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ObjectiveTo conduct a systematic literature review of dorsal root ganglion (DRG) stimulation for pain.DesignGrade the evidence for DRG stimulation.MethodsAn international, interdisciplinary work group conducted a literature search for DRG stimulation. Abstracts were reviewed to select studies for grading. General inclusion criteria were prospective trials (randomized controlled trials and observational studies) that were not part of a larger or previously reported group. Excluded studies were retrospective, too small, or existed only as abstracts. Studies were graded using the modified Interventional Pain Management Techniques–Quality Appraisal of Reliability and Risk of Bias Assessment, the Cochrane Collaborations Risk of Bias assessment, and the US Preventative Services Task Force level-of-evidence criteria.ResultsDRG stimulation has Level II evidence (moderate) based upon one high-quality pivotal randomized controlled trial and two lower-quality studies.ConclusionsModerate-level evidence supports DRG stimulation for treating chronic focal neuropathic pain and complex regional pain syndrome.

IntroductionSince 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 MethodsOne 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.ResultsOur 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 12months. The most commonly reported procedural or device complications were pain at the IPG pocket site, lead fracture, lead migration, and infection.ConclusionsDRG stimulation is an effective and safe therapy for various etiologies of chronic pain.

ObjectivesDorsal root ganglion (DRG) stimulation is a recent neuromodulation option that has delivered safe, effective pain relief for a number of etiologies. This prospective observational study was intended to establish the effectiveness of this treatment in a typical real-world clinical context.Materials and MethodsParticipants with chronic, intractable pain of the trunk or lower limbs were recruited from multiple pain clinics in the Netherlands. Subjects were trialed and implanted with DRG stimulation systems. Pain, function, mood, and quality of life, ratings were collected through 12 months postimplant.ResultsOf the 66 subjects enrolled, failed back surgery syndrome, peripheral nerve injury, and complex regional pain syndrome formed the largest etiologies. Permanent implants were placed in 86.2% subjects (56/65). After 12 months of treatment, average pain ratings in subjects' primary area of pain decreased from 8.0 cm at baseline to 4.1 cm, and 49% of subjects had 50% reduction in pain (visual analog scale). In addition, functional capacity was increased, and mood and quality of life improved. No confirmed lead migrations were observed, and there was a low rate of infection.ConclusionsDRG stimulation significantly reduced the severity of subjects' pain and enabled participatory changes that improved quality of life through 12-months postimplant.

ObjectiveTo conduct a systematic literature review of spinal cord stimulation (SCS) for pain.DesignGrade the evidence for SCS.MethodsAn international, interdisciplinary work group conducted literature searches, reviewed abstracts, and selected studies for grading. Inclusion/exclusion criteria included randomized controlled trials (RCTs) of patients with intractable pain of greater than one year’s duration. Full studies were graded by two independent reviewers. Excluded studies were retrospective, had small numbers of subjects, or existed only as abstracts. Studies were graded using the modified Interventional Pain Management Techniques–Quality Appraisal of Reliability and Risk of Bias Assessment, the Cochrane Collaborations Risk of Bias assessment, and the US Preventative Services Task Force level-of-evidence criteria.ResultsSCS has Level 1 evidence (strong) for axial back/lumbar radiculopathy or neuralgia (five high-quality RCTs) and complex regional pain syndrome (one high-quality RCT).ConclusionsHigh-level evidence supports SCS for treating chronic pain and complex regional pain syndrome. For patients with failed back surgery syndrome, SCS was more effective than reoperation or medical management. New stimulation waveforms and frequencies may provide a greater likelihood of pain relief compared with conventional SCS for patients with axial back pain, with or without radicular pain.

BACKGROUND The dorsal root ganglion (DRG) has been identified as an important neural structure in the development and maintenance of chronic pain. We present a retrospective case series of patients with refractory painful diabetic peripheral neuropathy (PDPN) that underwent electrical stimulation of the DRG and report on changes in their overall perceived pain and complication rates. METHODS Ten diabetic males (mean age 65.2 [SD 8.8] years) with painful symptoms of the lower limbs were enrolled and trialed with up to four quadripolar percutaneous DRG stimulation leads between L2 and L5 spinal levels. Patients received a fully implantable neurostimulation system (Abbott Laboratories, Sunnyvale, CA, USA) immediately or after a successful trial period (>50% reduction in pain). Overall perceived pain was measured by visual analogue scale (VAS) at baseline, one-week postimplantation and one-, three-, six-, and twelve-month follow-up (n = 5). RESULTS Ten patients were included in this retrospective study. Seven of these subjects received permanent stimulator implants after successful externalized or intraoperative trials. Two of those patients subsequently required explantation, due to failure to capture primary pain area (n = 1) and personal reasons (n = 1). For the five subjects that proceeded to clinical follow-ups, baseline VAS was reduced by an average of 63.90% (SD 21.39; p

