Dorsal Root Ganglion Stimulation for Chronic Pelvic Pain: A Case Series and Technical Report on a Novel Lead Configuration

The Neurostimulation Appropriateness Consensus Committee (NACC)®: Recommendations for Spinal Cord Stimulation Long-Term Outcome Optimization and Salvage Therapy

INTRODUCTION

The International Neuromodulation Society (INS) has recognized a need to establish best practices for optimizing implantable devices and salvage when ideal outcomes are not realized. This group has established the Neurostimulation Appropriateness Consensus Committee (NACC)® to offer guidance on matters needed for both our members and the broader community of those affected by neuromodulation devices.

MATERIALS AND METHODS

The executive committee of the INS nominated faculty for this NACC® publication on the basis of expertise, publications, and career work on the issue. In addition, the faculty was chosen in consideration of diversity and inclusion of different career paths and demographic categories. Once chosen, the faculty was asked to grade current evidence and along with expert opinion create consensus recommendations to address the lapses in information on this topic.

RESULTS

The NACC® group established informative and authoritative recommendations on the salvage and optimization of care for those with indwelling devices. The recommendations are based on evidence and expert opinion and will be expected to evolve as new data are generated for each topic.

CONCLUSIONS

NACC® guidance should be considered for any patient with less-than-optimal outcomes with a stimulation device implanted for treating chronic pain. Consideration should be given to these consensus points to salvage a potentially failed device before explant.

Effectiveness of Dorsal Root Ganglion Stimulation in Chronic Pain Management: A Systematic Review

OBJECTIVE

This systematic review aims to determine the effectiveness of dorsal root ganglion stimulation (DRGS) in chronic pain management.

METHODS

In 2023, a comprehensive systematic review was undertaken utilizing various electronic databases, employing MeSH terms and free search terms tailored to the study's aims. This review included primary research such as cohorts, case-control studies, and clinical trials, all focusing on the efficacy of DRGS in treating various chronic pain conditions. Nonhuman or animal studies were omitted from the selection process. A review of study quality was conducted, followed by a meticulous analysis of the findings to synthesize the evidence. This review represents the most current research, with updates extending to 2024. A total of 400 articles were reviewed. Twenty-nine articles were included in our review after meticulous screening.

RESULTS

Twenty-nine articles published in the last five years meeting selection criteria were identified, encompassing patients with various diagnoses warranting the use of DRGS beyond complex regional pain syndrome. Additionally, the analysis includes different outcome measurement tools, emphasizing improvements in pain management, functionality, and quality of life. Finally, common complications such as surgical site infections and issues with electrodes are highlighted.

CONCLUSIONS

This systematic review affirms the effectiveness of DRGS therapy in managing diverse chronic pain conditions, highlighting improvements in quality of life, functionality, and mood states, making it a viable alternative for patients unresponsive to traditional treatments.

Fluoroscopy-Guided Transgluteal Pudendal Nerve Block for Pudendal Neuralgia: A Retrospective Case Series

Background/Objective: Pudendal neuralgia is a distressing condition that presents with pain in the perineum. While a positive anesthetic pudendal nerve block is one of the essential criteria for diagnosing this condition, this block can also provide a therapeutic effect for those afflicted with pudendal neuralgia. There are multiple ways in which a pudendal nerve block can be performed. The objective of this study is to share our results and follow-up of fluoroscopy-guided transgluteal pudendal nerve blocks. Methods: This is a retrospective case series. Included were 101 patients who met four out of the five Nantes criteria (pain in the anatomical territory of the pudendal nerve, pain worsened by sitting, pain that does not wake the patient up at night, and no objective sensory loss on clinical examination) who did not respond to conservative treatment and subsequently underwent a fluoroscopy-guided transgluteal pudendal nerve block. Therapeutic success was defined as a 30% or greater reduction in pain. Success rates were calculated, and the duration over which that success was sustained was recorded. Results: For achieving at least 30% relief of pain, using worst-case analysis, the success rate at two weeks was 49.4% (95% CI: 38.5%, 60.3%). In addition to pain relief, patients experienced other therapeutic benefits, such as reductions in medication use and improvements in activities of daily living. Conclusions: Fluoroscopy-guided transgluteal pudendal nerve block appears to be effective in patients who have pudendal neuralgia that is resistant to conservative therapy, with good short-term success.

Spinal Cord Stimulation for Intractable Visceral Pain Originating from the Pelvic and Abdominal Region: A Narrative Review on a Possible New Indication for Patients with Therapy-Resistant Pain

Aim

Visceral pain, characterized by pain that is diffuse and challenging to localize, occurs frequently and is difficult to treat. In cases where the pain becomes intractable despite optimal medical management, it can affect patients' Quality of Life (QoL). Spinal Cord Stimulation (SCS) has emerged as a potential solution for intractable visceral pain.

Purpose

In this narrative review, we collected all evidence regarding the efficacy of SCS for visceral pain across various underlying conditions.

Methods

A comprehensive literature search was conducted in PubMed, Embase, and Web of Science in which articles published from October 1st, 1963 up to March 7th, 2023 were identified.

Results

Seventy articles were included in this review of which most were retrospective cohort studies, case series and case reports. The studies, often with a small number of participants, reported on SCS for chronic pancreatitis, anorectal pain and bowel disorders, gynaecological diagnoses, visceral pelvic pain, urological disorders and finally general visceral pain. They found positive effects on pain and/or symptom relief, opioid consumption, anxiety and depression and QoL. Complications occurred frequently but were often minor and reversible.

Conclusion

Better screening and selection criteria need to be established to optimally evaluate eligible patients who might benefit from SCS. A positive outcome of a sympathetic nerve block appears to be a potential indicator of SCS effectiveness. Additionally, women receiving SCS for endometriosis had a better outcome compared to other indications. Finally, SCS could also relief functional symptoms such as voiding problems and gastroparesis. Complications could often be resolved with revision surgery. Since SCS is expensive and not always covered by standard health insurance, the incorporation of cost-analyses is recommended. In order to establish a comprehensive treatment plan, including selection criteria for SCS, rigorous prospective, possibly randomized and controlled studies that are diagnosis-oriented, with substantial follow-up and adequate sample sizes, are needed.

Neuromodulation for the management of chronic pelvic pain syndromes: A systematic review

BACKGROUND

Chronic pelvic pain is a burdensome condition that involves multiple medical sub-specialties and is often difficult to treat. Sacral stimulation for functional bladder disease has been well established, but little large-scale evidence exists regarding utilization of other neuromodulation techniques to treat chronic pelvic pain. Emerging evidence does suggest that neuromodulation is a promising treatment, and we aim to characterize the use and efficacy of such techniques for treating chronic pelvic pain syndromes.

