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.

Clinical Longevity of 106,462 Rechargeable and Primary Cell Spinal Cord Stimulators: Real World Study in the Medicare Population.

INTRODUCTION: Spinal cord stimulators (SCS) are available with either primary cell (PC) or rechargeable cell (RC) batteries. Although RC systems are proposed to have a battery longevity upward of nine years, in comparison with four years for PC systems, there are few studies of longevity of SCS in the real world. MATERIALS AND METHODS: This was an observational, nonrandomized, retrospective study of Medicare beneficiaries who received neurostimulator implants in the outpatient hospital. This study used Medicare fee-for-service claims data from 2013 to 2020. The clinical longevity of the implantable pulse generator (IPG), defined as the duration from implant until removal for any reason, was compared between PC and RC devices. Life distribution analysis was used to approximate device lifespan. The secondary analysis separated removals into explant or replacements. The statistics were adjusted for relevant clinical covariates. RESULTS: A total of 25,856 PC and 79,606 RC systems were included in the study. At seven years after implant, 53.8% of PC IPGs and 55.0% of RC IPGs remained in use. The life distribution modeling analysis projected a median lifespan of 8.2 years for PC and 9.0 years for RC devices. The rate of explant was lower for PC devices (19.2%) than for RC devices (22.0%, hazard ratio (HR) = 0.96, p = 0.082), whereas the rate of replacements was higher for PC devices (33.7%) than for RC devices (29.5%, HR = 1.31, p < 0.001). An analysis of the battery type used in device replacements showed an increasing adoption of PC devices over time. CONCLUSIONS: This large, retrospective, real-world analysis of Medicare claims data demonstrated that the clinical longevity of neurostimulator devices is similar for PC and RC batteries. In the past, clinicians may have defaulted to RC devices based on the assumption that they provided extended battery life. Considering this longevity data, clinicians should now consider the choice between PC and RC devices based on other individual factors pertinent to the patient experience and not on purported longevity claims.

The Neurostimulation Appropriateness Consensus Committee (NACC): Recommendations on Best Practices for Cervical Neurostimulation.

INTRODUCTION: The International Neuromodulation Society convened a multispecialty group of physicians based on expertise with international representation to establish evidence-based guidance on the use of neurostimulation in the cervical region to improve outcomes. This Neurostimulation Appropriateness Consensus Committee (NACC) project intends to provide evidence-based guidance for an often-overlooked area of neurostimulation practice. MATERIALS AND METHODS: Authors were chosen based upon their clinical expertise, familiarity with the peer-reviewed literature, research productivity, and contributions to the neuromodulation literature. Section leaders supervised literature searches of MEDLINE, BioMed Central, Current Contents Connect, Embase, International Pharmaceutical Abstracts, Web of Science, Google Scholar, and PubMed from 2017 (when NACC last published guidelines) to the present. Identified studies were graded using the US Preventive Services Task Force criteria for evidence and certainty of net benefit. Recommendations are based on the strength of evidence or consensus when evidence was scant. RESULTS: The NACC examined the published literature and established evidence- and consensus-based recommendations to guide best practices. Additional guidance will occur as new evidence is developed in future iterations of this process. CONCLUSIONS: The NACC recommends best practices regarding the use of cervical neuromodulation to improve safety and efficacy. The evidence- and consensus-based recommendations should be utilized as a guide to assist decision making when clinically appropriate.

A Systematic Literature Review of Peripheral Nerve Stimulation Therapies for the Treatment of Pain.

OBJECTIVE: To conduct a systematic literature review of peripheral nerve stimulation (PNS) for pain. DESIGN: Grade the evidence for PNS. METHODS: An international interdisciplinary work group conducted a literature search for PNS. Abstracts were reviewed to select studies for grading. Inclusion/exclusion criteria included prospective randomized controlled trials (RCTs) with meaningful clinical outcomes that were not part of a larger or previously reported group. Excluded studies were retrospective, had less than two months of follow-up, or existed only as abstracts. Full studies were graded by two independent reviewers using the modified Interventional Pain Management Techniques-Quality Appraisal of Reliability and Risk of Bias Assessment, the Cochrane Collaborations Risk of Bias assessment, and the US Preventative Services Task Force level-of-evidence criteria. RESULTS: Peripheral nerve stimulation was studied in 14 RCTs for a variety of painful conditions (headache, shoulder, pelvic, back, extremity, and trunk pain). Moderate to strong evidence supported the use of PNS to treat pain. CONCLUSION: Peripheral nerve stimulation has moderate/strong evidence. Additional prospective trials could further refine appropriate populations and pain diagnoses.

