate these data to clinical outcomes. There is ample evidence that the individual components of the DREZC (the dorsal rami and its branches, the dorsal root ganglia, the dorsal rootlets, and the dorsal root entry zone) vary dramatically between vertebral levels and individual patients. Procedurally, fluoroscopy, the most commonly utilized technology is a 2-dimensional x-ray-based technology without the ability to accurately locate any one component of the DREZC dorsal afferent pathway, which results in clinical inaccuracies when naming each lesion. Despite the inherent anatomic variability and these procedural limitations, the expected poor clinical outcomes that might follow such nomenclature inaccuracies have not been shown to be prominent, likely because these are all lesions of the same anatomically linear sensory pathway, the DREZC, whereby a lesion in any one part of the pathway would be expected to interrupt sensory transmission of pain to all subsequent more proximal segments. Given that the common clinically available tools (fluoroscopy) are inaccurate to localize each component of the DREZC, it would be inappropriate to continue to erroneously refer to these lesions as lesions of individual components, when the more accurate “DREZC lesions” designation can be utilized. Hence, to avoid inaccuracies in nomenclature and until more accurate imaging technology is commonly utilized, the evidence herein supports the proposed change to this more sensitive and inclusive nomenclature, “DREZC lesions.”

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Long-term Inhibition of Soleus H-reflex with Epidural Adhesiolysis and Pulsed Radiofrequency in Lumbosacral Neuropathic Pain

INTRODUCTION

Scientific data about neurophysiological changes subsequent to pulsed radiofrequency (PRF) are still lacking. The goal of this study was to evaluate sural nerve conduction and Hoffmann reflex (H-reflex) in soleus muscle following adhesiolysis and PRF in patients with unilateral chronic lumbosacral L5-S1 neuropathic radiating pain.

METHODS

Seventeen patients received two cycles of 240 seconds high-voltage PRF and epidural adhesiolysis. Sural nerve action potential (SNAP) and the ratio of maximum H-reflex to maximum M response (H/M ratio) as well as pain scores were collected in both lower limbs before, immediately following, and 1 month after the treatment.

RESULTS

At follow-up, a significant reduction in numeric rating scale (NRS) and Douleur Neuropathique 4 Questions (DN4) scores was observed in 53% of patients reporting pain improvement of ≥ 30% over baseline. The H/M ratio was decreased in the affected limb following PRF (P = 0.01) and 1 month after the treatment (P = 0.04). A direct correlation was observed between H/M ratio variation and NRS score at follow-up in the treated limb (P = 0.04). No significant difference in sural nerve latency, amplitude, and velocity was detected between affected and normal side after treatment and at follow-up.

CONCLUSIONS

Epidural adhesiolysis and PRF of the dorsal root ganglion seem to significantly affect spinal reflexes in patients with lumbosacral neuropathic radiating pain.

[The optimization of differential diagnosis and treatment of cervical radiculopathy (SHERPA study)]

OBJECTIVE

To improve the algorithm of differential diagnosis and complex treatment of patients with CR.

MATERIAL AND METHODS

Forty-two patients with CR were divided into 2 groups. Patients of the first group (n=21) received basic treatment (NSAID, myorelaxants, local injections with glucocorticoids (on demand), B vitamins and non-pharmacological methods) and the anticholinesterase drug ipidacrine. The second group (n=21) had only basic treatment. The total duration of the study was 45 days. The effectiveness of treatment was evaluated with VAS, NDI, GROC and total duration of disability period.

RESULTS

A battery of tests for the diagnosis of CR that included Spurling test, motor strength deficiency, ULTT, pain pattern, shoulder adduction test (diagnostic complex SPASIBO), has been developed. A positive result of all 5 tests guarantees the 94.7% accuracy of CR diagnosis. The application of ipidacrine has allowed a significant (p<0.05) reduction of pain, enhancement of daily living activities and subjective improvement of well-being of patients after 1 month of treatment and mostly after 45 days. Besides, there was a considerable (p<0.05) reduction of the disability period in the first group of patients compared to the control one.

CONCLUSION

The diagnostic complex SPASIBO should be used in diagnosis of CR. It is highly recommended to include ipidacrine in the complex treatment of CR.

