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Background: Up to 30% of patients with knee osteoarthritis (KOA) have evidence of sensitization, with a similar proportion experiencing severe pain during procedures. Most patients with KOA are elderly and often develop side effects from intravenous sedation. Our study investigated the effectiveness of a methoxyflurane inhaler combined with local anesthesia in reducing procedural pain from genicular nerve block compared with local anesthesia alone., Methods: 42 adults with refractory KOA were randomized into two groups. Methoxyflurane group received a self-titrated methoxyflurane inhaler with local anesthesia whereas lidocaine group received local anesthesia only. The primary outcome was pain score on a 0-10 verbal numerical rating scale (VNRS) during the procedure. Secondary outcomes included changes in VNRS and behavioral pain scale (critical care pain observational tool) during the procedure, hemodynamic changes, anxiety level, sedation score, and adverse events., Results: 42 patients with a mean age of 66±12 years participated in this study. There were no significant baseline differences. During the procedure, the methoxyflurane group experienced a significantly greater VNRS pain reduction from baseline (2 (1, 4) vs -1 (-2, 0); p<0.01) and greater VNRS reduction over time (p=0.01) compared with the lidocaine group, with a higher sedation score (p<0.01). Immediately postprocedure, anxiety levels were lower in the methoxyflurane group compared with the lidocaine group (median State-Trait Anxiety Inventory score 21 (IQR 20, 24) vs 27 (23, 29); p=0.02), but the median reduction in anxiety level was not significant (6 (1, 12) vs 5 (0, 14); p=0.61). There were no differences in behavioral pain scores, hemodynamic parameters, recovery or discharge times, and adverse effects between the two groups., Conclusion: A methoxyflurane inhaler combined with local anesthesia provided better procedural pain control than local anesthesia alone with no observable differences in adverse effects. Future studies evaluating the impact of a methoxyflurane inhaler on different types of painful procedures are warranted., Competing Interests: Competing interests: SPC is a consultant for Avanos, SPR Therapeutics, Persica, and SWORD, and has previously served as a consultant for Clearing and Scilex in the past 3 years. Currently, SPC is the editorial board member of RAPM. SS, PK, WI, NT, SL, RS, and KP have no conflicts of interest to declare., (© American Society of Regional Anesthesia & Pain Medicine 2024. Re-use permitted under CC BY-NC. No commercial re-use. Published by BMJ.)

Background: There is potential for adverse events from corticosteroid injections, including increase in blood glucose, decrease in bone mineral density and suppression of the hypothalamic-pituitary axis. Published studies note that doses lower than those commonly injected provide similar benefit., Methods: Development of the practice guideline was approved by the Board of Directors of American Society of Regional Anesthesia and Pain Medicine with several other societies agreeing to participate. The scope of guidelines was agreed on to include safety of the injection technique (landmark-guided, ultrasound or radiology-aided injections); effect of the addition of the corticosteroid on the efficacy of the injectate (local anesthetic or saline); and adverse events related to the injection. Based on preliminary discussions, it was decided to structure the topics into three separate guidelines as follows: (1) sympathetic, peripheral nerve blocks and trigger point injections; (2) joints; and (3) neuraxial, facet, sacroiliac joints and related topics (vaccine and anticoagulants). Experts were assigned topics to perform a comprehensive review of the literature and to draft statements and recommendations, which were refined and voted for consensus (≥75% agreement) using a modified Delphi process. The United States Preventive Services Task Force grading of evidence and strength of recommendation was followed., Results: This guideline deals with the use and safety of corticosteroid injections for sympathetic, peripheral nerve blocks and trigger point injections for adult chronic pain conditions. All the statements and recommendations were approved by all participants after four rounds of discussion. The Practice Guidelines Committees and Board of Directors of the participating societies also approved all the statements and recommendations. The safety of some procedures, including stellate blocks, lower extremity peripheral nerve blocks and some sites of trigger point injections, is improved by imaging guidance. The addition of non-particulate corticosteroid to the local anesthetic is beneficial in cluster headaches but not in other types of headaches. Corticosteroid may provide additional benefit in transverse abdominal plane blocks and ilioinguinal/iliohypogastric nerve blocks in postherniorrhaphy pain but there is no evidence for pudendal nerve blocks. There is minimal benefit for the use of corticosteroids in trigger point injections., Conclusions: In this practice guideline, we provided recommendations on the use of corticosteroids in sympathetic blocks, peripheral nerve blocks, and trigger point injections to assist clinicians in making informed decisions., Competing Interests: Competing interests: HTB, MD: NIH NIAMS P30AR072579. AC, MD: Research Funding: RM1NS128956-01A1; Consultant: Swing Therapeutics, Scilex Pharmaceuticals. SS, MD: Consultant: SPR Therapeutics, Allergan, Inc. DS, MD: Advisory Board, Funded research: Scilex; Speaker: AbbVie. AN, MD: Speaker: Averitas Pharmaceuticals; Research: Saol Therapeutics. AA-E, MD: Consultant: Curonix. TD, MD: Research support: Biohaven, NIH; Consultant: Guidepoint Global; Speaker honorarium: Remedy Health Media. MSE, MD: Funded research: SPR Therapeutics; Consultant: Avanos, Abbott. TH, MD: Acella: Advisory board, speaker: Acella. CH, MD: Research grant: Nevro, Inc. CP, MD: Consulting: Mainstay Medical; Royalties, UpToDate. BS, MD: Consultant: State Farm, Carelon. AS, MD: NIH R34AR080279. MM, MD: Consultant: Juris Medicus. JAH, MD: Grants: Neiman Health Policy Institute (there is no number associated with this foundation grant; Consulting (last 12 months): Medtronic, Relievant, Persica; DMC Chair: Balt, Rapid Medical, Arsenal. AW, MD: Investigator-initiated grant, Goodblends, PA. DAP, MD: Consulting: Avanos, Boston Scientific, Medtronic, Nevro, and SI Bone. Research support: Avanos, Boston Scientific, Medtronic, Nevro, Stimgenics, Abbott. SPC, MD: Consulting (past 2 years): Avanos, Scilex, SPR, SWORD, Releviate (ended), Clearing (ended), Persica (inactive); Research funds paid to institution: Scilex, Avanos. TM, MD: Consultant, Interventional AnalgesiX. The remaining authors declare no competing interests., (© American Society of Regional Anesthesia & Pain Medicine 2024. No commercial re-use. See rights and permissions. Published by BMJ.)

