Cooled radiofrequency ablation versus standard medical management for chronic sacroiliac joint pain: a multicenter, randomized comparative effectiveness study.

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.

Pocket pain following spinal cord stimulator generator implantation: A narrative review of this under-reported risk.

INTRODUCTION: Spinal cord stimulation (SCS) is a well-established treatment option for chronic pain. Pain over the implantable pulse generator, or pocket pain, is an incompletely understood risk of SCS implantation which may limit the efficacy of treatment and patient quality of life. The goal of this narrative review is to analyze the literature to gain a more thorough understanding of the incidence and risk factors for the development of pocket pain to help guide treatment options and minimize its occurrence in the future. METHODS: A literature review was conducted investigating the development of pocket pain in patients with SCS for the management of a variety of pain conditions. RESULTS: In total, 305 articles were included in the original database search and 50 met the criteria for inclusion. The highest level of evidence for papers that specifically investigated pocket pain was level III. Four retrospective, observational analyses included pocket pain as a primary outcome. The remainder of the included studies listed pocket pain as an adverse event of SCS implantation. CONCLUSIONS: There is a relative dearth of primary literature that examines the incidence, characteristics, and health economic implications of pocket pain in patients with SCS. This highlights the need for large-scale, high-quality prospective or randomized controlled trials examining pocket pain. This may ultimately help prevent and reduce pocket pain leading to improved efficacy of treatment and greater patient quality of life.

Bipolar radiofrequency ablation lesion areas and confluence: An ex vivo study and technical report.

INTRODUCTION: Radiofrequency ablation (RFA) has been used for nearly 100 years, treating an array of medical conditions including chronic pain. Radiofrequency (RF) energy depolarizes and repolarizes tissues adjacent to a probe producing heat and causing direct thermal injury. When positioned adjacent to neural structures, it leads to neural tissue injury and cell death interrupting pain signaling with the ultimate goal of providing lasting pain relief. Today, RFA is commonly used to treat cervical, thoracic, and lumbar zygapophyseal joints, sacroiliac joint, and more recently large peripheral joint-mediated pain. There are several applications of RFA systems, including bipolar, conventional thermal, cooled, protruding, and pulsed. As yet, no study has determined the best technical practice for bipolar RFA. OBJECTIVE: This ex vivo study examines RFA lesion midpoint (LMP) area and lesion confluence comparing three different commonly used gauge (g) probes (18-g, 20-g, and 22-g) with 10-mm active tips at various interprobe distances (IPD) to guide best technical practices for its clinical application. METHODS: Bipolar RFA lesions were generated in preservative-free chicken breast specimens using three different gauge probes (18-g, 20-g, and 22-g) with 10-mm active tips at various IPD (6, 8, 10, 12, 14, 16, and 18 mm). RF was applied for 105 s (15-s ramp time) at 80°C for each lesion at both room and human physiological temperature. The specimen tissues were dissected through the lesion to obtain a length, width, and depth, which were used to calculate the LMP area (mm2 ). The LMP areas of each thermal ablation were investigated using visualization and descriptive analysis. The Kruskal-Wallis test was performed to compare LMP areas between the two temperature groups and the three different gauge probe subgroups at the various IPDs. RESULTS: Of the 36 RF lesions (14: 18-g, 12: 20-g, and 10: 22-g) performed, 24 demonstrated lesion confluence. The average time to reach 80°C was 16-17 s; therefore, the average time of RF-energy delivery (at goal temperature) was 88-89 s despite varying needle size or IPD. Comparing the 25 and 37°C groups, 18-g probes produced mean LMP areas of 73.7 and 79.2 mm2 , respectively; 20-g probes produced mean LMP areas of 66 and 66.8 mm2 , respectively; 22-g probes produced mean LMP areas of 56.6 and 59.7 mm2 , respectively. There was no statistical evidence to state a difference regarding LMP area between temperature groups; however, the 18-g probes produced consistently larger LMP areas in the 37°C compared to 25°C specimen groups at each IPD. Lesion confluence was lost for 18-g, 20-g, and 22-g probes at IPD of 14, 12, and 10 mm, respectively, in both 25 and 37°C groups. LMP area was similar between 6 and 8 mm IPD in all of the three-gauge groups; however, there was a significant drop in LMP area from 8 mm IPD to 10 mm and greater. The 18-g, 20-g, and 22-g probes all demonstrated a sharp decline in LMP area when increasing the IPD from 8 to 10 mm. CONCLUSION: This ex vivo technical study evaluated bipolar RFA LMP areas and lesion confluence, and determined the recommended IPD of 18-g, 20-g, and 22-g probes to be less than 12, 10, and 8 mm, respectively, for best clinical practice. Placing bipolar probes at an IPD greater than 14, 12, and 10 mm, respectively, risks the loss of lesion confluence and failure to produce a clinically significant treatment response due to lack of nerve capture. In clinical practice, the use of injectate may produce larger lesions than demonstrated in this study. Additionally, in vivo factors may impact ablation zone size and ablation patterns. As there are a paucity of studies comparing various RFA applications and conventional RFA needles are least expensive, it is possible that bipolar conventional RFA is more cost-effective than other techniques.