STUDY PROTOCOL - pulsed radiofrequency in addition to transforaminal epidural steroid injection in patients with acute and subacute sciatica due to lumbosacral disc herniation: rationale and design of a phase III, multicenter, randomized, controlled trial

Lumbosacral disc herniation (LDH) represents the most common cause of sciatica. Currently, there is limited evidence about minimally invasive interventional therapies for the treatment of this condition. This paper presents the protocol for a multicenter, prospective, randomized, controlled, phase III trial evaluating if PRF in addition to TFESI leads to better outcomes in patients with sciatica due to LDH, compared to TFESI alone, during the first year after treatment (Pulsed Radiofrequency in Addition to TFESI for Sciatica [PRATS]). Eligible patients are between 18 and 75 years of age, suffer from sciatica of less than 12-week duration with pain intensity >4 on the Visual Analogue Scale (VAS) and have unilateral LDH compatible with symptoms at MRI. The Medical Ethics Committee of participating hospitals approved the study protocol. Patients will be randomized to receive either combined treatment (PRF and TFESI) or TFESI alone. The primary outcome will be the assessment of pain intensity with VAS at different timepoints from week-1 to 52 after treatment; secondary outcomes will include Roland Disability Questionnaire for sciatica and Oswestry Disability Index, evaluated at 4, 12 and 52 weeks. The follow-up will last 52 weeks for each patient. Statistical analysis will be performed on a per-protocol basis.

Bipolar Pulsed Radiofrequency for Trigeminal Neuralgia: A Report of Two Cases

BACKGROUND

Trigeminal neuralgia (TN) is the most common cause of facial pain, leading to significant disability and impacting a patient's quality of life. Percutaneous procedures like continuous radiofrequency, pulsed radiofrequency (PRF), and combined continuous and pulsed radiofrequency have been studied in past years comparing different voltages in order to find more effective therapies with fewer complications (eg, numbness and masseter muscle weakness). With regard to young patients, there is still insufficient evidence on the most appropriate procedure in this patient population. PRF does not cause thermal damage. The mechanism of action involves delivering an electrical field to targeted nerves or tissues, modulating pain. We propose that bipolar pulsed radiofrequency (2 parallel cannulas) in the trigeminal ganglion produce a denser and larger field resulting in more effective controlled pain.

CASE PRESENTATION

We present 2 cases of 40- and 48-year-old men with severe V2 to V3 TN who underwent bipolar PRF. We performed bipolar PRF on the trigeminal ganglion through the foramen ovale using two 22-gauge 100-mm cannulas with 10-mm active tips. Parameters used were voltage of 85 V, pulse width of 20 milliseconds, and total duration time of 6 minutes. Both patients reported complete relief of pain after the procedure, and at 2-year follow-up they were pain free and experienced a better quality of life. No complications were reported.

CONCLUSION

Bipolar PRF could be a non-neurodestructive option for young people with TN and deserves further investigation as a treatment option.

Continuous But Not Pulsed Radiofrequency Current Generated by NeuroTherm NT500 Impairs Mitochondrial Membrane Potential in Human Monocytic Cells THP-1

Background

The application of pulsed radiofrequency (PRF) current to peripheral nerves with conditions related to neuropathic pain is considered to be clinically safe, while it has been reported that the destruction of mitochondria after PRF application was observed by electron microscopy. If it occurs reproducibly, PRF applied to peripheral nerves should provoke neurolysis because the impairment of mitochondria is known as the primary cause of apoptosis.

Methods

Human monocytic cells THP-1 loaded with 100 nM tetramethylrhodamine methyl ester (TMRM), a fluorescent dye that proves the mitochondrial membrane potential (MMP), were exposed to the electric field of continuous radiofrequency (CRF) or PRF current. The TMRM-related fluorescence from THP-1 cells was measured by flow cytometry.

Results

The exposure of THP-1 cells to a PRF electric field generated by NeuroTherm NT500 for 15 min with maximum power did not decrease MMP in these cells, nor did it cause the induction of apoptosis. By contrast, the application of CRF current at 70 °C for 3 min significantly decreased MMP and induced apoptosis within 10 min after CRF application.

Conclusion

We conclude from these findings that PRF application does not provoke mitochondrial injury in various types of mammalian cells because the size and the subcellular structure of the plasma membrane or mitochondria are similar among those. However, the present results cannot address the effect of PRF current on organic structure around the nervous system. Further study is required to solve the question of whether PRF current causes neurolysis or not.

Behavioral Survey of Effects of Pulsed Radiofrequency on Neuropathic and Nociceptive Pain in Rats: Treatment Profile and Device Implantation

OBJECTIVES

Pulsed radiofrequency (PRF) stimulation is widely used for intractable pain; however, there is no consensus on treatment protocols and appropriate types of pain. We compared effectiveness of bipolar and unipolar PRF on neuropathic or inflammatory pains, and of targets at the dorsal root ganglion (DRG) and sciatic nerve (SN). We also examined efficacy of repetitive PRF stimulations. This preclinical study could serve as an extensive survey before human trials.

MATERIALS

Spare nerve injury (SNI)-induced neuropathic pain and complete Freund's adjuvant (CFA) injection-induced inflammatory pain were used. Behavioral responses were measured using von Frey test, acetone test, and Hargreave's test at preinjury and postinjury time points. In both models, we evaluated results of DRG stimulation with unipolar PRF (45 V) versus bipolar PRF (5 V), stimulation at DRG vs. SN, and repetitive stimulations.