Chronic pain begins with acute pain. Physicians tend to classify pain by duration (acute vs chronic) and mechanism (nociceptive, neuropathic and nociplastic). Although this taxonomy may facilitate diagnosis and documentation, such categories are to some degree arbitrary constructs, with significant overlap in terms of mechanisms and treatments. In clinical practice, there are myriad different definitions for chronic pain and a substantial portion of chronic pain involves mixed phenotypes. Classification of pain based on acuity and mechanisms informs management at all levels and constitutes a critical part of guidelines and treatment for chronic pain care. Yet specialty care is often siloed, with advances in understanding lagging years behind in some areas in which these developments should be at the forefront of clinical practice. For example, in perioperative pain management, enhanced recovery protocols are not standardized and tend to drive treatment without consideration of mechanisms, which in many cases may be incongruent with personalized medicine and mechanism-based treatment. In this educational document, we discuss mechanisms and classification of pain as it pertains to commonly performed surgical procedures. Our goal is to provide a clinical reference for the acute pain physician to facilitate pain management decision-making (both diagnosis and therapy) in the perioperative period., Competing Interests: Competing interests: SPC: serves as a consultant for Avanos and SPR, which make radiofrequency equipment and peripheral nerve stimulators, that have been studied for perioperative pain., (© American Society of Regional Anesthesia & Pain Medicine 2024. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: Peer review represents a cornerstone of the scientific process, yet few studies have evaluated its association with scientific impact. The objective of this study is to assess the association of peer review scores with measures of impact for manuscripts submitted and ultimately published., Methods: 3173 manuscripts submitted to Regional Anesthesia & Pain Medicine (RAPM) between August 2018 and October 2021 were analyzed, with those containing an abstract included. Articles were categorized by topic, type, acceptance status, author demographics and open-access status. Articles were scored based on means for the initial peer review where each reviewer's recommendation was assigned a number: 5 for 'accept', 3 for 'minor revision', 2 for 'major revision' and 0 for 'reject'. Articles were further classified by whether any reviewers recommended 'reject'. Rejected articles were analyzed to determine whether they were subsequently published in an indexed journal, and their citations were compared with those of accepted articles when the impact factor was < 1.4 points lower than RAPM 's 5.1 impact factor. The main outcome measure was the number of Clarivate citations within 2 years from publication. Secondary outcome measures were Google Scholar citations within 2 years and Altmetric score., Results: 422 articles met inclusion criteria for analysis. There was no significant correlation between the number of Clarivate 2-year review citations and reviewer rating score (r=0.038, p=0.47), Google Scholar citations (r=0.053, p=0.31) or Altmetric score (p=0.38). There was no significant difference in 2-year Clarivate citations between accepted (median (IQR) 5 (2-10)) and rejected manuscripts published in journals with impact factors > 3.7 (median 5 (2-7); p=0.39). Altmetric score was significantly higher for RAPM -published papers compared with RAPM -rejected ones (median 10 (5-17) vs 1 (0-2); p<0.001)., Conclusions: Peer review rating scores were not associated with citations, though the impact of peer review on quality and association with other metrics remains unclear., Competing Interests: Competing interests: BDS, MD and SPC receive support for editorial work at Regional Anesthesia & Pain Medicine. SPC received research support from Avanos and Scilex (paid to institution) and serves as a consultant for Scilex, Avanos, SPR Therapeutics, Persica and Sword., (© American Society of Regional Anesthesia & Pain Medicine 2024. No commercial re-use. See rights and permissions. Published by BMJ.)

Introduction: Low back pain is the leading cause of disability worldwide, with sacroiliac joint pain comprising up to 30% of cases of axial lower back pain. Conservative therapies provide only modest relief. Although placebo-controlled trials show efficacy for sacral lateral branch cooled radiofrequency ablation, there are no comparative effectiveness studies., Methods: In this randomized, multicenter comparative effectiveness study, 210 patients with clinically suspected sacroiliac joint pain who obtained short-term benefit from diagnostic sacroiliac joint injections and prognostic lateral branch blocks were randomly assigned to receive cooled radiofrequency ablation of the L5 dorsal ramus and S1-S3 lateral branches or standard medical management consisting of pharmacotherapy, injections and integrative therapies. The primary outcome measure was mean reduction in low back pain score on a 0-10 Numeric Rating Scale at 3 months. Secondary outcomes included measures of quality of life and function., Results: 3 months post-treatment, the mean Numeric Rating Scale pain score for the cooled radiofrequency ablation group was 3.8±2.4 (mean reduction 2.5±2.5) compared with 5.9±1.7 (mean reduction 0.4±1.7) in the standard medical management group (p<0.0001). 52.3% of subjects in the cooled radiofrequency ablation group experienced > 2 points or 30% pain relief and were deemed responders versus 4.3% of standard medical management patients (p<0.0001). Comparable improvements favoring cooled radiofrequency ablation were noted in Oswestry Disability Index score (mean 29.7±15.2 vs 41.5+13.6; p<0.0001) and quality of life (mean EuroQoL-5 score 0.68±0.22 vs 0.47±0.29; p<0.0001)., Conclusions: In patients with sacroiliac joint pain, cooled radiofrequency ablation provided statistically superior improvements across the spectrum of patient outcomes compared with standard medical management., Trial Registration Number: NCT03601949., Competing Interests: Competing interests: All authors received institutional research funding. SPC, LKa, LKo, SL, DPB and MJD are consultants for Avanos (which makes radiofrequency equipment). Currently, SPC is the editorial board member of RAPM., (© American Society of Regional Anesthesia & Pain Medicine 2024. Re-use permitted under CC BY-NC. No commercial re-use. Published by BMJ.)

Introduction: We previously reported that a 6-day continuous peripheral nerve block reduces established postamputation phantom pain. To provide patients and providers with the information to best inform treatment decisions, here we reanalyze the data and present the results in a more patient-centered format. We also provide information on patient-defined clinically relevant benefits to facilitate evaluation of available studies and guide future trial design., Methods: The original trial enrolled participants with a limb amputation and phantom pain who were randomized to receive a 6-day continuous peripheral nerve block(s) of either ropivacaine (n=71) or saline (n=73) in a double-masked fashion. Here we calculate the percentage of each treatment group that experienced a clinically relevant improvement as defined by previous studies as well as present what the participants of our study defined as small, medium, and large analgesic improvements using the 7-point ordinal Patient Global Impression of Change scale., Results: Among patients who were given a 6-day ropivacaine infusion, 57% experienced at least a 2-point improvement on the 11-point numeric rating scale in their average and worst phantom pain 4 weeks postbaseline as compared with 26% (p<0.001) for average and 25% (p<0.001) for worst pain in patients given a placebo infusion. At 4 weeks, the percentage of participants rating their pain as improved was 53% for the active vs 30% for the placebo groups (95% CI 1.7 (1.1, 2.7), p = 0.008). For all patients combined, the median (IQR) phantom pain Numeric Rating Scale improvements at 4 weeks considered small, medium, and large were 2 (0-2), 3 (2-5), and 5 (3-7), respectively. The median improvements in the Brief Pain Inventory interference subscale (0-70) associated with small, medium, and large analgesic changes were 8 (1-18), 22 (14-31), and 39 (26-47)., Conclusions: Among patients with postamputation phantom pain, a continuous peripheral nerve block more than doubles the chance of a clinically relevant improvement in pain intensity. Amputees with phantom and/or residual limb pain rate analgesic improvements as clinically relevant similarly to other chronic pain etiologies, although their smallest relevant improvement in the Brief Pain Inventory was significantly larger than previously published values., Trial Registration Number: NCT01824082., Competing Interests: Competing interests: BMI and BK: The University of California has received funding and/or equipment for other research projects from Epimed International (Dallas, TX), Infutronics (Natick, MA), Avanos (Irvine, CA), and SPR Therapeutics (Cleveland, OH). DIS: Chair Data and Safety Monitoring Board, Neuros Medical QUEST trial. Consultant for Pacira Pharmaceuticals (Parsippany, NJ), and this company funds trials in the Department of Outcomes Research. SPC: receives research funding (paid to the institution) from Avanos (Irvine, CA), and research funding (paid to the institution) from Scilex (San Diego, CA). He serves as a consultant for SPR Therapeutics (Cleveland, OH). AT: Pacira Pharmaceuticals (Parsippany, NJ) funds trials in the Department of Outcomes Research., (© American Society of Regional Anesthesia & Pain Medicine 2023. Re-use permitted under CC BY-NC. No commercial re-use. Published by BMJ.)

