Continuous intrathecal morphine treatment for chronic pain of nonmalignant etiology: long-term benefits and efficacy

Deafferentation in Pain Medicine: A Narrative Review of Mechanisms and Management

Deafferentation is an umbrella term that includes several clinical conditions. The exact mechanism is not yet known, and the different clinical conditions do not necessarily share common pathophysiology. It includes both non-painful and painful conditions, including cancer pain conditions. Clinical presentation can be immediate or delayed, sometimes years after the causative lesion. Patients experience neuropathic pain symptoms in an area of abnormal or absent sensation. Laboratory tests show denervation and loss of function. Pain management strategies can be directed toward alleviating symptoms rather than eradication. The site of origin of the pain can help decide the treatment modalities to be tried. Gabapentinoids, antidepressants, and sodium channel blockers can be used. This type of pain is typically opioid-nonresponsive, but some patients may benefit. Neuronal destructive procedures are indicated for brachial plexus avulsion injuries. Spinal cord stimulation, dorsal root entry zone rhizotomy, deep brain thalamic stimulation, and motor cortex stimulation have been suggested for the management of the complex clinical conditions under the umbrella of deafferentation.

The Polyanalgesic Consensus Conference (PACC)®: Intrathecal Drug Delivery Guidance on Safety and Therapy Optimization When Treating Chronic Noncancer Pain

INTRODUCTION

The International Neuromodulation Society convened a multispecialty group of physicians and scientists based on expertise with international representation to establish evidence-based guidance on intrathecal drug delivery in treating chronic pain. This Polyanalgesic Consensus Conference (PACC)® project, created more than two decades ago, intends to provide evidence-based guidance for important safety and efficacy issues surrounding intrathecal drug delivery and its impact on the practice of neuromodulation.

MATERIALS AND METHODS

Authors were chosen on the basis of 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 PACC® last published guidelines) to the present. Identified studies were graded using the United States Preventive Services Task Force criteria for evidence and certainty of net benefit. Recommendations are based on the strength of evidence or consensus when evidence is scant.

RESULTS

The PACC® 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 PACC® recommends best practices regarding intrathecal drug delivery to improve safety and efficacy. The evidence- and consensus-based recommendations should be used as a guide to assist decision-making when clinically appropriate.

Case Report: An Unexpected Complication of Intrathecal Therapy

Traditionally, intrathecal therapy has been used for pain amelioration in cancer patients, but now has indications for nonmalignant chronic pain conditions. Due to its expanding use, it is imperative to understand the risks and management of intrathecal pump implantation. This case illustrates a series of uncommon intrathecal pump complications in a 52-year-old woman with complex regional pain syndrome. Considering the complications outlined in this case, there is a need to conduct retrospective studies and establish guidelines to address when it is optimal to remove a chronically placed catheter as well as the proper technique for removal.

Does lumbar spinal decompression or fusion surgery influence outcome parameters in patients with intrathecal morphine treatment for persistent spinal pain syndrome type 2 (PSPS-T2)

OBJECTIVES

Intrathecal morphine pump (ITMP) infusion therapy is efficient in managing chronic pain refractory to standard treatment. This study evaluates pain relief and improvement of quality of life in chronic pain patients after intrathecal morphine pump implantation for treatment of persistent pain after lumbar spinal fusion surgery and lumbar spinal decompression alone.

METHODS

Forty three chronic pain patients that received an ITMP at our department between 2009 and 2019 were retrospectively analyzed divided into 2 cohorts (lumbar spinal fusion surgery and lumbar spinal decompression alone). Pain intensity was evaluated using the numeric rating scale (NRS), quality of life was assessed by EQ-5D-3L, mental health was assessed by Beck Depression Inventory (BDI-V), and Pain Catastrophizing Scale (PCS). Morphine dosage was assessed over time. Data was collected preoperatively, 6 and 24 months postoperatively. Statistical analysis was performed using Friedman's analysis of variance to evaluate the development of NRS, PCS, BDI and EQ-5D-3L over time and Mann-Whitney-U-test for the differences between these parameters in the different cohorts. A two-sided p-value <0.05 was considered statistically significant.

