Impact of Long-Term Evoked Compound Action Potential Controlled Closed-Loop Spinal Cord Stimulation on Sleep Quality in Patients With Chronic Pain: An EVOKE Randomized Controlled Trial Study Subanalysis.

OBJECTIVE: Spinal cord stimulation (SCS) is considered an effective interventional nonpharmacologic treatment option for several chronic pain conditions. Here we present the effects of the novel evoked compound action potential (ECAP) controlled closed-loop (ECAP-CL) SCS system on long-term sleep quality outcomes from the EVOKE study. MATERIALS AND METHODS: The EVOKE study is a double-blind, randomized, controlled clinical trial conducted at 13 sites in the United States (N = 134 patients). The clinical trial utilized SCS to manage chronic pain and compared novel ECAP-CL technology to open-loop SCS. Additionally, sleep quality data was collected using the Pittsburgh Sleep Quality Index (PSQI) at baseline and all study visits. RESULTS: The mean PSQI global score for ECAP-CL patients at baseline was 14.0 (n = 62; ± 0.5, SD 3.8), indicating poor sleep quality. Clinically meaningful and statistically significant reductions (p < 0.001) in the global PSQI scores were noted at 12 months (n = 55; 5.7 ± 0.6, SD 4.2). A total of 76.4% of ECAP-CL patients met or exceeded Minimal Clinically Important Difference from baseline in PSQI at 12 months. Additionally, 30.9% of ECAP-CL patients achieved "good sleep quality" scores (PSQI ≤ 5), and 29.1% achieved sleep quality remission. "Normative" sleep scores were observed in 29.6% of ECAP-CL patients at 12 months, and these scores were better than the US general population. Additionally, ECAP-CL patients achieved statistically significant changes from baseline (p < 0.01) across all seven subcomponent scores of PSQI at 12 months. CONCLUSIONS: ECAP-CL SCS elicits consistent neural activation of the target leading to less variability in long-term therapy delivery. In the EVOKE study, this resulted in ECAP-CL patients demonstrating clinically superior and sustained pain relief. Results from this study provide new evidence of long-term improvement in sleep quality and quantity in patients with chronic pain resulting from the use of this novel ECAP-CL SCS technology. CLINICAL TRAIL REGISTRATION: The Clinicaltrials.gov registration number for the study is NCT02924129.

Holistic Treatment Response: An International Expert Panel Definition and Criteria for a New Paradigm in the Assessment of Clinical Outcomes of Spinal Cord Stimulation.

BACKGROUND: Treatment response to spinal cord stimulation (SCS) is focused on the magnitude of effects on pain intensity. However, chronic pain is a multidimensional condition that may affect individuals in different ways and as such it seems reductionist to evaluate treatment response based solely on a unidimensional measure such as pain intensity. AIM: The aim of this article is to add to a framework started by IMMPACT for assessing the wider health impact of treatment with SCS for people with chronic pain, a "holistic treatment response". DISCUSSION: Several aspects need consideration in the assessment of a holistic treatment response. SCS device data and how it relates to patient outcomes, is essential to improve the understanding of the different types of SCS, improve patient selection, long-term clinical outcomes, and reproducibility of findings. The outcomes to include in the evaluation of a holistic treatment response need to consider clinical relevance for patients and clinicians. Assessment of the holistic response combines two key concepts of patient assessment: (1) patients level of baseline (pre-treatment) unmet need across a range of health domains; (2) demonstration of patient-relevant improvements in these health domains with treatment. The minimal clinical important difference (MCID) is an established approach to reflect changes after a clinical intervention that are meaningful for the patient and can be used to identify treatment response to each individual domain. A holistic treatment response needs to account for MCIDs in all domains of importance for which the patient presents dysfunctional scores pre-treatment. The number of domains included in a holistic treatment response may vary and should be considered on an individual basis. Physiologic confirmation of therapy delivery and utilisation should be included as part of the evaluation of a holistic treatment response and is essential to advance the field of SCS and increase transparency and reproducibility of the findings.