Background: Variability in anatomy in the knees supports the use of aggressive lesioning techniques such as bipolar-radiofrequency ablation (RFA) to treat knee osteoarthritis (KOA). There are no randomized controlled trials evaluating the efficacy of bipolar-RFA., Methods: Sixty-four patients with KOA who experienced >50% pain relief from prognostic superomedial, superolateral and inferomedial genicular nerve blocks were randomly assigned to receive either genicular nerve local anesthetic and steroid injections with sham-RFA or local anesthetic and steroid plus bipolar-RFA. Participants and outcome adjudicators were blinded to allocation. The primary outcome was Visual Analog Scale pain score 12 months postprocedure. Secondary outcome measures included Western Ontario and McMaster Universities Arthritis (WOMAC) and Patient Global Improvement-Indexes (PGI-I)., Results: Both groups experienced significant reductions in pain, with no significant differences observed at 12 months (reduction from 5.7±1.9 to 3.2±2.6 in the RFA-group vs from 5.0±1.4 to 2.6±2.4 in the control-group (p=0.40)) or any other time point. No significant changes were observed between groups for WOMAC and PGI-I at the primary endpoint, with only the control group experiencing a significant improvement in function at 12-month follow-up (mean reduction from 91.2±38.2 to 67.1±51.9 in the RFA-group (p=0.06) vs from 95.8±41.1 to 60.6±42.8 in the control group (p=0.001); p=0.85 between groups)., Conclusion: Our failure to find efficacy for genicular nerve RFA, coupled with evidence showing that a plenitude of nerves supply the knee joint and preliminary studies indicating superiority of lesioning strategies targeting more than three nerves, suggest controlled trials using more aggressive lesioning strategies are warranted., Trial Registration Number: TCTR20170130003., Competing Interests: Competing interests: SPC is a consultant for Avanos (which makes radiofrequency equipment) and receives institutional research funding. WM, NT, RS and SW have no conflicts of interest to declare. Currently, SPC is the editorial board member of RAPM.FundingInternal funding was used to conduct this study. SPC receives funding from the U.S. Dept. of Defense (MIRROR, HU0001-15-2-0003; Congressionally Directed Medical Research Program, 105637007) and National Institutes of Health (GR101558, R01DA048206-01, U24NS115708, 1UH3135804)., (© American Society of Regional Anesthesia & Pain Medicine 2022. Re-use permitted under CC BY-NC. No commercial re-use. Published by BMJ.)

Background: There has been a worldwide surge in interventional procedures for low back pain (LBP), with studies yielding mixed results. These data support the need for identifying outcome predictors based on unique characteristics in a pragmatic setting., Methods: We prospectively evaluated the association between over two dozen demographic, clinical and technical factors on treatment outcomes for three procedures: epidural steroid injections (ESIs) for sciatica, and sacroiliac joint (SIJ) injections and facet interventions for axial LBP. The primary outcome was change in patient-reported average pain intensity on a numerical rating scale (average NRS-PI) using linear regression. For SIJ injections and facet radiofrequency ablation, this was average LBP score at 1 and 3 months postprocedure, respectively. For ESI, it was average leg pain 1- month postinjection. Secondary outcomes included a binary indicator of treatment response (success)., Results: 346 patients were enrolled at seven hospitals. All groups experienced a decrease in average NRS-PI (p<0.0001; mean 1.8±2.6). There were no differences in change in average NRS-PI among procedural groups (p=0.50). Lower baseline pain score (adjusted coefficient -0.32, 95% CI -0.48 to -0.16, p<0.0001), depressive symptomatology (adjusted coefficient 0.076, 95% CI 0.039 to 0.113, p<0.0001) and obesity (adjusted coefficient 0.62, 95% CI 0.038 to 1.21, p=0.037) were associated with smaller pain reductions. For procedural outcome, depression (adjusted OR 0.94, 95% CI 0.91, 0.97, p<0.0001) and poorer baseline function (adjusted OR 0.59, 95% CI 0.36, 0.96, p=0.034) were associated with failure. Smoking, sleep dysfunction and non-organic signs were associated with negative outcomes in univariate but not multivariate analyses., Conclusions: Identifying treatment responders is a critical endeavor for the viability of procedures in LBP. Patients with greater disease burden, depression and obesity are more likely to fail interventions. Steps to address these should be considered before or concurrent with procedures as considerations dictate., Trial Registration Number: NCT02329951., Competing Interests: Competing interests: SPC: consulting work in past 3 years for Avanos, SPR Therapeutics, Persica, Scilex and Relieviate., (© American Society of Regional Anesthesia & Pain Medicine 2022. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: The past two decades have witnessed a surge in the use of cervical spine joint procedures including joint injections, nerve blocks and radiofrequency ablation to treat chronic neck pain, yet many aspects of the procedures remain controversial., Methods: In August 2020, the American Society of Regional Anesthesia and Pain Medicine and the American Academy of Pain Medicine approved and charged the Cervical Joint Working Group to develop neck pain guidelines. Eighteen stakeholder societies were identified, and formal request-for-participation and member nomination letters were sent to those organizations. Participating entities selected panel members and an ad hoc steering committee selected preliminary questions, which were then revised by the full committee. Each question was assigned to a module composed of 4-5 members, who worked with the Subcommittee Lead and the Committee Chairs on preliminary versions, which were sent to the full committee after revisions. We used a modified Delphi method whereby the questions were sent to the committee en bloc and comments were returned in a non-blinded fashion to the Chairs, who incorporated the comments and sent out revised versions until consensus was reached. Before commencing, it was agreed that a recommendation would be noted with >50% agreement among committee members, but a consensus recommendation would require ≥75% agreement., Results: Twenty questions were selected, with 100% consensus achieved in committee on 17 topics. Among participating organizations, 14 of 15 that voted approved or supported the guidelines en bloc, with 14 questions being approved with no dissensions or abstentions. Specific questions addressed included the value of clinical presentation and imaging in selecting patients for procedures, whether conservative treatment should be used before injections, whether imaging is necessary for blocks, diagnostic and prognostic value of medial branch blocks and intra-articular joint injections, the effects of sedation and injectate volume on validity, whether facet blocks have therapeutic value, what the ideal cut-off value is for designating a block as positive, how many blocks should be performed before radiofrequency ablation, the orientation of electrodes, whether larger lesions translate into higher success rates, whether stimulation should be used before radiofrequency ablation, how best to mitigate complication risks, if different standards should be applied to clinical practice and trials, and the indications for repeating radiofrequency ablation., Conclusions: Cervical medial branch radiofrequency ablation may provide benefit to well-selected individuals, with medial branch blocks being more predictive than intra-articular injections. More stringent selection criteria are likely to improve denervation outcomes, but at the expense of false-negatives (ie, lower overall success rate). Clinical trials should be tailored based on objectives, and selection criteria for some may be more stringent than what is ideal in clinical practice., Competing Interests: Competing interests: SPC has served as a consultant for Avanos, SPR, Releviate, Persica and Scilex in the past 3 years. ZLM receives research funding from Avanos. Anuj Bhatia receives research funding from Medtronic and consults for Bioventus. DAP has consulted for Avanos, Boston Scientific, Heron, Medtronic, Wise and Nevro. He has received research support from Avanos, Medtronic, Nevro, Stimgenics, and Abbott. DWL has served as a member of the Abbott speaker’s bureau. WMH receives funding from US WorldMeds. BJS is a consultant for State Farm and AIM Specialty Health. NK served on an advisory board for Bright Minds Biosciences, received research funding from Nevro Corporation, and received royalties from UpToDate. TD is a consultant for Abbott, Vertos, Axonics, Flowonix, SpineThera, Saluda Medical, Nalu, Medtronic, Nevro, SI Bone, Stimgenics, SPR Therapeutics, Cornerloc, Boston Scientific, PainTeq, Ethos, and Vertiflex; is a member of the advisory board for Abbott, Vertos, Flowonix, Nalu, SPR Therapeutics and Vertiflex; has stock options in Bioness, Vertiflex, Axonic, Vertos, SpineThera, Nalu, Cornerloc, PainTeq and SPR Therapeutics, and has common stock in Saluda Medical. He is a research consultant for Abbott, Vertos, Mainstay Medical, Saluda Medical, SPR Therapeutics, Boston Scientific and Vertiflex, and has a patent pending for the dorsal root ganglion paddle lead with Abbott., (© American Society of Regional Anesthesia & Pain Medicine 2022. Re-use permitted under CC BY-NC. No commercial re-use. Published by BMJ.)