RESULTS

Both unipolar and bipolar PRFs reduced SNI- or CFA-induced pain for a similar duration. In the SNI model, PRF-DRG had a stronger effect on tactile pain than PRF-SN but lower effect on cold allodynia, whereas in the CFA model PRF-DRG and PRF-SN showed similar effects. Repetitive PRF stimulation, by open technique or implantation method, produced analogous effect by each stimulus, and no evident analgesic tolerance or neurological deficit was shown.

CONCLUSIONS

PRF temporarily attenuates neuropathic and inflammatory pain. Bipolar PRF generates significant analgesia with a much lower electrical power than unipolar PRF. Meanwhile, the minor variant effects between PRF-DRG and PRF-SN may indicate distinct mechanisms. The sustained-analgesia by repetitive treatments suggests implantation technique could be a promising choice.

Characterisation of the effects of pulsed radio frequency treatment of the dorsal root ganglion on cerebrospinal fluid cellular and peptide constituents in patients with chronic radicular pain: A randomised, triple-blinded, controlled trial

INTRODUCTION

Chronic radicular neuropathic pain is a major clinical problem with a life time prevalence of more than 50%. Pulsed radiofrequency (PRF) treatment is a recognised therapy. However, the pathophysiology of chronic neuropathic pain (CNP) and the mechanism of action of PRF remains ill-defined. Improving our knowledge of the mechanisms of CNP and PRF action will enhance our ability to treat patients with this common debilitating problem more effectively. This study aims to characterise the CSF cellular and peptide constituents in patients with CNP and the effect of pulsed radiofrequency (PRF) on these constituents and reported pain.

MATERIALS AND METHODS

Prospective randomised tripled-blinded control trial of patients receiving PRF treatment versus sham for radicular pain. All patients received local anaesthetic to the appropriate dermatome to confirm diagnosis. Clinical assessment using standard clinical assessment tools and examination of CSF using flow cytometry and ELISA for cellular and peptide constituents was carried out before and 3 months after treatment.

RESULTS

Ten patients were randomised to PRF (n = 5) or Sham (n = 5) treatment. PRF resulted in a significant reduction in pain score (NRS) at 3 months (6.8 to 2.6, p < .05). PRF reduced the TNF-α concentration and CD3+ count in CSF. CD4/CD8 ratio of patients with CNP was lower than historical controls (1.4 versus 3.0-4.2). The majority of CD3+ cells in the CNP patients were activated effector memory cells (80%) versus the surveillance central memory cells (85%) seen in healthy controls.

CONCLUSIONS

PRF is superior to local anaesthetic administration for the management of radicular pain and is associated with CSF constituent modulation in vivo. Patients with CNP have lymphocyte characteristics which suggest immune activation.

The Pathways and Processes Underlying Spinal Transmission of Low Back Pain: Observations From Dorsal Root Ganglion Stimulation Treatment

BACKGROUND

Dorsal root ganglion stimulation (DRG-S) is a novel approach to treat chronic pain. Lead placement at L2 has been reported to be an effective treatment for axial low back pain (LBP) primarily of discogenic etiology. We have recently shown, in a diverse cohort including cases of multilevel instrumentation following extensive prior back surgeries, that DRG-S lead placement at T12 is another promising target. Local effects at the T12 DRG, alone, are insufficient to explain these results.

MATERIALS AND METHODS

We performed a literature review to explore the mechanisms of LBP relief with T12 DRG-S.

FINDINGS

Branches of individual spinal nerve roots innervate facet joints and posterior spinal structures, while the discs and anterior vertebrae are carried via L2, and converge in the dorsal horn (DH) of the spinal cord at T8-T9. The T12 nerve root contains cutaneous afferents from the low back and enters the DH of the spinal cord at T10. Low back Aδ and C-fibers then ascend via Lissauer's tract (LT) to T8-T9, converging with other low back afferents. DRG-S at T12, then, results in inhibition of the converged low back fibers via endorphin-mediated and GABAergic frequency-dependent mechanisms. Therefore, T12 lead placement may be the optimal location for DRG-S to treat LBP.

Pulsed Radiofrequency Neuromodulation Contributes to Activation of Platelet-Rich Plasma in In Vitro Conditions

OBJECTIVES

Recent years have brought new developments in interventional chronic pain management, namely regenerative orthopedics utilizing platelet-rich plasma (PRP) as well as further evolution of pulsed radiofrequency neuromodulation (PRF). Both methods have been used separately. Here, we investigated whether PRF may potentiate the activation of platelets in PRP samples when both these techniques are combined together in in vitro conditions.

MATERIALS AND METHODS

Studies were performed on concentrated PRP samples (PRPs) obtained from acid citrate dextrose-treated blood taken from 11 healthy volunteers. PRPs were divided into four groups: 1) nonactivated PRP; 2) thrombin-activated PRP as a positive control for maximal platelets activation; 3) PRF-treated PRP exposed for 20 min to PRF energy generated by neurotherm radio frequency generator at 500 kHz, with a voltage of 40 V and maximal temperature of 42°C; and 4) a combination of groups 2 and 3.