RESULTS

Median age was 64 years (IQR25-75 56-71 years). NRS, EQ-5D-3L, BDI-V, and PCS showed a significant overall improvement after 6 and 24 months compared to baseline data (p<0.001). No statistically significant differences between patients with lumbar spinal fusion surgery and lumbar spinal decompression alone were seen. Furthermore, no statistically significant differences for age and gender were seen. The initially administered median morphine dosage was significantly higher in the fusion group (3.0 mg/day; IQR25-75 1.5-4.2 mg/day) compared to the decompression-alone group (1.5 mg/day; IQR25-75 1.0-2.6 mg/day); (p=0.027).

CONCLUSIONS

This retrospective study showed that ITMP have a major long-term impact on pain relief, improve the quality of life, psychological distress, as well as pain catastrophizing in patients with chronic pain following lumbar spinal surgery independent of the previous surgical procedure. After ITMP implantation initial median morphine dosage seems to be significantly higher after spinal fusion compared to decompressive surgery alone.

Intrathecal Baclofen and Opioid Therapy: Cerebrospinal Fluid Leak and Infection Incidence, Risk Factors, and Outcomes

BACKGROUND

Intrathecal drug therapy treats medically refractory spasticity and pain. cerebrospinal fluid (CSF) leak or infection can limit efficacy and increase morbidity. We aim to evaluate risk factors and outcomes after CSF leaks and infections requiring reoperation.

MATERIALS AND METHODS

We retrospectively analyzed our 7-year experience of intrathecal baclofen and opioid operations using a protocol designed to limit CSF leakage and infections. Postoperative complication incidence and risk factors for reoperation were compared with published reports. We assessed outcomes after these complications.

RESULTS

We analyzed 282 intrathecal baclofen (ITB) and intrathecal opioid (ITO) therapy operations (mean 2.27-year follow-up). 21% developed CSF leaks overall with similar incidences in ITB and ITO patients (19% vs. 25%, p0.3). Overall, 5% of patients developed deep infections with similar incidences between ITB and ITO cohorts (6% vs. 4%, p0.6). Tobacco use and age <50 years were significantly associated with CSF leak in ITO operations. Underweight body mass index, immunosuppression, tobacco use, and primary implantation were associated with infection. When CSF leak or infection occurred, patients suffered more perioperative adverse events and had elevated 90-day readmission rate compared with those without these complications.

CONCLUSIONS

Our 7-year ITB and ITO therapy using the 8781 Ascenda intrathecal catheter highlights a higher reoperation rate for CSF leak and similar infection incidence to reports using traditional catheters. Multiple modifiable risk factors for CSF leak include recent tobacco use among ITO patients. Body mass index optimization and immunosuppressant elimination may reduce reoperation for infection.

Intrathecal Drug Delivery: Advances and Applications in the Management of Chronic Pain Patient

Advances in our understanding of the biology of spinal systems in organizing and defining the content of exteroceptive information upon which higher centers define the state of the organism and its role in the regulation of somatic and automatic output, defining the motor response of the organism, along with the unique biology and spatial organization of this space, have resulted in an increased focus on therapeutics targeted at this extracranial neuraxial space. Intrathecal (IT) drug delivery systems (IDDS) are well-established as an effective therapeutic approach to patients with chronic non-malignant or malignant pain and as a tool for management of patients with severe spasticity and to deliver therapeutics that address a myriad of spinal pathologies. The risk to benefit ratio of IDD makes it a useful interventional approach. While not without risks, this approach has a significant therapeutic safety margin when employed using drugs with a validated safety profile and by skilled practioners. The present review addresses current advances in our understanding of the biology and dynamics of the intrathecal space, therapeutic platforms, novel therapeutics, delivery technology, issues of safety and rational implementation of its therapy, with a particular emphasis upon the management of pain.

