Role of patient selection and trial stimulation for spinal cord stimulation therapy for chronic non-cancer pain: a comprehensive narrative review.

BACKGROUND/IMPORTANCE: Patient selection for spinal cord stimulation (SCS) therapy is crucial and is traditionally performed with clinical selection followed by a screening trial. The factors influencing patient selection and the importance of trialing have not been systematically evaluated. OBJECTIVE: We report a narrative review conducted to synthesize evidence regarding patient selection and the role of SCS trials. EVIDENCE REVIEW: Medline, EMBASE and Cochrane databases were searched for reports (any design) of SCS in adult patients, from their inception until March 30, 2022. Study selection and data extraction were carried out using DistillerSR. Data were organized into tables and narrative summaries, categorized by study design. Importance of patient variables and trialing was considered by looking at their influence on the long-term therapy success. FINDINGS: Among 7321 citations, 201 reports consisting of 60 systematic reviews, 36 randomized controlled trials (RCTs), 41 observational studies (OSs), 51 registry-based reports, and 13 case reports on complications during trialing were included. Based on RCTs and OSs, the median trial success rate was 72% and 82%, and therapy success was 65% and 61% at 12 months, respectively. Although several psychological and non-psychological determinants have been investigated, studies do not report a consistent approach to patient selection. Among psychological factors, untreated depression was associated with poor long-term outcomes, but the effect of others was inconsistent. Most RCTs except for chronic angina involved trialing and only one RCT compared patient selection with or without trial. The median (range) trial duration was 10 (0-30) and 7 (0-56) days among RCTs and OSs, respectively. CONCLUSIONS: Due to lack of a consistent approach to identify responders for SCS therapy, trialing complements patient selection to exclude patients who do not find the therapy helpful and/or intolerant of the SCS system. However, more rigorous and large studies are necessary to better evaluate its role.

Evidence-based consensus guidelines on patient selection and trial stimulation for spinal cord stimulation therapy for chronic non-cancer pain.

Spinal cord stimulation (SCS) has demonstrated effectiveness for neuropathic pain. Unfortunately, some patients report inadequate long-term pain relief. Patient selection is emphasized for this therapy; however, the prognostic capabilities and deployment strategies of existing selection techniques, including an SCS trial, have been questioned. After approval by the Board of Directors of the American Society of Regional Anesthesia and Pain Medicine, a steering committee was formed to develop evidence-based guidelines for patient selection and the role of an SCS trial. Representatives of professional organizations with clinical expertize were invited to participate as committee members. A comprehensive literature review was carried out by the steering committee, and the results organized into narrative reports, which were circulated to all the committee members. Individual statements and recommendations within each of seven sections were formulated by the steering committee and circulated to members for voting. We used a modified Delphi method wherein drafts were circulated to each member in a blinded fashion for voting. Comments were incorporated in the subsequent revisions, which were recirculated for voting to achieve consensus. Seven sections with a total of 39 recommendations were approved with 100% consensus from all the members. Sections included definitions and terminology of SCS trial; benefits of SCS trial; screening for psychosocial characteristics; patient perceptions on SCS therapy and the use of trial; other patient predictors of SCS therapy; conduct of SCS trials; and evaluation of SCS trials including minimum criteria for success. Recommendations included that SCS trial should be performed before a definitive SCS implant except in anginal pain (grade B). All patients must be screened with an objective validated instrument for psychosocial factors, and this must include depression (grade B). Despite some limitations, a trial helps patient selection and provides patients with an opportunity to experience the therapy. These recommendations are expected to guide practicing physicians and other stakeholders and should not be mistaken as practice standards. Physicians should continue to make their best judgment based on individual patient considerations and preferences.

ASRA Pain Medicine consensus guidelines on the management of the perioperative patient on cannabis and cannabinoids.

BACKGROUND: The past two decades have seen an increase in cannabis use due to both regulatory changes and an interest in potential therapeutic effects of the substance, yet many aspects of the substance and their health implications remain controversial or unclear. METHODS: In November 2020, the American Society of Regional Anesthesia and Pain Medicine charged the Cannabis Working Group to develop guidelines for the perioperative use of cannabis. The Perioperative Use of Cannabis and Cannabinoids Guidelines Committee was charged with drafting responses to the nine key questions using a modified Delphi method with the overall goal of producing a document focused on the safe management of surgical patients using cannabinoids. A consensus recommendation required ≥75% agreement. RESULTS: Nine questions were selected, with 100% consensus achieved on third-round voting. Topics addressed included perioperative screening, postponement of elective surgery, concomitant use of opioid and cannabis perioperatively, implications for parturients, adjustment in anesthetic and analgesics intraoperatively, postoperative monitoring, cannabis use disorder, and postoperative concerns. Surgical patients using cannabinoids are at potential increased risk for negative perioperative outcomes. CONCLUSIONS: Specific clinical recommendations for perioperative management of cannabis and cannabinoids were successfully created.

