Maximal Analgesic Effect Attained by the Use of Objective Neurophysiological Measurements With Closed-Loop Spinal Cord Stimulation.

OBJECTIVES: Spinal cord stimulation (SCS) has been challenged by the lack of neurophysiologic data to guide therapy optimization. Current SCS programming by trial-and-error results in suboptimal and variable therapeutic effects. A novel system with a physiologic closed-loop feedback mechanism using evoked-compound action potentials enables the optimization of physiologic neural dose by consistently and accurately activating spinal cord fibers. We aimed to identify neurophysiologic dose metrics and their ranges that resulted in clinically meaningful treatment responses. MATERIALS AND METHODS: Subjects from 3 clinical studies (n = 180) with baseline back and leg pain ≥60 mm visual analog scale and physical function in the severe to crippled category were included. Maximal analgesic effect (MAE) was operationally defined as the greatest percent reduction in pain intensity or as the greatest cumulative responder score (minimal clinically important differences [MCIDs]) obtained within the first 3 months of SCS implant. The physiologic metrics that produced the MAE were analyzed. RESULTS: We showed that a neural dose regimen with a high neural dose accuracy of 2.8µV and dose ratio of 1.4 resulted in a profound clinical benefit to chronic pain patients (MAE of 79 ± 1% for pain reduction and 12.5 ± 0.4 MCIDs). No differences were observed for MAE or neurophysiological dose metrics between the trial phase and post-implant MAE visit. CONCLUSION: For the first time, an evidence-based neural dose regimen is available for a neurostimulation intervention as a starting point to enable optimization of clinical benefit, monitoring of adherence, and management of the therapy.

9. Chronic knee pain.

INTRODUCTION: Chronic knee pain is defined as pain that persists or recurs over 3 months. The most common is degenerative osteoarthritis (OA). This review represents a comprehensive description of the pathology, diagnosis, and treatment of OA of the knee. METHODS: The literature on the diagnosis and treatment of chronic knee pain was retrieved and summarized. A modified Delphi approach was used to formulate recommendations on interventional treatments. RESULTS: Patients with knee OA commonly present with insidious, chronic knee pain that gradually worsens. Pain caused by knee OA is predominantly nociceptive pain, with occasional nociplastic and infrequent neuropathic characteristics occurring in a diseased knee. A standard musculoskeletal and neurological examination is required for the diagnosis of knee OA. Although typical clinical OA findings are sufficient for diagnosis, medical imaging may be performed to improve specificity. The differential diagnosis should exclude other causes of knee pain including bone and joint disorders such as rheumatoid arthritis, spondylo- and other arthropathies, and infections. When conservative treatment fails, intra-articular injections of corticosteroids and radiofrequency (conventional and cooled) of the genicular nerves have been shown to be effective. Hyaluronic acid infiltrations are conditionally recommended. Platelet-rich plasma infiltrations, chemical ablation of genicular nerves, and neurostimulation have, at the moment, not enough evidence and can be considered in a study setting. The decision to perform joint-preserving and joint-replacement options should be made multidisciplinary. CONCLUSIONS: When conservative measures fail to provide satisfactory pain relief, a multidisciplinary approach is recommended including psychological therapy, integrative treatments, and procedural options such as intra-articular injections, radiofrequency ablation, and surgery.

