A Definition of Neuromodulation and Classification of Implantable Electrical Modulation for Chronic Pain

OBJECTIVES

Neuromodulation therapies use a variety of treatment modalities (eg, electrical stimulation) to treat chronic pain. These therapies have experienced rapid growth that has coincided with escalating confusion regarding the nomenclature surrounding these neuromodulation technologies. Furthermore, studies are often published without a complete description of the effective stimulation dose, making it impossible to replicate the findings. To improve clinical care and facilitate dissemination among the public, payors, research groups, and regulatory bodies, there is a clear need for a standardization of terms.

APPROACH

We formed an international group of authors comprising basic scientists, anesthesiologists, neurosurgeons, and engineers with expertise in neuromodulation. Because the field of neuromodulation is extensive, we chose to focus on creating a taxonomy and standardized definitions for implantable electrical modulation of chronic pain.

RESULTS

We first present a consensus definition of neuromodulation. We then describe a classification scheme based on the 1) intended use (the site of modulation and its indications) and 2) physical properties (waveforms and dose) of a neuromodulation therapy.

CONCLUSIONS

This framework will help guide future high-quality studies of implantable neuromodulatory treatments and improve reporting of their findings. Standardization with this classification scheme and clear definitions will help physicians, researchers, payors, and patients better understand the applications of implantable electrical modulation for pain and guide informed treatment decisions.

Congress of Neurological Surgeons Systematic Review and Evidence-Based Guidelines for Occipital Nerve Stimulation for the Treatment of Patients With Medically Refractory Occipital Neuralgia: Update

BACKGROUND

The Guidelines Task Force conducted a systematic review of the relevant literature on occipital nerve stimulation (ONS) for occipital neuralgia (ON) to update the original 2015 guidelines to ensure timeliness and accuracy for clinical practice.

OBJECTIVE

To conduct a systematic review of the literature and update the evidence-based guidelines on ONS for ON.

METHODS

The Guidelines Task Force conducted another systematic review of the relevant literature, using the same search terms and strategies used to search PubMed and Embase for relevant literature. The updated search included studies published between 1966 and January 2023. The same inclusion/exclusion criteria as the original guideline were also applied. Abstracts were reviewed, and relevant full text articles were retrieved and graded. Of 307 articles, 18 were retrieved for full-text review and analysis. Recommendations were updated according to new evidence yielded by this update .

RESULTS

Nine studies were included in the original guideline, reporting the use of ONS as an effective treatment option for patients with medically refractory ON. An additional 6 studies were included in this update. All studies in the original guideline and this current update provide Class III evidence.

CONCLUSION

Based on the availability of new literature, the current article is a minor update only that does not result in modification of the prior recommendations: Clinicians may use ONS as a treatment option for patients with medically refractory ON.

Efficacy of Continuous Intrathecal Infusion Trialing with a Mixture of Fentanyl and Bupivacaine in Chronic Low Back Pain Patients

Intrathecal trialing is used as a screening prognostic measure prior to intrathecal drug delivery system implant. The purpose of this study was to determine the efficacy of a continuous intrathecal infusion of an admixture of bupivacaine and fentanyl in patients with chronic low back pain. Patients with refractory chronic low back pain in the setting of previous lumbar spine surgery and/or chronic vertebral compression fracture(s) were enrolled in a randomized double blind cross-over study comparing saline infusion to infusion of a solution containing bupivacaine combined with low-dose fentanyl over a 14-18 hour period. The primary outcome measure was the change in pain intensity at the end of the screening trial. Patients who experienced significant pain reduction from either infusion relative to baseline pain were offered a permanent implant. In total, 36 patients were enrolled, with 31 patients trialed and 25 implanted. At the end of the screening trial, pain scores, at rest or with activity, decreased appreciably in both groups; however, significantly better improvements occurred in the fentanyl/bupivacaine group compared to saline both with activity and at rest (P = .016 and .006, respectively). Treatment order appeared to affect outcome with saline demonstrating a placebo response. At 12 months following implant, primary and secondary outcome measures continued to be significantly reduced from baseline. Continuous intrathecal delivery of a combination of zlow-dose fentanyl with bupivacaine is superior to saline in screening intrathecal trialing for back pain reduction. With longer term delivery, a sustained reduction of chronic low back pain was also observed.

Research design considerations for randomized controlled trials of spinal cord stimulation for pain: Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials/Institute of Neuromodulation/International Neuromodulation Society recommendations

ABSTRACT

Spinal cord stimulation (SCS) is an interventional nonpharmacologic treatment used for chronic pain and other indications. Methods for evaluating the safety and efficacy of SCS have evolved from uncontrolled and retrospective studies to prospective randomized controlled trials (RCTs). Although randomization overcomes certain types of bias, additional challenges to the validity of RCTs of SCS include blinding, choice of control groups, nonspecific effects of treatment variables (eg, paresthesia, device programming and recharging, psychological support, and rehabilitative techniques), and safety considerations. To address these challenges, 3 professional societies (Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials, Institute of Neuromodulation, and International Neuromodulation Society) convened a meeting to develop consensus recommendations on the design, conduct, analysis, and interpretation of RCTs of SCS for chronic pain. This article summarizes the results of this meeting. Highlights of our recommendations include disclosing all funding source and potential conflicts; incorporating mechanistic objectives when possible; avoiding noninferiority designs without internal demonstration of assay sensitivity; achieving and documenting double-blinding whenever possible; documenting investigator and site experience; keeping all information provided to patients balanced with respect to expectation of benefit; disclosing all information provided to patients, including verbal scripts; using placebo/sham controls when possible; capturing a complete set of outcome assessments; accounting for ancillary pharmacologic and nonpharmacologic treatments in a clear manner; providing a complete description of intended and actual programming interactions; making a prospective ascertainment of SCS-specific safety outcomes; training patients and researchers on appropriate expectations, outcome assessments, and other key aspects of study performance; and providing transparent and complete reporting of results according to applicable reporting guidelines.