Making a business plan for starting a transitional pain service within the US healthcare system.

Chronic pain imposes a tremendous economic burden of up to US$635 billion per year in terms of direct costs (such as the costs of treatment) and indirect costs (such as lost productivity and time away from work). In addition, the initiation of opioids for pain is associated with a more than doubling of pharmacy and all-cause medical costs. The high costs of chronic pain are particularly relevant for anesthesiologists because surgery represents an inciting event that can lead to chronic pain and long-term opioid use. While the presence of risk factors and an individual patient's postoperative pain trajectory may predict who is at high risk for chronic pain and opioid use after surgery, to date, there are few interventions proven to reduce these risks. One promising approach is the transitional pain service. Programs like this attempt to bridge the gap between acute and chronic pain management, provide continuity of care for complicated acute pain patients after discharge from the hospital, and offer interventions for patients who are on abnormal trajectories of pain resolution and/or opioid use. Despite awareness of chronic pain after surgery and the ongoing opioid epidemic, there are few examples of successful transitional pain service implementation in the USA. Key issues and concerns include financial incentives and the required investment from the hospital or healthcare system. We present an economic analysis and discussion of important considerations when developing a business plan for a transitional pain service.

Radiation safety and knowledge: an international survey of 708 interventional pain physicians.

INTRODUCTION: Interventional pain procedures have increased in complexity, often requiring longer radiation exposure times and subsequently higher doses. The practicing physician requires an in-depth knowledge and evidence-based knowledge of radiation safety to limit the health risks to themselves, patients and healthcare staff. The objective of this study was to examine current radiation safety practices and knowledge among interventional pain physicians and compare them to evidence-based recommendations. MATERIALS AND METHODS: A 49-question survey was developed based on an extensive review of national and international guidelines on radiation safety. The survey was web-based and distributed through the following professional organizations: Association of Pain Program Directors, American Academy of Pain Medicine, American Society of Regional Anesthesia and Pain Medicine, European Society of Regional Anesthesia and Pain Therapy, International Neuromodulation Society, and North American Neuromodulation Society. Responses to radiation safety practices and knowledge questions were evaluated and compared with evidence-based recommendations. An exploratory data analysis examined associations with radiation safety training/education, geographical location, practice type, self-perceived understanding, and fellowship experience. RESULTS: Of 708 responding physicians, 93% reported concern over the health effects of radiation, while only 63% had ever received radiation safety training/education. Overall, ≥80% physician compliance with evidence-based radiation safety practice recommendations was demonstrated for only 2/15 survey questions. Physician knowledge of radiation safety principles was low, with 0/10 survey questions having correct response rates ≥80%. CONCLUSION: We have identified deficiencies in the implementation of evidence-based practices and knowledge gaps in radiation safety. Further education and training are warranted for both fellowship training and postgraduate medical practice. The substantial gaps identified should be addressed to better protect physicians, staff and patients from unnecessary exposure to ionizing radiation during interventional pain procedures.

A physician survey of perioperative neuraxial anesthesia management in patients on a direct oral anticoagulant.