Recommendations to standardize patients' follow-up after interventional procedures in chronic pain treatment: A Delphi study.

OBJECTIVE: To determine, using the Delphi method, standardized recommendations for the follow-up of patients undergoing an interventional procedure for the treatment of chronic pain in Spain. METHODS: First, a systematic literature review was performed to identify the literature on the management of patients with chronic pain undergoing interventional techniques; subsequently, a two-round Delphi survey with 108 questions was conducted. The questionnaire was validated by a Scientific Committee (5 experts) and sent to 47 experts specialized in chronic pain. "Consensus" or "intermediate consensus" was determined when ≥ 75% or < 75% to ≥ 65% of the experts selected the same answer for each item, respectively. Then, a face-to-face deliberation process was held with the Scientific Committee to analyze and discuss the results. RESULTS: The questionnaire was completed by 24 panelists (51%). Consensus was reached on 88.4% of the questions. The panelists identified pain, drug consumption, and quality of life as essential variables in the follow-up of patients with chronic pain. Consensus was reached on most of the scales/questionnaires to be used in measuring outcomes during follow-up, except for psychological status. Regarding the follow-up frequency, in radicular spinal chronic pain, a consensus was reached on the first visit 1-2 months after the intervention, during the first year, at 1, 3, 6, and 12 months, and then every 6 months thereafter. For non-radicular spinal chronic pain, the first visit 1-2 months after surgery was agreed upon, however, there was no consensus on follow-up during the first year. For non-spinal chronic pain, consensus was reached regarding the first visit at 1-2 months after surgery and during the first year at 1, 3, 6, and 12 months. No consensus was reached on follow-up frequency for oncological chronic pain. After receiving a permanent neurostimulator implant for chronic pain, the first visit was agreed upon at 1-3 weeks, during the first year, at 2 weeks, 1, 3, 6, and 12 months, and after, every 6 months. For intrathecal infusion, it was agreed that the first visit should occur during the first month, and thereafter whenever the pump requires a refill. CONCLUSIONS: These findings provide recommendations in relation to the frequency of follow-up and the scales to be used with chronic pain patients undergoing interventional techniques in Spain.

Randomized Prospective Study in Patients With Complex Regional Pain Syndrome of the Upper Limb With High-Frequency Spinal Cord Stimulation (10-kHz) and Low-Frequency Spinal Cord Stimulation.

OBJECTIVE: The objective of this prospective randomized study of cases and controls was to evaluate the efficacy of treatment with low-frequency spinal cord stimulation (LF-SCS) and 10 kHz spinal cord stimulation (10-kHz SCS) in patients diagnosed with complex regional pain syndrome type I (CRPS) with upper limb involvement. MATERIALS AND METHODS: Fifty patients were randomized to receive conventional treatment or SCS with a commercially available low-frequency or 10-kHz system. Patients were assessed at 1, 3, 6, and 12 months. The primary endpoint was at 12-months post permanent implantation of the SCS devices. Outcome measures assessed included: Numerical Rating Scale (NRS), 12-Item Short-Format Health Survey (SF-12), Oswestry Disability Index (ODI), Study Sleep Scale medical outcomes (MOS-SS), Douleur Neuropathique 4 questions pain questionnaire (DN4), Patient Global Impression Scale on the impact of treatment improvement (PGI-I), Clinician Global Impression Scale on the impact of improving the patient (CGI-I). RESULTS: Forty-one patients were finally included in the analysis, 19 patients in the conventional treatment group, 12 in the LF-SCS group, and 10 in the 10-kHz SCS group. At the primary endpoint, patients treated with LF-SCS presented improvements in the NRS and DN4 outcomes around 2.4 and 1.5 times above the minimal clinically important difference (MCID) thresholds. At the primary endpoint, patients treated with 10-kHz SCS presented improvements in the NRS and DN4 outcomes around 2 and 1.4 times above the MCID thresholds. CONCLUSIONS: Patients experienced considerable improvement after SCS. The results show that LF-SCS has very good results when compared with conventional treatment. The results obtained with 10-kHz SCS are encouraging, with the advantages of the absence of paresthesia making it an alternative in the treatment of CRPS.