Comparative Effectiveness of Targeted Intrathecal Drug Delivery Using a Combination of Bupivacaine with Either Low-Dose Fentanyl or Hydromorphone in Chronic Back Pain Patients with Lumbar Postlaminectomy Syndrome

OBJECTIVE

Targeted intrathecal drug delivery (TIDD) is an effective interventional pain management modality often used in postlaminectomy patients with refractory chronic low back pain. A combination of intrathecal bupivacaine with an opioid is often used. However, intrathecal catheter tip granulomas have occurred with use of morphine or hydromorphone but generally not with fentanyl. The objective of this study was to compare the efficacy of TIDD using bupivacaine/fentanyl vs bupivacaine/hydromorphone in patients with chronic intractable low back pain postlaminectomy.

MATERIALS AND METHODS

A retrospective comparative analysis of consecutive patients with lumbar postlaminectomy syndrome who were trialed and later received TIDD with a combination of bupivacaine/hydromorphone or bupivacaine/fentanyl between June 2009 and May 2016 at a single tertiary medical center.

RESULTS

We identified a cohort of 58 lumbar postlaminectomy patients receiving a TIDD admixture of either hydromorphone/bupivacaine (30 patients) or low-dose fentanyl/bupivacaine (28 patients) with at least two years of follow-up. The fentanyl group had significantly lower baseline opioid consumption and a lower rate of intrathecal opioid dose escalation. Both groups had similar and significant reductions in pain scores over the two-year follow-up period. No granulomas were observed.

CONCLUSION

TIDD using a low-dose fentanyl admixture with bupivacaine in patients with postlaminectomy syndrome and refractory chronic low back pain results in similar pain relief to TIDD with hydromorphone and bupivacaine. Low-dose intrathecal fentanyl leads to a lower rate of opioid escalation and may be safer than hydromorphone.

Peripheral Nerve Stimulation for Facial Pain Using Wireless Devices

Since its original introduction several decades ago, peripheral nerve stimulation (PNS) of the craniofacial region has been traditionally performed using devices intended for spinal cord stimulation applications with inevitably high rate of technical challenges and procedural complications. The lower invasiveness of recently developed wireless neurostimulation systems makes them much better suited for craniofacial applications. Here, we discuss the preliminary clinical data from several published reports and the ongoing multicenter prospective study of wireless PNS in the craniofacial region. Advances in wireless transmission of electrical signals may make wireless neurostimulation even more attractive in the future. Since most of the evidence supporting PNS for facial pain comes from small subsets of the population, case series and case reports, there will need to be larger, randomized controlled trials with cost efficacy analyses in order to validate the role of wireless PNS as the standard of care.

Pain Management Best Practices from Multispecialty Organizations During the COVID-19 Pandemic and Public Health Crises

BACKGROUND

It is nearly impossible to overestimate the burden of chronic pain, which is associated with enormous personal and socioeconomic costs. Chronic pain is the leading cause of disability in the world, is associated with multiple psychiatric comorbidities, and has been causally linked to the opioid crisis. Access to pain treatment has been called a fundamental human right by numerous organizations. The current COVID-19 pandemic has strained medical resources, creating a dilemma for physicians charged with the responsibility to limit spread of the contagion and to treat the patients they are entrusted to care for.

METHODS

To address these issues, an expert panel was convened that included pain management experts from the military, Veterans Health Administration, and academia. Endorsement from stakeholder societies was sought upon completion of the document within a one-week period.

RESULTS

In these guidelines, we provide a framework for pain practitioners and institutions to balance the often-conflicting goals of risk mitigation for health care providers, risk mitigation for patients, conservation of resources, and access to pain management services. Specific issues discussed include general and intervention-specific risk mitigation, patient flow issues and staffing plans, telemedicine options, triaging recommendations, strategies to reduce psychological sequelae in health care providers, and resource utilization.

CONCLUSIONS

The COVID-19 public health crisis has strained health care systems, creating a conundrum for patients, pain medicine practitioners, hospital leaders, and regulatory officials. Although this document provides a framework for pain management services, systems-wide and individual decisions must take into account clinical considerations, regional health conditions, government and hospital directives, resource availability, and the welfare of health care providers.

Systematic Review of Research Methods and Reporting Quality of Randomized Clinical Trials of Spinal Cord Stimulation for Pain

This systematic review assessed design characteristics and reporting quality of published randomized clinical trials of spinal cord stimulation (SCS) for treatment of pain in adults and adolescents. The study protocol was registered with PROSPERO (CRD42018090412). Relevant articles were identified by searching the following databases through December 31, 2018: MEDLINE, Embase, WikiStim, The Cochrane Database of Systematic Reviews, and The Cochrane Central Register of Controlled Trials. Forty-six studies were included. Eighty-seven percent of articles identified a pain-related primary outcome. Secondary outcomes included physical functioning, health-related quality of life, and reductions in opioid use. Nineteen of the 46 studies prespecified adverse events as an outcome, with 4 assessing them as a primary outcome. Eleven studies stated that they blinded participants. Of these, only 5 were assessed as being adequately blinded. The number of participants enrolled was generally low (median 38) and study durations were short (median 12 weeks), particularly in studies of angina. Fifteen studies employed an intention-to-treat analysis, of which only seven specified a method to accommodate missing data. Review of these studies identified deficiencies in both reporting and methodology. The review's findings suggest areas for improving the design of future studies and increasing transparency of reporting. PERSPECTIVE: This article presents a systematic review of research methods and reporting quality of randomized clinical trials of SCS for the treatment of various pain complaints. The review identifies deficiencies in both methodology and reporting, which may inform the design of future studies and improve reporting standards.

Effects of Bupivacaine on Opioid Patient-Controlled Intrathecal Analgesia in Chronic Pain Patients Implanted with Drug Delivery Systems

Background

Combining neuraxial opioids and local anesthetics in acute pain results in improved duration of analgesia and reduced dosages and adverse effects. Although commonly used in intrathecal drug delivery systems (IDDS) for chronic pain, the effectiveness of this admixture has not been examined specifically in relation to patient-controlled intrathecal analgesia (PCIA).

Methods

IDDS-implanted chronic noncancer pain patients receiving opioids with bupivacaine (O + B) were randomized to receive either opioids without bupivacaine (O) or O + B in a double-blind manner, at IDDS refills, for one week and then crossed over to the other solution for another week. Primary outcome measures included numeric rating scale (NRS) pain scores before and within 30 minutes after PCIA boluses. Secondary outcome measures included average NRS scores and functional outcome measures.