11. Cervicogenic headache and occipital neuralgia.

INTRODUCTION: Cervicogenic headache (CEH) and occipital neuralgia (ON) are headaches originating in the occiput and that radiate to the vertex. Because of the intimate relationship between structures based in the occiput and those in the upper cervical region, there is significant overlap between the presentation of CEH and ON. Diagnosis starts with a headache history to assess for diagnostic criteria formulated by the International Headache Society. Physical examination evaluates range of motion of the neck and the presence of tender areas or pressure points. METHODS: The literature for the diagnosis and treatment of CEH and ON was searched from 2015 through August 2022, retrieved, and summarized. RESULTS: Conservative treatment includes pain education and self-care, analgesic medication, physical therapy (such as reducing secondary muscle tension and improving posture), the use of TENS (transcutaneous electrical nerve stimulation), or a combination of the aforementioned treatments. Injection at various anatomical locations with local anesthetic with or without corticosteroids can provide pain relief for a short period. Deep cervical plexus block can result in improved pain for less than 6 months. In both CEH and ON, an occipital nerve block can provide important diagnostic information and improve pain in some patients, with PRF providing greater long-term pain control. Radiofrequency ablation of the cervical facet joints can result in improvement for over 1 year. Occipital nerve stimulation (ONS) should be considered for the treatment of refractory ON. CONCLUSION: The treatment of CEH preferentially consists of radiofrequency treatment of the facet joints, while for ON, pulsed radiofrequency of the occipital nerves is indicated. For refractory cases, ONS may be considered.

Low-energy differential target multiplexed SCS derivative reduces pain and improves quality of life through 12 months in patients with chronic back and/or leg pain.

INTRODUCTION: Energy-reducing spinal cord stimulation (SCS) approaches have the potential to impact patient experience with rechargeable and non-rechargeable SCS devices through reducing device recharge time or enhancing device longevity. This prospective, multi-center study evaluated the safety, effectiveness, and actual energy usage of differential target multiplexed (DTM) endurance therapy, a reduced energy DTM SCS derivative. METHODS: Subjects who reported an overall pain visual analog score (VAS) of ≥6/10 cm and an Oswestry Disability Index score of 21-80 out of 100 at baseline with moderate to severe chronic, intractable back and/or leg pain were eligible. Evaluation visits occurred at 1, 3, 6, and 12 months post-device activation. The primary objective was to characterize change in overall pain intensity, as measured by VAS, from baseline to 3-month visit. RESULTS: Fifty-seven subjects enrolled at 12 US sites from November 2020 through June 2021, 35 were implanted with a rechargeable SCS device, and 27 completed the 12-month visit. Subjects experienced a 50.4% mean reduction in overall pain from baseline at the 3-month follow-up that was sustained through 12 months. Additional outcomes including changes in overall, back, and leg pain intensity, quality of life, disability, therapy satisfaction, safety, and current battery usage are shown through 12-month follow-up. CONCLUSION: The use of DTM endurance SCS therapy in this study resulted in reductions in pain relief through 12 months, demonstrating that energy-reducing stimulation patterns can provide clinical benefit. Clinically effective, reduced energy SCS derivatives have the potential to impact patient experience through either reduced recharge requirements or increased device longevity.

Intravenous lidocaine for refractory pain in patients with pancreatic ductal adenocarcinoma and chronic pancreatitis (LIDOPAN): a multicenter prospective non-randomized pilot study.

INTRODUCTION: Refractory pain is a major clinical problem in patients with pancreatic ductal adenocarcinoma (PDAC) and chronic pancreatitis (CP). New, effective therapies to reduce pain are urgently needed. Intravenous lidocaine is used in clinical practice in patients with PDAC and CP, but its efficacy has not been studied prospectively. METHODS: Multicentre prospective non-randomized pilot study including patients with moderate or severe pain (NRS ≥ 4) associated with PDAC or CP in 5 Dutch centers. An intravenous lidocaine bolus of 1.5mg/kg, was followed by continuous infusion at 1.5 mg/kg/hour. The dose was raised every 15 minutes until treatment response (up to a maximum 2mg/kg/hour) and consecutively administered for two hours. Primary outcome was the mean difference in pain severity, pre-infusion and the first day after (Brief Pain Inventory [BPI] scale 1-10). A BPI decrease ≥ 1.3 points was considered clinically relevant. RESULTS: Overall, 30 patients were included, 19 with PDAC (63%) and 11 with CP (37%). The mean difference in BPI at day one was 1.1 (SD±1.3) points for patients with PDAC and 0.5 (SD±1.7) for CP patients. A clinically relevant decrease in BPI on day one was reported in 9/29 patients (31%), this response lasted up to one month. No serious complications were reported, and only three minor complications (vertigo, nausea, tingling of mouth). Treatment with lidocaine did not impact quality of life. CONCLUSION: Intravenous lidocaine in patients with painful PDAC and CP did not show an overall clinically relevant reduction of pain. However, this pilot study shows that the treatment is feasible in this patient group, and had a positive effect in a third of patients which lasted up to a month with only minor side effects. To prove or exclude the efficacy of intravenous lidocaine, the study should be performed in a study with a greater sample size and less heterogeneous patient group.