Results From a Prospective, Clinical Study (US-nPower) Evaluating a Miniature Spinal Cord Stimulator for the Management of Chronic, Intractable Pain.

BACKGROUND: Chronic, intractable, neuropathic pain is readily treatable with spinal cord stimulation (SCS). Technological advancements, including device miniaturization, are advancing the field of neuromodulation. OBJECTIVES: We report here the results of an SCS clinical trial to treat chronic, low back and leg pain, with a micro-implantable pulse generator (micro-IPG). STUDY DESIGN: This was a single-arm, prospective, multicenter, postmarket, observational study. SETTING: Patients were recruited from 15 US-based comprehensive pain centers. METHODS: This open-label clinical trial was designed to evaluate the performance of the Nalu™ Neurostimulation System (Nalu Medical, Inc., Carlsbad, CA) in the treatment of low back and leg pain. Patients, who provided informed consent and were successfully screened for study entry, were implanted with temporary trial leads. Patients went on to receive a permanent implant of the leads and micro-IPG if they demonstrated a >= 50% reduction in pain during the temporary trial period. Patient-reported outcomes (PROs), such as pain scores, functional disability, mood, patient impression of change, comfort, therapy use profile, and device ease of use, were captured. RESULTS: At baseline, the average pain Visual Analog Scale (VAS) score was 72.1 ± 17.9 in the leg and 78.0 ± 15.4 in the low back. At 90 days following permanent implant (end of study), pain scores improved by 76% (VAS 18.5 ± 18.8) in the leg and 75% (VAS 19.7 ± 20.8) in the low back. Eighty-six percent  of both leg pain and low back pain patients demonstrated a >= 50% reduction in pain at 90 days following implant. The comfort of the external wearable (Therapy Disc and Adhesive Clip) was rated 1.16 ± 1.53, on average, at 90 days on an 11-point rating scale (0 = very comfortable, 10 = very uncomfortable). All PROs demonstrated statistically significant symptomatic improvement at 90 days following implant of the micro-IPG. LIMITATIONS:   Limitations of this study include the lack of long-term results (beyond 90 days) and a relatively small sample size of 35 patients who were part of the analysis; additionally, there was no control arm or randomization as this was a single-arm study, without a comparator, designed to document the efficacy and safety of the device. Therefore, no direct comparisons to other SCS systems were possible. CONCLUSIONS: This clinical study demonstrated profound leg and low back pain relief in terms of overall pain reduction, as well as the proportion of therapy responders. The study patients reported the wearable aspects of the system to be very comfortable.

A Novel Pulsed Stimulation Pattern in Spinal Cord Stimulation: Clinical Results and Postulated Mechanisms of Action in the Treatment of Chronic Low Back and Leg Pain.