Results

Seventeen patients were enrolled, and 16 patients completed the study. There were no differences in NRS scores before and after PCIA boluses between the O and O + B conditions, though pain scores improved significantly (average decrease in NRS scores: O 1.81 ± 1.47 vs O + B 1.87 ± 1.40, P = 0.688). No differences were noted in speed of onset or duration of analgesia. Although more patients subjectively preferred the O + B treatment, the difference was not statistically significant. No differences were noted in secondary outcome measures, with the exception of global impression of change having higher scores in O compared with O + B.

Conclusions

Acutely removing bupivacaine from a chronic intrathecal infusion of opioids and bupivacaine in patients with chronic noncancer pain did not adversely affect PCIA effectiveness, nor did it affect speed of onset or duration of effect. These findings are divergent from those in acute pain and may have to do with study conditions and pain phenotypes.

Spinal Cord Stimulation (SCS) with Anatomically Guided (3D) Neural Targeting Shows Superior Chronic Axial Low Back Pain Relief Compared to Traditional SCS-LUMINA Study

Background

The aim of this study was to determine whether spinal cord stimulation (SCS) using 3D neural targeting provided sustained overall and low back pain relief in a broad routine clinical practice population.

Study Design and Methods

This was a multicenter, open-label observational study with an observational arm and retrospective analysis of a matched cohort. After IPG implantation, programming was done using a patient-specific, model-based algorithm to adjust for lead position (3D neural targeting) or previous generation software (traditional). Demographics, medical histories, SCS parameters, pain locations, pain intensities, disabilities, and safety data were collected for all patients.

Results

A total of 213 patients using 3D neural targeting were included, with a trial-to-implant ratio of 86%. Patients used seven different lead configurations, with 62% receiving 24 to 32 contacts, and a broad range of stimulation parameters utilizing a mean of 14.3 (±6.1) contacts. At 24 months postimplant, pain intensity decreased significantly from baseline (ΔNRS = 4.2, N = 169, P  < 0.0001) and even more in in the severe pain subgroup (ΔNRS = 5.3, N = 91, P  < 0.0001). Axial low back pain also decreased significantly from baseline to 24 months (ΔNRS = 4.1, N = 70, P  < 0.0001, on the overall cohort and ΔNRS = 5.6, N = 38, on the severe subgroup). Matched cohort comparison with 213 patients treated with traditional SCS at the same centers showed overall pain responder rates of 51% (traditional SCS) and 74% (neural targeting SCS) and axial low back pain responder rates of 41% and 71% in the traditional SCS and neural targeting SCS cohorts, respectively. Lastly, complications occurred in a total of 33 of the 213 patients, with a 1.6% lead replacement rate and a 1.6% explant rate.

Conclusions

Our results suggest that 3D neural targeting SCS and its associated hardware flexibility provide effective treatment for both chronic leg and chronic axial low back pain that is significantly superior to traditional SCS.

Intrathecal Trialing of Continuous Infusion Combination Therapy With Hydromorphone and Bupivacaine in Failed Back Surgery Patients

OBJECTIVES

Intrathecal (IT) trial is a prognostic interventional pain management procedure employed to determine the potential success of treating intractable pain with an implantable infusion device system. There is a dearth of data regarding trials with continuous infusion of combination therapy (e.g. opioid combined with local anesthetic). The objective of the this study was to determine the overall outcomes of continuous infusion IT trials and factors influencing long-term success of IT therapy in patients with chronic intractable pain post-laminectomy.

MATERIALS AND METHODS

This is a retrospective analysis of all patients with lumbar failed back surgery syndrome (FBSS) who were trialed with a combination of hydromorphone and bupivacaine with a temporary externalized IT catheter from March 2007 to June 2014.

RESULTS

From a cohort of 62 patients fulfilling the inclusion criteria, 54 (87.10%) patients had successful IT trials. No significant differences were found between successful and failed trial patients with regards to age, sex, pre-trial pain numeric rating scale scores, pre-trial morphine equivalent daily dose, or trial dosages. Significant positive correlations were found between pretrial oral opioid intake and end of trial hydromorphone dose and hydromorphone dose escalation at 12 months and 24 months.

CONCLUSIONS

Patients with refractory low back pain due to FBSS who underwent successful combination IT trial with hydromorphone and bupivacaine infused through a temporary IT catheter had significantly improved pain intensity scores following permanent implant. Higher pre-trial MEDD was correlated with higher trial and post-implant opioid doses and higher rates of opioid dose escalation post-implant.

The Polyanalgesic Consensus Conference (PACC): Recommendations for Trialing of Intrathecal Drug Delivery Infusion Therapy

INTRODUCTION

Intrathecal (IT) drug infusion is an appropriate and necessary tool in the algorithm to treat refractory cancer and noncancer pain. The decision-making steps/methodology for selecting appropriate patients for implanted targeted drug delivery systems is controversial and complicated. Therefore, a consensus on best practices for determining appropriate use of IT drug infusion may involve testing/trialing this therapy before implantation.

METHODS

This current Polyanalgesic Consensus Conference (PACC) update was designed to address the deficiencies and emerging innovations since the previous PACC convened in 2012. A literature search identified publications available since the previous PACC publications in 2014, and relevant sources were contributed by the PACC members. After reviewing the literature, the panel determined the evidence levels and degrees of recommendations. The developed consensus was ranked as strong (>80%), moderate (50-79%), or weak (<49%).

RESULTS

The trialing for IT drug delivery systems (IDDS) remains an area of continued controversy. The PACC recommendations for trialing are presented in 34 consensus points and cover trialing for morphine, ziconotide, and medication admixtures; starting doses and titration practices; measurements of success; trial settings and monitoring; management of systemic opioids during trialing; and the role of psychological evaluation. Finally, the PACC describes clinical scenarios in which IT trialing is required or not required.

CONCLUSION

The PACC provides consensus guidance on best practices of trialing for IDDS implants. In addition, the PACC recommends that no trial may be required in certain patient populations.

Primary Hydromorphone-Related Intrathecal Catheter Tip Granulomas: Is There a Role for Dose and Concentration?