Durability of Evoked Compound Action Potential (ECAP)-Controlled, Closed-Loop Spinal Cord Stimulation (SCS) in a Real-World European Chronic Pain Population.

INTRODUCTION: Closed-loop spinal cord stimulation (CL-SCS) is a recently introduced system that records evoked compound action potentials (ECAPs) from the spinal cord elicited by each stimulation pulse and uses this information to automatically adjust the stimulation strength in real time, known as ECAP-controlled SCS. This innovative system compensates for fluctuations in the distance between the epidural leads and the spinal cord by maintaining the neural response (ECAP) at a predetermined target level. This data collection study was designed to assess the performance of the first CL-SCS system in a real-world setting under normal conditions of use in multiple European centers. The study analyzes and presents clinical outcomes and electrophysiological and device data and compares these findings with those reported in earlier pre-market studies of the same system. METHODS: This prospective, multicenter, observational study was conducted in 13 European centers and aimed to gather electrophysiological and device data. The study focused on the real-world application of this system in treating chronic pain affecting the trunk and/or limbs, adhering to standard conditions of use. In addition to collecting and analyzing basic demographic information, the study presents data from the inaugural patient cohort permanently implanted at multiple European centers. RESULTS: A significant decrease in pain intensity was observed for overall back or leg pain scores (verbal numerical rating score [VNRS]) between baseline (mean ± standard error of the mean [SEM]; n = 135; 8.2 ± 0.1), 3 months (n = 93; 2.3 ± 0.2), 6 months (n = 82; 2.5 ± 0.3), and 12 months (n = 76; 2.5 ± 0.3). Comparison of overall pain relief (%) to the AVALON and EVOKE studies showed no significant differences at 3 and 12 months between the real-world data release (RWE; 71.3%; 69.6%) and the AVALON (71.2%; 73.6%) and EVOKE (78.1%; 76.7%) studies. Further investigation was undertaken to objectively characterize the physiological parameters of SCS therapy in this cohort using the metrics of percent time above ECAP threshold (%), dose ratio, and dose accuracy (µV), according to previously described methods. Results showed that a median of 90% (40.7-99.2) of stimuli were above the ECAP threshold, with a dose ratio of 1.3 (1.1-1.4) and dose accuracy of 4.4 µV (0.0-7.1), based on data from 236, 230, and 254 patients, respectively. Thus, across all three metrics, the majority of patients had objective therapy metrics corresponding to the highest levels of pain relief in previously reported studies (usage over threshold > 80%, dose ratio > 1.2, and error < 10 µV). CONCLUSIONS: In conclusion, this study provides valuable insights into the real-world application of the ECAP-controlled CL-SCS system, highlighting its potential for maintaining effective pain relief and objective neurophysiological therapy metrics at levels seen in randomized control trials, and potential for quantifying patient burden associated with SCS system use via patient-device interaction metrics. CLINICAL TRIAL REGISTRATION: In the Netherlands, the study is duly registered on the International Clinical Trials Registry Platform (Trial NL7889). In Germany, the study is duly registered as NCT05272137 and in the United Kingdom as ISCRTN27710516 and has been reviewed by the ethics committee in both countries.

Radiofrequency for chronic lumbosacral and cervical pain: Results of a consensus study using the RAND/UCLA appropriateness method.