The Neuromodulation Appropriateness Consensus Committee on Best Practices for Dorsal Root Ganglion Stimulation.

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

Peripheral Nerve Field Stimulation Therapy for Patients With Thoracic Pain: A Prospective Study.

OBJECTIVE: Relative to the number of patients suffering chronic lumbar and cervical pain, fewer patients suffer persistent thoracic pain. Consequently there is less literature, with smaller sample sizes, reporting treatment of this cohort. Here, we assess peripheral nerve field stimulation (PNfS) as a potential treatment for chronic thoracic pain. MATERIALS AND METHODS: This study included 20 consecutive chronic thoracic pain sufferers that responded successfully to PNfS trial. The patients were subsequently implanted with permanent eight-contact electrode linear percutaneous leads within their major area of pain. Patients were followed up at 12 months for outcome reporting. All 20 patients were considered in the statistical analysis, despite removal of three devices prior to follow up. RESULTS: The average baseline pre-treatment Numerical Pain Rating Scale (NPRS) score was 7.75 ± 1.4. Following PNfS, the mean NPRS score was 2.25 ±2.14, reflecting a significant average improvement of 5.5 ± 3.31. Three patients were explanted prior to follow up: the first gained excellent thoracic pain relief but pain at the Implantable Pulse Generator (IPG) site could not be overcome, the second achieved excellent pain relief but the PNfS was removed due to recurrent infection and in the final instance, the intervention offered only poor relief and the device removed. CONCLUSION: PNfS is an effective intervention for intractable disabling thoracic pain, offering sustained and worthwhile pain relief, for the overwhelming majority of the cohort. This may be especially true when considering a combined treatment approach of PNfS and analgesic use to manage remnant pain.

Peripheral Nerve Stimulation for Back Pain.

Peripheral nerve stimulation (PNS) generally refers to stimulation of a named nerve via direct placement of a lead next to the nerve either via a percutaneous or open approach; in peripheral nerve field stimulation (PNFS), leads are subcutaneously placed to stimulate the region of affected nerves, cutaneous afferents, or the dermatomal distribution of the nerves which converge back to the spinal cord. Recently, there has been a renewed interest in using the PNS approach for many otherwise refractory pain conditions; however, PNFS appears to be more effective for the management of low back pain and therefore more attractive. Here we discuss procedural details of PNFS trial and implant, and provide scientific and clinical rationale for placing PNFS electrodes at a certain depth under the skin. We also summarize results of published studies on use of PNFS in the management of low back pain and list the criteria that are used for proper patient selection. Our experience and the published studies provide evidence that PNFS is a safe and well-tolerated pain control option for intractable pain conditions, including chronic low back pain. Notably, achieving efficacious pain relief relies on correct patient selection and the optimal placement of the leads, ensuring, in particular, a lead depth of 10-12 mm from the surface to maximize the target sensation (mediated by fast-adapting Aß fibers) of PNFS, which is believed to be most effective for the pain relief.

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.

Peripheral nerve field stimulation for chronic headache: 60 cases and long-term follow-up.

OBJECTIVE: The objective of this study is to evaluate the efficacy of peripheral nerve field stimulation (PNFS) for the treatment of chronic headache conditions. MATERIALS AND METHODS: For more than a four-year period, 83 patients underwent a trial of a PNFS system targeting the nerve regions including occipital and supraorbital and infraorbital nerves, which best corresponded with their area of head pain. Sixty patients reported a successful trial and underwent a subsequent implant of the PNFS system. Questionnaires, along with patients' charts, were used to assess outcomes as follows: pain (11-point numerical pain rating scale), analgesic use, depression (Zung Depression Scale), disability (Neck Disability Index), patient satisfaction, and surgical complications. Patients were followed up for an average of 12.9 ± 9.4 months (range 3-42 months). RESULTS: An average pain reduction of 4.8 ± 2.3 pain scale points was observed (preimplant 7.4 ± 1.6; follow-up 2.6 ± 2.1 [p ≤ 0.001]). Of the 60 patients implanted, 41 reported >50% pain relief. Medication use was reduced in 83% of patients who were previously taking analgesics or prophylactic medications. Similarly, reductions in degree of disability and depression also were observed. Of the 60 cases, ten surgical revisions were required; however, no long-term complications were reported. CONCLUSIONS: PNFS for chronic headache is an evolving therapy. This study demonstrates that this reversible and effective treatment can be a promising pain relief strategy for this often intractable condition.