BACKGROUND

Intrathecal drug delivery therapy has been used effectively in treating patients with intractable chronic pain. The development of an intrathecal catheter tip granuloma (ICTG) related to delivery of intrathecal opiates is a relatively infrequent, but potentially devastating complication. While there are many morphine-related ICTG cases described, reports of hydromorphone-related ICTG are limited. In addition, studies suggest a strong correlation between the use of higher doses and concentrations of intrathecal opiates and ICTG formation.

OBJECTIVE

The objective of this study is to determine the incidence and the association of intrathecal hydromorphone dose, concentration, duration of treatment and concomitant agents with ICTG formation.

STUDY DESIGN

This is a retrospective analysis of 101 consecutive patients implanted with intrathecal infusion delivery devices. Data were collected from chart review, and records of pump refills from the division of Pain Medicine of University Hospitals or outsourced to a home pump refill service.

RESULTS

From a cohort of 101 consecutively implanted patients, 69 were treated with intrathecal hydromorphone and followed up postimplant for an average of 33.5 ± 24 months (range 0-93 months; 95% CI of 27-39 months). The incidence of ICTG in our patient population was 8.7% during this period of time postimplant with mean time to granuloma detection 35.1 ± 7.9 months. Patients developing granuloma (n = 6) were treated with a combination of intrathecal hydromorphone and bupivacaine infusion. Exposure time to intrathecal agents was not different between the granuloma and nongranuloma group. Monthly dose increase of hydromorphone was higher in granuloma group vs. non-granuloma group (58 ± 34 mcg/month n = 6 vs. 25 ± 8 mcg/month n = 63). Four out of six granuloma cases occurred with low dose and concentration of IT hydromorphone (160-370 mcg/day; 0.75-1.0 mg/mL concentration). Intrathecal bupivacaine dose was not different between groups. A subset of patients was treated with intrathecal fentanyl and bupivacaine. No intrathecal granulomas occurred in this patient cohort.

CONCLUSION

This is the first clinical report demonstrating an association of hydromorphone with intrathecal granulomas, particularly at low doses and concentrations of hydromorphone. This study supports the notion that using low dose of IT opioids might not protect against ICTG development but that the level of exposure and type of opioid used in IT space might be highly correlated with ICTG development. Further research and recommendations related to chronic intrathecal opioid infusions are necessary to raise awareness of significant incidence of ICTG and development of tests to isolate patient populations at high risk.

Occipital Nerve Stimulation for the Treatment of Patients With Medically Refractory Occipital Neuralgia: Congress of Neurological Surgeons Systematic Review and Evidence-Based Guideline

BACKGROUND

Occipital neuralgia (ON) is a disorder characterized by sharp, electrical, paroxysmal pain, originating from the occiput and extending along the posterior scalp, in the distribution of the greater, lesser, and/or third occipital nerve. Occipital nerve stimulation (ONS) constitutes a promising therapy for medically refractory ON because it is reversible with minimal side effects and has shown continued efficacy with long-term follow-up.

OBJECTIVE

To conduct a systematic literature review and provide treatment recommendations for the use of ONS for the treatment of patients with medically refractory ON.

METHODS

A systematic literature search was conducted using the PubMed database and the Cochrane Library to locate articles published between 1966 and April 2014 using MeSH headings and keywords relevant to ONS as a means to treat ON. A second literature search was conducted using the PubMed database and the Cochrane Library to locate articles published between 1966 and June 2014 using MeSH headings and keywords relevant to interventions that predict response to ONS in ON. The strength of evidence of each article that underwent full text review and the resulting strength of recommendation were graded according to the guidelines development methodology of the American Association of Neurological Surgeons/Congress of Neurological Surgeons Joint Guidelines Committee.

RESULTS

Nine studies met the criteria for inclusion in this guideline. All articles provided Class III Level evidence.

CONCLUSION

Based on the data derived from this systematic literature review, the following Level III recommendation can be made: the use of ONS is a treatment option for patients with medically refractory ON.

Advanced Innovations for Pain

Chronic pain represents one of the most important public health problems in terms of both the number of patients afflicted and health care costs. Most patients with chronic pain are treated with medications as the mainstay of therapy, and yet most medically treated patients continue to report ongoing pain. Additionally, adverse effects from pain medications represent a major challenge for clinicians and patients. Spinal cord stimulation and intrathecal drug delivery systems are well-established techniques that have been utilized for over 25 years. Intrathecal drug delivery systems have proven efficacy for a wide variety of intractable pain conditions and fewer adverse effects than systemic medical therapy in patients with refractory cancer-related pain. Spinal cord stimulation is cost-effective and provides improved pain control compared with medical therapy in patients with a variety of refractory pain conditions including complex regional pain syndrome, painful diabetic neuropathy, and chronic radiculopathy. Patients who have intractable pain that has not responded to reasonable attempts at conservative pain care measures should be referred to a qualified interventional pain specialist to determine candidacy for the procedures discussed in this article.

Percutaneous and Endoscopic Adhesiolysis in Managing Low Back and Lower Extremity Pain: A Systematic Review and Meta-analysis

BACKGROUND

Chronic refractory low back and lower extremity pain is frustrating to treat. Percutaneous adhesiolysis and spinal endoscopy are techniques which can treat chronic refractory low back and lower extremity pain.Percutaneous adhesiolysis is performed by placing the catheter into the tissue plane at the ventrolateral aspect of the foramen so that medications can be injected. Adhesiolysis is used both for pain caused by scarring which is not resistant to catheter placement and other sources of pain, including inflammation in the absence of scarring.Mechanical lysis of scars with a catheter may or may not be necessary for percutaneous adhesiolysis to be effective. Spinal endoscopy allows direct visualization of the epidural space and has the possibility to use laser energy to treat pathology.

STUDY DESIGN

A systematic review of the effectiveness of percutaneous adhesiolysis and spinal endoscopic adhesiolysis to treat chronic refractory low back and lower extremity pain.

OBJECTIVE

To evaluate and update the effectiveness of percutaneous adhesiolysis and spinal endoscopic adhesiolysis to treat chronic refractory low back and lower extremity pain.