BACKGROUND: Despite the routine use of radiofrequency (RF) for the treatment of chronic pain in the lumbosacral and cervical region, there remains uncertainty on the most appropriate patient selection criteria. This study aimed to develop appropriateness criteria for RF in relation to relevant patient characteristics, considering RF ablation (RFA) for the treatment of chronic axial pain and pulsed RF (PRF) for the treatment of chronic radicular pain. METHODS: The RAND/UCLA Appropriateness Method (RUAM) was used to explore the opinions of a multidisciplinary European panel on the appropriateness of RFA and PRF for a variety of clinical scenarios. Depending on the type of pain (axial or radicular), the expert panel rated the appropriateness of RFA and PRF for a total of 219 clinical scenarios. RESULTS: For axial pain in the lumbosacral or cervical region, appropriateness of RFA was determined by the dominant pain trigger and location of tenderness on palpation with higher appropriateness scores if these variables were suggestive of the diagnosis of facet or sacroiliac joint pain. Although the opinions on the appropriateness of PRF for lumbosacral and cervical radicular pain were fairly dispersed, there was agreement that PRF is an appropriate option for well-selected patients with radicular pain due to herniated disc or foraminal stenosis, particularly in the absence of motor deficits. The panel outcomes were embedded in an educational e-health tool that also covers the psychosocial aspects of chronic pain, providing integrated recommendations on the appropriate use of (P)RF interventions for the treatment of chronic axial and radicular pain in the lumbosacral and cervical region. CONCLUSIONS: A multidisciplinary European expert panel established patient-specific recommendations that may support the (pre)selection of patients with chronic axial and radicular pain in the lumbosacral and cervical region for either RFA or PRF (accessible via https://rftool.org). Future studies should validate these recommendations by determining their predictive value for the outcomes of (P)RF interventions.

6. Persistent spinal pain syndrome type 2.

INTRODUCTION: Persistent Spinal Pain Syndrome (PSPS) refers to chronic axial pain and/or extremity pain. Two subtypes have been defined: PSPS-type 1 is chronic pain without previous spinal surgery and PSPS-type 2 is chronic pain, persisting after spine surgery, and is formerly known as Failed Back Surgery Syndrome (FBSS) or post-laminectomy syndrome. The etiology of PSPS-type 2 can be gleaned using elements from the patient history, physical examination, and additional medical imaging. Origins of persistent pain following spinal surgery may be categorized into an inappropriate procedure (eg a lumbar fusion at an incorrect level or for sacroiliac joint [SIJ] pain); technical failure (eg operation at non-affected levels, retained disk fragment, pseudoarthrosis), biomechanical sequelae of surgery (eg adjacent segment disease or SIJ pain after a fusion to the sacrum, muscle wasting, spinal instability); and complications (eg battered root syndrome, excessive epidural fibrosis, and arachnoiditis), or undetermined. METHODS: The literature on the diagnosis and treatment of PSPS-type 2 was retrieved and summarized. RESULTS: There is low-quality evidence for the efficacy of conservative treatments including exercise, rehabilitation, manipulation, and behavioral therapy, and very limited evidence for the pharmacological treatment of PSPS-type 2. Interventional treatments such as pulsed radiofrequency (PRF) of the dorsal root ganglia, epidural adhesiolysis, and spinal endoscopy (epiduroscopy) might be beneficial in patients with PSPS-type 2. Spinal cord stimulation (SCS) has been shown to be an effective treatment for chronic, intractable neuropathic limb pain, and possibly well-selected candidates with axial pain. CONCLUSIONS: The diagnosis of PSPS-type 2 is based on patient history, clinical examination, and medical imaging. Low-quality evidence exists for conservative interventions. Pulsed radiofrequency, adhesiolysis and SCS have a higher level of evidence with a high safety margin and should be considered as interventional treatment options when conservative treatment fails.

First evidence of a biomarker-based dose-response relationship in chronic pain using physiological closed-loop spinal cord stimulation.