OBJECTIVES: The aim of this article is to discuss the possible mechanisms of action (MOAs) and results of a pilot study of a novel, anatomically placed, and paresthesia-independent, neurostimulation waveform for the management of chronic intractable pain. MATERIALS AND METHODS: A novel, multilayered pulsed stimulation pattern (PSP) that comprises three temporal layers, a Pulse Pattern layer, Train layer, and Dosage layer, was developed for the treatment of chronic intractable pain. During preliminary development, the utility was evaluated of anatomical PSP (aPSP) in human subjects with chronic intractable pain of the leg(s) and/or low back, compared with that of traditional spinal cord stimulation (T-SCS) and physiological PSP. The scientific theory and testing presented in this article provide the preliminary justification for the potential MOAs by which PSP may operate. RESULTS: During the pilot study, aPSP (n = 31) yielded a greater decrease in both back and leg pain than did T-SCS (back: -60% vs -46%; legs: -63% vs -43%). In addition, aPSP yielded higher responder rates for both back and leg pain than did T-SCS (61% vs 48% and 78% vs 50%, respectively). DISCUSSION: The novel, multilayered approach of PSP may provide multimechanistic therapeutic relief through preferential fiber activation in the dorsal column, optimization of the neural onset response, and use of both the medial and lateral pathway through the thalamic nuclei. The results of the pilot study presented here suggest a robust responder rate, with several subjects (five subjects with back pain and three subjects with leg pain) achieving complete relief from PSP during the acute follow-up period. These clinical findings suggest PSP may provide a multimechanistic, anatomical, and clinically effective management for intractable chronic pain. Because of the limited sample size of clinical data, further testing and long-term clinical assessments are warranted to confirm these preliminary findings.

Cluneal neuropathy: Background, diagnosis, and treatment.

BACKGROUND AND AIMS: Cluneal neuropathy is encompassed by three distinct clinical entities. Superior, middle, and inferior cluneal neuralgia make up the constellation of symptoms associated with cluneal neuropathy. Each has its own variable anatomy. MATERIALS AND METHODS: We compiled a narrative review including a review of available literature. We conducted searches on PubMed/MEDLINE, Embase and Google Scholar on the topics of cluneal neuropathy and treatment therein. RESULTS: We collected source articles regarding original descriptions of the disease entities in addition to articles focused on treatment. DISCUSSION: Adjusted incidence rates of superior cluneal neuropathy are 1.6%-11.7%. Accurate diagnosis remains challenging due to the lack of standardized criteria and the aforementioned variability. Treatment may include therapeutic nerve blocks, ablative techniques, neuromodulation, and surgical decompression. Gaps including those related to true incidence and work up exist. Outcomes from interventional studies are limited and mixed due to significant population heterogeneity and non-standardized treatment approaches coupled with very small sample sizes.

Physical Therapy Considerations and Recommendations for Patients Following Spinal Cord Stimulator Implant Surgery.

OBJECTIVES: Spinal cord stimulation (SCS) is an established therapy option in interventional pain medicine. Recent advances in technology have allowed for greater compliance with treatment and improved efficacy in pain control. This article was proposed to fill the gap in the literature addressing this specific patient population and to facilitate further research. Even though there is a lack of consensus among societies and experts on exact parameters of physical therapy (PT) considerations and postoperative limitations in patients with SCS, we propose rehabilitative care for this population should be standardized. As the number of patients with SCS implants grow, it is vital to understand how to appropriately approach patients with implantable devices when additional treatments such as PT are prescribed. MATERIALS AND METHODS: A literature search was performed on the use of PT following SCS implantation. Presently, there is no literature to date which addresses the use of PT in this patient population. The lack of data is the largest hurdle in the creation of formal SCS therapy guidelines. The authors therefore proposed recommendations for rehabilitation based upon a detailed understanding of SCS hardware alongside well-studied physiotherapy concepts. RESULTS: Considerations when initiating PT in the SCS patient population should include: 1) biomechanics and quality of SCS output; 2) therapeutic exercise and spinal manipulation in association with risk for lead migration and fracture; 3) the application of therapeutic modalities and risk for injury to the patient and/or damage to the SCS componentry; and 4) integration of a biopsychosocial, person-centered approach. CONCLUSIONS: PT treatment protocol in patients with a recently implanted SCS device should be person-centered addressing individual needs, values, and goals. Further research is needed to fully appreciate the impact of an interprofessional approach to management of SCS patients, particularly following stimulator implantation.