METHODS

The available literature on percutaneous adhesiolysis and spinal endoscopic adhesiolysis in treating persistent low back and leg pain was reviewed. The quality of each article used in this analysis was assessed. The level of evidence was classified on a 5-point scale from strong, based upon multiple randomized controlled trials to weak, based upon consensus, as developed by the U.S. Preventive Services Task Force (USPSTF) and modified by ASIPP. Data sources included relevant literature identified through searches of PubMed and EMBASE from 1966 to September 2015, and manual searches of the bibliographies of known primary and review articles.

OUTCOME MEASURES

Pain relief of at least 50% and functional improvement of at least 40% were the primary outcome measures. Short-term efficacy was defined as improvement of 6 months or less; whereas, long-term efficacy was defined more than 6 months.

RESULTS

For this systematic review, 45 studies were identified. Of these, for percutaneous adhesiolysis there were 7 randomized controlled trials and 3 observational studies which met the inclusion criteria. For spinal endoscopy, there was one randomized controlled trial and 3 observational studies. Based upon 7 randomized controlled trials showing efficacy, with no negative trials, there is Level I or strong evidence of the efficacy of percutaneous adhesiolysis in the treatment of chronic refractory low back and lower extremity pain. Based upon one high-quality randomized controlled trial, there is Level II to III evidence supporting the use of spinal endoscopy in treating chronic refractory low back and lower extremity pain.

CONCLUSION

The evidence is Level I or strong that percutaneous adhesiolysis is efficacious in the treatment of chronic refractory low back and lower extremity pain. Percutaneous adhesiolysis may be considered as a first-line treatment for chronic refractory low back and lower extremity pain. The evidence is Level II to III that spinal endoscopy is effective in the treatment of chronic refractory low back and lower extremity pain.

KEY WORDS

Spinal pain, chronic low back pain, post lumbar surgery syndrome, epidural scarring, adhesiolysis, endoscopy, radicular pain.

Effectiveness of Spinal Cord Stimulation in Chronic Spinal Pain: A Systematic Review

BACKGROUND

Chronic neuropathic pain has been recognized as contributing to a significant proportion of chronic pain globally. Among these, spinal pain is of significance with failed back surgery syndrome (FBSS), generating considerable expense for the health care systems with increasing prevalence and health impact.

OBJECTIVE

To assess the role and effectiveness of spinal cord stimulation (SCS) in chronic spinal pain.

STUDY DESIGN

A systematic review of randomized controlled trials (RCTs) of SCS in chronic spinal pain.

METHODS

The available literature on SCS was reviewed. The quality assessment criteria utilized were Cochrane review criteria to assess sources of risk of bias and Interventional Pain Management Techniques - Quality Appraisal of Reliability and Risk of Bias Assessment (IPM - QRB) criteria for randomized trials.The level of evidence was based on a best evidence synthesis with modified grading of qualitative evidence from Level I to Level V.Data sources included relevant literature published from 1966 through March 2015 that were identified through searches of PubMed and EMBASE, manual searches of the bibliographies of known primary and review articles, and all other sources.

OUTCOME MEASURES

RCTs of efficacy with a minimum 12-month follow-up were considered for inclusion. For trials of adaptive stimulation, high frequency stimulation, and burst stimulation, shorter follow-up periods were considered.

RESULTS

Results showed 6 RCTs with 3 efficacy trials and 3 stimulation trials. There were also 2 cost effectiveness studies available. Based on a best evidence synthesis with 3 high quality RCTs, the evidence of efficacy for SCS in lumbar FBSS is Level I to II. The evidence for high frequency stimulation based on one high quality RCT is Level II to III. Based on a lack of high quality studies demonstrating the efficacy of adaptive stimulation or burst stimulation, evidence is limited for these 2 modalities.

LIMITATIONS

The limitations of this systematic review continue to require future studies illustrating effectiveness and also the superiority of high frequency stimulation and potentially burst stimulation.

CONCLUSION

There is significant (Level I to II) evidence of the efficacy of spinal cord stimulation in lumbar FBSS; whereas, there is moderate (Level II to III) evidence for high frequency stimulation; there is limited evidence for adaptive stimulation and burst stimulation.

Intrathecal Hydromorphone and Bupivacaine Combination Therapy for Post-Laminectomy Syndrome Optimized with Patient-Activated Bolus Device

BACKGROUND

Intrathecal (IT) pumps have become a valuable tool in managing intractable non-cancer pain. The purpose of this study was to evaluate the efficacy of using a rigorous treatment algorithm for trialing and implanting IT pumps with hydromorphone and bupivacaine in managing a more homogeneous population of post-laminectomy syndrome or failed back surgery syndrome (FBSS) patients.

METHODS

This is a retrospective analysis of FBSS patients with chronic intractable back pain implanted with IT pumps delivering hydromorphone and bupivacaine.

RESULTS

A cohort of 57 (26 males, 31 females) consecutively implanted FBSS patients was analyzed. The average age at implant was 65.4 years. Average pain scores were 8.4 ± 0.2 (pre-implant), 4.9 ± 0.4 (6 months), 5.2 ± 0.5 (12 months), and 4.3 ± 0.5 (24 months). Average oral opioid doses in morphine equivalents were 56 ± 10 mg/day (pre-implant), 12.0 ± 3.5 mg/day (12 months), 15 ± 6 mg/day (24 months). Average IT hydromorphone doses were 79 ± 6.8 mcg/day (at implant), 184 ± 22 mcg/day (6 months), 329 ± 48 mcg/day (12 months), and 487 ± 80 mcg (24 months). IT hydromorphone dose escalation from baseline was 133% (6 months vs baseline), 78% (12 months vs 6 months), and 48% from 12 months to 24 months. Average IT bupivacaine doses were 5.8 ± 0.3 mg/day (implant), 9.5 ± 0.6 mg/day (6 months), 12.2 ± 0.7 mg/day (12 months), and 12.6 ± 0.9 mg/day (24 months).

CONCLUSION

IT hydromorphone and bupivacaine are effective in treating chronic pain of FBSS, as demonstrated by the reduction of pain intensity and oral opioid consumption. However, an IT dose escalation phenomenon was observed, although at a reduced rate compared with what had been previously reported in the literature. It is possible that the local anesthetic combination delivered via a patient-activaed bolus device is an important factor. Despite demonstrating effectiveness, the clinical utility of myPTM-optimized IT therapy remains limited by a lack of prospective, placebo-controlled trials and comparative effectiveness research.