A safety review of approved intrathecal analgesics for chronic pain management

Introduction: Intrathecal (IT) drug therapy is an effective treatment option for patients with chronic pain of malignant or nonmalignant origin, with an established safety profile and fewer adverse effects compared to oral or parenteral pain medications. Morphine (a μ-opioid receptor agonist) and ziconotide (a non-opioid calcium channel antagonist) are the only IT agents approved by the U.S. Food and Drug Administration for the treatment of chronic pain. Although both are considered first-line IT therapies, each drug has unique properties and considerations.Areas Covered: This review will evaluate the pivotal trials that established the use of morphine and ziconotide as first-line IT therapy for patients with chronic pain, as well as safety and efficacy data generated from various retrospective and prospective studies.Expert Opinion: Morphine and ziconotide are effective IT therapies for patients with chronic malignant or nonmalignant pain that is refractory to other interventions. IT ziconotide is recommended as a first-line therapy due to its efficacy and avoidance of many adverse effects commonly associated with opioids. The use of IT morphine is also considered first-line; however, the risks of respiratory depression, withdrawal with drug discontinuation or pump malfunction, and the development of tolerance require careful patient selection and management.

Intrathecal opioids: equally efficacious at any age

BACKGROUND

Intrathecal opioid pumps have been used in the management of severe chronic pain for more than 40 years. Numerous studies have shown significant therapeutic effects alongside tolerable side effects. In the last decades, life expectancy has increased in many countries in the world. With an aging population, the question arises whether effects equal to those in younger patients can also be achieved in elderly patients.

MATERIALS AND METHODS

This study is an in-depth re-analysis of data published previously. 36 patients were analyzed. The sample included 18 elderly patients (> 65 years) and 18 younger patients.

RESULTS

No differences between the two samples were found with regard to pain intensity under intrathecal opioid therapy and prior to implantation of the opioid pump. Likewise, there were no differences in anxiety/depression scores and pain-related disability. Side effects were reported at similar rates by the elderly patients and by the younger patients. Elderly patients showed a tendency towards lower opioid doses and slower dose increases.

CONCLUSION

Our data hint at a consistent efficacy of intrathecal opioid therapy in elderly patients even after long-term treatment. Side effects of the treatment are relatively frequent but mild and no side effects were particularly frequent in elderly people.

Patient Satisfaction Following Intrathecal Targeted Drug Delivery for Benign Chronic Pain: Results of a Single-Center Survey Study

OBJECTIVES

Targeted Drug Delivery (TDD) is commonly used for the management of patients with intractable pain. Past studies have proven efficacy in pain relief and reduction in opioid use and cost-effectiveness in long-term pain management. There are few studies investigating satisfaction among patients with implanted pain pumps that are managed with targeted intrathecal medications.

MATERIAL AND METHODS

Patients in a single medical practice implanted with pain pumps for relief of intractable pain were identified and extracted from the electronic health record (EHR). Six hundred and ten active TDD patients were identified and an anonymous 18-question survey was administered to determine satisfaction with TDD therapy. During an 18-month period from May 2018 to August 2019, patients were invited to take a satisfaction survey. Both primary and secondary outcomes were reported as proportions; P < 0.05 was considered significant.

RESULTS

Four hundred and forty-three patients (74% of the active pump population) completed the survey. The majority of patients reported improvement in pain, improvement of physical function, improvement in quality of life and reduction in opioid use. Complete discontinuation of oral opioid intake was reported in 38.9% of patients. The majority of patients had a 40 cc reservoir implanted in an upper buttock pocket site and overall, 91% of patients were happy with pump pocket location.

CONCLUSION

Intrathecal TDD therapy can relieve pain and improve quality of life in patients with intractable pain and offers a reasonable alternative to long-term oral or skin patch opioid management. Patients utilizing TDD therapy reported high degrees of satisfaction.

Treatment of restless legs syndrome with a pump; efficacy and complications

OBJECTIVES

Restless legs syndrome (RLS) has a prevalence of 2.5%-15% in the general population. For those who suffer from a medically refractory RLS, intrathecal morphine treatment has been shown to be effective. The aim of this retrospective study was to investigate efficacy, complications and side effects in patients treated over several years with an implantable pump. A comparison was done to a group of patients treated with a similar pump system due to spasticity.

MATERIALS AND METHODS

The charts of ten patients with severe or very severe RLS have been reviewed. These patients have received an intrathecal drug delivery system during 2000-2016. To compare the rate of complications, a control group of 20 patients treated with intrathecal baclofen due to spasticity was included in the study. Their time of treatment corresponded to the RLS patients.

RESULTS

The severity of symptoms related to RLS decreased significantly after treatment. Doses required ranged from 68 to 140 µg/d. Two cases of side effects were detected; one case with nausea and dizziness and one case with headache and fatigue. The rate of mechanical, infectious and other complications was similar between the two groups.