MATERIALS AND METHODS

A systematic review of the literature demonstrating the treatment of chronic pelvic pain syndromes with neuromodulation. Abstracts were reviewed and selected for inclusion, including case series, prospective studies, and randomized controlled trials (RCTs). Case studies and publications in abstract only were not included. The reporting for this systematic review follows Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA). The literature search was performed using MEDLINE, Embase, Cochrane Library, PubMed, CINAHL, and Scopus.

RESULTS

A total of 50 studies were included in this review, three of which were randomized controlled trials, and the remaining were prospective and retrospective case series. The range of pelvic pain conditions treated included interstitial cystitis, peripheral neuralgia, pudendal neuralgia, gastrointestinal pain, urogenital pain, sacroiliac joint pain, and visceral chronic pelvic pain. We reported on outcomes involving pain, functionality, psychosocial improvement, and medication reduction.

CONCLUSIONS

Neuromodulation is a growing treatment for various chronic pain syndromes. Peripheral nerve stimulation was the least studied form of stimulation. Posterior tibial nerve stimulation appears to offer short-term benefit, but long-term results are challenging. Sacral nerve stimulation is established for use in functional bladder syndromes and appears to offer pain improvement in these patients as well. Dorsal root ganglion stimulation and spinal cord stimulation have been used for a variety of conditions with promising results. Further studies of homogeneous patient populations are necessary before strong recommendations can be made at this time, although pooled analysis may also be impactful.

Pain Education and Knowledge (PEAK) Consensus Guidelines for Neuromodulation: A Proposal for Standardization in Fellowship and Training Programs

The need to be competent in neuromodulation is and should be a prerequisite prior to completing a fellowship in interventional pain medicine. Unfortunately, many programs lack acceptable candidates for these advanced therapies, and fellows may not receive adequate exposure to neuromodulation procedures. The American Society of Pain and Neuroscience (ASPN) desires to create a consensus of experts to set a minimum standard of competence for neurostimulation procedures, including spinal cord stimulation (SCS), dorsal root ganglion stimulation (DRG-S), and peripheral nerve stimulation (PNS). The executive board of ASPN accepted nominations for colleagues with excellence in the subject matter of neuromodulation and physician education. This diverse group used peer-reviewed literature and, based on grading of evidence and expert opinion, developed critical consensus guides for training that all accredited fellowship programs should adopt. For each consensus point, transparency and recusal were used to eliminate bias, and an author was nominated for evidence grading oversight and bias control. Pain Education and Knowledge (PEAK) Consensus Guidelines for Neuromodulation sets a standard for neuromodulation training in pain fellowship training programs. The consensus panel has determined several recommendations to improve care in the United States for patients undergoing neuromodulation. As neuromodulation training in the United States has evolved dramatically, these therapies have become ubiquitous in pain medicine. Unfortunately, fellowship programs and the Accreditation Council for Graduate Medical Education (ACGME) pain program requirements have not progressed training to match the demands of modern advancements. PEAK sets a new standard for fellowship training and presents thirteen practice areas vital for physician competence in neuromodulation.

Dorsal root ganglion stimulation for the treatment of chronic pelvic pain: A systematic review

BACKGROUND

Chronic pelvic pain (CPP) is a difficult condition to treat. Due to complex pelvic innervation, dorsal column spinal cord stimulation (SCS) has not been shown to produce the same effect as dorsal root ganglion stimulation (DRGS) given emerging evidence suggesting that applying DRGS may result in favorable outcomes for individuals with CPP. The aim of this systematic review is to investigate the clinical use and effectiveness of DRGS for patients with CPP.

MATERIALS AND METHODS

A systematic review of clinical studies demonstrating the use of DRGS for CPP. Searches were conducted using four electronic databases (PubMed, EMBASE, CINAHL, and Web of Science) across August and September 2022.

RESULTS

A total of nine studies comprising 65 total patients with variable pelvic pain etiologies met the inclusion criteria. The majority of subjects implanted with DRGS reported >50% mean pain reduction at variable times of follow-up. Secondary outcomes reported throughout studies including quality of life (QOL) and pain medication consumption were reported to be significantly improved.

CONCLUSIONS

Dorsal root ganglion stimulation for CPP continues to lack supportive evidence from well-designed, high-quality studies and recommendations from consensus committee experts. However, we present consistent evidence from level IV studies showing success with the use of DRGS for CPP in reducing pain symptoms along with reports of improved QOL through periods as short as 2 months to as long as 3 years. Because the available studies at this time are of low quality with a high risk of bias, we strongly recommend the facilitation of high-quality studies with larger sample sizes in order to better ascertain the utility of DRGS for this specific patient population. At the same time, from a clinical perspective, it may be reasonable and appropriate to evaluate patients for DRGS candidacy on a case-by-case basis, especially those patients who report CPP symptoms that are refractory to noninterventional measures and who may not be ideal candidates for other forms of neuromodulation.

MR thermometry imaging for low intensity focused ultrasound modulation of spinal nervous tissue

OBJECTIVES

Previously in rodent and swine models, we have shown that external low intensity focused ultrasound (liFUS) can be used to modulate pain responses. To ensure no adverse heating events occur with liFUS modulation in a non-invasive manner, we perform initial work in swine to show that magnetic resonance thermometry imaging (MRTI) is capable of measuring <2.0 °C changes at the L5 DRG. Further, we show that our device can be constructed in an MR-compatible fashion to minimize artifact.

METHODS

Three MRTI techniques (referenceless, corrected proton resonance frequency shift (PRFS), and PRFS) were applied to assess accuracy of detecting thermal changes at the L5 DRG in unheated euthanized swine. A region of interest (ROI) that includes the L5 DRG was delineated, within which MRTI temperature changes were spatially averaged (ground truth 0 °C). In separate experiments with phantoms, B0 field-inhomogeneity, RF transmit (B1+) and fast gradient echo (fSPGR) magnitude images were acquired to downselect liFUS device materials that produce the least MRI artifacts.

RESULTS

Referenceless, corrected PRFS, and PRFS MRTI resulted in temperature measurements of 0.8 ± 1.1 °C, 1.1 ± 1.3 °C and 5.2 ± 5 °C, respectively. Both materials caused B0 perturbation but minimal B1+ and MRTI artifacts. The presence of imaging artifacts did not preclude thermal imaging of the region.

SIGNIFICANCE

We provide preliminary data suggesting that referenceless MRTI can adequately detect small thermal changes at the DRG that may occur with neuromodulation, which is one of the first steps in creating a table of safe parameters for liFUS therapy in humans.