RESULTS

PRF-induced platelet activation measured by platelet factor 4 (PF4) and ATP release from PRPs was significantly higher compared to nonactivated PRPs, and similar to PF4 and ATP release from thrombin-activated PRPs. Thrombin activation did not potentiate PF4 release in PRF samples and even reduced ATP level. Additionally, PRF neither induced any platelet membrane damage measured by lactic dehydrogenase release from PRP nor modified any platelets viability or metabolism measured by MTT.

CONCLUSIONS

We confirmed that PRF may activate PRP without additional platelet activators. So, a combination of both methods PRF and PRP application may provide a more effective opportunity for tissue regeneration in dentistry, surgery, dermatology, or in orthopedics.

Pulsed radiofrequency inhibits expression of P2X3 receptors and alleviates neuropathic pain induced by chronic constriction injury in rats

Background:

Pulsed radiofrequency (PRF) is a minimally invasive interventional technique that provides a novel and effective treatment strategy for neuropathic pain (NP). PRF is advantageous because it does not damage nerves and avoids sensory loss after treatment. At present, animal studies have demonstrated that PRF is safe and effective for relieving the NP associated with sciatic nerve damage in rats with chronic constriction injury (CCI). However, the mechanism through which this effect occurs is unknown. An increasing body of evidence shows that the expression of the P2X ligand-gated ion channel 3 (P2X₃) receptor is closely related to NP; this study was to investigate whether the expression of this receptor is involved in NP relief due to PRF.

Methods:

A total of 36 healthy adult male Sprague-Dawley (SD) rats were randomly divided into three groups: Sham group, CCI group, and PRF group. The right sciatic nerve was ligated in CCI group and PRF group to establish a CCI model; the right sciatic nerve was separated but not ligated in Sham group. On day 14 after the operation, PRF was administered to the ligated sciatic nerve in PRF group (42°C, 45 V, 2 min). A non-live electrode was placed at the exposed sciatic nerve for the rats in Sham and CCI groups. The hindpaw withdrawal threshold (HWT) and thermal withdrawal latency (TWL) were measured at the right hindpaw at different time points before and after PRF or sham therapy. On day 28 after treatment, the dorsal root ganglion (DRG) and spinal dorsal horn of the right L4–6 were harvested from each group to determine the mRNA and protein levels of the P2X₃ receptor.

Results:

On day 28 after PRF treatment, the HWT (8.33 ± 0.67 g vs. 3.62 ± 0.48 g) and TWL (25.42 ± 1.90 s vs. 15.10 ± 1.71 s) were significantly higher in PRF group as compared to CCI group (P < 0.05). The mRNA expression of the P2X₃ receptor in the DRG in PRF group was 23.7% lower than that in CCI group (P < 0.05), in the spinal dorsal horns in PRF group was 22.7% lower than that in CCI group (P < 0.05). The protein expression of the P2X₃ receptor in the DRG in PRF group was 27.8% lower than that in CCI group (P < 0.05), in the spinal dorsal horns in PRF group was 35.6% lower than that in CCI group (P < 0.05).

Conclusion:

PRF possibly reduces NP in CCI rats by inhibiting the expression of the P2X₃ receptor in the L4–6 DRG and spinal dorsal horns.

Dorsal root ganglion pulsed radiofrequency treatment for chronic cervical radicular pain: a retrospective review of outcomes in fifty-nine cases

Pulsed radiofrequency treatment adjacent to the cervical dorsal root ganglion is used to treat persistent cervical radicular pain that has not responded to conservative therapies. This technique has gained popularity in years for both cervical and lumbosacral radicular pain. The evidence to support its use is still evolving.

METHODS

We performed a retrospective review of outcomes in 59 patients who underwent this therapy over a 3-year period in our institution. We evaluated a reduction in pain, duration of pain relief, reduction in use of analgesics and progression to surgery.

RESULTS

Our results demonstrated 49 patients experienced some relief. Forty patients of the 59 experienced an improvement in pain of 50% or more. The mean duration of relief in this group was 37 weeks. Seven patients experienced complete resolution of their pain. In this group, the mean duration of relief was 39 weeks. Regarding the 53 patients who were taking medication for pain prior to the procedure, 37 patients reduced or discontinued their usage after the procedure.

CONCLUSION

Despite the limitations of a retrospective study, we feel our study adds to the growing evidence base that pulsed radiofrequency treatment adjacent to the cervical dorsal root ganglion has a role in the treatment of chronic cervical radicular pain.