How to Restart the Interventional Activity in the COVID-19 Era: The Experience of a Private Pain Unit in Spain.

INTRODUCTION: The situation generated in the health system by the COVID-19 pandemic has provoked a crisis involving the necessity to cancel non-urgent and oncologic activity in the operating room and in day-to-day practice. As the situation continues, the need to reinstate attention for patients with chronic pain grows. The restoration of this activity has to begin with on-site appointments and possible surgical procedures. On-site clinical activity has to guarantee the safety of patients and health workers. OBJECTIVES: The objective of this review was to evaluate how to manage activity in pain units, considering the scenario generated by the pandemic and the implications of chronic pain on the immune system and proposed pharmacological and interventional therapies. METHODS: Besides the established general recommendations (physical distance, surgical masks, gloves, etc.), we established specific recommendations that will allow patient treatment and relieve the disruption of the immune response. It is important to highlight the use of opioids with the least influence in the immune system. Further, individualized corticoid use, risk assessment, reduced immune suppression, and dose adjustment should take patient needs into account. In this scenario, we highlight the use of radiofrequency and neuromodulation therapies, techniques that do not interfere with the immune response. CONCLUSIONS: We describe procedures to implement these recommendations for individual clinical situations, the therapeutic possibilities and safety guidelines for each center, and government recommendations during the COVID-19 pandemic.

Threshold Evolution as an Analysis of the Different Pulse Frequencies in Rechargeable Systems for Spinal Cord Stimulation.

INTRODUCTION: Pulse frequency (Fc) is one of the most important parameters in neurostimulation, with Pulse Amplitude (Pw) and Amplitude (I). Up to certain Fc, increasing the number of pulses will generate action potentials in neighboring neural structures and may facilitate deeper penetration of the electromagnetic fields. In addition, changes in frequency modify the patient's sensation with stimulation. MATERIALS/METHODS: Fifty patients previously implanted with rechargeable current control spinal cord stimulation. With pulse width fixed at 300 µsec, we stimulated at 26 different Fc values between 40 and 1200 Hz and determine the influence of these changes on different stimulation thresholds: perception threshold (Tp ), therapeutic perception (Tt), and discomfort threshold (Td). Simultaneously, paresthesia coverage of the painful area and patient's sensation and satisfaction related to the quality of stimulation were recorded. RESULTS: Pulse Fc is inversely proportional to stimulation thresholds and this influence is statistically significant (p < 0.05). As Pulse Fc increased from 40 to 1200 Hz, the mean threshold decreases from 7.25 to 1.38 mA (Tp ), 8.17 to 1.63 (Tt ), and 9.20 to 1.85 (Td). Significant differences for Tp and Tt began at 750 Hz (Tp , Tt ) and at 650 Hz for Td. No significant influence was found regarding paresthesia coverage. As expected, Fc affects significantly patient's sensation and satisfaction. DISCUSSION: Changes in Fc affect the quality of paresthesias. Within the evaluated parameters higher frequencies are inversely proportional to stimulation thresholds and Tt. It seems that Fc is a vital parameter to achieve therapeutic success. CONCLUSIONS: Changes in Fc is a useful parameter to modulate the patient's sensory perception. Fc can be successfully used to adjust the quality of the paresthesias and to modify patient's subjective sensation. We showed that as the frequency increases, the patient's satisfaction with the perceived sensation decreases, suggesting that higher Fc may need to be set up at subthreshold amplitude to achieve positive response.

Is the introduction of another variable to the strength-duration curve necessary in neurostimulation?