Degenerative spondylolisthesis is a common back pathology in the general adult population. Patients with this condition may present for epidural steroid injection, epidural blood patch, or epidural analgesia. We report five patients with degenerative spondylolisthesis who experienced inadvertent dural puncture during interlaminar epidural steroid injection attempts: four with intrathecal contrast spread or cerebrospinal backflow into the epidural needle and one with subdural contrast spread. Patients with degenerative spondylolisthesis may be at higher risk for dural puncture due to stretching of the dura and contraction of the epidural space at the translated spinal level. In the following report, we summarize the cases and suggest risk mitigation strategies for both chronic and acute pain physicians., Competing Interests: Competing interests: None declared., (© American Society of Regional Anesthesia & Pain Medicine 2021. No commercial re-use. See rights and permissions. Published by BMJ.)

Genicular nerve radiofrequency ablation has emerged as a treatment option for patients with painful knee osteoarthritis who have failed conservative management but who may not qualify or wish to avoid a surgical procedure. Radiofrequency ablation techniques targeting the genicular nerves have evolved as our understanding of the anatomy of the anterior knee joint capsule has become more defined. The article aims to review the basic anatomy of the anterior knee joint and both the traditional and revised approaches to nerve ablation., Competing Interests: Competing interests: None declared., (© American Society of Regional Anesthesia & Pain Medicine 2021. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: There has been a surge in interest in radiofrequency ablation (RFA) of the genicular nerves over the past decade, with wide variability in selection, technique and outcomes. The aim of this study is to determine factors associated with treatment outcome., Methods: We retrospectively evaluated the effect of 23 demographic, clinical and technical variables on outcomes in 265 patients who underwent genicular nerve RFA for knee pain at 2 civilian and 1 military hospital. A primary outcome was designated as a > 30% decrease in average knee pain score lasting at least 3 months without cointerventions., Results: The overall rate of a positive response was 61.1% (95% CI 55.2% to 67.0%). In univariable analysis, larger electrode size (p=0.01), repeated lesions (p=0.02), having > 80% pain relief during the prognostic block (p=0.02), not being on opioids (p=0.04), having no coexisting psychiatric condition (p=0.02), having a lower baseline pain score (p=0.01) and having >3 nerves targeted (p=0.02) were associated with a positive outcome. In multivariate logistic analysis, being obese (OR 3.68, 95% CI 1.66 to 8.19, p=0.001), not using opioids (OR 0.35, 95% CI 0.16 to 0.77, p=0.009), not being depressed (OR 0.29, 95% CI 0.10 to 0.82, p=0.02), use of cooled RFA (OR 3.88, 95% CI 1.63 to 9.23, p=0.002) and performing multiple lesions at each neural target (OR 15.88, 95% CI 4.24 to 59.50, p<0.001) were associated with positive outcome., Conclusions: We identified multiple clinical and technical factors associated with treatment outcome, which should be considered when selecting patients for RFA treatment and in the design of clinical trials., Competing Interests: Competing interests: SPC has served as a consultant for Avanos (Alpharetta, GA) in the past 2 years., (© American Society of Regional Anesthesia & Pain Medicine 2021. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: Numerous factors are considered in the academic promotion of pain medicine physicians. In this study, we investigated the importance of research productivity, career duration, leadership, and gender on attaining professorship in chronic pain medicine fellowship programs in the USA., Methods: We identified 98 pain fellowship programs in the American Medical Association Fellowship and Residency Electronic Interactive Database. Faculty demographics and institutional characteristics were obtained from institutional websites, and h-index (number of publications (h) cited at least h times) and m-index (h-index divided by research career duration) were calculated from Scopus. A nested mixed effect hierarchical modeling was used to determine factors that were associated with attaining professorship., Results: A total of 696 chronic pain medicine faculty members from 98 academic pain fellowship programs were identified, of whom 74.7% were males. For the 15.5% who were full professors, the median h-index was 16.5 (6.0 to 30.0), the median career duration was 20.5 (16.0 to 27.0) years, and the median m-index was 0.7 (0.3 to 1.3). In an adjusted analysis, the top quartile (compared with bottom) h-index (OR 6.27; 95% CI: 2.11 to 18.59), publication citations (OR 1.13; 95% CI: 1.10 to 1.21), division chief position (OR 3.72; 95% CI: 1.62 to 8.50), institutions located in the western region (OR 3.81; 95% CI: 1.52 to 9.57), and graduating from a foreign medical school (OR 1.98; 95% CI: 1.10 to 3.92) were independently associated with attaining professorship (p<0.05), but gender was not (p=0.71)., Conclusions: Our study shows that, higher h-index, publication citations, division chief position, affiliation at a lower tier medical school, and location in the Western region were independently associated with full professorship, whereas gender was not. The identified variables for professorship may be considered as factors in faculty promotions., Competing Interests: Competing interests: None declared., (© American Society of Regional Anesthesia & Pain Medicine 2020. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: The past two decades have witnessed a surge in the use of lumbar facet blocks and radiofrequency ablation (RFA) to treat low back pain (LBP), yet nearly all aspects of the procedures remain controversial., Methods: After approval by the Board of Directors of the American Society of Regional Anesthesia and Pain Medicine, letters were sent to a dozen pain societies, as well as representatives from the US Departments of Veterans Affairs and Defense. A steering committee was convened to select preliminary questions, which were revised by the full committee. Questions were assigned to 4-5 person modules, who worked with the Subcommittee Lead and Committee Chair on preliminary versions, which were sent to the full committee. We used a modified Delphi method, whereby the questions were sent to the committee en bloc and comments were returned in a non-blinded fashion to the Chair, who incorporated the comments and sent out revised versions until consensus was reached., Results: 17 questions were selected for guideline development, with 100% consensus achieved by committee members on all topics. All societies except for one approved every recommendation, with one society dissenting on two questions (number of blocks and cut-off for a positive block before RFA), but approving the document. Specific questions that were addressed included the value of history and physical examination in selecting patients for blocks, the value of imaging in patient selection, whether conservative treatment should be used before injections, whether imaging is necessary for block performance, the diagnostic and prognostic value of medial branch blocks (MBB) and intra-articular (IA) injections, the effects of sedation and injectate volume on validity, whether facet blocks have therapeutic value, what the ideal cut-off value is for a prognostic block, how many blocks should be performed before RFA, how electrodes should be oriented, the evidence for larger lesions, whether stimulation should be used before RFA, ways to mitigate complications, if different standards should be applied to clinical practice and clinical trials and the evidence for repeating RFA (see table 12 for summary)., Conclusions: Lumbar medial branch RFA may provide benefit to well-selected individuals, with MBB being more predictive than IA injections. More stringent selection criteria are likely to improve denervation outcomes, but at the expense of more false-negatives. Clinical trials should be tailored based on objectives, and selection criteria for some may be more stringent than what is ideal in clinical practice., Competing Interests: Competing interests: TD: consultant for Abbott, Axonics, Nalu, Saluda, Medtronic, Vertiflex (Boston Scientific), Nevro, Vertos, Vertiflex, SPR. Funded research: Vertiflex, Vertos, Abbott, Saluda, SPR. Minor Equity: Bioness, Vertiflex, Vertos, Saluda, SPR. SPC: funded research: Avanos Consultant: Abbott, Medtronic, Boston Scientific David Provenzano: consultant for Avanos, Boston Scientific, Medtronic, Nevro, Esteve and Salix Research support: Medtronic, Nevro, Stimgenics and Abbott., (© American Society of Regional Anesthesia & Pain Medicine 2020. Re-use permitted under CC BY-NC. No commercial re-use. Published by BMJ.)