Pulsed radiofrequency to the dorsal root ganglion or the sciatic nerve reduces neuropathic pain behavior, decreases peripheral pro-inflammatory cytokines and spinal β-catenin in chronic constriction injury rats

BACKGROUND AND OBJECTIVES

Pulsed radiofrequency (PRF) is a minimal neurodestructive interventional pain therapy. However, its analgesic mechanism remains largely unclear. We aimed to investigate the peripheral and spinal mechanisms of PRF applied either adjacent to the ipsilateral L5 dorsal root ganglion (PRF-DRG) or PRF to the sciatic nerve (PRF-SN) in the neuropathic pain behavior induced by chronic constriction injury (CCI) in rats.

METHODS

On day 0, CCI or sham surgeries were performed. Rats then received either PRF-DRG, PRF-SN, or sham PRF treatment on day 4. Pain behavioral tests were conducted before surgeries and on days 1, 3, 5, 7, 9, 11, 13, and 14. After the behavioral tests, the rats were sacrificed. The venous blood or sciatic nerve samples were collected for ELISAs and the dorsal horns of the L4-L6 spinal cord were collected for western blot examination.

RESULTS

The mechanical allodynia and the thermal hyperalgesia has been relieved by a single PRF-DRG or PRF-SN application. In addition, the analgesic effect of PRF-DRG was superior to PRF-SN on CCI-induced neuropathic pain. Either PRF-DRG or PRF-SN reversed the enhancement of interleukin 1β (IL-1β) and tumor necrosis factor alpha (TNF-α) levels in the blood of CCI rats. PRF-DRG or PRF-SN also downregulated spinal β-catenin expression.

CONCLUSIONS

PRF treatment either to DRG or to sciatic nerve reduced neuropathic pain behavior, and reduced peripheral levels of pro-inflammatory cytokines and spinal β-catenin expression in CCI rats. PRF to DRG has a better analgesic effect than PRF to the nerve.

Pulsed radiofrequency of the brachial plexus in the treatment of chemotherapy-induced peripheral neuropathy of the upper limb

We describe the treatment of chemotherapy-induced peripheral neuropathy in the upper limb of a patient via ultrasound-guided pulsed radiofrequency of the brachial plexus. A 54-year-old female, who underwent chemotherapy and mastectomy for left-sided breast cancer, presented to the pain clinic describing continuous and severe shock-like pain in the posterolateral aspect of the left upper limb, above the elbow. A diagnosis of chemotherapy-induced peripheral neuropathy was made. Pain management with multi-modal analgesia was not fully effective and pulsed radiofrequency was offered as an alternative. Ultrasonography of the supraclavicular region was used to identify the brachial plexus, followed by pulsed radiofrequency using an insulated-tip needle that produced paraesthesia in the affected area. Onset of pain relief occurred one week post-procedure and lasted approximately 10 weeks. An estimated 80% decrease in pain intensity was reported by the patient. We propose that pulsed radiofrequency can be offered as a pain management alternative in certain presentations of chemotherapy-induced peripheral neuropathy.

Low back pain

Low back pain affects individuals of all ages and is a leading contributor to disease burden worldwide. Despite advancements in assessment and treatment methods, the management of low back pain remains a challenge for researchers and clinicians alike. One reason for the limited success in identifying effective treatments is the large variation in the manifestations, possible causes, precipitating and maintaining factors, course, prognosis and consequences in terms of activity interference and quality of life. However, despite these challenges, steady progress has been achieved in the understanding of back pain, and important steps in the understanding of the psychological and social risk factors, genetics and brain mechanisms of low back pain have been made. These new findings have given impetus to the development of new diagnostic procedures, evidence-based screening methods and more targeted interventions, which underscore the need for a multidisciplinary approach to the management of low back pain that integrates biological, psychological and social aspects.

Enhanced expression of gene coding for β-endorphin in human monocytic cells exposed to pulsed radio frequency electric fields through thermal and non-thermal effects

Background

The enhanced expression of endogenous opioid peptides, including β-endorphin, has been implicated in the mechanism of action of pulsed radio frequency (PRF) application in pain modulation. Because thermal effects cannot be separated from the physical property of PRF application to biological tissues, we evaluated whether temperatures higher than that of the normal body temperature (37°C) modulate mRNA expression for the precursor of β-endorphin, proopiomelanocortin (POMC) in human monocytic cells THP-1. We also attempted to examine whether mechanisms other than thermal effects also modulate such gene expression.

Methods and results

The mRNA for POMC in THP-1 cells increased by a 15-minutes incubation at 42°C, 45°C, or 70°C without PRF application as compared with that in cells incubated at 37°C. On the other hand, gene expression for POMC in cells incubated at 20°C as well as at 37°C with PRF application for 15 minutes increased as compared to that in cells incubated at 37°C without PRF application. Continuous radio frequency at 70°C but not PRF provoked apoptotic cell death at 1–2 hour, and necrotic cell death at 24 hours after the RF application.