BACKGROUND: The perioperative management of patients taking a direct oral anticoagulant (DOAC) who require a high-bleed-risk surgery and/or neuraxial anesthesia is uncertain. We surveyed clinician practices relating to DOAC interruption and related perioperative management in patients having high-bleed-risk surgery with neuraxial anesthesia, and assess the suitability of a randomized trial of different perioperative DOAC management strategies. METHODS: We surveyed members of the American Society of Regional Anesthesia and Pain Medicine, the Canadian Anesthesia Society and Thrombosis Canada. We developed four clinical scenarios involving DOAC-treated patients who required anticoagulant interruption for elective high-bleed-risk surgery. In three scenarios, patients were to receive neuraxial anesthesia, and in one scenario they were to receive general anesthesia. We also asked about the merit of a randomized trial to compare a 2-day versus longer (3- to 5-day) duration of DOAC interruption. RESULTS: There were 399 survey respondents of whom 356 (89%) were anesthetists and 43 (11%) were medical specialists. The responses indicate uncertainty about the DOAC interruption interval for high-bleed-risk surgery and/or neuraxial anesthesia; anesthetists favor 3- to 5-day interruption whereas medical specialists favor 2-day interruption. Anesthetists were unwilling to proceed with neuraxial anesthesia in patients with a 2-day DOAC interruption interval, preferring to cancel the surgery or switch to general anesthesia. There is general agreement on the need for a randomized trial in this field to compare a 2-day and a 3- to 5-day DOAC interruption management strategy. CONCLUSIONS: There is variability in practices relating to the perioperative management of DOAC-treated patients who require a high-bleed-risk surgery with neuraxial anesthesia; this variability relates to the duration of DOAC interruption in such patients.

Spinal cord stimulation in chronic pain: evidence and theory for mechanisms of action.

Well-established in the field of bioelectronic medicine, Spinal Cord Stimulation (SCS) offers an implantable, non-pharmacologic treatment for patients with intractable chronic pain conditions. Chronic pain is a widely heterogenous syndrome with regard to both pathophysiology and the resultant phenotype. Despite advances in our understanding of SCS-mediated antinociception, there still exists limited evidence clarifying the pathways recruited when patterned electric pulses are applied to the epidural space. The rapid clinical implementation of novel SCS methods including burst, high frequency and dorsal root ganglion SCS has provided the clinician with multiple options to treat refractory chronic pain. While compelling evidence for safety and efficacy exists in support of these novel paradigms, our understanding of their mechanisms of action (MOA) dramatically lags behind clinical data. In this review, we reconstruct the available basic science and clinical literature that offers support for mechanisms of both paresthesia spinal cord stimulation (P-SCS) and paresthesia-free spinal cord stimulation (PF-SCS). While P-SCS has been heavily examined since its inception, PF-SCS paradigms have recently been clinically approved with the support of limited preclinical research. Thus, wide knowledge gaps exist between their clinical efficacy and MOA. To close this gap, many rich investigative avenues for both P-SCS and PF-SCS are underway, which will further open the door for paradigm optimization, adjunctive therapies and new indications for SCS. As our understanding of these mechanisms evolves, clinicians will be empowered with the possibility of improving patient care using SCS to selectively target specific pathophysiological processes in chronic pain.

Interventional Spine and Pain Procedures in Patients on Antiplatelet and Anticoagulant Medications (Second Edition): Guidelines From the American Society of Regional Anesthesia and Pain Medicine, the European Society of Regional Anaesthesia and Pain Therapy, the American Academy of Pain Medicine, the International Neuromodulation Society, the North American Neuromodulation Society, and the World Institute of Pain.

The American Society of Regional Anesthesia and Pain Medicine (ASRA) 2012 survey of meeting attendees showed that existing ASRA anticoagulation guidelines for regional anesthesia were insufficient for their needs. Those surveyed agreed that procedure-specific and patient-specific factors required separate guidelines for pain and spine procedures. In response, a guidelines committee was formed. After preliminary review of published complications reports and studies, the committee stratified interventional spine and pain procedures according to potential bleeding risk: low-, intermediate-, and high-risk procedures. The ASRA regional anesthesia anticoagulation guidelines were largely deemed appropriate for the low- and intermediate-risk categories, but the high-risk category required further investigation. The first guidelines specific to interventional spine and pain procedures were published in 2015. Recent reviews evaluating bleeding complications in patients undergoing specific interventional pain procedures, the development of new regional anesthesia and acute pain guidelines, and the development of new anticoagulants and antiplatelet medications necessitate complementary updated guidelines. The authors desired coordination with the authors of the recently updated regional and acute pain anticoagulation guidelines. The latest evidence was sought through extensive database search strategies and the recommendations were evidence based when available and pharmacology driven otherwise. We could not provide strength and grading of these recommendations because there are not enough well-designed large studies concerning interventional pain procedures to support such grading. Although the guidelines could not always be based on randomized studies or on large numbers of patients from pooled databases, it is hoped that they will provide sound recommendations and the evidentiary basis for such recommendations. This publication is intended as a living document to be updated periodically with consideration of new evidence.