INTRODUCTION: Neurostimulation is the process and technology derived from the application of electricity with different parameters to activate or inhibit nerve pathways. Pulse width (Pw) is the duration of each electrical impulse and, along with amplitude (I), determines the total energy charge of the stimulation. OBJECTIVES: The aim of the study was to test Pw values to find the most adequate pulse widths in rechargeable systems to obtain the largest coverage of the painful area, the most comfortable paresthesia, and the greatest patient satisfaction. MATERIAL AND METHODS: A study of the parameters was performed, varying Pw while maintaining a fixed frequency at 50 Hz. Data on perception threshold (Tp ), discomfort threshold (Td ), and therapeutic threshold (Tt ) were recorded, applying 14 increasing Pw values ranging from 50 µsec to 1000 µsec. Lastly, the behavior of the therapeutic range (TR), the coverage of the painful area, the subjective patient perception of paresthesia, and the degree of patient satisfaction were assessed. RESULTS: The findings after analyzing the different thresholds were as follows: When varying the Pw, the differences obtained at each threshold (Tp , Tt , and Td ) were statistically significant (p < 0.05). The differences among the resulting Tp values and among the resulting Tt values were statistically significant when varying Pw from 50 up to 600 µsec (p < 0.05). For Pw levels 600 µsec and up, no differences were observed in these thresholds. In the case of Td , significant differences existed as Pw increased from 50 to 700 µsec (p ≤ 0.05). The coverage increased in a statistically significant way (p < 0.05) from Pw values of 50 µsec to 300 µsec. Good or very good subjective perception was shown at about Pw 300 µsec. CONCLUSIONS: The patient paresthesia coverage was introduced as an extra variable in the chronaxie-rheobase curve, allowing the adjustment of Pw values for optimal programming. The coverage of the patient against the current chronaxie-rheobase formula will be represented on three axes; an extra axis (z) will appear, multiplying each combination of Pw value and amplitude by the percentage of coverage corresponding to those values. Using this new comparison of chronaxie-rheobase curve vs. coverage, maximum Pw values will be obtained different from those obtained by classic methods.

Improving patient experience with spinal cord stimulation: implications of position-related changes in neurostimulation.

OBJECTIVES: The objective of this narrative review is to discuss the clinical implications of position-related changes in spinal cord stimulation and technological improvements to better meet patient needs. METHODS: Keywords applicable to spinal cord stimulation therapy, including paresthesia perception, spinal cord position, lead impedance, and sensor technologies, were searched in the PubMed, EMBASE, and Cochrane Library databases. Literature analysis, combined with extensive clinical experience with spinal cord stimulation therapy, forms the basis of this review. RESULTS: Fluctuations in paresthesia perception are largely caused by variation in the distance between the fixed electrodes and the spinal cord consequent to patient movement. Patients employ multiple strategies with varying success to manage position-related fluctuations in stimulation perception, which may result in suboptimum therapy delivery. CONCLUSIONS: A new type of spinal cord stimulation system that incorporates accelerometer technology to automatically adjust stimulation amplitude based on patient position may better meet patient analgesic needs and is in early clinical application.

The appropriate use of neurostimulation of the spinal cord and peripheral nervous system for the treatment of chronic pain and ischemic diseases: the Neuromodulation Appropriateness Consensus Committee.

INTRODUCTION: The Neuromodulation Appropriateness Consensus Committee (NACC) of the International Neuromodulation Society (INS) evaluated evidence regarding the safety and efficacy of neurostimulation to treat chronic pain, chronic critical limb ischemia, and refractory angina and recommended appropriate clinical applications. METHODS: The NACC used literature reviews, expert opinion, clinical experience, and individual research. Authors consulted the Practice Parameters for the Use of Spinal Cord Stimulation in the Treatment of Neuropathic Pain (2006), systematic reviews (1984 to 2013), and prospective and randomized controlled trials (2005 to 2013) identified through PubMed, EMBASE, and Google Scholar. RESULTS: Neurostimulation is relatively safe because of its minimally invasive and reversible characteristics. Comparison with medical management is difficult, as patients considered for neurostimulation have failed conservative management. Unlike alternative therapies, neurostimulation is not associated with medication-related side effects and has enduring effect. Device-related complications are not uncommon; however, the incidence is becoming less frequent as technology progresses and surgical skills improve. Randomized controlled studies support the efficacy of spinal cord stimulation in treating failed back surgery syndrome and complex regional pain syndrome. Similar studies of neurostimulation for peripheral neuropathic pain, postamputation pain, postherpetic neuralgia, and other causes of nerve injury are needed. International guidelines recommend spinal cord stimulation to treat refractory angina; other indications, such as congestive heart failure, are being investigated. CONCLUSIONS: Appropriate neurostimulation is safe and effective in some chronic pain conditions. Technological refinements and clinical evidence will continue to expand its use. The NACC seeks to facilitate the efficacy and safety of neurostimulation.