CONCLUSIONS

In light of the decrease in symptom severity and the low rate of side effects, intrathecal morphine can be considered an adequate treatment for those suffering from medically refractory RLS. The occurrence of complications did not differ between subjects with RLS and spasticity.

Neuromodulation in Pediatrics: Case Series

OBJECTIVES

Neuromodulation, particularly intrathecal drug delivery systems and spinal cord stimulators (SCSs), can be a valuable tool when treating chronic pain in adults. However, there is a paucity of literature with regard to its use in pediatrics.

MATERIALS AND METHODS

We present a series of 14 children and adolescents with intractable pain who received a SCS or a pump for the intrathecal delivery of medications between 2010 and 2016 at our institution.

RESULTS

During the study period, we placed 10 intrathecal pumps and 4 SCSs with an average age of 17 years old. Pain scores significantly improved after the implant (P<0.007) and function improved in 79% of patients. Opioid use was also significantly reduced. Three patients eventually had their device removed due to psychiatric comorbidities. Four patients had complications that were treated without further sequelae.

CONCLUSIONS

Neuromodulation can offer important options in treating some pediatric chronic pain patients. In-depth knowledge of primary disease and strict patient selection in the context of the patient's social situation is vital to successful treatment.

Intrathecal Therapy for Chronic Pain: A Review of Morphine and Ziconotide as Firstline Options

Objectives

To evaluate the evidence for morphine and ziconotide as firstline intrathecal (IT) analgesia agents for patients with chronic pain.

Methods

Medline was searched (through July 2017) for “ziconotide” or “morphine” AND “intrathecal” AND “chronic pain,” with results limited to studies in human populations.

Results

The literature supports the use of morphine (based primarily on noncontrolled, prospective, and retrospective studies) and ziconotide (based on randomized controlled trials and prospective observational studies) as first-choice IT therapies. The 2016 Polyanalgesic Consensus Conference (PACC) guidelines recommended both morphine and ziconotide as firstline IT monotherapy for localized and diffuse chronic pain of cancer-related and non–cancer-related etiologies; however, one consensus point emphasized ziconotide use, unless contraindicated, as firstline IT therapy in patients with chronic non–cancer-related pain. Initial IT therapy choice should take into consideration individual patient characteristics (e.g., pain location, response to previous therapies, comorbid medical conditions, psychiatric history). Trialing is recommended to assess medication efficacy and tolerability. For both morphine and ziconotide, the PACC guidelines recommend conservative initial dosing strategies. Due to its narrow therapeutic window, ziconotide requires careful dose titration. Ziconotide is contraindicated in patients with a history of psychosis. IT morphine administration may be associated with serious side effects (e.g., respiratory depression, catheter tip granuloma), require dose increases, and cause dependence over time.

Conclusion

Based on the available evidence, morphine and ziconotide are recommended as firstline IT monotherapy for cancer-related and non–cancer-related pain. The choice of first-in-pump therapy should take into consideration patient characteristics and the advantages and disadvantages of each medication.

Efficacy, Safety, and Feasibility of the Morphine Microdose Method in Community-Based Clinics

Objectives

The goal of this study was to assess the success of the morphine microdose method in a community pain clinic setting by monitoring follow-up frequency, dose escalation, and monotherapy/polytherapy ratio. The morphine microdose method involves a pretrial reduction or elimination of systemic opioids followed by a period of abstinence. Intrathecal (IT) morphine is then started at doses of less than 0.2 mg per day. Systemic opioid abstinence is then continued after pump implant and IT morphine monotherapy.

Design

Retrospective review of medical records.

Setting

Private and academic pain clinic practices.

Subjects

Chronic noncancer pain patients.

Methods

We reviewed the charts of 60 patients who had completed a microdose regimen and had an IT pump implanted between June 11, 2008, and October 11, 2014. During IT therapy, dose change over time, pain scores, side effects, max dose, and duration were recorded.

Results

The majority of patients (35/60, 58%) were successfully managed solely on morphine microdose monotherapy. These patients did not require additional oral therapy. There was a significant reduction in mean pain scores, from 7.4 ± 0.32 before microdose therapy to 4.8 ± 0.3 after microdose therapy.