Risk Factors for Chronic Saphenous Neuralgia Following Coronary Artery Bypass Graft Surgery Utilizing Saphenous Vein Grafts.

OBJECTIVES: The aim of this trial was to determine risk factors for chronic saphenous neuralgia (SN) following harvesting of the great saphenous vein (GSV) for coronary artery bypass graft (CABG) surgery. METHODS: In a prospective observational trial, 526 patients with no history of chronic painful disorders or surgery in the lower limbs were followed up for 13 weeks after undergoing CABG surgery in which GSV grafts were used. The primary outcome measure was persistence of clinically significant pain of neuropathic type in the territory supplied by the saphenous nerve beyond 12 weeks after surgery. RESULTS: Eighty-one (15.4%) patients consistently had probable neuropathic pain of clinically significant severity throughout the follow-up period and were labeled as suffering from chronic SN. Multivariable binary logistic regression analysis showed that younger age (OR, 0.92; 95% CI, 0.88-0.95; P-value, < 0.0001), female gender (OR, 2.28; 95% CI, 1.21-4.29; P-value, 0.011), higher body mass index (OR, 1.25; 95% CI, 1.17-1.35; P-value, < 0.0001), diabetes mellitus (OR, 2.13; 95% CI, 1.13-4.01; P-value, 0.020), distal-to-proximal dissection of the GSV (OR, 7.28; 95% CI, 3.62-14.66; P-value, < 0.0001), and closure of the leg wound in two layers (OR, 3.28; 95% CI, 1.81-5.95; P-value, 0.0001) were independent risk factors for chronic SN. CONCLUSIONS: Chronic SN after CABG surgery utilizing GSV grafts is not uncommon. Risk factors identified in this trial are younger age, female gender, higher body mass index, diabetes mellitus, distal-to-proximal dissection of the GSV, and closure of the leg wound in two layers.

The appropriate use of neurostimulation: new and evolving neurostimulation therapies and applicable treatment for chronic pain and selected disease states. Neuromodulation Appropriateness Consensus Committee.

INTRODUCTION: The International Neuromodulation Society (INS) has determined that there is a need to provide an expert consensus that defines the appropriate use of neuromodulation technologies for appropriate patients. The Neuromodulation Appropriateness Consensus Committee (NACC) was formed to give guidance to current practice and insight into future developments. METHODS: The INS executive board selected members of the international scientific community to analyze scientific evidence for current and future innovations and to use clinical experience to fill in any gaps in information. The NACC used PubMed and Google Scholar to obtain current evidence in the field and used clinical and research experience to give a more complete picture of the innovations in the field. RESULTS: The NACC has determined that currently approved neurostimulation techniques and technologies have expanded our ability to treat patients in a more effective and specific fashion. Despite these advances, the NACC has identified several additional promising technologies and potential applications for neurostimulation that could move this field forward and expand the applicability of neuromodulation. CONCLUSIONS: The NACC concludes that the field of neurostimulation is an evolving and rapidly changing one that will lead to improved patient access, safety, and outcomes.

Patients with a history of spine surgery or spinal injury may have a higher chance of intrathecal catheter granuloma formation.

BACKGROUND GOALS: Intrathecal drug delivery is an effective method to treat intractable pain. However, intrathecal catheter tip granuloma (ICTG) is a devastating complication of intrathecal drug delivery systems. It typically occurs in the thoracic region; particularly, in patients receiving high doses or high concentrations of intrathecal drug infusions. MATERIALS AND METHODS: The PUBMED/MEDLINE and Cochrane databases were also systematically searched for all reports on ICTG published in any language. The key words included "intrathecal," "granuloma," and "spine surgery," and all related publications between the earliest available date (the first granuloma-related chronic complication of intrathecal infusion reported in PUBMED/MEDLINE in 1996) and June (week 1) of 2012 were searched. This case report is unique because it describes the formation of an intrathecal granuloma in the lumbar region of a patient who received a low-dose intrathecal infusion. RESULTS AND CONCLUSION: Cerebrospinal fluid flow dynamics within the spinal canal along with the physical, chemical, and immunological properties of intrathecal medications have been suggested to be responsible for the growth of inflammatory mass lesions at the tips of intrathecal drug delivery catheters. Our literature review supports the possible role of certain factors, specifically previous spine surgery or spinal injury, in granuloma formation. The rate of development of ICTG appears to be higher in patients who have had previous spine surgery or spinal injury (68%) than in a general cohort of patients (48%), with an intrathecal pump. Therefore patients with a history of spine surgery or injury may be at increased risk of ICTG when receiving chronic intrathecal analgesia.