Successful Management of Corneal Neuropathic Pain with Intrathecal Targeted Drug Delivery

OBJECTIVE

To describe the successful treatment of refractory corneal neuropathic pain with neuromodulation techniques.

DESIGN

Single case report.

SETTING

Academic tertiary care center in the United States of America.

SUBJECT AND METHODS

A 30-year-old woman presented with a 7-year history of refractory bilateral keratoneuralgia following laser-assisted in-situ keratomileusis (LASIK) procedure on both eyes. Having failed all conservative measures, the patient initially underwent trigeminal nerve stimulation and subsequently was implanted with an intrathecal drug delivery system (IDDS) with the catheter placed at the level C1.

RESULTS

Following an initial favorable response to the trigeminal nerve stimulator, the pain became refractory to neurostimulation after a few months and the system was explanted. The patient was successfully trialed with an intrathecal catheter placed at the level of C1 delivering a combination of bupivacaine and low dose fentanyl. The patient was then implanted with an IDDS equipped with a patient-activated bolus system. The patient was very satisfied with the treatment and has had greater than 50% pain relief for over a year.

CONCLUSIONS

Intrathecal delivery of bupivacaine and low dose fentanyl in the upper cervical spine can be effective in controlling refractory eye pain in properly selected patients and treatment centers.

Treatment-Limiting Complications of Percutaneous Spinal Cord Stimulator Implants: A Review of Eight Years of Experience From an Academic Center Database

OBJECTIVE

The study aims to evaluate the long-term implant survival and complications of spinal cord stimulation (SCS) leading to surgical revision or explant in patients treated for chronic noncancer pain.

MATERIALS AND METHODS

This is a retrospective study of all patients who underwent a percutaneous spinal cord stimulation trial followed by implant in an academic Pain Medicine division by four practitioners from 2007 to 2013, with follow-up data through April 2014.

RESULTS

A total of 345 patients were considered candidates for dorsal column stimulation and underwent a trial. Two hundred thirty-four patients were implanted with an implant-to-trial ratio of 67-86% across various chronic pain entities (postlaminectomy syndrome, complex regional pain syndrome, small-fiber peripheral neuropathy, abdominal/pelvic pain, nonsurgical candidates with lumbosacral neuropathy, and neuropathic pain not otherwise specified), with the exception of nonsurgical candidates with lumbosacral neuropathy who had an implant ratio of 43%. The complication rate was 34.6%, with the hardware related being the most common reason, comprising 74.1% of all complications. The revision and explant rates were 23.9% each. The most common reason for explant was loss of therapeutic effect (41.1%).

CONCLUSIONS

SCS is an effective treatment for chronic noncancer pain. It is a minimally invasive procedure, safe, and with good long-term outcomes. However, the surgical revision and explant rates are relatively high. As the use of SCS continues to grow, research into the causes of and risk factors for SCS-related complications is paramount to decrease complication rates in the future.

Ziconotide Combination Intrathecal Therapy for Noncancer Pain Is Limited Secondary to Delayed Adverse Effects: A Case Series With a 24-Month Follow-Up

OBJECTIVES

The efficacy and safety of ziconotide as a single agent has been evaluated in few short-term clinical trials and open-label studies. Ziconotide use is challenging given its adverse effect (AE) profile. The objective of this study is to describe the long-term efficacy and AEs of ziconotide used as an adjunct to other intrathecal (IT) agents in chronic noncancer pain patients.

MATERIALS AND METHODS

A case series of chronic noncancer pain patients who had suboptimal pain control from IT therapy. Ziconotide was introduced in the IT infusion mixture after a successful ziconotide trial. Pain scores, IT doses, as well as AEs were recorded and analyzed from trial to initial ziconotide infusion and up to 24 months.

RESULTS

Fifteen patients underwent ziconotide trials. Four subjects failed the trial, and 11 proceeded to continuous ziconotide treatment. Seven out of 11 patients experienced AEs resulting in ziconotide discontinuation. Two of the seven subjects who required discontinuation of ziconotide had improved pain. Four subjects were able to continue IT ziconotide through 24 months.

CONCLUSIONS

A high incidence of AEs limits the usefulness of IT ziconotide as adjunct therapy. Our results are limited by the size of our patient population; however, they represent a long follow-up period, which is limited in most current publications on this IT peptide. While ziconotide is a needed IT agent, more studies are necessary to better understand the factors that would improve the treatment to trial ratio as well as the long-term efficacy of IT ziconotide treatment.

Nerve blocks for chronic pain

Nerve blocks are often performed as therapeutic or palliative interventions for pain relief. However, they are often performed for diagnostic or prognostic purposes. When considering nerve blocks for chronic pain, clinicians must always consider the indications, risks, benefits, and proper technique. Nerve blocks encompass a wide variety of interventional procedures. The most common nerve blocks for chronic pain and that may be applicable to the neurosurgical patient population are reviewed in this article. This article is an introduction and brief synopsis of the different available blocks that can be offered to a patient.

Spinal endoscopic adhesiolysis in post lumbar surgery syndrome: an update of assessment of the evidence

BACKGROUND

Post lumbar surgery syndrome refers to pain occurring or present after lumbar surgery. While the causes of pain after lumbar surgery are multi-factorial, scarring is a significant source of that pain. Low back and/or leg pain after lumbar surgery can persist despite appropriate conservative therapy. Spinal endoscopy allows direct visual evaluation of the epidural space, along with mechanical lysis of any adhesions present.

STUDY DESIGN

A systematic review of the effectiveness of spinal endoscopic adhesiolysis in post lumbar surgery syndrome.

OBJECTIVE

To evaluate and update the effectiveness of spinal endoscopic adhesiolysis in treating post lumbar surgery syndrome.

METHODS

  The available literature on spinal endoscopic adhesiolysis in treating post lumbar surgery syndrome was reviewed. The quality assessment and clinical relevance criteria utilized were the Cochrane Musculoskeletal Review Group criteria as utilized for interventional techniques for randomized trials and the criteria developed by the Newcastle-Ottawa Scale criteria for observational studies.The level of evidence was classified as good, fair, and limited or poor based on the quality of evidence developed by the U.S. Preventive Services Task Force (USPSTF). Data sources included relevant literature identified through searches of PubMed and EMBASE from 1966 to September 2012, and manual searches of the bibliographies of known primary and review articles.