Numerical Simulation and Experimental Studies of a Ribbon Coil for Trans Spinal Magnetic Stimulation (TSMS) in Rats. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2023;2023:1-4. [PMID: 38082681 DOI: 10.1109/embc40787.2023.10340213] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

We propose a non-invasive Trans Spinal Magnetic Stimulation (TSMS) coil allowing for focal stimulation. The device is based on a new figure-8 ribbon design, ensuring low R0, and low heating. The two coils were designed and studied using the finite element method (FEM) coupled with NEURON and tested for efficacy on rats. The numerical simulations confirmed the generation of the observed action potentials when the coil was driven with 2.8kA.Clinical Relevance- Chronic neuropathic back and leg pain is one of the main indications for spinal cord stimulation in the United States. Chronic low back pain is one of the most common reasons patients seek medical care, and in 2013 resulted in 87.6 billion dollars in healthcare costs in the USA. Patients would most likely prefer a low-risk, non-invasive procedure, such as TSMS, to surgery with a significant rate of complications.

Interventional Pain Management in the Treatment of Chronic Pelvic Pain

PURPOSE OF REVIEW

Chronic pelvic pain syndrome (CPPS) is a common yet complex disease in the field of urology, gynecology, and pain management. This review article summarizes the anatomy and physiology of CPP with an in-depth discussion of established and emerging interventional treatment options.

RECENT FINDINGS

Though psychosocial variables play a significant role in the development and propagation of CPPS, interventional treatment strategies are available to ameliorate symptoms. Sympathetic and peripheral nerve blocks along with chemical and radiofrequency denervation are conventional, evidence-based treatments. Recent advances in spinal cord stimulation and dorsal root ganglion stimulation offer novel and effective therapeutic options to treat CPPS. A biopsychosocial model should be employed for effective management of CPPS with advances in neuromodulation offering newfound hope in alleviating symptoms and restoring function.

Dorsal Root Ganglion Stimulation Therapy for Refractory Idiopathic Pudendal Neuralgia

Dorsal root ganglion stimulation is a relatively new treatment option for chronic pain conditions such as pudendal neuralgia, which is a chronic pain condition affecting the pudendal nerve in the pelvic region. Pudendal neuralgia is a debilitating condition that can significantly affect the patient's quality of life. In dorsal root ganglion stimulation, a small device is implanted that delivers electrical impulses to the dorsal root ganglion to modulate pain signals coming from the pudendal nerve. The procedure is considered investigational and has been investigated in case series and case reports with promising results. However, more research is needed to fully understand its safety and effectiveness. This case report highlights the potential of dorsal root ganglion stimulation as a treatment option for pudendal neuralgia and the need for further research to establish it as a standard treatment option.

Pain specialist management of sexual pain: III-neuromodulation

INTRODUCTION

Some women with sexual pain do not respond to conservative multi-modal care modalities. Neuromodulation is a group of methods which alter nerve activity by delivering electrical energy or pharmaceutical agents directly to target neural structures. Multiple forms of neuromodulation may provide durable treatment options to fill the unmet therapeutic need of a certain population of women with chronic sexual pain.

OBJECTIVES

To provide a current review of neuromodulation treatments used for female sexual pain and introduce neuromodulation techniques which may be applied in novel ways to specific sexual pain phenotypes.

METHODS

Internet, PubMed and Cochrane Library were searched for relevant articles on female sexual pain within the clinical purview and scope of practice of pain management.

RESULTS

A thorough review of the literature was conducted to include basic science studies, clinical trials, systematic reviews, consensus statements, and case-reports. A sampling of information on real-world patient outcomes was included. The amount and quality of evidence for neuromodulation to treat female sexual pain is low-moderate. Descriptions of neuromodulation procedures for sexual pain were made and clinical studies reviewed. The effects of autonomic nervous system (ANS) dysregulation on the experience of pain were discussed with consideration of interventional procedures to facilitate restoration of ANS equilibrium.

CONCLUSION

Treating female sexual pain is complex. There are considerable numbers of women who have unsatisfactory sexual pain relief despite evidence-based interdisciplinary care. These women may benefit from referral to consider neuromodulation treatment options. Neuromodulation is a relatively new capability in the arsenal of pain management and other specialists that can be considered for women with treatment refractory sexual pain.

Best Practices for Dorsal Root Ganglion Stimulation for Chronic Pain: Guidelines from the American Society of Pain and Neuroscience

With continued innovations in neuromodulation comes the need for evolving reviews of best practices. Dorsal root ganglion stimulation (DRG-S) has significantly improved the treatment of complex regional pain syndrome (CRPS), and it has broad applicability across a wide range of other conditions. Through funding and organizational leadership by the American Society for Pain and Neuroscience (ASPN), this best practices consensus document has been developed for the selection, implantation, and use of DRG stimulation for the treatment of chronic pain syndromes. This document is composed of a comprehensive narrative literature review that has been performed regarding the role of the DRG in chronic pain and the clinical evidence for DRG-S as a treatment for multiple pain etiologies. Best practice recommendations encompass safety management, implantation techniques, and mitigation of the potential complications reported in the literature. Looking to the future of neuromodulation, DRG-S holds promise as a robust intervention for otherwise intractable pain.

Diagnosis and treatment of pudendal and inferior cluneal nerve entrapment syndrome: a narrative review

AIM

Pudendal and inferior cluneal nerve entrapment can cause a neuropathic pain syndrome in the sensitive areas innervated by these nerves. Diagnosis is challenging and patients often suffer several years before diagnosis is made. The purpose of the review was to inform healthcare workers about this disease and to provide a basis of anatomy and physiopathology, to inform about diagnostic tools and invasive or non-invasive treatment modalities and outcome.

METHODS

A description of pudendal and inferior cluneal nerve anatomy is given. Physiopathology for entrapment is explained. Diagnostic criteria are described, and all non-invasive and invasive treatment options are discussed.

RESULTS

The Nantes criteria offer a solid basis for diagnosing this rare condition. Treatment should be offered in a pluri-disciplinary setting and consists of avoidance of painful stimuli, physiotherapy, psychotherapy, pharmacological treatment led by tricyclic antidepressants and anticonvulsants. Nerve blocks are efficient at short term and serve mainly as a diagnostic tool. Pulsed radiofrequency (PRF) is described as a successful treatment option for pudendal neuralgia in patients non-responding to non-invasive treatment. If all other treatments fail, surgery can be offered. Different surgical procedures exist but only the open transgluteal approach has proven its efficacy compared to medical treatment. The minimal-invasive ENTRAMI technique offers the possibility to combine nerve release with pudendal neuromodulation.

CONCLUSIONS

Pudendal and inferior cluneal nerve entrapment syndrome are a challenge not only for diagnosis but also for treatment. Different non-invasive and invasive treatment options exist and should be offered in a pluri-disciplinary setting.