Introduction: Peripheral nerve stimulation (PNS) has historically been used to treat chronic pain, but generally requires implantation of a permanent system for sustained relief. A recent study found that a 60-day PNS treatment decreases post-amputation pain, and the current work investigates longer-term outcomes out to 12 months in the same cohort., Methods: As previously reported, 28 traumatic lower extremity amputees with residual and/or phantom limb pain were randomized to receive 8 weeks of PNS (group 1) or 4 weeks of placebo followed by a crossover 4 weeks of PNS (group 2). Percutaneous leads were implanted under ultrasound guidance targeting the femoral and sciatic nerves. During follow-up, changes in average pain and pain interference were assessed using the Brief Pain Inventory-Short Form and comparing with baseline., Results: Significantly more participants in group 1 reported ≥50% reductions in average weekly pain at 12 months (67%, 6/9) compared with group 2 at the end of the placebo period (0%, 0/14, p=0.001). Similarly, 56% (5/9) of participants in group 1 reported ≥50% reductions in pain interference at 12 months, compared with 2/13 (15%, p=0.074) in group 2 at crossover. Reductions in depression were also statistically significantly greater at 12 months in group 1 compared with group 2 at crossover., Conclusions: This work suggests that percutaneous PNS delivered over a 60-day period may provide significant carry-over effects including pain relief, potentially avoiding the need for a permanently implanted system while enabling improved function in patients with chronic pain., Trial Registration Number: NCT01996254., Competing Interests: Competing interests: CG, JR, MJD, and RR have consulted for SPR Therapeutics. The institutions of CG, BMI, SL, MJD, JM, and RR have received funding from SPR Therapeutics for other clinical studies. NDC and JB are employees of SPR Therapeutics., (© American Society of Regional Anesthesia & Pain Medicine 2019. Re-use permitted under CC BY-NC. No commercial re-use. Published by BMJ.)

Competing Interests: Competing interests: None declared.

Background: Studies have found that diffuse pain, indicative of central sensitization, portends poor interventional outcomes. Multiple chemical sensitivities are associated with signs of central sensitization. We sought to prospectively determine whether hypersensitivity reactions (HR) were associated with epidural steroid injection (ESI) outcomes., Methods: HR were classified as immune-related or non-immune-related and categorized by number (0=low, 1 or 2=intermediate, ≥3=high). The primary outcome measure was mean reduction in average leg pain score 1 month post-procedure. A positive outcome was defined as a two-point or greater decrease in average leg pain accompanied by satisfaction 1 month post-procedure., Results: The mean number of immune-mediated and non-immune-mediated HR were 0.6±1.2 and 0.8±1.4, respectively. Individuals in the high (n=24) total HR group had a mean reduction in average leg pain of 0.1±2.7, compared with those in the low (n=61; 1.8±2.1, p=0.025) and intermediate groups (n=52; 1.6±3.1, p=0.060). For back pain and categorical successful outcome, those with fewer HR experienced greater benefit. There were no differences in outcomes when patients were stratified by immune-related HR. Among participants in the low, intermediate and high non-immune-mediated HR groups, the mean reductions in average leg pain scores were 1.7±2.5, 1.6±3.0, and -0.2±2.3, respectively (p = 0.002). 51%, 35%, and 12% of people with low, intermediate and high numbers of non-immune-mediated HR experienced a positive categorical outcome, respectively (p=0.007)., Conclusions: Non-immune-related HR were inversely correlated with some ESI outcome measures., Competing Interests: Competing interests: SPC serves as a consultant to Semnur Pharmaceuticals, which is developing a steroid approved by the US FDA for epidural administration., (© American Society of Regional Anesthesia & Pain Medicine 2019. No commercial re-use. See rights and permissions. Published by BMJ.)

In recent years as the use of interventional pain procedures has soared, so too has outside and internal scrutiny. This scrutiny includes agreater emphasis on weighing the risks and benefits of procedures, increased surveillance for adverse events, and cost containment strategies. In 2016, the first reports of gadolinium deposition in the central nervous system began to surface, though retention in other organ systems has been appreciated for over a decade. In this issue of Regional Anesthesia & Pain Medicine, Benzon et al. report a series of patients with document edhypersensitivity reactions to iodinated contrast medium who were inadvertently administered iodine-based contrast without adverse consequences. In this article, we discuss the epidemiology of contrast-mediated adverse effects, the mechanistic basis for hypersensitivity reactions, the risks and benefits of various approaches in the patient with a documented contrast hypersensitivity reaction, and risk mitigation strategies., Competing Interests: Competing interests: None declared., (© American Society of Regional Anesthesia & Pain Medicine 2019. No commercial re-use. See rights and permissions. Published by BMJ.)

Background and Objectives: Dorsal root ganglion stimulation is an emerging therapy in the treatment of chronic pain. Compared with traditional spinal cord stimulation, it allows a discretely targeted stimulation profile and may act via differing mechanisms of action. Despite these advantages, little is known about the complications associated with this new modality., Methods: We queried the MAUDE (Manufacturer and User Facility Device Experience) database for all entries named 'Dorsal root ganglion stimulator for pain relief' reported between May 1, 2016 and December 31, 2017. We verified these data through the Office of the Freedom of Information Act at the US Food and Drug Administration. We then eliminated duplicate entries and categorized each complication based on the event description. A secondary analysis was performed to characterize the serious adverse events and the severity of new neurologic symptoms and infections., Results: We identified 979 unique episodes following our process of deduplication. Almost half (47%) of entries were categorized as device-related complications, a quarter (28%) as procedural complications, with the remainder as patient complaints (12%), serious adverse events (2.4%), and 'other' complications (4.6%). The majority of complications were managed surgically with revision (n = 488; 49.8%) rather than explant (n = 161; 16.4%) events, respectively., Conclusions: The 'Dorsal root ganglion stimulator for pain relief' device has been publicized as a breakthrough in neuromodulation technologies. As with any new technology, we must proceed with caution and re-evaluate effectiveness as information becomes available. The MAUDE database has provided safety data unique for this device that will aid in informed consent and further refinement of this innovative therapy., Competing Interests: Competing interests: SPC has served as a consultant to Abbott in the past 3 years on the topic of radiofrequency ablation. All other authors declare no conflicts of interest., (© American Society of Regional Anesthesia & Pain Medicine 2019. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: Ketamine infusions have been used for decades to treat acute pain, but a recent surge in usage has made the infusions a mainstay of treatment in emergency departments, in the perioperative period in individuals with refractory pain, and in opioid-tolerant patients. The widespread variability in patient selection, treatment parameters, and monitoring indicates a need for the creation of consensus guidelines., Methods: The development of acute pain ketamine guidelines grew as a corollary from the genesis of chronic pain ketamine guidelines. The charge for the development of acute pain ketamine guidelines was provided by the Boards of Directors of both the American Society of Regional Anesthesia and Pain Medicine and the American Academy of Pain Medicine, who approved the document along with the American Society of Anesthesiologists' Committees on Pain Medicine and Standards and Practice Parameters. The committee chair developed questions based on input from the committee during conference calls, which the committee then refined. Groups of 3 to 5 panel members and the committee chair were responsible for answering individual questions. After preliminary consensus was achieved, the entire committee made further revisions via e-mail and conference calls., Results: Consensus guidelines were prepared in the following areas: indications, contraindications for acute pain and whether they differ from those for chronic pain, the evidence for the use of ketamine as an adjunct to opioid-based therapy, the evidence supporting patient-controlled ketamine analgesia, the use of nonparenteral forms of ketamine, and the subanesthetic dosage range and whether the evidence supports those dosages for acute pain. The group was able to reach consensus on the answers to all questions., Conclusions: Evidence supports the use of ketamine for acute pain in a variety of contexts, including as a stand-alone treatment, as an adjunct to opioids, and, to a lesser extent, as an intranasal formulation. Contraindications for acute pain are similar to those for chronic pain, partly based on the observation that the dosage ranges are similar. Larger studies evaluating different acute pain conditions are needed to enhance patient selection, determine the effectiveness of nonparenteral ketamine alternatives, define optimal treatment parameters, and develop protocols optimizing safety and access to care.