BACKGROUND AND OBJECTIVES: In spinal cord stimulation (SCS) therapy, electricity is the medication delivered to the spinal cord for pain relief. In contrast to conventional medication where dose is determined by desired therapeutic plasma concentration, there is lack of equivalent means of determining dose delivery in SCS. In open-loop (OL) SCS, due to the dynamic nature of the epidural space, the activating electric field delivered is inconsistent at the level of the dorsal columns. Recent Food and Drug Administration guidance suggests accurate and consistent therapy delivered using physiologic closed-loop control (PCLC) devices can minimize underdosage or overdosage and enhance medical care. PCLC-based evoked compound action potential (ECAP)-controlled technology provides the ability to prescribe a precise stimulation dose unique to each patient, continuously measure neural activation, and objectively inform SCS therapy optimization. METHODS: Neurophysiological indicator metrics of therapy dose, usage above neural activation threshold, and accuracy of SCS therapy were assessed for relationship with pain reduction in over 600 SCS patients. RESULTS: Significant relationships between objective metrics and pain relief across the patient population are shown, including first evidence for a dose-response relationship in SCS. CONCLUSIONS: Higher dose, more time over ECAP threshold, and higher accuracy are associated with better outcomes across patients. There is potential to optimize individual patient outcomes based on unique objective measurable electrophysiological inputs.

Cooled versus conventional radiofrequency treatment of the genicular nerves for chronic knee pain: 12-month and cost-effectiveness results from the multicenter COCOGEN trial.

BACKGROUND: Radiofrequency (RF) treatment of the genicular nerves reduces chronic knee pain in patients with osteoarthritis (OA) or persistent postsurgical pain (PPSP) after total knee arthroplasty (TKA). The objective of this study is to compare long-term outcomes of cooled and conventional RF and perform an economic evaluation. METHODS: The COCOGEN trial is a double-blinded, non-inferiority, pilot, randomized controlled trial that compared the effects up to 12 months of cooled and conventional RF in patients with chronic knee pain suffering from OA or PPSP after TKA following a 1:1 randomization rate. Outcomes were knee pain, functionality, quality of life, emotional health, medication use, and adverse events. A trial-based economic evaluation was performed with a 12-month societal perspective. Here, the primary outcome was the incremental costs per quality-adjusted life year (QALY). RESULTS: 41 of the 49 included patients completed the 12-month follow-up. One patient in the PPSP cooled RF group had substantial missing data at 12-month follow-up. The proportion of patients with ≥50% pain reduction at 12 months was 22.2% (4/18) in patients treated with conventional RF versus 22.7% (5/22) in patients treated with cooled RF (p>0.05). There was a statistically significant difference in the mean absolute numerical rating scale at 12 months after cooled RF and conventional RF in patients with PPSP (p=0.02). Differences between other outcomes were not statistically significant. The health economic analysis indicated that cooled RF resulted in lower costs and improved QALYs compared with conventional RF in PPSP but not in OA. There were no serious adverse events. CONCLUSIONS: Both RF treatments demonstrated in approximately 22% of patients a ≥50% pain reduction at 12 months. In patients with PPSP, contrary to OA, cooled RF seems to be more effective than conventional RF. Additionally, cooled RF has in patients with PPSP, as opposed to OA, greater effectiveness at lower costs compared with conventional RF. TRIAL REGISTRATION NUMBER: NCT03865849.

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

Aim: Visceral pain, characterized by pain that is diffuse and challenging to localize, occurs frequently and is difficult to treat. In cases where the pain becomes intractable despite optimal medical management, it can affect patients' Quality of Life (QoL). Spinal Cord Stimulation (SCS) has emerged as a potential solution for intractable visceral pain. Purpose: In this narrative review, we collected all evidence regarding the efficacy of SCS for visceral pain across various underlying conditions. Methods: A comprehensive literature search was conducted in PubMed, Embase, and Web of Science in which articles published from October 1st, 1963 up to March 7th, 2023 were identified. Results: Seventy articles were included in this review of which most were retrospective cohort studies, case series and case reports. The studies, often with a small number of participants, reported on SCS for chronic pancreatitis, anorectal pain and bowel disorders, gynaecological diagnoses, visceral pelvic pain, urological disorders and finally general visceral pain. They found positive effects on pain and/or symptom relief, opioid consumption, anxiety and depression and QoL. Complications occurred frequently but were often minor and reversible. Conclusion: Better screening and selection criteria need to be established to optimally evaluate eligible patients who might benefit from SCS. A positive outcome of a sympathetic nerve block appears to be a potential indicator of SCS effectiveness. Additionally, women receiving SCS for endometriosis had a better outcome compared to other indications. Finally, SCS could also relief functional symptoms such as voiding problems and gastroparesis. Complications could often be resolved with revision surgery. Since SCS is expensive and not always covered by standard health insurance, the incorporation of cost-analyses is recommended. In order to establish a comprehensive treatment plan, including selection criteria for SCS, rigorous prospective, possibly randomized and controlled studies that are diagnosis-oriented, with substantial follow-up and adequate sample sizes, are needed.