What's out There? A Systematic Review of the Efficacy and Availability of Targeted Treatments for Central Sensitisation in Women with Endometriosis

OBJECTIVES

Central sensitisation contributes to patient variability when treating pain in endometriosis. Targeting this process may alleviate hyperalgesia and allodynia in women refractory to current treatments. Thus far, there has been no review of targeted treatments for central sensitisation in women with endometriosis. Therefore, this review aims to identify and summarise the findings of studies regarding the availability and efficacy of targeted treatments for central sensitisation in women with endometriosis.

METHODS

A systematic review was conducted searching MEDLINE, Embase and CINAHL. Inclusion criteria: primary research articles, women with endometriosis and central sensitisation features, and description of treatments for central sensitisation, or its effects on hyperalgesia and allodynia. Exclusion criteria: review articles, letters to the editor, commentaries, editorials, protocols, or women with endometriosis infiltrating nerves. Risk of bias analysis was conducted. Data was reviewed and summarised by treatment method.

RESULTS

Eight studies met inclusion criteria, demonstrating limited research in this area. Four treatment options were addressed: surgical approaches, nerve stimulation approaches, injection-based therapies, and hormonal therapies. Surgery and nerve stimulation appear the most promising treatments for central sensitisation. Injections have limited and mixed evidence of efficacy. Limited evidence suggests hormonal therapies may be ineffective.

DISCUSSION

Given the lack of evidence for any treatment, all require further research to determine treatment efficacy before options will be available clinically. There is a clear need for consistency in defining and identifying central sensitisation in study populations. This review identifies areas of interest, particularly surgery and nerve stimulation, from which future research must stem.

Interventional Treatment Modalities for Chronic Abdominal and Pelvic Visceral Pain

PURPOSE OF REVIEW

Chronic abdominal and pelvic visceral pain is an oftentimes difficult to treat pain condition that requires a multidisciplinary approach. This article specifically reviews the interventional treatment options for pain resulting from visceral abdominal and pelvic pain.

RECENT FINDINGS

Sympathetic nerve blocks are the main interventional option for the treatment of chronic abdominal and pelvic visceral pain. Initially, nerve blocks are performed, and subsequently, neurolytic injections (alcohol or phenol) are longer term options. This review describes different techniques for sympathetic blockade. Neuromodulation is a potential option via dorsal column stimulation or dorsal root ganglion stimulation. Finally, intrathecal drug delivery is sometimes appropriate for refractory cases. This paper will review interventional options for the treatment of chronic abdominal and pelvic visceral pain.

Progress in the efficacy and mechanism of spinal cord stimulation in neuropathological pain

Neuropathic pain (NP) is a long-term recurrent disease caused by somatosensory nervous system injury, with spontaneous pain, hyperalgesia, ectopic pain, and paresthesia as the main clinical manifestations. It adversely affects patients' quality of life. NP treatments often include medication, physical therapy, and invasive therapy; the first two therapies are generally ineffective for some NP patients. These patients sometimes rely on invasive therapy to alleviate pain. Spinal cord stimulation (SCS) is a very effective therapeutic method. SCS is a neuroregulatory method that involves placing the electrodes on the corresponding painful spinal cords. Pain is greatly alleviated after SCS. SCS has been proven to be an effective therapeutic method for the treatment of neurological pain. Furthermore, SCS provides a feasible approach for patients with unsuccessful drug treatment. This paper reviews the relevant literature of spinal cord electrical stimulation, focusing on the mechanism of action, clinical application, clinical efficacy and technical progress of spinal cord electrical stimulation. SCS is widely used in the treatment of NP diseases such as postherpetic neuralgia, back surgery failure syndrome, and phantom limb pain. With advancements in science and technology, tremendous progress has also been made in the spinal cord electrical stimulation method and good momentum has been maintained.

Current Challenges in the Management of Chronic Pelvic Pain in Women: From Bench to Bedside

Chronic pelvic pain (CPP) affects a significant proportion of women worldwide And has a negative impact on several aspects of these women’s lives including mental health, work, relationships and sexual function, among others. This set of factors ultimately reflects negatively on quality Of life. The physiopathology of CPP is complex and remains to be fully clarified; however, recent advances have increased understanding of the mechanisms involved in chronic pain in general, and more specifically, CPP. Nonetheless, even when a detailed clinical history is obtained, meticulous physical examination is performed and imaging resources are appropriately used, the organic cause of the pain may still fail to be identified in a substantial number of women with CPP. Management of CPP may therefore be challenging. This narrative review was aimed at adding to the available literature on the subject, presenting and discussing the principal characteristics of CPP in women. The paper highlights gaps in the literature while providing the most up-to-date evidence associated with the physiopathology and classification of pain, its diagnosis and treatment. In addition, current challenges in the management of women with CPP are discussed.

Current role of neuromodulation in bladder pain syndrome/interstitial cystitis

Neuromodulation is recommended by major international guidelines as a fourth-line treatment in bladder pain syndrome/interstitial cystitis (BPS/IC) patients after failure of behavioural, oral and intravesical pharmacological treatments, including hydrodistension. A non-systematic review of studies identified by electronic search of MEDLINE was performed with no time limitation. A narrative synthesis of the existing evidence regarding the results of sacral, tibial and pudendal nerve stimulation in the management of BPS/IC was developed. Neuromodulation in pelvic chronic pain disorders, including BPS/IC, is a useful tool for refractory patients to conventional treatments. Sacral neuromodulation may be effective in patients with BPS without Hunner's lesions, and the effect seems to be maintained in the mid- and long-term. Posterior tibial nerve stimulation can be offered to patients with BPS/IC in the context of a multidisciplinary approach. When pudendal neuralgia is suspected, selective pudendal nerve stimulation has a high response rate. The aetiology of the pain can influence the outcomes in the mid- and long-term of the different neuromodulation approaches, thus careful diagnosis is recommended.

Recommendations for anesthetic management for intraoperative neuromodulation cases

This paper performs a review of current literature as well as uses our single-center experience to discuss pre-operative, intra-operative and, briefly, postoperative management for dorsal column stimulators (DCSs), dorsal root ganglion (DRG) stimulators, peripheral nerve stimulators (PNSs) and intrathecal pumps. Generally, pre-operative antibiotics are recommended with discontinuation within 24 h postoperatively. For dorsal column and DRG stimulation, monitored anesthesia care or general anesthesia with intra-operative neuromonitoring is recommended; for peripheral nerve stimulation and intrathecal pump implementation, monitored anesthesia care is preferred. There is little information on appropriate anesthetic management during these forms of neuromodulation. More research is necessary to articulate specific pre-operative, intra-operative and postoperative management guidelines and recommendations for dorsal column stimulator, DRG stimulation, PNS and intrathecal pump implantation.