Management of thyroid incidentalomas encountered by anesthesiologists and pain physicians.

Unexpected, asymptomatic thyroid lesions incidentally discovered during unrelated diagnostic or therapeutic interventions are called thyroid incidentalomas (TIs). These lesions are extremely common, creating a clinical problem that most anesthesiologists and pain specialists are unfamiliar with. Ultrasonography (US), which allows high-quality real-time visualization of tissues during brachial plexus block, stellate ganglion block, central vascular access, and other interventions, is the imaging modality of choice of many anesthesiologists and pain medicine specialists for therapeutic interventions on the neck. The increasing number of US procedures performed on the neck will eventually result in an upsurge of anesthesiologists and pain specialists encountering a TI. Interventionalists are responsible for acquiring optimal images, accurate needle positioning during interventions, and storage and appropriate labeling of the obtained images. Ignoring the TI or disclosing the presence of a "tumor" can substantially affect the patient's well-being. In this literature review, we discuss 2 clinical cases of incidentalomas, summarize the current evidence-based strategies, and provide readers with practical guidelines-possibly applicable to other abnormal findings-for the management of incidentally found thyroid lesions.

Risk factors for new-onset persistent low-back pain following nonobstetric surgery performed with epidural anesthesia.

BACKGROUND: The aim of this trial was to identify risk factors for persistent low-back pain (LBP) of new onset following nonobstetric surgery performed with lumbar epidural anesthesia. METHODS: Four-hundred eighty-three patients with no history of LBP were screened for backache 2 days, 10 days, and 13 weeks after nonobstetric surgeries were performed with lumbar epidural anesthesia. Demographic data, details of epidural techniques, and operative data were compared in patients who developed back pain that persisted for 13 weeks with those patients who did not. Multivariate logistic regression analysis was performed to identify predictors of persistent LBP. RESULTS: Ten patients (2.1%) consistently experienced clinically significant LBP at 2 days, 10 days, and 13 weeks after surgery; they were labeled as having persistent LBP. Multivariate analysis showed that higher body mass index (P < 0.001), multiple attempts at epidural placement (P = 0.026), surgery in the lithotomy position (P = 0.013), and duration of surgery exceeding 2½ hrs (P = 0.025) were independent risk factors for persistent LBP. As much as 51% of variation in the outcome measure could be explained by the model (R = 0.51), which had an overall accuracy of 98.1%. CONCLUSIONS: Persistent LBP after nonobstetric surgery performed with lumbar epidural anesthesia is rather rare. Independent risk factors for this untoward outcome are higher body mass index, multiple trials at epidural placement, surgery in the lithotomy position, and operative time exceeding 2½ hrs. These results need to be validated by prospective trials using larger cohorts.

Sphenopalatine ganglion interventions: technical aspects and application.

Recent research has highlighted the important role of the sphenopalatine ganglion (SPG) in cerebrovascular autonomic physiology and in the pathophysiology of cluster and migraine headaches as well as conditions of stroke and cerebral vasospasm. The relatively accessible location of the SPG within the pterygopalatine fossa and the development of options for minimally invasive approaches to the SPG make it an attractive target for neuromodulation approaches. The obvious advantage of SPG stimulation compared to ablative procedures on the SPG such as radiofrequency destruction and stereotactic radiosurgery is its reversibility and adjustable features. The on-going design of strategies for transient and continuous SPG stimulation on as needed basis using implantable SPG stimulators is an exciting new development which is expected to expand the clinical versatility of this technique.

Ultrasound-guided interventional procedures in pain medicine: a review of anatomy, sonoanatomy, and procedures. Part II: axial structures.

There is a growing trend in using ultrasonography in pain medicine as evident by the plethora of published reports. Ultrasound(US) provides direct visualization of various soft tissues and real-time needle advancement and avoids exposing both the health care provider and the patient to the risks of radiation. The US machine is more affordable and transferrable than fluoroscopy, computed tomography scan,or magnetic resonance imaging machine. In a previous review, we discussed the challenges and limitations of US, anatomy, sonoanatomy, and techniques of interventional procedures of peripheral structures. In the present review, we discuss the anatomy, sonoanatomy, and US-guided techniques of interventional pain procedures for axial structures and review the pertinent literature.