Social Media and Professional Conduct (SMART): Best Practice Guidelines from the American Society of Pain and Neuroscience (ASPN).

Social media has revolutionized internet communication and become ubiquitous in modern life. Though it originated as a medium for friendship, social media has evolved into an ideal venue for professional networking, scientific exchange, and brand building. As such, it is a powerful tool with which interventional pain physicians should become familiar. However, given the permanence and visibility of online posts, it is prudent for interventional pain physicians to utilize social media in a manner that is consistent with the ethical and professionalism standards to which they are held by their patients, employers, peers, and state medical boards. While there are extensive publications of professional codes of conduct by medical societies, there is a paucity of literature regarding social media best practices guidelines. Further, to date there have been no social media best practices recommendations specific to interventional pain medicine physicians. While not exhaustive, the aim of this document is to provide recommendations to pain physicians on how to maintain an effective professional and ethical online presence. Specifically, we provide guidance on online persona and professional image, patient-physician interactions online, patient privacy, industry relations, patient education, and brand building.

Cooled radiofrequency ablation of the genicular nerves for chronic pain due to osteoarthritis of the knee: a cost-effectiveness analysis compared with intra-articular hyaluronan injections based on trial data.

BACKGROUND: Effective symptom control in painful knee osteoarthritis (OA) may improve patient quality of life. In a randomised crossover trial (NCT03381248), COOLIEF* cooled radiofrequency ablation (CRFA) reduced pain and stiffness and improved physical function and quality of life compared with intra-articular hyaluronan (HA) injections. The present study aimed to establish the cost effectiveness of CRFA versus intra-articular HA injections for treating moderate-to-severe OA knee pain from a US Medicare perspective. METHODS: We conducted a cost-effectiveness analysis using utility data (EQ-5D) from the randomised crossover trial of CRFA versus intra-articular HA injections, which had follow-ups at 1, 3, 6, and 12 months. Patients in the HA group with unsatisfactory outcomes (e.g., continued pain) at 6 months could cross over to CRFA. Economic analysis outcomes included quality-adjusted life-years (QALYs), costs, and cost effectiveness (cost per QALY gained). Base-case analyses were modelled on a 6-month time horizon (to trial crossover). Due to limited trial data in the HA arm beyond 6 months, scenarios explored potential outcomes to 12 months if: 1) Utility with HA persisted for a further 6 months; 2) A second HA injection was received at 6 months and achieved the same utility change for the second 6 months. In both scenarios, the CRFA arm used trial data for patients who received CRFA from baseline to 12 months. Alternative costing scenarios were also explored. RESULTS: CRFA resulted in an incremental QALY gain of 0.020 at an incremental cost of US$1707, equating to an incremental cost-effectiveness ratio (ICER) of US$84,392 per QALY over 6 months, versus intra-articular HA injections. Extending the analysis to 12 months and assuming persistence in utility in the HA arm resulted in a larger utility gain for CRFA (0.056 QALYs) and a lower ICER of US$30,275 per QALY. If patients received a second HA injection, the incremental benefit of CRFA out to 12 months was reduced (QALY gain 0.043) but was offset by the costs of the second HA injection (incremental cost US$832). This resulted in an ICER of US$19,316 per QALY. CONCLUSIONS: CRFA is a cost-effective treatment option for patients with OA-related knee pain considering the typical US threshold of US$100,000/QALY.

Spinal Cord Stimulation: A Psychiatric Perspective.

The rapid development of neuromodulation specifically as it pertains to spinal cord stimulation (SCS) has ushered in an era of new and novel waveforms and programming methodologies. Accompanying this evolution has been a significant investment in clinical trials and outcomes-based research solidifying the foundation of SCS while investing in future indications and therapy expansion. Critically evaluating the existing literature to apply these therapies diligently remains vital to the future of neuromodulation.