A narrative review and future considerations of spinal cord stimulation, dorsal root ganglion stimulation and peripheral nerve stimulation

PURPOSE OF REVIEW

In recent years, neuromodulation has experienced a renaissance. Novel waveforms and anatomic targets show potential improvements in therapy that may signify substantial benefits. New innovations in peripheral nerve stimulation and dorsal root ganglion stimulation have shown prospective evidence and sustainability of results. Sub-perception physiologic bursting, high-frequency stimulation and feedback loop mechanisms provide significant benefits over traditional tonic spinal cords stimulation (SCS) in peer reviewed investigations. We reviewed the themes associated with novel technology in the context of historical stalwart publications.

RECENT FINDINGS

New innovations have led to better nerve targeting, improvements in disease-based treatment, and opioid alternatives for those in chronic pain. In addition, new neural targets from both structural and cellular perspectives have changed the field of Neurostimulation.

SUMMARY

For many years, tonic SCS was representative of neuromodulation, but as this review examines, the progression of the field in the past decade has reshaped patient options.

Advances in the therapeutic approach of pudendal neuralgia: a systematic review

CONTEXT

Although pudendal neuralgia (PN) has received growing interest over the last few years, diagnosis remains difficult, and many different therapeutic approaches can be considered.

OBJECTIVES

This article aims to provide an overview of the possible treatments of PN and investigate their efficacies.

METHODS

Utilizing PubMed and ScienceDirect databases, a systematic review was carried out and allowed identification of studies involving patients with PN, as defined by Nantes criteria, and their associated treatments. Relevant data were manually reported.

RESULTS

Twenty-eight articles were selected, totaling 1,013 patients (mean age, 49 years) and six different types of interventions. Clinical outcomes, most frequently quantified utilizing the Visual Analog Scale (VAS), vary greatly with both the therapy and time after intervention (from 100 to <10%). However, neither peri nor postoperative serious complications (grade > II of Clavien-Dindo classification) are reported. Although surgery seems to provide a higher proportion of long-term benefits, identifying the most efficient therapeutic approach is made impossible by the multitude of outcome measurements and follow-up frequencies. It should also be noted that literature is sparse regarding randomized controlled trials with long-term follow-up.

CONCLUSIONS

Although there are a number of modalities utilized for the treatment of PN, there are no current recommendations based on treatment efficacies. This seems to be largely in part caused by the lack of standardization in outcome quantification. Future research in this field should focus on prospective cohort studies with high levels of evidence, aimed at assessing the long-term, if not permanent, benefits of available therapies.

Stimulation of the dorsal root ganglion using an Injectrode®

Objective. The goal of this work was to compare afferent fiber recruitment by dorsal root ganglion (DRG) stimulation using an injectable polymer electrode (Injectrode^®) and a more traditional cylindrical metal electrode.Approach. We exposed the L6 and L7 DRG in four cats via a partial laminectomy or burr hole. We stimulated the DRG using an Injectrode or a stainless steel (SS) electrode using biphasic pulses at three different pulse widths (80, 150, 300μs) and pulse amplitudes spanning the range used for clinical DRG stimulation. We recorded antidromic evoked compound action potentials (ECAPs) in the sciatic, tibial, and common peroneal nerves using nerve cuffs. We calculated the conduction velocity of the ECAPs and determined the charge-thresholds and recruitment rates for ECAPs from Aα, Aβ, and Aδfibers. We also performed electrochemical impedance spectroscopy measurements for both electrode types.Main results. The ECAP thresholds for the Injectrode did not differ from the SS electrode across all primary afferents (Aα, Aβ, Aδ) and pulse widths; charge-thresholds increased with wider pulse widths. Thresholds for generating ECAPs from Aβfibers were 100.0 ± 32.3 nC using the SS electrode, and 90.9 ± 42.9 nC using the Injectrode. The ECAP thresholds from the Injectrode were consistent over several hours of stimulation. The rate of recruitment was similar between the Injectrodes and SS electrode and decreased with wider pulse widths.Significance. The Injectrode can effectively excite primary afferents when used for DRG stimulation within the range of parameters used for clinical DRG stimulation. The Injectrode can be implanted through minimally invasive techniques while achieving similar neural activation to conventional electrodes, making it an excellent candidate for future DRG stimulation and neuroprosthetic applications.

Dorsal Root Ganglion Stimulation Lead Fracture Within the Superficial Fascial Layers in 4 Cases

We present 4 cases of dorsal root ganglion stimulation lead fracture. In these cases, the surgical technique involved (1) traversing fascial layers for placement of leads via a Tuohy needle in the upper low back, (2) subcutaneous tunneling from the implantable pulse generator site to the lead puncture site without dissecting below the superficial fascial plane at the puncture site, and (3) connection of the lead/extension with the generator. All fractures occurred adjacent to the original lead puncture site. These cases suggest lead entrapment within the membranous fascial plane, with tension on a thin lead, is a mechanism underlying lead fracture.

The American Society of Pain and Neuroscience (ASPN) Best Practices and Guidelines for the Interventional Management of Cancer-Associated Pain

Moderate to severe pain occurs in many cancer patients during their clinical course and may stem from the primary pathology, metastasis, or as treatment side effects. Uncontrolled pain using conservative medical therapy can often lead to patient distress, loss of productivity, shorter life expectancy, longer hospital stays, and increase in healthcare utilization. Various publications shed light on strategies for conservative medical management for cancer pain and a few international publications have reviewed limited interventional data. Our multi-institutional working group was assembled to review and highlight the body of evidence that exists for opioid utilization for cancer pain, adjunct medication such as ketamine and methadone and interventional therapies. We discuss neurolysis via injections, neuromodulation including targeted drug delivery and spinal cord stimulation, vertebral tumor ablation and augmentation, radiotherapy and surgical techniques. In the United States, there is a significant variance in the interventional treatment of cancer pain based on fellowship training. As a first of its kind, this best practices and interventional guideline will offer evidenced-based recommendations for reducing pain and suffering associated with malignancy.

Infectious Complications of Dorsal Root Ganglion Stimulation: A Systematic Review and Pooled Analysis of Incidence

BACKGROUND AND OBJECTIVES

Dorsal root ganglion stimulation (DRGS) is a newer form of neuromodulation that targets the dorsal root ganglion. DRGS has superior efficacy in complex regional pain syndrome compared to spinal cord stimulation (SCS) and may have efficacy in other forms of chronic pain. While decades of safety data are available for SCS, there is less available safety information for DRGS. The objectives of this systematic review and pooled analysis of incidence are to determine the overall incidence of DRGS infections, incidence at each stage (trial vs. implant vs. revision), infection characteristics, and outcomes.

MATERIALS AND METHODS

A comprehensive search of databases from January 1980 to January 2021 was conducted.