The appropriate use of neurostimulation: avoidance and treatment of complications of neurostimulation therapies for the treatment of chronic pain. Neuromodulation Appropriateness Consensus Committee.

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

Confirmatory study of the usefulness of quantum molecular resonance and microdissectomy for the treatment of lumbar radiculopathy in a prospective cohort at 6 months follow-up.

OBJECTIVES: Low back pain is a common musculoskeletal complaint and while prognosis is usually favorable, some patients experience persistent pain despite conservative treatment and invasive treatment to target the root cause of the pain may be necessary. The aim of this study is to evaluate patient outcomes after treatment of lumbar radiculopathy (LR) with quantum molecular resonance radiofrequency coblation disc decompression and percutaneous microdiscectomy with grasper forceps (QMRG). METHODS: This prospective cohort study was carried out in two Spanish hospitals on 58 patients with LR secondary to a contained hydrated lumbar disc hernia or lumbar disc protrusion of more than 6 months of evolution, which persisted despite conservative treatment with analgesia, rehabilitation, and physiotherapy, and/or epidural block, in the previous 2 years. Patients were treated with QMRG and the outcomes were measured mainly using the Douleur Neuropathique en 4 Questions, Numeric Rating Scale, Oswestry Disability Index, SF12: Short Form 12 Health Survey, Patient Global Impression of Improvement, Clinical Global Impression of Improvement, and Medical Outcomes Study Sleep Scale. RESULTS: Patients who received QMRG showed significant improvement in their baseline scores at 6 months post-treatment. The minimal clinically important difference (MCID) threshold was met by 26-98% of patients, depending on the outcome measure, for non-sleep-related outcomes, and between 17 and 62% for sleep-related outcome measures. Of the 14 outcome measures studied, at least 50% of the patients met the MCID threshold in 8 of them. CONCLUSION: Treatment of LR with QMRG appears to be effective at 6 months post-intervention.

Quantum Molecular Resonance Radiofrequency Disc Decompression and Percutaneous Microdiscectomy for Lumbar Radiculopathy.

Within the practice of pain management, one of the most commonly encountered events is low back pain. Lumbar radiculopathy (LR) is a pain syndrome caused by the compression or irritation of the nerve roots in the lower back due to lumbar disc herniation, vertebra degeneration, or foramen narrowing. Symptoms of LR include low back pain that propagates toward the legs, numbness, weakness, and loss of reflexes. The aim of this study is to assess the long-term effectiveness of quantum molecular resonance disc decompression and its combination with a percutaneous microdiscectomy using Grasper© forceps (QMRG) in patients with persistent lumbar radiculopathy (LR) in relation to patient physical stress status. The main outcome measures of this prospective observational study were DN4, NRS, ODI, SF12, PGI, CGI, and MOS Sleep Scale. An improvement 12 months post-intervention was observed in patients without physical stress, presenting better overall results. The mean change was over the minimal clinically important difference in 64.3% of outcome measures studied for the whole sample. QMRG appears to be an effective treatment option for LR, but a reduction in physical stress is needed to ensure long-term effectiveness.

Real-world outcomes of single-stage spinal cord stimulation in chronic pain patients: A multicentre, European case series.