60-Day PNS Treatment May Improve Identification of Delayed Responders and Delayed Non-Responders to Neurostimulation for Pain Relief.

Objective: Conventional neurostimulation typically involves a brief (eg, ≤10-day) trial to assess presumed effectiveness prior to permanent implantation. Low trial conversion rates and high explant rates due to inadequate pain relief highlight the need for improved patient identification strategies. The development of a 60-day percutaneous peripheral nerve stimulation (PNS) system enables evaluation of outcomes following an extended temporary treatment period of up to 60 days, that may obviate or validate the need for permanent implant. The present study provides the first real-world evidence regarding patient response throughout a 60-day PNS treatment period. Methods: Anonymized data listings were compiled from patients who underwent implantation of temporary percutaneous leads and opted-in to provide real-world data to the device manufacturer during routine interactions with device representatives throughout the 60-day treatment. Results: Overall, 30% (222/747) of patients were early responders (≥50% pain relief throughout treatment). Another 31% (231/747) of patients initially presented as non-responders but surpassed 50% pain relief by the end of treatment. Conversely, 32% (239/747) of patients were non-responders throughout treatment. An additional 7% (55/747) of patients initially presented as responders but fell below 50% relief by the end of the treatment period. Conclusion: An extended, 60-day PNS treatment may help identify delayed responders, providing the opportunity for sustained relief and improving access to effective PNS treatment. Compared to a conventionally short trial of ≤10 days, a longer 60-day PNS treatment may also help reduce explant rates by identifying delayed non-responders unlikely to benefit long-term. These scenarios support the importance of an extended 60-day temporary PNS stimulation period to help inform stepwise treatment strategies that may optimize outcomes and cost-effectiveness.

MRI for in vivo Analysis of Ablation Zones Formed by Cooled Radiofrequency Neurotomy to Treat Chronic Joint Pain Across Multiple Axial Spine Sites.

PURPOSE: Radiofrequency (RF) ablation is the targeted damage of neural tissues to disrupt pain transmission in sensory nerves using thermal energy generated in situ by an RF probe. The present study aims to evaluate the utility of magnetic resonance imaging (MRI) for in vivo quantitative assessment of ablation zones in human subjects following cooled radiofrequency neurotomy for chronic pain at spinal facet or sacroiliac joints. Ablation zone size and shape have been shown in animal models to be influenced by size and type of RF probe - with cooled RF probes typically forming larger, more spherical ablation zones. To date, MRI of RF ablation zones in humans has been limited to two single retrospective case reports. PATIENTS AND METHODS: A prospective, open-label pilot study of MRI for evaluation of cooled radiofrequency ablation zones following standard of care procedures in adult outpatients was conducted. Adult subjects (n=13) received monopolar cooled RF (CRF) ablation (COOLIEF™, Avanos Medical) of sensory nerves at spinal facet or sacroiliac joints, followed by an MRI 2-7 days after the procedure. MRI data were acquired using both Short Tau Inversion Recovery (STIR) and contrast-enhanced T1-weighted (T1C) protocols. T1C MRI was used to calculate 3-dimensional ellipsoid ablation zone volumes (V), where well-defined regions of signal hyperintensity were used to identify three orthogonal diameters (T, D, L) and apply the formula V=π/6×T×D×L. RESULTS: Among 13 patients, 96 CRF ablation zones were created at 4 different anatomic sites (sacroiliac, lumbar, thoracic and cervical). CRF ablation zone morphology varied by anatomical location and structural features of surrounding tissues. In some cases, proximity to bone and striations of surrounding musculature obscured ablation zone borders. The volumes of 75 of the 96 ablation zones were measurable from MRI, with values (mean±SD) ranging from 0.4679 (±0.29) cm3 to 2.735 (±2.62) cm3 for the cervical and thoracic sites, respectively. CONCLUSION: In vivo T1C MRI analysis of cooled RF ablation zones at spinal facet and sacroiliac joints demonstrated variable effects of local tissues on ablation zone morphology. Placement of the CRFA probe very close to bone alters the ablation zone in a negative way, causing non-spherical and incomplete lesioning. These new data may serve to inform practicing physicians about optimal cooled RF probe placement in clinical procedures.