Conclusion

A simple experimental system using human monocytic cells in culture demonstrated that a 15 minute elevation of temperature above 37°C enhanced gene expression for POMC in THP-1 cells, while a 15 minute application of PRF to these cells incubated at 37°C or lower, also enhanced gene expression, indicating that temperature-independent mechanisms as well as thermal effects may be involved in such gene expression.

Radiculopathy Contralateral to the Side of Disc Herniation -Microendoscopic Observation

INTRODUCTION

There are patients with lumbar disc herniation (LDH) having contralateral sciatic symptoms although the mechanisms of this clinical feature are still not well understood. The purpose of this study was to investigate these mechanisms by microendoscopic findings.

METHODS

Patients were performed microendoscopic surgery using over-the-top approach (ME-OTT), with laminoplasty, extirpation of herniation, and observation of the contralateral nerve root. The over-the-top approach was applied through the same incision from the herniation side. Clinical results were assessed according to the clinical scoring system established by the Japanese Orthopedic Association (JOA) score.

RESULTS

This study consisted of five patients, with the average age of 55.6 years old. The mean preoperative JOA score was 13 points. Three cases were Grade II and two were Grade III degrees of disc herniation. Levels of herniation were one at L3-4 and four at L4-5. Remission of sciatic symptoms was obtained in all cases after surgery. The average and percent improvements (%IP) of JOA scores at 2 months after surgery were 27.8 points and 92%, respectively. By the approach from the herniation side using ME-OTT, image around the contralateral nerve root was obtained without radical intervention. By ME-OTT, redness of the nerve root and fibrosis around the symptomatic nerve root were identified, whereas inflammatory changes were not apparent on the ipsilateral nerve root.

CONCLUSIONS

Operative treatment of LDH with contralateral symptoms by ME-OTT was a useful procedure for decompression and observation of the affected nerve root. Asymptomatic disc herniation, "silent disc herniation," was considered at the herniation side since there were less inflammatory changes around the ipsilateral nerve root. In contrast, compression of dura toward the opposite side by disc herniation could have led to mechanical stress against the contralateral nerve root and triggered inflammation at lateral recess, resulting in radicular pain.

Wi-Fi is an important threat to human health

Repeated Wi-Fi studies show that Wi-Fi causes oxidative stress, sperm/testicular damage, neuropsychiatric effects including EEG changes, apoptosis, cellular DNA damage, endocrine changes, and calcium overload. Each of these effects are also caused by exposures to other microwave frequency EMFs, with each such effect being documented in from 10 to 16 reviews. Therefore, each of these seven EMF effects are established effects of Wi-Fi and of other microwave frequency EMFs. Each of these seven is also produced by downstream effects of the main action of such EMFs, voltage-gated calcium channel (VGCC) activation. While VGCC activation via EMF interaction with the VGCC voltage sensor seems to be the predominant mechanism of action of EMFs, other mechanisms appear to have minor roles. Minor roles include activation of other voltage-gated ion channels, calcium cyclotron resonance and the geomagnetic magnetoreception mechanism. Five properties of non-thermal EMF effects are discussed. These are that pulsed EMFs are, in most cases, more active than are non-pulsed EMFs; artificial EMFs are polarized and such polarized EMFs are much more active than non-polarized EMFs; dose-response curves are non-linear and non-monotone; EMF effects are often cumulative; and EMFs may impact young people more than adults. These general findings and data presented earlier on Wi-Fi effects were used to assess the Foster and Moulder (F&M) review of Wi-Fi. The F&M study claimed that there were seven important studies of Wi-Fi that each showed no effect. However, none of these were Wi-Fi studies, with each differing from genuine Wi-Fi in three distinct ways. F&M could, at most conclude that there was no statistically significant evidence of an effect. The tiny numbers studied in each of these seven F&M-linked studies show that each of them lack power to make any substantive conclusions. In conclusion, there are seven repeatedly found Wi-Fi effects which have also been shown to be caused by other similar EMF exposures. Each of the seven should be considered, therefore, as established effects of Wi-Fi.

Predictors of the analgesic efficacy of pulsed radiofrequency treatment in patients with chronic lumbosacral radicular pain: a retrospective observational study

Background

Pulsed radiofrequency (RF) targeting the adjacent dorsal root ganglion (DRG) is one treatment option for lumbosacral radicular pain. However, the analgesic efficacy of this procedure is not always guaranteed. The aim of this retrospective study was to identify the predictors of the analgesic efficacy of pulsed DRG RF treatment in patients with chronic lumbosacral radicular pain.

Methods

Patients who underwent pulsed DRG RF treatment from 2006 to 2017 at our clinic were enrolled. Positive response was defined as a ≥50% reduction in pain score from baseline at day 30. Patient demographics, pain-related factors, and clinical factors were evaluated using logistic regression analysis to identify the predictors of a positive response to the treatment.