Background: Spinal cord stimulation (SCS) is effective in treating chronic neuropathic pain. A screening trial is typically conducted prior to implantation to evaluate whether a patient is a good candidate for SCS. However, the need for a screening trial has been debated. We evaluated real-world clinical outcomes in patients who underwent a single-stage procedure to receive SCS therapy (i.e., no screening trial period) (SS-SCS). Methods: This observational, multicentre, real-world consecutive case series evaluated SS-SCS chronic pain patients. Pain and other functional outcomes were collected as part of standard care by site personnel with no sponsor involvement. Assessments included Numerical rating scale (NRS), Percent Pain Relief (PPR) and EQ-5D-5L (EuroQol 5 Dimensions-5L), recorded prior to SCS and following implantation. Results: A total of 171 chronic pain patients (mean age: 59.4; 53.2% females) underwent a single-stage procedure (mean last follow-up, 408 days) and were included in the analysis. A 5.0 â€‹± â€‹2.1-point improvement in overall pain was reported at 3 months and sustained until the last follow-up post-implantation (p â€‹< â€‹0.0001). At last follow-up, 50.3% (86/171) of patients reported an NRS pain score ≤3. Additionally, quality of life also improved (46.1-point change, from 70.2 to 25) at the last follow-up, based on EQ-5D-5L scores. Conclusions: In routine clinical practice, SS-SCS can provide significant long-term pain relief and improve quality of life in chronic pain patients. Our results suggest that effective long-term outcomes and success may be achieved without a trial period prior to permanent implantation of an SCS system.

Subcutaneous stimulation: how to assess optimal implantation depth.

INTRODUCTION: Subcutaneous stimulation (peripheral nerve field stimulation) is a novel neuromodulation modality that has increased in its utilization during the last 10 years. It consists of introducing a lead in the subdermal level to stimulate the small nerve fibers in that layer. Unlike other neuromodulation techniques including direct peripheral nerve stimulation, spinal cord stimulation, or deep brain stimulation, the precise target is not identified. MATERIALS AND METHODS: To date, there is no clear guideline on the appropriate depth or a method to achieve reproducibility of the appropriate depth to place these leads. From clinical experience, we have found that when electrodes are placed in a layer that is too superficial, stimulation is often painful or lacks efficacy. Further, if they are too deep, the patient may not feel adequate paresthesia or get uncomfortable stimulation including, in some circumstances, muscle contractions. RESULTS: In this small series, we demonstrate a novel concept using a radiofrequency stimulation probe to identify the appropriate depth to place the lead. Reproducibility of results will add clarity to the accumulating data and hopefully increase the chances of adequate stimulation coverage and pain relief.

Real-World Outcomes Using a Spinal Cord Stimulation Device Capable of Combination Therapy for Chronic Pain: A European, Multicenter Experience.

Given the differing mechanisms thought to underlie therapeutic sub- and supra-perception-based neurostimulative modalities, Spinal Cord Stimulation (SCS) systems designed for combined delivery of these approaches may help improve analgesic outcomes and quality of life, and reduce treatment failures. This multicenter, observational case-series evaluated 188 patients with chronic back and/or leg pain implanted with an SCS device capable of sequential or simultaneous delivery of sub-perception and supra-perception stimulation programming (i.e., combination therapy) at 16 in Europe. Following implantation, patients were provided with an array of advanced supra-perception programs (e.g., paresthesia-based SCS using multiple independent current sources), and a custom set of sub-perception programs optimized with specific waveforms and/or field shapes. A mean overall pain score of 7.9 ± 1.7 (Standard Deviation (SD)) was reported pre-trial (Baseline). Overall pain was reduced by 4.4 ± 2.8 points (NRS) at 3-months (n = 117) and at 12 months post-implant (n = 90), respectively (p < 0.0001). Substantial quality-of-life (EQ-5D-5L) improvement as assessed at last follow-up was also observed (n = 60). These results suggest that an implanted SCS device capable of combination therapy, while also enabled with patient-specific waveform optimization and stimulation field targeting capabilities, can enable highly effective pain relief and improve quality of life in patients suffering with chronic pain.

Electric parameters optimization in spinal cord stimulation. Study in conventional nonrechargeable systems.