Introduction Chronic low back pain affects millions of people worldwide and can arise through a variety of clinical origins. In the case of Failed Back Surgery Syndrome (FBSS), previous surgical procedures can contribute to low back pain that is often unresponsive to intervention. Although spinal cord stimulation can be an effective treatment modality, it does not provide sufficient pain relief for some intractable cases. Recently, alternative neuromodulation options have been developed, including dorsal root ganglion (DRG) stimulation. The objective of this report is to further investigate these clinical observations. Methods Twelve patients with significant chronic discogenic low back pain due to FBSS were included. All subjects were implanted with DRG stimulation systems that had at least one lead placed at L2 or L3. Subjects’ pain ratings, mood, and quality of life was tracked prospectively for up to 12 months. Results More than half of subjects reported 50% or better pain relief in the low back, and the average low back pain relief was 45.5% at 12 months. Concomitant reductions in overall pain, leg pain, pain interference, mood, and quality of life were also found. Discussion For the studied population, DRG stimulation at the L2-L3 levels was effective at relieving low back pain. These reductions in pain were associated with improvements in quality of life. Thus, DRG stimulation at these levels may be effective for low back pain by recruiting both segmental and non-segmental neural pathways that are not otherwise accessible via traditional SCS. This article is protected by copyright. All rights reserved.

INTRODUCTION: The Neuromodulation Appropriateness Consensus Committee (NACC) is dedicated to improving the safety and efficacy of neuromodulation and thus improving the lives of patients undergoing neuromodulation therapies. With continued innovations in neuromodulation comes the need for evolving reviews of best practices. Dorsal root ganglion (DRG) stimulation has significantly improved the treatment of complex regional pain syndrome (CRPS), among other conditions. Through funding and organizational leadership by the International Neuromodulation Society (INS), the NACC reconvened to develop the best practices consensus document for the selection, implantation and use of DRG stimulation for the treatment of chronic pain syndromes. METHODS: The NACC performed a comprehensive literature search of articles about DRG published from 1995 through June, 2017. A total of 2538 article abstracts were then reviewed, and selected articles graded for strength of evidence based on scoring criteria established by the US Preventive Services Task Force. Graded evidence was considered along with clinical experience to create the best practices consensus and recommendations. RESULTS: The NACC achieved consensus based on peer-reviewed literature and experience to create consensus points to improve patient selection, guide surgical methods, improve post-operative care, and make recommendations for management of patients treated with DRG stimulation. CONCLUSION: The NACC recommendations are intended to improve patient care in the use of this evolving therapy for chronic pain. Clinicians who choose to follow these recommendations may improve outcomes.

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.

textabstractObjectives: One prominent side effect from neurostimulation techniques, and in particular spinal cord stimulation (SCS), is the change in intensity of stimulation when moving from an upright (vertical) to a recumbent or supine (horizontal) position and vice versa. It is well understood that the effects of gravity combined with highly conductive cerebrospinal fluid provide the mechanism by which changes in body position can alter the intensity of stimulation-induced paresthesias. While these effects are well established for leads that are placed within the more medial aspects of the spinal canal, little is known about these potential effects in leads placed in the lateral epidural space and in particular within the neural foramina near the dorsal root ganglion (DRG). Materials and Methods: We prospectively validated a newly developed paresthesia intensity rating scale and compared perceived paresthesia intensities when subjects assumed upright vs. supine bodily positions during neuromodulation of the DRG. Results: On average, the correlation coefficient between stimulation intensity (pulse amplitude) and perceived paresthesia intensity was 0.83, demonstrating a strong linear relationship. No significant differences in paresthesia intensities were reported within subjects when moving from an upright (4.5 ± 0.14) to supine position 4.5 (±0.12) (p > 0.05). This effect persisted through 12 months following implant. Conclusions: Neuromodulation of the DRG produces paresthesias that remain consistent across body positions, suggesting that this paradigm may be less susceptible to positional effects than dorsal column stimulation.