Results

A total of 60 patients satisfied the study protocol requirements. Twenty-eight patients (46.7%) had a positive outcome. Multivariate logistic regression analysis revealed that the absence of comorbid musculoskeletal pain (OR=0.518, 95% CI=0.029-0.858, P=0.033) and positive response to previous epidural steroid injection (OR=3.269, 95% CI=1.046-10.215, P=0.042) were independent predictors of the analgesic efficacy of pulsed DRG RF treatment.

Conclusion

Comorbid musculoskeletal pain and previous epidural injection response appear to affect the outcome of pulsed DRG RF treatment in patients with chronic lumbosacral radicular pain.

Pulsed radiofrequency in chronic pain

PURPOSE OF REVIEW

The increasing number of publications on pulsed radiofrequency (PRF) treatment of chronic pain reflects the interest for this technique. We summarize the literature for PRF in five indications: radicular pain, trigeminal neuralgia (TN), occipital neuralgia, shoulder and knee pain.

RECENT FINDINGS

The efficacy and safety of PRF adjacent to the dorsal root ganglion was documented on cervical and on lumbar level.PRF has been used for the treatment of TN. The observed duration of effect is shorter than that of conventional radiofrequency, but no neurological complications are reported with PRF.PRF of the nervi occipitales is superior to steroid injections in occipital neuralgia.Several studies showed that PRF of the nervus suprascapularis may relief shoulder pain and can improve mobility of the shoulder joint.For the treatment of knee pain, different nerves have been targeted for PRF treatment.

SUMMARY

PRF treatment has progressively gained a place in the management of chronic pain syndromes. The concept is appealing because long-lasting effects are reported without complications. Future research is needed with high quality randomized controlled trials and identification of the optimal parameters of PRF in clinical practice.

Human dorsal root ganglion pulsed radiofrequency treatment modulates cerebrospinal fluid lymphocytes and neuroinflammatory markers in chronic radicular pain

Radicular pain is a common cause of disability. Traditionally treatment has been either epidural steroid injection providing short-term relief or surgery with associated complications. Pulsed radiofrequency (PRF) applied to the dorsal root ganglion (DRG) is a minimally invasive day-care treatment, which is gaining significant clinical acceptance in a selective group of patients with pure radicular pain. Greater insights into the immunomodulatory effects of this procedure may help to further optimise its application and find alternative treatment options. We have examined it's effect on lymphocyte frequencies and secreted inflammatory markers in the cerebrospinal fluid (CSF) and correlated this with clinical outcome to identify clinical markers of chronic radicular pain. Ten patients were recruited for the study. CSF lymphocyte frequencies and levels of cytokines, chemokines and growth factors were quantified using flow cytometry and enzyme-linked immunosorbent assay (ELISA), respectively. Clinical assessment utilised Brief Pain Inventory scores. Nine out of ten patients (90%) demonstrated significant reduction in pain severity (p = 0.0007) and pain interference scores (p = 0.0015) three months post-treatment. Our data revealed significant reductions in CD56⁺, CD3^-, NK cell frequencies (p = 0.03) and IFN-γ levels (p = 0.03) in treatment responders, while CD8⁺ T cell frequencies (p = 0.02) and IL-6 levels were increased (p = 0.05). IL-17 inversely correlated with post-treatment pain severity score (p = 0.01) and pre and post-treatment pain interference scores (p = 0.03, p = 0.01). These results support the concept that chronic radicular pain is a centrally mediated neuroimmune phenomenon and the mechanism of action of DRG PRF treatment is immunomodulatory.

The Dorsal Root Ganglion as a Therapeutic Target for Chronic Pain

Chronic neuropathic pain is a widespread problem with negative personal and societal consequences. Despite considerable clinical neuroscience research, the goal of developing effective, reliable, and durable treatments has remained elusive. The critical role played by the dorsal root ganglion (DRG) in the induction and maintenance of chronic pain has been largely overlooked in these efforts, however. It may be that, by targeting this site, robust new options for pain management will be revealed. This review summarizes recent advances in the knowledge base for DRG-targeted treatments for neuropathic pain:• Pharmacological options including the chemical targeting of voltage-dependent calcium channels, transient receptor potential channels, neurotrophin production, potentiation of opioid transduction pathways, and excitatory glutamate receptors.• Ablation or modulation of the DRG via continuous thermal radiofrequency and pulsed radiofrequency treatments.• Implanted electrical neurostimulator technologies.• Interventions involving the modification of DRG cellular function at the genetic level by using viral vectors and gene silencing methods.