Background: Over the past 2 decades, the use of intravenous ketamine infusions as a treatment for chronic pain has increased dramatically, with wide variation in patient selection, dosing, and monitoring. This has led to a chorus of calls from various sources for the development of consensus guidelines., Methods: In November 2016, the charge for developing consensus guidelines was approved by the boards of directors of the American Society of Regional Anesthesia and Pain Medicine and, shortly thereafter, the American Academy of Pain Medicine. In late 2017, the completed document was sent to the American Society of Anesthesiologists' Committees on Pain Medicine and Standards and Practice Parameters, after which additional modifications were made. Panel members were selected by the committee chair and both boards of directors based on their expertise in evaluating clinical trials, past research experience, and clinical experience in developing protocols and treating patients with ketamine. Questions were developed and refined by the committee, and the groups responsible for addressing each question consisted of modules composed of 3 to 5 panel members in addition to the committee chair. Once a preliminary consensus was achieved, sections were sent to the entire panel, and further revisions were made. In addition to consensus guidelines, a comprehensive narrative review was performed, which formed part of the basis for guidelines., Results: Guidelines were prepared for the following areas: indications; contraindications; whether there was evidence for a dose-response relationship, or a minimum or therapeutic dose range; whether oral ketamine or another N-methyl-D-aspartate receptor antagonist was a reasonable treatment option as a follow-up to infusions; preinfusion testing requirements; settings and personnel necessary to administer and monitor treatment; the use of preemptive and rescue medications to address adverse effects; and what constitutes a positive treatment response. The group was able to reach consensus on all questions., Conclusions: Evidence supports the use of ketamine for chronic pain, but the level of evidence varies by condition and dose range. Most studies evaluating the efficacy of ketamine were small and uncontrolled and were either unblinded or ineffectively blinded. Adverse effects were few and the rate of serious adverse effects was similar to placebo in most studies, with higher dosages and more frequent infusions associated with greater risks. Larger studies, evaluating a wider variety of conditions, are needed to better quantify efficacy, improve patient selection, refine the therapeutic dose range, determine the effectiveness of nonintravenous ketamine alternatives, and develop a greater understanding of the long-term risks of repeated treatments.

Background and Objectives: Chronic hip pain from osteoarthritis and other degenerative conditions is a common problem. A few publications have recently reported analgesic success of radiofrequency (RF) procedures on nerves innervating the hip, but interpretation is hampered by lack of clarity regarding indications, clinical protocols, anatomic targets, and longevity of benefit from RF procedures., Methods: We reviewed the following medical literature databases for publications on RF procedures on the hip joint for chronic pain: MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, and Google Scholar through February 28, 2017. Existing knowledge on innervation of the hip joint was synthesized. Data on analgesic and functional outcomes and adverse effects measured at any time points following the interventions were also collected, analyzed, and reported in this narrative review., Results: Fourteen publications on ablative RF treatments of innervation of the hip joint were identified. A high success rate of these procedures in relieving chronic pain of the hip joint was reported at 8 days to 36 months after the procedures, but none of the publications were randomized controlled trials. There was evidence for improvement in function and a lack of serious adverse events of RF treatments., Conclusions: Radiofrequency treatments for the sensory innervation of the hip joint have the potential to reduce pain secondary to degenerative conditions. Ongoing concerns remain regarding the anatomic targets, as well as quality, procedural aspects, and monitoring of outcomes in publications on this topic. Randomized controlled trials of high methodological quality are required to further elaborate the role of these interventions in this population.

Background and Objectives: Neck pain exerts a steep personal and socioeconomic toll, ranking as the fourth leading cause of disability. The principal determinant in treatment decisions is whether pain is neuropathic or nonneuropathic, as this affects treatment at all levels. Yet, no study has sought to classify neck pain in this manner., Methods: One hundred participants referred to an urban, academic military treatment facility with a primary diagnosis of neck pain were enrolled and followed up for 6 months. Pain was classified as neuropathic, possible neuropathic, or nonneuropathic using painDETECT and as neuropathic, mixed, or nociceptive by s-LANSS (self-completed Leeds Assessment of Neuropathic Symptoms and Signs pain scale) and physician designation. Based on previous studies, the intermediate possible neuropathic pain category was considered to be a mixed condition. The final classification was based on a metric combining all 3 systems, slightly weighted toward physician's judgment, which is considered the reference standard., Results: Fifty percent of participants were classified as having possible neuropathic pain, 43% as having nonneuropathic pain, and 7% with primarily neuropathic pain. Concordance was high between the various classification schemes, ranging from a low of 62% between painDETECT and physician designation for possible neuropathic pain, to 83% concordance between s-LANSS and the 2 other systems for neuropathic pain. Individuals with neuropathic pain reported higher levels of baseline disability, were more likely to have a coexisting psychiatric illness, and underwent surgery more frequently than other pain categories, but were also more likely to report greater reductions in disability after 6 months., Conclusions: Although pure neuropathic pain comprised a small percentage of our cohort, 50% of our population consisted of mixed pain conditions containing a possible neuropathic component. There was significant overlap between the various classification schemes.

Background and Objectives: Chronic knee pain from osteoarthritis or following arthroplasty is a common problem. A number of publications have reported analgesic success of radiofrequency (RF) procedures on nerves innervating the knee, but interpretation is hampered by lack of clarity regarding indications, clinical protocols, targets, and longevity of benefit from RF procedures., Methods: We reviewed the following medical literature databases for publications on RF procedures on the knee joint for chronic pain: MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, and Google Scholar up to August 9, 2015. Data on scores for pain, validated scores for measuring physical disability, and adverse effects measured at any timepoint after 1 month following the interventions were collected, analyzed, and reported in this narrative review., Results: Thirteen publications on ablative or pulsed RF treatments of innervation of the knee joint were identified. A high success rate of these procedures in relieving chronic pain of the knee joint was reported at 1 to 12 months after the procedures, but only 2 of the publications were randomized controlled trials. There was evidence for improvement in function and a lack of serious adverse events of RF treatments., Conclusions: Radiofrequency treatments on the knee joint (major or periarticular nerve supply or intra-articular branches) have the potential to reduce pain from osteoarthritis or persistent postarthroplasty pain. Ongoing concerns regarding the quality, procedural aspects, and monitoring of outcomes in publications on this topic remain. Randomized controlled trials of high methodological quality are required to further elaborate role of these interventions in this population.

Background and Objectives: Systematic reviews evaluate the utility of procedural interventions of the spine, including epidural steroid injections (ESIs). However, existing quality assessment tools either fail to account for proper technical quality and patient selection or are not validated. We developed and validated a simple scale for ESIs to provide a quality assessment and rating of technique for injections of the spine (AQUARIUS)., Methods: Seven experts generated items iteratively based on prior ESI technique studies and professional judgment. Following testing for face and content validity, a 17-item instrument was used by 8 raters from 2 different backgrounds to assess 12 randomized controlled trials, selected from 3 different categories. Using frequency of assessment, a 12-item instrument was also generated. Both instruments underwent reliability (intraclass correlation coefficient), validity (ability to distinguish "low," "random," and "high" study categories), and diagnostic accuracy (receiver operating characteristics) testing., Results: Both 17- and 12-item instruments were scored consistently by raters regardless of background, with overall intraclass correlation coefficients of 0.72 (95% confidence interval [CI], 0.53-0.89) and 0.71 (95% CI, 0.51-0.89), respectively. Both instruments discriminated between clinical trials from all 3 categories. Diagnostic accuracy was similar for the 2 instruments, with areas under receiver operating characteristic curves of 0.89 (95% CI, 0.82-0.96) and 0.90 (95% CI, 0.82-0.97), respectively., Conclusions: The instrument in both 17- and 12-item formats demonstrates good reliability and diagnostic accuracy in rating ESI studies. As a complement to other tools that assess bias, the instrument may improve the ability to evaluate evidence for systematic reviews and improve clinical trial design.