BACKGROUND: Spinal cord stimulation devices provide a means of creating an electric field. The parameters used to produce this electric field are: pulse amplitude, pulse width (Pw), and pulse frequency (F). AIMS: The purpose is to document the effects that the various stimulus parameters have on patient perception of paresthesia and the relationship that this perception has on pain relief. METHODS: Stimulus parameters were varied independently keeping the electrode polarity constant while recording stimulation thresholds. The Pw was varied from 195 to 300 µ sec while maintaining the frequency at 50 Hz. The F was varied from 10 to 100 Hz while maintaining the Pw at 300 µ sec. We also measured the paresthesia coverage percentage and the subjective perception of quality reported by the patients with each one of the parameter changes. RESULTS: There was a statistically significant correlation between Pw and all the stimulation thresholds. As for the therapeutic range, the differences observed also were statistically significant. Pw variation did not produce significant differences in coverage and subjective quality of the paresthesia. The perception threshold did not vary significantly with F changes. However, F significantly affected both coverage of the painful area and paresthesia perception quality. CONCLUSIONS: In the usual Pw ranges, it seems that its usefulness is limited to obtaining finer adjustments in the stimulation amplitude. Frequency management may be significantly useful to get a wider coverage of the stimulated area.

Use of intraoperative neurophysiological monitoring during epiduroscopy as a safety measure.

OBJECTIVE: In this study, we present the first 12 cases of the use of intraoperative neurophysiological monitoring (IONM) during therapeutic epiduroscopy in patients with clinical canal stenosis. METHODS: IESS was performed using two working instruments: an epidural balloon to dilate the epidural space without damaging the nerve structures (Resaloon®) and an element to perform flavotomy of the ligamentum flavum (Resaflex®). The procedure was performed at levels of the greatest stenosis, as detected using preoperative magnetic resonance imaging. RESULTS: Of the 12 cases that used IONM, 2 patients presented neurotonic activity in roots during ligamentum flavum ablation, 1 patient presented neurotonic activity while using Resaloon® in a root contralateral to the level at which the procedure was conducted, and other presented neurotonic activity in a root below the level at which the ligamentum flavum was ablated. In all cases, potentially harmful discharges stopped when the procedure was interrupted momentarily. CONCLUSIONS: Intraoperative neurophysiological monitoring detected alterations in surgical field and roots below and/or contralateral to the field, which disappeared with complete recovery after interrupting the procedure; this can avoid the possible prolonged or even permanent complications postoperatively. SIGNIFICANCE: Intraoperative neurophysiological monitoring during epiduroscopy is safe, thus optimizing surgical outcomes.

A Cost-Consequence Analysis Examining the Differences Between Non-Rechargeable and Rechargeable Systems.

BACKGROUND: Spinal cord stimulation (SCS) is an effective treatment option to relieve chronic intractable pain, and failed back surgery syndrome (FBSS) is a key indication. OBJECTIVES: The objective of the current study was to analyze the cost consequences of using non-rechargeable (NR)-SCS and rechargeable (R)-SCS. METHODS: Real data taken from a review of 86 patients were used to simulate costs and review which patients might have benefitted more from R-SCS. Calculations were made to see what is the impact from a monetary point of view. RESULTS: On average, NR-SCS devices lasted for 58 months (M). Only 14 patients were not eligible to receive an R-SCS implant. We found that using R-SCS batteries would save up to €56.322 on average over a patient's life expectancy, which means a saving of 43% compared to using NR-SCS systems. In our analysis, we found that if R-SCS implants were used instead of NR-SCS batteries, a saving of €5,735,334.23 over patients' life expectancy would be made, which represented a 63% saving to the public health system. We found that R-SCS was cost-beneficial from second year compared to NR-SCS, saving up to 70% when patients are implanted for 9 years. CONCLUSIONS: This cost-consequences analysis suggests that R-SCS implants are more cost-beneficial than NR-SCS systems in well-selected patient candidates for this type of treatment.