A multicenter, prospective trial to assess the safety and performance of the spinal modulation dorsal root ganglion neurostimulator system in the treatment of chronic pain.

OBJECTIVES: This multicenter prospective trial was conducted to evaluate the clinical performance of a new neurostimulation system designed to treat chronic pain through the electrical neuromodulation of the dorsal root ganglia (DRG) neurophysiologically associated with painful regions of the limbs and/or trunk. MATERIALS AND METHODS: Thirty-two subjects were implanted with a novel neuromodulation device. Pain ratings during stimulation were followed up to six months and compared with baseline ratings. Subjects also completed two separate reversal periods in which stimulation was briefly stopped in order to establish the effects of the intervention. RESULTS: At all assessments, more than half of subjects reported pain relief of 50% or better. At six months postimplant, average overall pain ratings were 58% lower than baseline (p < 0.001), and the proportions of subjects experiencing 50% or more reduction in pain specific to back, leg, and foot regions were 57%, 70%, and 89%, respectively. When stimulation was discontinued for a short time, pain returned to baseline levels. Discrete coverage of hard-to-treat areas was obtained across a variety of anatomical pain distributions. Paresthesia intensity remained stable over time and there was no significant difference in the paresthesia intensity perceived during different body postures/positions (standing up vs. lying down). CONCLUSIONS: Results of this clinical trial demonstrate that neurostimulation of the DRG is a viable neuromodulatory technique for the treatment of chronic pain. Additionally, the capture of discrete painful areas such as the feet combined with stable paresthesia intensities across body positions suggest that this stimulation modality may allow more selective targeting of painful areas and reduce unwanted side-effects observed in traditional spinal cord stimulation (SCS).

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.

Peripheral nerve field stimulation for chronic pain: 100 cases and review of the literature.

OBJECTIVE: To evaluate the clinical outcomes of 100 consecutive patients receiving peripheral nerve field stimulation (PNFS) for the treatment of chronic intractable pain. DESIGN: Prospective, observational study. SETTING: A private interventional pain specialty referral practice. PATIENTS: One hundred consecutive private practice patients receiving PNFS for the treatment of chronic craniofacial, thorax, lumbosacral, abdominal, pelvic, and groin pain conditions. OUTCOME MEASURES: Pain (11-point numerical rating scale), complications, changes to analgesic use and employment status, disability (Oswestry or Neck Disability Indexes), depression (Zung Depression Index), and patient satisfaction. RESULTS: We demonstrate an average pain reduction of 4.2 ± 2.5 pain scale points on an 11-point scale following PNFS (preimplant pain score of 7.4 ± 1.7 to a follow-up average of 3.2 ± 2.3 pain scale points) (P≤0.00). At a follow-up period of 8.1 ± 4.7 months (range 1-23 months), an overall 72% of patients reduced their analgesic use following PNFS. Patients receiving a lumbosacral PNFS for chronic low back pain reported a significant reduction in disability following treatment, as determined by the Oswestry Disability Index. Of the 100 cases, no long-term complications were reported. CONCLUSIONS: This prospective 100 consecutive PNFS patient outcome study demonstrates that PNFS can be a safe and effective treatment option for, otherwise, intractable chronic pain conditions. PNFS has the potential to fundamentally change the way we think about pain management.

Interventions in chronic low back pain.

BACKGROUND: Chronic low back pain presents a major challenge for general practitioners and is a significant drain on community resources. Patients often feel frustrated by modern medicine's apparent failure to validate their symptoms with a specific diagnosis and management plan. OBJECTIVE: This article presents an evidence based guide to current interventions, including an algorithm for the interventional diagnostic workup of low back pain that has persisted beyond 3 months. DISCUSSION: Modern imaging techniques rarely determine the cause of pain. The GP must look for 'red flag' clues in the history. Management of low back pain includes NSAIDs, simple injections of plain local anaesthetic without adrenalin or cortisone, referral to a masseuse, cortisone, physiotherapist and/or a musculoskeletal pain physician. Specific management includes medial branch and sacroiliac joint blocks, and radiofrequency neurotomy. Patients with long term pain may be referred to a psychologist for cognitive behavioural therapy.