Objectives Spinal cord stimulation of the dorsal root ganglion (DRG-SCS) is a new therapy for treating chronic neuropathic pain. Previous work has demonstrated the effectiveness of DRG-SCS for pain associated with failed back surgery syndrome, complex regional pain syndrome, chronic postsurgical pain, and other etiologies through 6 months of treatment; this report describes the maintenance of pain relief, improvement in mood, and quality of life through 12 months. Materials and Methods Subjects with intractable pain in the back and/or lower limbs were implanted with an active neurostimulator device. Up to four percutaneous leads were placed epidurally near DRGs. Subjects were tracked prospectively for 12 months. Results Overall, pain was reduced by 56% at 12 months post-implantation, and 60% of subjects reported greater than 50% improvement in their pain. Pain localized to the back, legs, and feet was reduced by 42%, 62%, and 80%, respectively. Measures of quality of life and mood were also improved over the course of the study, and subjects reported high levels of satisfaction. Importantly, excellent pain–paresthesia overlap was reported, remaining stable through 12 months. Discussion Despite methodological differences in the literature, DRG-SCS appears to be comparable to traditional SCS in terms of pain relief and associated benefits in mood and quality of life. Its benefits may include the ability to achieve precise pain–paresthesia concordance, including in regions that are typically difficult to target with SCS, and to consistently maintain that coverage over time.

Introduction The International Neuromodulation Society (INS) has determined that there is a need to provide an expert consensus that defines the appropriate use of neuromodulation technologies for appropriate patients. The Neuromodulation Appropriateness Consensus Committee (NACC) was formed to give guidance to current practice and insight into future developments. Methods The INS executive board selected members of the international scientific community to analyze scientific evidence for current and future innovations and to use clinical experience to fill in any gaps in information. The NACC used PubMed and Google Scholar to obtain current evidence in the field and used clinical and research experience to give a more complete picture of the innovations in the field. Results The NACC has determined that currently approved neurostimulation techniques and technologies have expanded our ability to treat patients in a more effective and specific fashion. Despite these advances, the NACC has identified several additional promising technologies and potential applications for neurostimulation that could move this field forward and expand the applicability of neuromodulation. Conclusions The NACC concludes that the field of neurostimulation is an evolving and rapidly changing one that will lead to improved patient access, safety, and outcomes.

Introduction The International Neuromodulation Society (INS) has determined that there is a need for guidance regarding safety and risk reduction for implantable neurostimulation devices. The INS convened an international committee of experts in the field to explore the evidence and clinical experience regarding safety, risks, and steps to risk reduction to improve outcomes. Methods The Neuromodulation Appropriateness Consensus Committee (NACC) reviewed the world literature in English by searching MEDLINE, PubMed, and Google Scholar to evaluate the evidence for ways to reduce risks of neurostimulation therapies. This evidence, obtained from the relevant literature, and clinical experience obtained from the convened consensus panel were used to make final recommendations on improving safety and reducing risks. Results The NACC determined that the ability to reduce risk associated with the use of neurostimulation devices is a valuable goal and possible with best practice. The NACC has recommended several practice modifications that will lead to improved care. The NACC also sets out the minimum training standards necessary to become an implanting physician. Conclusions The NACC has identified the possibility of improving patient care and safety through practice modification. We recommend that all implanting physicians review this guidance and consider adapting their practice accordingly.

Background Complex regional pain syndrome (CRPS) is a chronic and progressive pain condition usually involving the extremities and characterized by sensorimotor, vascular, and trophic changes. Spinal cord stimulation (SCS) is an effective intervention for this condition, but is hampered by the technical challenges associated with precisely directing stimulation to distal extremities. Dorsal root ganglia (DRG) may be more effective as a physiological target for electrical modulation due to recruitment of the primary sensory neurons that innervate the painful distal anatomical regions. Methods Eleven subjects diagnosed with uni- or bilateral lower-extremity CRPS were recruited as part of a larger study involving chronic pain of heterogeneous etiologies. Quadripolar epidural leads of a newly developed neurostimulation system were placed near lumbar DRGs using conventional percutaneous techniques. The neurostimulators were trialed; 8 were successful and permanently implanted and programed to achieve optimal pain–paresthesia overlap. Results All 8 subjects experienced some degree of pain relief and subjective improvement in function, as measured by multiple metrics. One month after implantation of the neurostimulator, there was significant reduction in average self-reported pain to 62% relative to baseline values. Pain relief persisted through 12 months in most subjects. In some subjects, edema and trophic skin changes associated with CRPS were also mitigated and function improved. Neuromodulation of the DRG was able to provide excellent pain–paresthesia concordance in locations that are typically hard to target with traditional SCS, and the stimulation reduced the area of pain distributions. Conclusions Neuromodulation of the DRG appears to be a promising option for relieving chronic pain and other symptoms associated with CRPS. The capture of discrete painful areas such as the feet, combined with stable paresthesia intensities independent of body position, suggests this stimulation modality may allow more selective and consistent targeting of painful areas than traditional SCS.