OUTCOME MEASURES

Pain relief and functional improvement were the primary outcome measures. Other outcome measures were improvement of psychological status, opioid intake, and return to work. Short-term effectiveness was defined as improvement of 12 months or less; whereas, long-term effectiveness was defined 12 months or longer.

RESULTS

For this systematic review, 21 studies were identified. Of these, one randomized controlled trial (RCT) and 5 observational studies met the inclusion criteria. Two of the observational studies were excluded because of other methodological issues, despite showing positive outcomes.Using current criteria for successful outcomes, these studies indicate that there is fair evidence for the effectiveness of spinal endoscopy in the treatment of persistent low back and/or leg pain in post lumbar surgery syndrome.

LIMITATIONS

  The limitations of this systematic review include the paucity of literature.

CONCLUSIONS

The evidence is fair that spinal endoscopy is effective in the treatment of post lumbar surgery syndrome.

Intrathecal infusion systems for long-term management of chronic non-cancer pain: an update of assessment of evidence

BACKGROUND

Intrathecal infusion systems are often used for patients with intractable pain when all else fails, including surgery. There is, however, some concern as to the effectiveness and safety of this treatment.

STUDY DESIGN

  A systematic review of intrathecal infusion systems for long-term management of chronic non-cancer pain.

OBJECTIVE

To evaluate and update the effect of intrathecal infusion systems in managing chronic non-cancer pain.

METHODS

The available literature on intrathecal infusion systems in managing chronic pain was reviewed. The quality assessment and clinical relevance criteria utilized were the Cochrane Musculoskeletal Review Group criteria as utilized for interventional techniques for randomized trials and the Newcastle-Ottawa Scale criteria for observational studies. The level of evidence was classified as good, fair, and limited or poor based on the quality of evidence developed by the U.S. Preventative Services Task Force (USPSTF). Data sources included relevant literature identified through searches of PubMed and EMBASE from 1966 to December 2012, and manual searches of the bibliographies of known primary and review articles.

OUTCOME MEASURES

The primary outcome measure was pain relief with short-term relief < 12 months and long-term relief ≥ 12 months. Secondary outcome measures were improvement in functional status, psychological status, return to work, and reduction in opioid intake.

RESULTS

There were 28 studies identified for this systematic review. Of these, 21 were excluded from further review. A total of 7 non-randomized studies met inclusion criteria for methodological quality assessment. No randomized trials met the inclusion requirements.The evidence is limited based on observational studies.

LIMITATIONS

The limitations of this systematic review include the paucity of literature.

CONCLUSION

The evidence is limited for intrathecal infusion systems.

American Society of Interventional Pain Physicians (ASIPP) guidelines for responsible opioid prescribing in chronic non-cancer pain: Part 2--guidance

RESULTS

Part 2 of the guidelines on responsible opioid prescribing provides the following recommendations for initiating and maintaining chronic opioid therapy of 90 days or longer. 1. A) Comprehensive assessment and documentation is recommended before initiating opioid therapy, including documentation of comprehensive history, general medical condition, psychosocial history, psychiatric status, and substance use history. (

EVIDENCE

good) B) Despite limited evidence for reliability and accuracy, screening for opioid use is recommended, as it will identify opioid abusers and reduce opioid abuse. (

EVIDENCE

limited) C) Prescription monitoring programs must be implemented, as they provide data on patterns of prescription usage, reduce prescription drug abuse or doctor shopping. (

EVIDENCE

good to fair) D) Urine drug testing (UDT) must be implemented from initiation along with subsequent adherence monitoring to decrease prescription drug abuse or illicit drug use when patients are in chronic pain management therapy. (

EVIDENCE

good) 2. A) Establish appropriate physical diagnosis and psychological diagnosis if available prior to initiating opioid therapy. (

EVIDENCE

good) B) Caution must be exercised in ordering various imaging and other evaluations, interpretation and communication with the patient, to avoid increased fear, activity restriction, requests for increased opioids, and maladaptive behaviors. (

EVIDENCE

good) C) Stratify patients into one of the 3 risk categories - low, medium, or high risk. D) A pain management consultation, may assist non-pain physicians, if high-dose opioid therapy is utilized. (

EVIDENCE

fair) 3. Essential to establish medical necessity prior to initiation or maintenance of opioid therapy. (

EVIDENCE

good) 4. Establish treatment goals of opioid therapy with regard to pain relief and improvement in function. (

EVIDENCE

good) 5. A) Long-acting opioids in high doses are recommended only in specific circumstances with severe intractable pain that is not amenable to short-acting or moderate doses of long-acting opioids, as there is no significant difference between long-acting and short-acting opioids for their effectiveness or adverse effects. (

EVIDENCE

fair) B) The relative and absolute contraindications to opioid use in chronic non-cancer pain must be evaluated including respiratory instability, acute psychiatric instability, uncontrolled suicide risk, active or history of alcohol or substance abuse, confirmed allergy to opioid agents, coadministration of drugs capable of inducing life-limiting drug interaction, concomitant use of benzodiazepines, active diversion of controlled substances, and concomitant use of heavy doses of central nervous system depressants. (

EVIDENCE

fair to limited) 6. A robust agreement which is followed by all parties is essential in initiating and maintaining opioid therapy as such agreements reduce overuse, misuse, abuse, and diversion. (

EVIDENCE

fair) 7. A) Once medical necessity is established, opioid therapy may be initiated with low doses and short-acting drugs with appropriate monitoring to provide effective relief and avoid side effects. (

EVIDENCE

fair for short-term effectiveness, limited for long-term effectiveness) B) Up to 40 mg of morphine equivalent is considered as low dose, 41 to 90 mg of morphine equivalent as a moderate dose, and greater than 91 mg of morphine equivalence as high dose. (

EVIDENCE

fair) C) In reference to long-acting opioids, titration must be carried out with caution and overdose and misuse must be avoided. (

EVIDENCE

good) 8. A) Methadone is recommended for use in late stages after failure of other opioid therapy and only by clinicians with specific training in the risks and uses. (

EVIDENCE

limited) B) Monitoring recommendation for methadone prescription is that an electrocardiogram should be obtained prior to initiation, at 30 days and yearly thereafter. (

EVIDENCE

fair) 9. In order to reduce prescription drug abuse and doctor shopping, adherence monitoring by UDT and PMDPs provide evidence that is essential to the identification of those patients who are non-compliant or abusing prescription drugs or illicit drugs. (

EVIDENCE

fair) 10. Constipation must be closely monitored and a bowel regimen be initiated as soon as deemed necessary. (

EVIDENCE

good) 11. Chronic opioid therapy may be continued, with continuous adherence monitoring, in well-selected populations, in conjunction with or after failure of other modalities of treatments with improvement in physical and functional status and minimal adverse effects. (

EVIDENCE

fair).