Introduction of a Post-Anaesthesia Care Unit in a Teaching Hospital Is Associated with a Reduced Length of Hospital Stay in Noncardiac Surgery: A Single-Centre Interrupted Time Series Analysis.

BACKGROUND: A post-anaesthesia care unit (PACU) may improve postoperative care compared with intermediate care units (IMCU) due to its dedication to operative care and an individualized duration of postoperative stay. The effects of transition from IMCU to PACU for postoperative care following intermediate to high-risk noncardiac surgery on length of hospital stay, intensive care unit (ICU) utilization, and postoperative complications were investigated. METHODS: This single-centre interrupted time series analysis included patients undergoing eleven different noncardiac surgical procedures associated with frequent postoperative admissions to an IMCU or PACU between January 2018 and March 2019 (IMCU episode) and between October 2019 and December 2020 (PACU episode). Primary outcome was hospital length of stay, secondary outcomes included postoperative complications and ICU admissions. RESULTS: In total, 3300 patients were included. The hospital length of stay was lower following PACU admission compared to IMCU admission (IMCU 7.2 days [4.2-12.0] vs. PACU 6.0 days [3.6-9.1]; p < 0.001). Segmented regression analysis demonstrated that the introduction of the PACU was associated with a decrease in hospital length of stay (GMR 0.77 [95% CI 0.66-0.91]; p = 0.002). No differences between episodes were detected in the number of postoperative complications or postoperative ICU admissions. CONCLUSIONS: The introduction of a PACU for postoperative care of patients undergoing intermediate to high-risk noncardiac surgery was associated with a reduction in the length of stay at the hospital, without increasing postoperative complications.

3. Pain originating from the lumbar facet joints.

INTRODUCTION: Pain originating from the lumbar facets can be defined as pain that arises from the innervated structures comprising the joint: the subchondral bone, synovium, synovial folds, and joint capsule. Reported prevalence rates range from 4.8% to over 50% among patients with mechanical low back pain, with diagnosis heavily dependent on the criteria employed. In well-designed studies, the prevalence is generally between 10% and 20%, increasing with age. METHODS: The literature on the diagnosis and treatment of lumbar facet joint pain was retrieved and summarized. RESULTS: There are no pathognomic signs or symptoms of pain originating from the lumbar facet joints. The most common reported symptom is uni- or bilateral (in more advanced cases) axial low back pain, which often radiates into the upper legs in a non-dermatomal distribution. Most patients report an aching type of pain exacerbated by activity, sometimes with morning stiffness. The diagnostic value of abnormal radiologic findings is poor owing to the low specificity. SPECT can accurately identify joint inflammation and has a predictive value for diagnostic lumbar facet injections. After "red flags" are ruled out, conservatives should be considered. In those unresponsive to conservative therapy with symptoms and physical examination suggesting lumbar facet joint pain, a diagnostic/prognostic medial branch block can be performed which remains the most reliable way to select patients for radiofrequency ablation. CONCLUSIONS: Well-selected individuals with chronic low back originating from the facet joints may benefit from lumbar medial branch radiofrequency ablation.

Lead migration rate in dorsal root ganglion stimulation using lead anchoring techniques: A follow-up study.