Objectives This multicenter prospective trial was conducted to evaluate the clinical performance of a new neurostimulation system designed to treat chronic pain through the electrical neuromodulation of the dorsal root ganglia (DRG) neurophysiologically associated with painful regions of the limbs and/or trunk. Materials and Methods Thirty-two subjects were implanted with a novel neuromodulation device. Pain ratings during stimulation were followed up to six months and compared with baseline ratings. Subjects also completed two separate reversal periods in which stimulation was briefly stopped in order to establish the effects of the intervention. Results At all assessments, more than half of subjects reported pain relief of 50% or better. At six months postimplant, average overall pain ratings were 58% lower than baseline (p

Chronic neuropathic groin pain is a sequela of hernia surgery that occurs at unacceptably high rates, causing widespread impacts on quality of life. Although the medical community is beginning to recognize the role of surgical technique in the initiation and maintenance of postherniorrhaphy neuropathic pain, little information exists regarding pain management strategies for this condition. This review presents a summary of the pain condition state, its treatment options, and treatment recommendations. Both literature review and clinical experience were used to develop a proposed a treatment algorithm for the treatment of postherniorrhaphy pain. The development of chronic pain may be prevented via a number of perioperative measures. For pain that is already established, some surgical approaches including inguinal neurectomy can be effective, in addition to standard pharmacological treatments and local infiltrations. An unmet need may still exist with these options, however, leaving a role for neuromodulation for the treatment of intractable cases. A pain management algorithm for iterative interventions including stimulation of the dorsal root ganglion (DRG) is described. It is expected that cross-disciplinary awareness of surgeons for nonsurgical pain management options in the treatment of chronic neuropathic postherniorrhaphy pain will contribute to better clinical outcomes.

Introduction: Continuous intrathecal infusion of drugs to treat chronic pain and spasticity has become a standard part of the algorithm of care. The use of opioids has been associated with noninfectious inflammatory masses at the tip of the intrathecal catheter, which can result in neurologic complications. Methods: The Polyanalgesic Consensus Conference is a meeting of a group of well-published and experienced practitioners; the purpose of the meeting is to update the standard of care for intrathecal therapies to reflect current knowledge gleaned from literature and clinical experience. An exhaustive literature search was performed, and information from this search was provided to panel members. Analysis of the published literature was coupled with the clinical experience of panel participants to form recommendations regarding intrathecal inflammatory masses or granulomas. Results: The panel has made recommendations for the prevention, diagnosis, and management of intrathecal granulomas. Conclusion: The use of chronic infusions of intrathecal opioids is associated with the formation of inflammatory masses at the intrathecal catheter tip in a small minority of treated patients. Nonetheless, the appearance of these space-occupying lesions can lead to devastating neurologic sequelae. The prevention, early detection, and successful treatment of intraspinal granulomas are important considerations when offering intrathecal drug therapy to patients with chronic intractable pain.

Introduction: Targeted intrathecal drug infusion to treat moderate to severe chronic pain has become a standard part of treatment algorithms when more conservative options fail. This therapy is well established in the literature, has shown efficacy, and is an important tool for the treatment of both cancer and noncancer pain; however, it has become clear in recent years that intrathecal drug delivery is associated with risks for serious morbidity and mortality. Methods: The Polyanalgesic Consensus Conference is a meeting of experienced implanting physicians who strive to improve care in those receiving implantable devices. Employing data generated through an extensive literature search combined with clinical experience, this work group formulated recommendations regarding awareness, education, and mitigation of the morbidity and mortality associated with intrathecal therapy to establish best practices for targeted intrathecal drug delivery systems. Results: Best practices for improved patient care and outcomes with targeted intrathecal infusion are recommended to minimize the risk of morbidity and mortality. Areas of focus include respiratory depression, infection, granuloma, device-related complications, endocrinopathies, and human error. Specific guidance is given with each of these issues and the general use of the therapy. Conclusions: Targeted intrathecal drug delivery systems are associated with risks for morbidity and mortality that can be devastating. The panel has given guidance to treating physicians and healthcare providers to reduce the incidence of these problems and to improve outcomes when problems occur.