RESULTS

Ten studies met inclusion criteria. Eight studies reported patients with trial data (n = 291), ten studies reported patients with implant data (n = 250), and seven studies reported data with revisions (n = 26). The pooled incidence of trial infections was 1.03% (95% CI 0.35-2.99%), implant infections was 4.80% (95% CI 2.77-8.20%), revision infections was 3.85% (95% CI 0.20-21.59%), and overall infections was 2.82% (95% CI 1.62-4.54%). There was a statistically significant difference in infection rates between the trial, implant, and revision stages, X² (2, N = 567) = 8.9839, p = 0.01.

CONCLUSIONS

This is the first systematic review and pooled analysis that followed PRISMA guidelines to report infectious complications of DRGS by stage (trial vs. implant vs. revision). DRGS trial appears to be low risk for infection but that risk is significantly increased with DRGS implant. Our findings highlight the need for further study of infectious complications, their risks, and optimal prophylaxis.

The Effectiveness of Dorsal Root Ganglion Neurostimulation for the Treatment of Chronic Pelvic Pain and Chronic Neuropathic Pain of the Lower Extremity: A Comprehensive Review of the Published Data

OBJECTIVE

To evaluate the effectiveness of dorsal root ganglion neurostimulation for the treatment of refractory, focal pain in the pelvis and lower extremities.

DESIGN

Systematic review.

OUTCOME MEASURES

The primary outcome was ≥50% pain relief. Secondary outcomes were physical function, mood, quality of life, opioid usage, and complications.

RESULTS

One pragmatic randomized controlled trial, four prospective cohort studies, and eight case series met the inclusion criteria. A worst-case scenario analysis from the randomized controlled trial reported ≥50% pain relief in 74% of patients with dorsal root ganglion neurostimulation vs. 51% of patients who experienced at least 50% relief with spinal cord stimulation at 3 months. Cohort data success rates ranged from 43% to 83% at ≤6 months and 27% to 100% at >6 months. Significant improvements were also reported in the secondary outcomes assessed, including mood, quality of life, opioid usage, and health care utilization, though a lack of available quantitative data limits further statistical analysis. Complication rates vary, though the only randomized controlled trial reported a higher rate of adverse events than that seen with traditional neurostimulation.

CONCLUSIONS

In accordance with the Grades of Recommendation, Assessment, Development, and Evaluation system, low-quality evidence supports dorsal root ganglion neurostimulation as a more effective treatment than traditional neurostimulation for pain and dysfunction associated with complex regional pain syndrome or causalgia. Very low-quality evidence supports dorsal root ganglion neurostimulation for the treatment of chronic pelvic pain, chronic neuropathic groin pain, phantom limb pain, chronic neuropathic pain of the trunk and/or limbs, and diabetic neuropathy.

Dorsal Root Ganglion Stimulation for Treatment of Chemotherapy-Induced Neuropathy

ABSTRACT

Chemotherapy-induced neuropathy has limited treatment options, and conventional medications used to treat neuropathic pain often do not provide adequate pain relief for patients with a history of cancer. Neuromodulation such as dorsal root ganglion stimulation remains a treatment that has been studied for chronic painful conditions such as low back pain, pelvic pain, complex regional pain syndrome, and phantom limb pain. Dorsal root ganglion stimulation has been presented for treatment of chemotherapy-induced neuropathy, but with limited duration of follow-up. We present a case of pain resolution after placement of a dorsal root ganglion stimulation for persistent chemotherapy-induced neuropathy. Our patient developed burning pain and allodynia in both feet 3 mos into her chemotherapy regimen, with worsened symptoms after cessation of chemotherapy. After failure of conservative pharmacotherapies, a 7-day dorsal root ganglion stimulation trial was implanted, resulting in 100% pain relief. A dorsal root ganglion stimulation was then implanted permanently, and our patient reported continued resolution of symptoms at evaluation 3 yrs after placement. To the author's knowledge, this is the first case of sustained relief with dorsal root ganglion stimulation placement for chemotherapy-induced neuropathy and presents a treatment option that warrants further investigation.

Dorsal Root Ganglion (DRG) and Chronic Pain

Context

Chronic neuropathic pain is a common condition, and up to 11.9% of the population have been reported to suffer from uncontrolled neuropathic pain. Chronic pain leads to significant morbidity, lowered quality of life, and loss of workdays, and thus carries a significant price tag in healthcare costs and lost productivity. dorsal root ganglia (DRG) stimulation has been recently increasingly reported and shows promising results in the alleviation of chronic pain. This paper reviews the background of DRG stimulation, anatomical, and clinical consideration and reviews the clinical evidence to support its use.

Evidence Acquisition

The DRG span the length of the spinal cord and house the neurons responsible for sensation from the periphery. They may become irritated by direct compression or local inflammation. Glial cells in the DRG respond to nerve injury, producing inflammatory markers and contribute to the development of chronic pain, even after the resolution of the original insult. While the underlying mechanism is still being explored, recent studies explored the efficacy of DRG stimulation and neuromodulation for chronic pain treatment.

Results

Several reported cases and a small number of randomized trials were published in recent years, describing different methods of DRG stimulation and neuromodulation with promising results. Though evidence quality is mostly low, these results provide evidence to support the utilization of this technique.

Conclusions

Chronic neuropathic pain is a common condition and carries significant morbidity and impact on the quality of life. Recent evidence supports the use of DRG neuromodulation as an effective technique to control chronic pain. Though studies are still emerging, the evidence appears to support this technique. Further studies, including large randomized trials evaluating DRG modulation versus other interventional and non-interventional techniques, are needed to further elucidate the efficacy of this method. These studies are also likely to inform the patient selection and the course of treatment.

Interventional treatment options for women with pelvic pain

Purpose of review

I.To provide an overview of current interventional treatment options for women with chronic pelvic pain (CPP).

Recent findings

II.Accessibility of CT imaging, ultrasound, and fluoroscopy have assisted the development of novel interventional techniques. Similarly, neuromodulation techniques have improved with the development of novel stimulation patterns and device implants.

Summary

III.Numerous small-scale studies report high success rates with injection intervention therapies in CPP but there are limited well designed large-scale studies that demonstrate superiority of treatment. Female pelvic pain is difficult to diagnose due to the multifactorial etiology and the variable presentation causing delay in accurate diagnosis and lack of response to conventional medical and initial interventional therapies. Despite the shortfalls of current studies, collectively our understanding of chronic pain conditions and helpful injection interventions are improving. Undoubtedly the breadth of current research will provide a rich foundation for future large-scale well-designed studies involving multiple disciplines with more uniform methods and criteria to produce reliable and reproducible results.