BACKGROUND: Lead anchoring has previously been shown to reduce the rate of dorsal root ganglion stimulation (DRG-S) lead migration. The aim of this study was to assess longer-term follow-up and consistency of lead migration prevention with lead anchoring in a new cohort of patients. METHODS: We performed a retrospective chart review from September 2017 to November 2022 of all patients who had DRG-S implants at our institute to identify the number of lead migrations that occurred over this period. The first cohort consisted of patients reported on in a previous publication (implanted from September 2017 through September 2020) subdivided into unanchored or anchored lead groups. The second cohort consisted of patients implanted during or after October 2020 who were not previously reported on for whom leads were anchored using silastic anchoring only. RESULTS: At the November 2022 data cutoff, in the initial cohort, 8 migrations had occurred in unanchored leads over an average follow-up of 49 months, equating to a migration rate of 9.1% per lead. Patients with anchored leads in the initial cohort experienced 2 migrations over an average follow-up of 38 months (0.7% migration rate per lead). There were no new lead migrations in these groups over the extended follow-up reported here. The migration rate in the new cohort was similar, with 1 migration over an average follow-up of 13 months (0.5% migration rate per lead). CONCLUSION: These results underscore the necessity of anchor placement during DRG-S lead implantation to prevent lead migration.

Durable multimodal and holistic response for physiologic closed-loop spinal cord stimulation supported by objective evidence from the EVOKE double-blind randomized controlled trial.

INTRODUCTION: Chronic pain patients may experience impairments in multiple health-related domains. The design and interpretation of clinical trials of chronic pain interventions, however, remains primarily focused on treatment effects on pain intensity. This study investigates a novel, multidimensional holistic treatment response to evoked compound action potential-controlled closed-loop versus open-loop spinal cord stimulation as well as the degree of neural activation that produced that treatment response. METHODS: Outcome data for pain intensity, physical function, health-related quality of life, sleep quality and emotional function were derived from individual patient level data from the EVOKE multicenter, participant, investigator, and outcome assessor-blinded, parallel-arm randomized controlled trial with 24 month follow-up. Evaluation of holistic treatment response considered whether the baseline score was worse than normative values and whether minimal clinical important differences were reached in each of the domains that were impaired at baseline. A cumulative responder score was calculated to reflect the total minimal clinical important differences accumulated across all domains. Objective neurophysiological data, including spinal cord activation were measured. RESULTS: Patients were randomized to closed-loop (n=67) or open-loop (n=67). A greater proportion of patients with closed-loop spinal cord stimulation (49.3% vs 26.9%) were holistic responders at 24-month follow-up, with at least one minimal clinical important difference in all impaired domains (absolute risk difference: 22.4%, 95% CI 6.4% to 38.4%, p=0.012). The cumulative responder score was significantly greater for closed-loop patients at all time points and resulted in the achievement of more than three additional minimal clinical important differences at 24-month follow-up (mean difference 3.4, 95% CI 1.3 to 5.5, p=0.002). Neural activation was three times more accurate in closed-loop spinal cord stimulation (p<0.001 at all time points). CONCLUSION: The results of this study suggest that closed-loop spinal cord stimulation can provide sustained clinically meaningful improvements in multiple domains and provide holistic improvement in the long-term for patients with chronic refractory pain. TRIAL REGISTRATION NUMBER: NCT02924129.

1. Lumbosacral radicular pain.

INTRODUCTION: Patients suffering lumbosacral radicular pain report radiating pain in one or more lumbar or sacral dermatomes. In the general population, low back pain with leg pain extending below the knee has an annual prevalence that varies from 9.9% to 25%. METHODS: The literature on the diagnosis and treatment of lumbosacral radicular pain was reviewed and summarized. RESULTS: Although a patient's history, the pain distribution pattern, and clinical examination may yield a presumptive diagnosis of lumbosacral radicular pain, additional clinical tests may be required. Medical imaging studies can demonstrate or exclude specific underlying pathologies and identify nerve root irritation, while selective diagnostic nerve root blocks can be used to confirm the affected level(s). In subacute lumbosacral radicular pain, transforaminal corticosteroid administration provides short-term pain relief and improves mobility. In chronic lumbosacral radicular pain, pulsed radiofrequency (PRF) treatment adjacent to the spinal ganglion (DRG) can provide pain relief for a longer period in well-selected patients. In cases of refractory pain, epidural adhesiolysis and spinal cord stimulation can be considered in experienced centers. CONCLUSIONS: The diagnosis of lumbosacral radicular pain is based on a combination of history, clinical examination, and additional investigations. Epidural steroids can be considered for subacute lumbosacral radicular pain. In chronic lumbosacral radicular pain, PRF adjacent to the DRG is recommended. SCS and epidural adhesiolysis can be considered for cases of refractory pain in specialized centers.