Dorsal root ganglion (DRG) stimulation has recently emerged as a new neuromodulation modality that stays on the intersection of the peripheral and central nervous system. With DRG location within the spinal column and with electrodes for DRG stimulation placed through the intraspinal epidural space, it may make more sense to group DRG stimulation together with more commonly used spinal cord stimulation (SCS) rather than peripheral nerve stimulation (PNS), particularly if one agrees that the stimulation delivered to DRG partly works downstream at the spinal cord level. Based on current experience, it appears that DRG stimulation of the spinal cord is as effective as SCS in relieving various neuropathic pain syndromes including pain due to failed back surgery syndrome, complex regional pain syndromes, and chronic postsurgical pain. In addition to its efficacy, DRG stimulation of the spinal cord is associated with a lower rate of migrations and lack of positional side effects that may be seen with SCS and PNS. Here we summarize the knowledge base and clinical evidence for DRG stimulation of the spinal cord, and present hypotheses of its mechanism of action.

As the cellular basis of the sensory nervous system was being mapped, the anatomy and physiology of the primary sensory neurons was quickly recognized to be important. The dorsal root ganglion (DRG) is more than a common pathway by which sensory information is transmitted from the periphery proximally to spinal and supraspinal regions. Research in the past 10 years has demonstrated the importance of the primary sensory neurons housed in the DRG with regard to the development and maintenance of chronic pain conditions. Alterations in the neurophysiology of these cells are manifested in several ways, and many of these alterations are specific to the cell soma in the DRG and not to other regions along the path of the pseudounipolar projections. Since the DRG is a potentially important target for treatment, various techniques such as local pharmacologic injections and delivery of radiofrequency energy have been utilized. These techniques provide relatively short-term pain relief. A new method for stimulating the DRG has been developed, the goal of which is to produce long-term neuromodulation of cells in the ganglion to treat chronic pain conditions. This technique uses specialized equipment and low-energy output to produce therapeutic result. Specific potential advantages to this approach are discussed.

The International Neuromodulation Society (INS) has determined that there is a need to provide an expert consensus that defines the appropriate use of neuromodulation technologies for appropriate patients. The Neuromodulation Appropriateness Consensus Committee (NACC) was formed to give guidance to current practice and insight into future developments.The INS executive board selected members of the international scientific community to analyze scientific evidence for current and future innovations and to use clinical experience to fill in any gaps in information. The NACC used PubMed and Google Scholar to obtain current evidence in the field and used clinical and research experience to give a more complete picture of the innovations in the field.The NACC has determined that currently approved neurostimulation techniques and technologies have expanded our ability to treat patients in a more effective and specific fashion. Despite these advances, the NACC has identified several additional promising technologies and potential applications for neurostimulation that could move this field forward and expand the applicability of neuromodulation.The NACC concludes that the field of neurostimulation is an evolving and rapidly changing one that will lead to improved patient access, safety, and outcomes.

The International Neuromodulation Society (INS) has determined that there is a need for guidance regarding safety and risk reduction for implantable neurostimulation devices. The INS convened an international committee of experts in the field to explore the evidence and clinical experience regarding safety, risks, and steps to risk reduction to improve outcomes.The Neuromodulation Appropriateness Consensus Committee (NACC) reviewed the world literature in English by searching MEDLINE, PubMed, and Google Scholar to evaluate the evidence for ways to reduce risks of neurostimulation therapies. This evidence, obtained from the relevant literature, and clinical experience obtained from the convened consensus panel were used to make final recommendations on improving safety and reducing risks.The NACC determined that the ability to reduce risk associated with the use of neurostimulation devices is a valuable goal and possible with best practice. The NACC has recommended several practice modifications that will lead to improved care. The NACC also sets out the minimum training standards necessary to become an implanting physician.The NACC has identified the possibility of improving patient care and safety through practice modification. We recommend that all implanting physicians review this guidance and consider adapting their practice accordingly.

Introduction: The use of intrathecal (IT) infusion of analgesic medications to treat patients with chronic refractory pain has increased since its inception in the 1980s, and the need for clinical research in IT therapy is ongoing. The Polyanalgesic Consensus Conference (PACC) panel of experts convened in 2000, 2003, and 2007 to make recommendations on the rational use of IT analgesics based on preclinical and clinical literature and clinical experiences. Methods: The PACC panel convened again in 2011 to update the standard of care for IT therapies to reflect current knowledge gleaned from literature and clinical experience. A thorough literature search was performed, and information from this search was provided to panel members. Analysis of published literature was coupled with the clinical experience of panel members to form recommendations regarding the use of IT analgesics to treat chronic pain. Results: After a review of literature published from 2007 to 2011 and discussions of clinical experience, the panel created updated algorithms for the rational use of IT medications for the treatment of neuropathic pain and nociceptive pain. Conclusions: The advent of new algorithmic tracks for neuropathic and nociceptive pain is an important step in improving patient care. The panel encourages continued research and development, including the development of new drugs, devices, and safety recommendations to improve the care of patients with chronic pain.