The interdisciplinary management of coccydynia: A narrative review.

Pain that develops in the coccyx or surrounding tissues is known as coccydynia, which occurs as a result of many etiologies both traumatic and nontraumatic. Although coccydynia most commonly affects middle-aged women, it may be found in both sexes and in all age groups. The aim of this article is to provide an overview of the presentation, diagnostic imaging, and pathophysiology of coccydynia, and to comprehensively review the current treatment options. A review of publications from 1990 to 2020 using search words related to the treatment of coccydynia in PubMed and Google Scholar was completed. Level II evidence was found supporting stretching, manipulation, and extracorporeal shock wave therapy. There are no data from high-quality studies to support injection-based therapy including corticosteroids, prolotherapy, nerve blocks, and radiofrequency ablation, although there are small retrospective and prospective observational studies suggesting benefit. Level III evidence was found supporting coccygectomy for chronic/refractory coccydynia. There are no data from randomized controlled trials to support the use of neuromodulation (sacral burst and dorsal root ganglion stimulation), although there are case reports suggesting benefit. High-level, comparative studies are lacking to guide the treatment of coccydynia and should be a focus for future research studies.

Treatment of chronic axial back pain with 60-day percutaneous medial branch PNS: Primary end point results from a prospective, multicenter study.

BACKGROUND: The objective of this prospective, multicenter study is to characterize responses to percutaneous medial branch peripheral nerve stimulation (PNS) to determine if results from earlier, smaller single-center studies and reports were generalizable when performed at a larger number and wider variety of centers in patients recalcitrant to nonsurgical treatments. MATERIALS & METHODS: Participants with chronic axial low back pain (LBP) were implanted with percutaneous PNS leads targeting the lumbar medial branch nerves for up to 60 days, after which the leads were removed. Participants were followed long-term for 12 months after the 2-month PNS treatment. Data collection is complete for visits through end of treatment with PNS (primary end point) and 6 months after lead removal (8 months after start of treatment), with some participant follow-up visits thereafter in progress. RESULTS: Clinically and statistically significant reductions in pain intensity, disability, and pain interference were reported by a majority of participants. Seventy-three percent of participants were successes for the primary end point, reporting clinically significant (≥30%) reductions in back pain intensity after the 2-month percutaneous PNS treatment (n = 54/74). Whereas prospective follow-up is ongoing, among those who had already completed the long-term follow-up visits (n = 51), reductions in pain intensity, disability, and pain interference were sustained in a majority of participants through 14 months after the start of treatment. CONCLUSION: Given the minimally invasive, nondestructive nature of percutaneous PNS and the significant benefits experienced by participants who were recalcitrant to nonsurgical treatments, percutaneous PNS may provide a promising first-line neurostimulation treatment option for patients with chronic axial back pain.

Percutaneous Peripheral Nerve Stimulation of the Medial Branch Nerves for the Treatment of Chronic Axial Back Pain in Patients After Radiofrequency Ablation.

OBJECTIVE: Lumbar radiofrequency ablation is a commonly used intervention for chronic back pain. However, the pain typically returns, and though retreatment may be successful, the procedure involves destruction of the medial branch nerves, which denervates the multifidus. Repeated procedures typically have diminishing returns, which can lead to opioid use, surgery, or implantation of permanent neuromodulation systems. The objective of this report is to demonstrate the potential use of percutaneous peripheral nerve stimulation (PNS) as a minimally invasive, nondestructive, motor-sparing alternative to repeat radiofrequency ablation and more invasive surgical procedures. DESIGN: Prospective, multicenter trial. METHODS: Individuals with a return of chronic axial pain after radiofrequency ablation underwent implantation of percutaneous PNS leads targeting the medial branch nerves. Stimulation was delivered for up to 60 days, after which the leads were removed. Participants were followed up to 5 months after the start of PNS. Outcomes included pain intensity, disability, and pain interference. RESULTS: Highly clinically significant (≥50%) reductions in average pain intensity were reported by a majority of participants (67%, n = 10/15) after 2 months with PNS, and a majority experienced clinically significant improvements in functional outcomes, as measured by disability (87%, n = 13/15) and pain interference (80%, n = 12/15). Five months after PNS, 93% (n = 14/15) reported clinically meaningful improvement in one or more outcome measures, and a majority experienced clinically meaningful improvements in all three outcomes (i.e., pain intensity, disability, and pain interference). CONCLUSIONS: Percutaneous PNS has the potential to shift the pain management paradigm by providing an effective, nondestructive, motor-sparing neuromodulation treatment.