Burst Spinal Cord Stimulation as Compared With L2 Dorsal Root Ganglion Stimulation in Pain Relief for Nonoperated Discogenic Low Back Pain: Analysis of Two Prospective Studies.

INTRODUCTION: Chronic discogenic low back pain (CD-LBP) is caused by degenerated disks marked by neural and vascular ingrowth. Spinal cord stimulation (SCS) has been shown to be effective for pain relief in patients who are not responsive to conventional treatments. Previously, the pain-relieving effect of two variations of SCS has been evaluated in CD-LBP: Burst SCS and L2 dorsal root ganglion stimulation (DRGS). The aim of this study is to compare the effectivity in pain relief and pain experience of Burst SCS with that of conventional L2 DRGS in patients with CD-LBP. MATERIALS AND METHODS: Subjects were implanted with either Burst SCS (n = 14) or L2 DRGS with conventional stimulation (n = 15). Patients completed the numeric pain rating score (NRS) for back pain and Oswestry disability index (ODI) and EuroQoL 5D (EQ-5D) questionnaires at baseline, and at three, six, and 12 months after implantation. Data were compared between time points and between groups. RESULTS: Both Burst SCS and L2 DRGS significantly decreased NRS, ODI, and EQ-5D scores as compared with baseline. L2 DRGS resulted in significantly lower NRS scores at 12 months and significantly increased EQ-5D scores at six and 12 months. CONCLUSIONS: Both L2 DRGS and Burst SCS resulted in reduction of pain and disability, and increased quality of life in patients with CD-LBP. L2 DRGS provided significantly increased pain relief and improvement in quality of life when compared with Burst SCS. CLINICAL TRIAL REGISTRATION: The clinical trial registration numbers for the study are NCT03958604 and NL54405.091.15.

5. Sacroiliac joint pain.

INTRODUCTION: Sacroiliac (SI) joint pain is defined as pain localized in the anatomical region of the SI joint. The reported prevalence of SI joint pain among patients with mechanical low back pain varies between 15% and 30%. METHODS: In this narrative review, the literature on the diagnosis and treatment of SI joint pain was updated and summarized. RESULTS: Patient's history provides clues on the source of pain. The specificity and sensitivity of provocative maneuvers are relatively high when three or more tests are positive, though recent studies have questioned the predictive value of single or even batteries of provocative tests. Medical imaging is indicated only to rule out red flags for potentially serious conditions. The diagnostic value of SI joint infiltration with local anesthetic remains controversial due to the potential for false-positive and false-negative results. Treatment of SI joint pain ideally consists of a multidisciplinary approach that includes conservative measures as first-line therapies (eg, pharmacological treatment, cognitive-behavioral therapy, manual medicine, exercise therapy and rehabilitation treatment, and if necessary, psychological support). Intra- and extra-articular corticosteroid injections have been documented to produce pain relief for over 3 months in some people. Radiofrequency ablation (RFA) of the L5 dorsal ramus and S1-3 (or 4) lateral branches has been shown to be efficacious in numerous studies, with extensive lesioning strategies (eg, cooled RFA) demonstrating the strongest evidence. The reported rate of complications for SI joint treatments is low. CONCLUSIONS: SI joint pain should ideally be managed in a multidisciplinary and multimodal manner. When conservative treatment fails, corticosteroid injections and radiofrequency treatment can be considered.