Neuromodulation in Treating Pelvic Pain

PURPOSE OF REVIEW

Chronic pelvic pain (CPP) is a complex condition that can be multifactorial, disabling, and difficult to treat. It is important to understand the various diagnoses and pathways that can be involved and have an understanding of the available treatment options.

RECENT FINDINGS

There is a complex innervation of the pelvic region which makes its treatment very challenging. There are pathophysiological similarities of CPP to disease states like complex regional pain syndrome and sympathetically driven pain. CPP is poorly understood and includes psychological, psychosocial, cultural, and economic influences. Treatment options vary, but neuromodulation does remain a centerpiece and can include sacral stimulation, SCS, DRG stimulation, and PNS.

Effect of Patient Characteristics on Clinical Outcomes More Than 12 Months Following Dorsal Root Ganglion Stimulation Implantation: A Retrospective Review

INTRODUCTION

Dorsal root ganglion (DRG) stimulation is an effective treatment option for lower extremity complex regional pain syndrome and other focal pain conditions. However, the patient characteristics that may predict long-term outcomes have not been defined.

MATERIALS AND METHODS

This was a retrospective observational study that included 93 patients who were implanted with a DRG stimulator at a single private practice institution. A variety of demographic data was collected. Follow-up results were reviewed from multiple time points more than 12 months. Patients were classified as either "responder" or "nonresponder" status using two different thresholds, "greater than or equal to 50% pain relief" and "greater than or equal to 80% pain relief."

RESULTS

A history of prior chronic opioid use was associated with significantly lower rates of responder status based on both a 50% pain relief threshold and 80% pain relief threshold at the one week to one month, three months, and 12-months visits.

CONCLUSIONS

This single-center retrospective study found patients prescribed chronic opioids at the time of DRG stimulator implantation had a higher likelihood of less than 50% pain relief and 80% pain relief at one month, three months, and 12 months follow-up visits.

Dorsal Root Ganglion Stimulation for the Treatment of Non-Complex Regional Pain Syndrome Related Chronic Pain Syndromes: A Systematic Review

BACKGROUND

While the majority of indications and approvals for dorsal root ganglion stimulation (DRGS) are for the refractory management of complex regional pain syndrome (CRPS), emerging evidence has suggested that DRGS may be favorably used for a plethora of other chronic pain phenomena. Consequently, we aimed to characterize the use and efficacy of DRGS for these non-CRPS-related chronic pain syndromes.

MATERIALS AND METHODS

A systematic review of clinical studies demonstrating the use of DRGS for non-CRPS-related chronic pain syndromes. The literature search was performed using PubMed, Cochrane Library, and CINAHL plus across August and September 2020.

RESULTS

A total of 28 reports comprising 354 total patients were included in the analysis. Of the chronic pain syndromes presented, axial low back pain, chronic pelvic and groin pain, other peripheral neuropathies, and studies with multiple concomitant pain syndromes, a majority demonstrated >50% mean pain reduction at the time of last follow-up following DRGS. Physical function, quality of life (QOL), and lesser pain medication usage also were repeatedly reported to be significantly improved.

CONCLUSIONS

DRGS continues to lack supportive evidence from well designed, high level studies and recommendations from consensus committee experts. However, we present repeated and consistent evidence from lower level studies showing success with the use of DRGS for various non-CRPS chronic pain syndromes in reducing pain along with increasing function and QOL from one week to three years. Due to such low-level, high bias evidence, we strongly encourage the continuation of high-level studies in order to provide a stronger foundation for the use of DRGS in non-CRPS chronic pain patients. However, it may be reasonable and appropriate to evaluate patients for DRGS candidacy on a case-by-case basis particularly if they manifest focal pain syndromes refractory to noninterventional measures and may not be ideal candidates for other forms of neuromodulation.

Spinal Cord Stimulation for Visceral Pain: Present Approaches and Future Strategies

INTRODUCTION

The introduction of successful neuromodulation strategies for managing chronic visceral pain lag behind what is now treatment of choice in refractory chronic back and extremity pain for many providers in the United States and Europe. Changes in public policy and monetary support to identify nonopioid treatments for chronic pain have sparked interest in alternative options. In this review, we discuss the scope of spinal cord stimulation (SCS) for visceral pain, its limitations, and the potential role for new intradural devices of the type that we are developing in our laboratories, which may be able to overcome existing challenges.

METHODS

A review of the available literature relevant to this topic was performed, with particular focus on the pertinent neuroanatomy and uses of spinal cord stimulation systems in the treatment of malignant and nonmalignant gastrointestinal, genitourinary, and chronic pelvic pain.

RESULTS

To date, there have been multiple off-label reports testing SCS for refractory gastrointestinal and genitourinary conditions. Though some findings have been favorable for these organs and systems, there is insufficient evidence to make this practice routine. The unique configuration and layout of the pelvic pain pathways may not be ideally treated using traditional SCS implantation techniques, and intradural stimulation may be a viable alternative.

CONCLUSIONS

Despite the prevalence of visceral pain, the application of neuromodulation therapies, a standard approach for other painful conditions, has received far too little attention, despite promising outcomes from uncontrolled trials. Detailed descriptions of visceral pain pathways may offer several clues that could be used to implement devices tailored to this unique anatomy.

Peripheral Nerve Stimulation for Pudendal Neuralgia: A Technical Note

Background

Pudendal neuropathy is a chronic, disabling form of perineal pain that involves the pudendal nerve, a mixed somatic and autonomic nerve that originates from sacral nerve roots. Peripheral nerve stimulation of the pudendal nerve can be useful to decrease symptom burden in patients who have failed initial conservative treatment modalities.

Methods

In this manuscript, we describe an approach to the placement of a peripheral nerve stimulator for the treatment of pudendal neuralgia. We present a case of complex pelvic neuropathy and review the factors that lead to successful placement. Technical aspects of stimulator placement and ultrasound landmarks are reviewed.

Results

A lateral to medial approach with ultrasound guidance at the level of the ischial spine is likely to facilitate proper lead placement along the course of the pudendal nerve. Aftercare and adherence to postimplant activity restrictions–particularly avoiding use of the extremes of hip flexion and extension for four weeks—lead to the absence of lead migration.

Conclusions

Pudendal nerve stimulation is an emerging technique for neuromodulation of refractory pudendal neuralgia. Ultrasound-guided pudendal nerve stimulation is a viable technique for neuromodulation of pudendal neuralgia. Optimization of patient selection, ultrasound guidance, and proper adherence to postimplant activity restrictions may be helpful for long-term therapeutic success.