Background: Medial branch blocks (MBBs) and intra-articular (IA) facet joint injections are both used to diagnose facet joint pain and are presumed to be equivalent. No study has sought to determine which has a better prognostic value before radiofrequency (RF) denervation., Methods: A case-control study was performed at 4 institutions in which RF denervation outcomes in patients who obtained 50% or more pain relief from either MBB (n = 212) or IA injections (n = 212) were compared. "Control" patients (MBB) were matched to "cases" by treating physician, last name, and date of treatments. During data mining, 87 patients were identified who underwent RF ablation after receiving both IA injections and MBB and were used for secondary analyses., Results: A total of 70.3% of MBB patients experienced 50% or more pain relief at the 3-month follow-up versus 60.8% in those who underwent IA injections (P = 0.041). In multivariable analysis, undergoing MBB was associated with RF treatment success (odds ratio [OR], 1.57; 95% confidence interval [95% CI], 1.0-2.39; P = 0.036), whereas opioid use (OR, 0.52; 95% CI, 0.34-0.79; P = 0.002) and previous back surgery (OR, 0.60; 95% CI, 0.38-0.95; P = 0.028) were associated with treatment failure. No significant differences were noted between MBB alone and combination treatment or single versus multiple blocks. In the secondary multivariable analysis including the combination IA + MBB group, MBB alone was again independently associated with an RF ablation treatment success (OR, 1.73; 95% CI, 1.12-2.67; P = 0.014)., Conclusions: When used as a prognostic tool before lumbar facet radiofrequency, MBB may be associated with a higher success rate than IA injections. Our results should be confirmed by large, prospective, randomized studies.

Background: Facet joint radiofrequency (RF) ablation is characterized by a high failure rate, which is partly due to the fact that pain relief after diagnostic blocks is inherently subjective. An area that has yet to be explored is whether more objective measures, such as changes in vital signs after blocks, might be used to predict treatment outcomes., Methods: A multicenter, prospective study was performed in 223 patients who underwent diagnostic lumbar medial branch blocks, of whom 87 proceeded to RF denervation. Blood pressure (BP), heart rate (HR), and pain scores were recorded preblock and 20 minutes postblock. A positive vital sign response was designated as a decrease of less than 7.5 units in BP or HR, and a positive facet block as pain relief of 50% or greater based on 6-hour pain diary scores., Results: Overall, 125 subjects (56.1%; 95% confidence interval, 49.3%-62.6%) experienced a positive facet block, and 71 had 3-month follow-up information after denervation. Correlations between changes in NRS scores and HR (r = -0.01, P = 0.893), systolic BP (r = 0.05, P = 0.47), diastolic BP (DBP) (r = 0.08, P = 0.22), and mean arterial pressure (r = 0.08, P = 0.21) were weak and nonsignificant. No associations were found between facet block results and any vital sign. Six (85.7%) of 7 patients who experienced a decrease in DBP of greater than 7.5 mm Hg after facet block had a positive RF denervation outcome at 3 months, compared with 43.8% who did not (odds ratio, 7.52; 95% confidence interval, 0.84-363.8; P = 0.049). A classification tree based on significant decrease in DBP, pain duration, and baseline NRS pain score showed a 76.7% (range, 65.8%-86.3%) accuracy rate., Conclusions: Although a decrease in DBP of more than 7.5 mm Hg had 97.3% specificity and 85.7% positive predictive value for predicting positive RF ablation outcomes, the low negative predictive value (56.3%) precludes its use as a solitary screening tool. An algorithm based on age, baseline NRS pain score, and a significant decrease in DBP was able to predict 76.7% (range, 65.8%-86.3%) of RF denervation outcomes.

Epidural steroid injections (ESIs) are the most widely utilized pain management procedure in the world, their use supported by more than 45 placebo-controlled studies and dozens of systematic reviews. Despite the extensive literature on the subject, there continues to be considerable controversy surrounding their safety and efficacy. The results of clinical trials and review articles are heavily influenced by specialty, with those done by interventional pain physicians more likely to yield positive findings. Overall, more than half of controlled studies have demonstrated positive findings, suggesting a modest effect size lasting less than 3 months in well-selected individuals. Transforaminal injections are more likely to yield positive results than interlaminar or caudal injections, and subgroup analyses indicate a slightly greater likelihood for a positive response for lumbar herniated disk, compared with spinal stenosis or axial spinal pain. Other factors that may increase the likelihood of a positive outcome in clinical trials include the use of a nonepidural (eg, intramuscular) control group, higher volumes in the treatment group, and the use of depo-steroid. Serious complications are rare following ESIs, provided proper precautions are taken. Although there are no clinical trials comparing different numbers of injections, guidelines suggest that the number of injections should be tailored to individual response, rather than a set series. Most subgroup analyses of controlled studies show no difference in surgical rates between ESI and control patients; however, randomized studies conducted by spine surgeons, in surgically amenable patients with standardized operative criteria, indicate that in some patients the strategic use of ESI may prevent surgery.

Background and Objectives: The placement of lumbar spinal drains is being done with increasing frequency to facilitate high-risk surgical procedures. One risk associated with these procedures is catheter shearing, resulting in a retained foreign body in the intrathecal space. Unlike retained epidural fragments, there are no guidelines on the management of this complication. The purpose of this article was to synthesize the literature on this subject to come up with guidelines for preventing and managing this complication., Methods: Case report and review of all published cases., Results: Most cases of retained catheters are associated with difficulty inserting or advancing the catheter. Among those cases treated conservatively, approximately one third of patients developed symptoms. Factors that must be considered when weighing the decision to surgically remove the retained catheter include patient comorbidities and desires, size and location of the fragment, infectious risk, the presence of neurologic symptoms, and scheduled surgical procedure., Conclusions: A retained intrathecal catheter can be managed conservatively in certain contexts. Periodic follow-up visits, with or without repeat imaging, are recommended in these circumstances.

Background and Objective: Sacroiliac (SI) joint pain is a challenging condition characterized by limited treatment options. Recently, numerous studies have reported excellent intermediate-term outcomes after lateral-branch radiofrequency (RF) denervation, but these studies are characterized by wide variability in technique, selection criteria, and patient characteristics. The purpose of this study was to determine whether any demographic or clinical variables can be used to predict SI joint RF denervation outcome., Methods: Seventy-seven patients with refractory, injection-confirmed SI joint pain underwent SI joint denervation at 2 academic institutions. A composite binary variable "successful" outcome was predefined as greater than 50% reduction in pain lasting at least 6 months coupled with a positive global perceived effect. Secondary outcome measures included Oswestry Disability Index scores, medication reduction, and retention on active duty for soldiers. Factors retrospectively evaluated for their association with outcome included demographic variables, duration of pain, opioid usage, pain referral pattern, physical examination signs, number of blocks and percentage of pain relief after SI joint injection, prognostic lateral-branch blocks, previous surgery, levels lesioned, RF technique, disability status, and coexisting medical conditions., Results: Forty patients (52%) obtained a positive outcome. In multivariate analysis, preprocedure pain intensity, age older than 65 years, and pain radiating below the knee were significant predictors of failure. A trend was noted whereby patients receiving regular opioid therapy were more likely to experience a negative outcome. The use of cooled, rather than conventional RF, was associated with a higher percentage of positive outcomes., Conclusions: Whereas several factors were found to influence outcome, no single clinical variable reliably predicted treatment results. The use of more stringent selection criteria was not associated with better outcomes.