Postoperative Infections Associated With Prolonged Spinal Cord Stimulation Trial Duration (PROMISE RCT).

INTRODUCTION: In the PROMISE study, a multinational randomized controlled trial (RCT) of the effectiveness of spinal cord stimulation (SCS) with multicolumn surgical leads as a treatment of low back pain, clinicians followed their usual practice. An early, unplanned safety analysis revealed that the infection rate in Belgium (5/23), where trial duration was a median 21.5 days, was significantly higher than the 1/64 rate observed in the other study countries (median 5.8 days, p < 0.01). This report reviews infections observed in the PROMISE study after study completion. MATERIALS AND METHODS: For all infections related to SCS, we used descriptive statistics and tests of independent variables to analyze potentially contributing factors (age, sex, coexisting medical conditions, tobacco use, lead type, and trial duration) between subjects with infections versus those without. Cumulative incidence curves were created using the Kaplan-Meier method and compared between the two strata using a log-rank test. RESULTS: Among nine (5.2%) infections in 174 subjects trialed, the only significant contributing factor to infection was trial duration: median 21 days (range 3-56) for those with infection vs. six days (1-41) for those without (p = 0.001; Wilcoxon rank-sum test). The cumulative incidence of infection for subjects trialed >10 days was 24.1% vs. 1.4% for subjects trialed ≤10 days (p < 0.001). After the protocol was amended to limit trial duration to 10 days, 14 infection-free trials were performed in Belgium. CONCLUSIONS: Although not part of the preplanned analysis, our observation supports the hypothesis of a cause-effect relationship between trial duration and the risk of infection and the conclusion that prolonged SCS trials should be avoided.

Axillary Peripheral Nerve Stimulation for Chronic Shoulder Pain: A Retrospective Case Series.

OBJECTIVE: The objective of this study was to determine the effect of axillary peripheral nerve stimulation (PNS) on pain reduction in patients with chronic shoulder pain. Chronic shoulder pain was defined as pain greater than six months originating from any of the following and not the result of a stroke: subacromial impingement syndrome/rotator cuff pathology, glenohumeral joint arthritis, acromioclavicular joint arthritis, adhesive capsulitis, or biceps tendinopathy. MATERIALS AND METHODS: Eight adult patients with chronic shoulder pain, as defined above, who either did not respond to surgical intervention or who were deemed not ideal surgical candidates underwent permanent axillary PNS therapy. Follow-up ranged from 44 to 733 days (avg 445 days). The primary outcome was percent pain reduction, determined by the change in average numerical pain rating scale (NPRS). Additionally, secondary outcome measures were the change in opioid requirements and satisfaction rate. RESULTS: Based on the ≥50% pain reduction for treatment success, 88% (7/8) were "responders." Overall average pain reduction was 67% and 70% among responders; 62.5% (5/8) of patients reported that they used opioids prior to axillary PNS therapy for pain relief. Among these patients, 100% reported decreased opioid use after axillary PNS implant, with an average reduction of 88% (based on self-reported reductions). Additionally, 100% (8/8) of patients reported that they would recommend this therapy to other patients suffering from chronic pain. CONCLUSIONS: This retrospective case series provides level IV evidence supporting the use of axillary PNS therapy for the management of chronic shoulder pain. Additional, higher-level studies are required to further support its use.