Proclaim™ DRG Neurostimulator System for the management of chronic, intractable pain

Chronic pain is consistently listed as one of the most costly and disabling health problems worldwide. In an effort to treat these suffering individuals, significant amounts of time and energy have been devoted to discover safe and effective pain relieving treatments. Dorsal root ganglion stimulation is the newest treatment modality to be created for chronic intractable pain. In this manuscript, we review the history and development, published research and safety profile of the Proclaim™ DRG Neurostimulator System (Abbott, TX, USA). At last, we offer our outlook on future developments with dorsal root ganglion stimulation.

Complications and Effects of Dorsal Root Ganglion Stimulation in the Treatment of Chronic Neuropathic Pain: A Nationwide Cohort Study in Denmark

OBJECTIVES

Dorsal root ganglion (DRG) stimulation is a novel treatment of chronic neuropathic pain and has been shown to be efficacious across several case reports and randomized trials. However, long-term follow-up is limited, as are reports of complication rates. This study presents efficacy and complications for patients treated with DRG stimulation.

MATERIALS AND METHODS

We performed an observational, multicenter cohort study of all patients in Denmark implanted with FDA-approved DRG stimulation systems to treat chronic, neuropathic pain between 2014 and 2018. Follow-up period was one to three years.

RESULTS

Forty-three patients underwent trial DRG stimulation; 33 were subsequently fully implanted. Pain location: 58% lower extremity; 21% upper extremity; 21% thoracic/abdominal. At the end of the observation period, 58% of fully implanted patients were still implanted; 42% had fully functional systems. In these patients, average Numerical Rating Scale (NRS)-score of pain was reduced from 6.8 to 3.5 (p = 0.00049) and worst NRS-score was reduced from 8.6 to 6.0 (p = 0.0039) at 12 months follow-up. Pain Catastrophizing Score was reduced from 32 to 15 (p = 0.0039). Thirteen patients experienced complications related to defect leads (39% of implanted systems). In four patients (12%), lead removal left fragments in the root canal due to lead fracture, and three patients suffered permanent nerve damage during attempts to replace broken leads.

CONCLUSIONS

This study suggests a significant, clinically relevant effect of DRG stimulation on neuropathic pain, but also demonstrates substantial problems with maintenance and revision of currently available systems. Consequently, treatment with equipment marketed specifically for DRG stimulation is currently paused in Denmark.

Neuromodulation of the Dorsal Root Ganglion for Chronic Postsurgical Pain

Objective

The objective of this study is to review the available evidence for dorsal root ganglion (DRG) stimulation for the treatment of complex regional pain syndrome type II (CRPS II; peripheral causalgia) associated with chronic neuropathic postsurgical pain (NPP).

Design

Available literature was identified through a search of the US National Library of Medicine’s Medline database, PubMed.gov. References from published articles also were reviewed for relevant citations.

Results

The data published to date support the use of DRG stimulation to treat chronic NPP of the groin, knee, and foot. NPP following procedures such as thoracotomy, hernia surgery, and knee replacement surgery were identified as some of the conditions for which DRG stimulation is likely to be effective.

Conclusion

DRG stimulation is known to be an effective treatment for focal neuropathic pain. Currently, NPP of the foot, groin, and knee all appear to be the conditions with the most clinical experience, backed by a limited but growing body of evidence. However, prospective studies lag behind real-world clinical experience and are needed to confirm these findings.

Effectiveness and Safety of Dorsal Root Ganglion Stimulation for the Treatment of Chronic Pain: A Pooled Analysis

INTRODUCTION

Since it became available in the mid-2010s, dorsal root ganglion (DRG) stimulation has become part of the armamentarium to treat chronic pain. To date, one randomized controlled trial, and several studies of moderate sample size and various etiologies have been published on this topic. We conducted a pooled analysis to investigate the generalizability of individual studies and to identify differences in outcome between chronic pain etiologic subgroups and/or pain location.

MATERIALS AND METHODS

One prospective, randomized comparative trial and six prospective, single-arm, observational studies were identified that met pre-defined acceptance criteria. Pain scores and patient-reported outcome (PRO) measures were weighted by study sample sizes and pooled. Safety data are reported in aggregate form.

RESULTS

Our analysis included 217 patients with a permanent implant at 12-month follow-up. Analysis of pooled data showed an overall weighted mean pain score of 3.4, with 63% of patients reporting ≥50% pain relief. Effectiveness sub-analyses in CRPS-I, causalgia, and back pain resulted in a mean reduction in pain intensity of 4.9, 4.6, and 3.9 points, respectively. Our pooled analysis showed a pain score for primary affected region ranging from 1.7 (groin) to 3.0 (buttocks) and responder rates of 80% for foot and groin, 75% for leg, and 70% for back. A substantial improvement in all PROs was observed at 12 months. The most commonly reported procedural or device complications were pain at the IPG pocket site, lead fracture, lead migration, and infection.

CONCLUSIONS

DRG stimulation is an effective and safe therapy for various etiologies of chronic pain.

Neuromodulation with electrical field stimulation of dorsal root ganglion in various pain syndromes: a systematic review with focus on participant selection

Objective

We conducted a systematic review about patient selection, efficacy, and safety of neuromodulation with electrical field stimulation (EFS) of dorsal root ganglion (DRG) in various painful conditions. We also analyzed conclusion statements as well as conflict of interest and financing of the included studies.

Methods

All study designs were eligible for inclusion. We searched MEDLINE, CINAHL, Embase, PsycINFO, and clinical trial registries until September 7, 2018. We assessed risk of bias by using Cochrane tool for randomized controlled trials (RCTs).

Results

Among the 29 included studies, only one was RCT, majority being case series and case reports. The evidence is based on studies with small number of participants (median: 6, range 1–152) with various painful conditions. Neuromodulation with EFS of DRG was mostly performed in participants who have failed other treatment modalities. Most of the authors of the included studies reported positive, but inconclusive, evidence regarding efficacy of neuro-modulation with EFS of DRG. Meta-analysis was not possible since only one RCT was included.

Conclusion

Available evidence suggest that neuromodulation with EFS of DRG may help highly selected participants with various pain syndromes, who have failed to achieve adequate pain relief with other pharmacological and nonpharmacological interventions. However, these findings should be confirmed in high-quality RCTs with sufficient numbers of participants.

Neurostimulation for Intractable Chronic Pain

The field of neuromodulation has seen unprecedented growth over the course of the last decade with novel waveforms, hardware advancements, and novel chronic pain indications. We present here an updated review on spinal cord stimulation, dorsal root ganglion stimulation, and peripheral nerve stimulation. We focus on mechanisms of action, clinical indications, and future areas of research. We also present current drawbacks with current stimulation technology and suggest areas of future advancements. Given the current shortage of viable treatment options using a pharmacological based approach and conservative interventional therapies, neuromodulation presents an interesting area of growth and development for the interventional pain field and provides current and future practitioners a fresh outlook with regards to its place in the chronic pain treatment paradigm.