Background and Objectives: The concept of opioid-induced hyperalgesia has recently gained prominence as a contributing factor for opioid tolerance and long-term treatment failure. But whereas the preclinical data for this phenomenon are strong, the mixed clinical data derive primarily from experimental pain models conducted in volunteers and heroin addicts, and nonstandardized clinical stimuli, e.g., surgery. The primary objective of this study is to delineate the effect of opioid dose and treatment duration on pain intensity and unpleasantness ratings following a standardized clinical pain stimulus., Methods: Three hundred and fifty-five patients, on a steady regimen of analgesic medications and scheduled for an interventional procedure, received a standardized subcutaneous injection of lidocaine prior to a full dose of local anesthetic. Before and immediately following the injection, subjects were asked to rate pain and unpleasantness intensity on a 0 to 10 numerical rating scale. Subjects were stratified into 6 groups based on opioid dosage. A control group of 27 volunteers who had no pain and were taking no analgesics were also injected., Results: Both opioid dose and duration of treatment directly correlated with pain intensity and unpleasantness scores. Baseline pain intensity was also positively associated with both outcome variables. Gender was found to be associated with pain intensity and unpleasantness, with females scoring higher in both categories than males. Compared with patients not receiving opioid treatment, patients receiving opioid therapy were more likely to rate the standardized pain stimulus as being more unpleasant than painful., Conclusions: The results of this study bolster preclinical and experimental pain models demonstrating enhanced pain perception in subjects receiving opioid therapy. This simple clinical model may provide a useful tool in examining opioid-induced hyperalgesia.

Background and Objectives: The concept of radiofrequency denervation has recently come under question in light of several studies showing minimal to no benefit. One possibility proposed for these negative outcomes is poor selection criteria. Unlike virtually all other spine interventions, the factors associated with success and failure for cervical facet denervation have yet to be determined. The purpose of this study is to determine which demographic, clinical and treatment factors are associated with cervical facet radiofrequency denervation outcomes., Methods: Data were garnered from 3 academic medical centers on 92 patients with chronic neck pain who underwent radiofrequency denervation after a positive response to diagnostic local anesthetic blocks. Success was defined as at least 50% pain relief lasting at least 6 months. Variables evaluated for their association with outcome included age, sex, duration of pain, opioid use, pain referral pattern, paraspinal tenderness, pain exacerbated by extension/rotation, magnetic resonance image abnormalities, diabetes, smoking, scoliosis, obesity, prior surgery, and levels treated., Results: The only clinical variable associated with success was paraspinal tenderness. Factors associated with treatment failure included radiation to the head, opioid use, and pain exacerbated by neck extension and/or rotation., Conclusions: Selecting patients based on key clinical variables may increase the chance of treatment success for cervical facet radiofrequency denervation.

Background and Objectives: Gabapentin is an anticonvulsant that has been shown to be effective in the treatment of neuropathic and inflammatory pain in animal and human studies. The analgesic effect of its perioperative use has not been fully elucidated., Methods: This systematic review (meta-analysis) included 12 randomized controlled trials of 896 patients undergoing a variety of surgical procedures that investigated the impact of perioperative administration of gabapentin on postoperative outcome., Results: The pooled visual analog scores for pain at 4 hours and 24 hours were significantly less in those patients who received gabapentin (weighted mean difference [WMD] = -1.57; 95% confidence interval [CI], -2.14 to -0.99 and WMD = -0.74; CI, -1.03 to -0.45, respectively). A concomitant decrease in opioid usage by those patients who received gabapentin was also noted (odds ratio [OR] = -17.84; CI, -23.50 to -12.18). Gabapentin administration was associated with sedation and anxiolysis (OR = 3.28; CI, 1.21-8.87) but not associated with a difference in lightheadedness, dizziness, nausea, or vomiting., Conclusions: Based on this systematic review, perioperative oral gabapentin is a useful adjunct for the management of postoperative pain that provides analgesia through a different mechanism than opioids and other analgesic agents and would make a reasonable addition to a multimodal analgesic treatment plan.

Background and Objectives: Medial branch blocks have been widely described in the literature as a diagnostic tool for facet joint pain. Recently, a new "single-needle' technique was described that is purported to be equally accurate, and in some respects, superior to the standard multiple-needle technique. To date, no studies have been performed that compared these 2 techniques., Methods: In a multicenter setting, 24 subjects underwent 2 separate diagnostic medial-branch blocks in a randomized, single-blind crossover comparison of the single-needle and multiple-needle techniques. Multiple variables were compared between the 2 techniques, including procedure-related discomfort, post-procedure pain relief, volume of local anesthetic required, accuracy as determined by final needle position and contrast-media spread, and time needed to perform the procedure., Results: In this pilot study, the single-needle technique resulted in less procedure-related pain (P = .0003), required less superficial local anesthesia (P =.0006), and took less time to complete (P < .0001) than did the multiple-needle approach. With regard to final needle position, contrast spread, and post-procedure pain relief (P = .8), no differences were noted between the 2 techniques., Conclusions: Our results indicate that the single-needle technique takes less time to perform and causes less patient discomfort than does the standard technique but provides the same degree of accuracy. More studies with larger sample sizes are needed to corroborate these results and explore the effect the single-needle approach has on the rate of false-positive medial branch blocks.

Background and Objectives: Since its advent more than 50 years ago, the use of discography has been mired in controversy. The purpose of this review is to provide a clinical overview of lumbar discography and discogenic back pain, with special emphasis on determining the accuracy of discography and whether or not the procedure improves outcomes for surgery., Methods: Material for this review was obtained from a MEDLINE search conducted from 1951 thru September 2004, bibliographic references, book chapters, and conference proceedings., Results: Based on a large number of comparative studies, plain discography is less accurate than magnetic resonance imaging in diagnosing lumbar herniated nucleus pulposus and comparable or slightly more sensitive in detecting degenerative disc disease. For disc degeneration, CT discography remains the gold standard for diagnosis. There are very few studies comparing surgical outcomes between patients who have undergone preoperative provocative discography and those who have not. What little evidence exists is conflicting. Before disc replacement surgery, approximately half the studies have used preoperative discography. A comparison of outcomes did not reveal any significant difference between the 2 groups but none of the studies was controlled, and they used different outcome measures, follow-up periods, and surgical techniques. Because all intradiscal electrothermal therapy (IDET) studies have used discography before surgery, no conclusions can be drawn regarding its effects on outcome., Conclusions: Although discography, especially combined with CT scanning, may be more accurate than other radiologic studies in detecting degenerative disc disease, its ability to improve surgical outcomes has yet to be proven. In the United States and Europe, there are inconsistencies in the use of lumbar discography such that it is routinely used before IDET, yet only occasionally used before spinal fusion.

Background and Objectives: Pain arising from the sacroiliac (SI) joint is a common cause of low back pain for which there is no universally accepted, long-term treatment. Previous studies have shown radiofrequency (RF) procedures to be an effective treatment for other types of spinal pain. The purpose of this study was to determine the efficacy of reducing SI joint pain by percutaneous RF lesioning of the nerves innervating the SI joint., Methods: Eighteen patients with confirmed SI joint pain underwent nerve blocks of the L4-5 primary dorsal rami and S1-3 lateral branches innervating the affected joint. Those who obtained 50% or greater pain relief from these blocks proceeded to undergo RF denervation of the nerves., Results: Thirteen of 18 patients who underwent L4-5 dorsal rami and S1-3 lateral branch blocks (LBB) obtained significant pain relief, with 2 patients reporting prolonged benefit. At their next visit, 9 patients who experienced >50% pain relief underwent RF lesioning of the nerves. Eight of 9 patients (89%) obtained >/=50% pain relief from this procedure that persisted at their 9-month follow-up., Conclusions: In patients with SI joint pain who respond to L4-5 dorsal rami and S1-3 LBB, RF denervation of these nerves appears to be an effective treatment. Randomized, controlled trials are needed to further evaluate this procedure.