Cervical radiculopathy

Cervical radiculopathy is a common clinical scenario. Patients with radiculopathy typically present with neck pain, arm pain, or both. We review the epidemiology of cervical radiculopathy and discuss the diagnosis of this condition. This includes an overview of the pertinent findings on the patient history and physical examination. We also discuss relevant clinical syndromes that must be considered in the differential diagnosis including peripheral nerve entrapment syndromes and shoulder pathology. The natural history of cervical radiculopathy is reviewed and options for management are discussed. These options include conservative management, non-operative modalities such as physical therapy, steroid injections, and operative intervention. While the exact indications for surgical intervention have not yet been elucidated, we provide an overview of the available literature regarding indications and discuss the timing of intervention. The surgical outcomes of anterior cervical decompression and fusion (ACDF), cervical disc arthroplasty (CDA), and posterior cervical foraminotomy (PCF) are discussed.

Pulsed radiofrequency in clinical practice - A retrospective analysis of 238 patients with chronic non-cancer pain treated at an academic tertiary pain centre

BACKGROUND AND AIMS

Pulsed radiofrequency is a non-neurodestructive invasive pain treatment which, in contrast to conventional continuous radiofrequency treatment, does not entail nerve tissue destruction. The aim of this study was to retrospectively analyse the short-term benefits of a broad use of pulsed radiofrequency in clinical practice.

METHODS

The medical records of all patients treated with pulsed radiofrequency, or who received a diagnostic test block with a local anaesthetic in view of such a treatment, were retrospectively analysed. The patients had been referred to a tertiary pain centre in Sweden. The treatment effect one month after pulsed radiofrequency was retrospectively graded as follows, based on the wordings of the medical records: major improvement; minor improvement; no change; or worsened.

RESULTS

A total of 238 patients received 587 interventions from 2009 to 2014. Chronic low back pain (CLBP) was by far the most common treatment indication (57% of patients), followed by CLBP with sciatica (9%). The age at first pulsed radiofrequency was 55 (15-94) years (mean, range), and 65% were female. Thirty-six patients (15%) underwent only a diagnostic test block using a local anaesthetic, i.e., the test block did not lead to treatment with pulsed radiofrequency. A total of 445 pulsed radiofrequency interventions were performed on 202 patients. Dichotomizing data into responders (i.e., minor or major improvement) and non-responders (i.e., worsened or no change), we found that, out of 63 responders to a median branch diagnostic test block (either at the cervical or lumbar level), 33 were responders to the first following median branch pulsed radiofrequency. Hence the positive predictive value of a median branch test block was 52%. In 127 patients, the lumbar level was targeted for median branch pulsed radiofrequency because of clinically suspected lumbar facetogenic pain. Looking at the first treatment, 30% experienced major improvement after 1 month, 16% minor improvement, 36% no change, 5% a worsened situation, and the effect was not assessable in 13% of patients. Lone dorsal root ganglion L2-treatment for suspected discogenic lumbar pain was done on 39 patients and, after one month, the effect was not assessable in 17% of patients, 14% had major improvement, 14% minor improvement, and 55% had no change. In 40 patients, a dorsal root ganglion or a peripheral nerve was targeted because of a non-axial chronic pain condition. There was a plethora of indications, but the most common was by far related to some form of neuropathic pain (52% of interventions, mainly because of neuralgia), followed by chronic nociceptive shoulder pain (8% of interventions).

CONCLUSIONS

This study shows that, after one month, the effect size of a broad and indiscriminate clinical use of pulsed radiofrequency is rather small.

IMPLICATIONS

The clinical effectiveness of pulsed radiofrequency has to be investigated further in carefully selected and more homogenous patient groups, in order to define effective treatment niches for this nondestructive invasive treatment method.

Long-Term Anti-Allodynic Effect of Immediate Pulsed Radiofrequency Modulation through Down-Regulation of Insulin-Like Growth Factor 2 in a Neuropathic Pain Model

Pulsed radiofrequency (PRF) is effective in the treatment of neuropathic pain in clinical practice. Its application to sites proximal to nerve injury can inhibit the activity of extra-cellular signal-regulated kinase (ERK) for up to 28 days. The spared nerve injury (SNI)+ immPRF group (immediate exposure to PRF for 6 min after SNI) exhibited a greater anti-allodynic effect compared with the control group (SNI alone) or the SNI + postPRF group (application of PRF for 6 min on the 14th day after SNI). Insulin-like growth factor 2 (IGF2) was selected using microarray assays and according to web-based gene ontology annotations in the SNI + immPRF group. An increase in IGF2 and activation of ERK1/2 were attenuated by the immPRF treatment compared with an SNI control group. Using immunofluorescent staining, we detected co-localized phosphorylated ERK1/2 and IGF2 in the dorsal horn regions of rats from the SNI group, where the IGF2 protein predominantly arose in CD11b- or NeuN-positive cells, whereas IGF2 immunoreactivity was not detected in the SNI + immPRF group. Taken together, these results suggest that PRF treatment immediately after nerve injury significantly inhibited the development of neuropathic pain with a lasting effect, most likely through IGF2 down-regulation and the inhibition of ERK1/2 activity primarily in microglial cells.