DISCLAIMER

The guidelines are based on the best available evidence and do not constitute inflexible treatment recommendations. Due to the changing body of evidence, this document is not intended to be a "standard of care."

American Society of Interventional Pain Physicians (ASIPP) guidelines for responsible opioid prescribing in chronic non-cancer pain: Part I--evidence assessment

BACKGROUND

Opioid abuse has continued to increase at an alarming rate since the 1990 s. As documented by different medical specialties, medical boards, advocacy groups, and the Drug Enforcement Administration, available evidence suggests a wide variance in chronic opioid therapy of 90 days or longer in chronic non-cancer pain. Part 1 describes evidence assessment.

OBJECTIVES

The objectives of opioid guidelines as issued by the American Society of Interventional Pain Physicians (ASIPP) are to provide guidance for the use of opioids for the treatment of chronic non-cancer pain, to produce consistency in the application of an opioid philosophy among the many diverse groups involved, to improve the treatment of chronic non-cancer pain, and to reduce the incidence of abuse and drug diversion. The focus of these guidelines is to curtail the abuse of opioids without jeopardizing non-cancer pain management with opioids.

RESULTS

1) There is good evidence that non-medical use of opioids is extensive; one-third of chronic pain patients may not use prescribed opioids as prescribed or may abuse them, and illicit drug use is significantly higher in these patients. 2) There is good evidence that opioid prescriptions are increasing rapidly, as the majority of prescriptions are from non-pain physicians, many patients are on long-acting opioids, and many patients are provided with combinations of long-acting and short-acting opioids. 3) There is good evidence that the increased supply of opioids, use of high dose opioids, doctor shoppers, and patients with multiple comorbid factors contribute to the majority of the fatalities. 4) There is fair evidence that long-acting opioids and a combination of long-acting and short-acting opioids contribute to increasing fatalities and that even low-doses of 40 mg or 50 mg of daily morphine equivalent doses may be responsible for emergency room admissions with overdoses and deaths. 5) There is good evidence that approximately 60% of fatalities originate from opioids prescribed within the guidelines, with approximately 40% of fatalities occurring in 10% of drug abusers. 6) The short-term effectiveness of opioids is fair, whereas the long-term effectiveness of opioids is limited due to a lack of long-term (> 3 months) high quality studies, with fair evidence with no significant difference between long-acting and short-acting opioids. 7) Among the individual drugs, most opioids have fair evidence for short-term and limited evidence for long-term due to a lack of quality studies. 8) The evidence for the effectiveness and safety of chronic opioid therapy in the elderly for chronic non-cancer pain is fair for short-term and limited for long-term due to lack of high quality studies; limited in children and adolescents and patients with comorbid psychological disorders due to lack of quality studies; and the evidence is poor in pregnant women. 9) There is limited evidence for reliability and accuracy of screening tests for opioid abuse due to lack of high quality studies. 10) There is fair evidence to support the identification of patients who are non-compliant or abusing prescription drugs or illicit drugs through urine drug testing and prescription drug monitoring programs, both of which can reduce prescription drug abuse or doctor shopping.

DISCLAIMER

The guidelines are based on the best available evidence and do not constitute inflexible treatment recommendations. Due to the changing body of evidence, this document is not intended to be a "standard of care."

A review of epidural catheter-related infections

Spinal drug delivery is a generally safe and effective therapy for the treatment of both acute and chronic pain. However, it can be occasionally associated with significant complications, including neurologic injury, as a result of bleeding and infection in a confined space. This article focuses on risk factors for developing epidural catheter-related infections as well as strategies to minimize risks. Additionally, the diagnosis and management of epidural catheter-related infections, both superficial and deep, are discussed.

Age-dependent intrathecal opioid escalation in chronic noncancer pain patients

BACKGROUND

Age and gender may exert important influences on opioid responsiveness and chronic pain. These effects have not been explored in the setting of chronic intrathecal (IT) opioid therapy. The objective of this study was to evaluate the effect of age and sex on IT opioid requirements during the first year after implantation of an intrathecal drug delivery system (IDDS) in chronic noncancer pain patients.

DESIGN

Retrospective study. METHODS AND PATIENT POPULATION: In this retrospective study, 135 chronic noncancer pain patients consecutively implanted with IDDSs for opioid therapy had their first year postimplant records examined.

RESULTS

Similar pain relief was achieved at 12 months after implant in both age groups. Relative to the dose at implant, younger patients had significantly higher rates of IT opioid dose escalation compared with older patients at 12 months (750 ± 450% in patients ≤50 years old vs 195 ± 120% in patients >50 years old, P < 0.001). Oral opioid consumption was significantly decreased at 12 months in the older patient population (140 ± 89 to 62 ± 35 mg/day at 12 months, P < 0.001, n = 85), while in the younger patient group, there was no change in oral opioid consumption (128 ± 81 mg/day to 105 ± 140 mg/day at 12 months, P = 0.65, n = 50). Gender-based analysis (55% males and 45% females) revealed similar reductions in pain scores during the first year postimplant. Oral opioid consumption was significantly higher in females (126 ± 138 mg) vs males (79 ± 89 mg) at 12 months postimplant; however, IT opioid dose escalation at 12 months postimplant was not statistically different between males and females.

CONCLUSION

IT opioid dose escalation occurs more steeply in the younger (under 50 years old) IDDS patient population without a concomitant significant decrease in oral consumption of opioids. Age-dependent changes may have important clinical implications on the effectiveness of IT opioid therapy in noncancer pain and its potential complications.