Conclusions

Microdose therapy achieved analgesia, improved safety, and avoided systemic side effects. The safety of IT therapy was increased by using a lower concentration (2 mg/mL) and lower daily doses (<3 mg/d) of morphine. Furthermore, microdose therapy was feasible, safe, and cost-effective in the outpatient setting.

Cross-talk between Human Spinal Cord μ-opioid Receptor 1Y Isoform and Gastrin-releasing Peptide Receptor Mediates Opioid-induced Scratching Behavior

BACKGROUND

Although spinal opioids are safe and effective, pruritus is common and distressing. The authors previously demonstrated in mouse spinal cord that interactions between μ-opioid receptor isoform 1D and gastrin releasing peptide receptor mediate morphine-induced scratch. The C-terminal of 1D inhibits morphine-induced scratch without affecting analgesia. The authors hypothesize that human spinal cord also contains itch-specific μ-opioid receptor isoforms which interact with gastrin releasing peptide receptor.

METHODS

Reverse transcription polymerase chain reaction was performed on human spinal cord complimentary DNA from two human cadavers. Calcium responses to morphine (1 μM) were examined using calcium imaging microscopy on human cells (HEK293) coexpressing gastrin releasing peptide receptor and different human μ-opioid receptor isoforms. The authors assessed morphine-induced scratching behavior and thermal analgesia in mice following intrathecal injection of morphine (0.3 nmol) and a transactivator of transcription peptide designed from C-terminal sequences of 1Y isoform (0, 0.1, and 0.4 nmol).

RESULTS

The authors demonstrated 1Y expression in the spinal cord dorsal horn. Morphine administration evoked a calcium response (mean ± SD) (57 ± 13 nM) in cells coexpressing both gastrin releasing peptide receptor and the 1Y isomer. This was blocked by 10 μM naltrexone (0.7 ± 0.4 nM; P < 0.0001), 1 μM gastrin-releasing peptide receptor antagonist (3 ± 2 nM; P < 0.0001), or 200 μM 1Y-peptide (2 + 2 nM; P < 0.0001). In mice, 0.4 nmol 1Y-peptide significantly attenuated morphine-induced scratching behaviors (scratching bouts, vehicle vs. 1Y-peptide) (92 ± 31 vs. 38 ± 29; P = 0.011; n = 6 to 7 mice per group), without affecting morphine antinociception in warm water tail immersion test (% of maximum possible effect) (70 ± 21 vs. 67 ± 22; P = 0.80; n = 6 mice per group).

CONCLUSIONS

Human μ-opioid receptor 1Y isomer is a C-terminal splicing variant of Oprm1 gene identified in human spinal cord. Cross-talk between 1Y and gastrin releasing peptide receptor is required for mediating opioid-induced pruritus. Disrupting the cross talk may have implications for therapeutic uncoupling of desired analgesic effects from side effects of opioids.

Managing Chronic Non-Malignant Pain in the Elderly: Intrathecal Therapy

Intrathecal drug delivery (IDD) was first described in 1981 by Onofrio, who used a pump for continuous and intrathecal delivery of morphine to treat cancer pain. Over the following four decades, many reports supported this treatment method with implanted pumps for cancer and non-cancer pain. To date, more than 300,000 pumps for pain therapy and spasticity have been implanted worldwide. This article reviews current knowledge regarding intrathecal opioid therapy, focusing particularly on the use of IDD in elderly patients. Current literature is presented, and the arguments in favor of and against this therapy in elderly patients are discussed.

Long-term Outcomes Using Intrathecal Drug Delivery Systems in Complex Regional Pain Syndrome

OBJECTIVE

Providing durable long-term pain control for patients with complex regional pain syndrome (CRPS) is challenging. A multidisciplinary approach focused on physical therapy is frequently prescribed, with opioids and invasive procedures reserved for those challenged by functional progression. In this study, we examined the long-term efficacy of intrathecal drug delivery systems (IDDS) in patients with CRPS at our institution.

METHODS

Patients with CRPS implanted with an IDDS between 2000 and 2013 who had four or more years of continuous follow-up were included in the analysis. The outcome variables of interest were pain intensity and oral opioid intake. The primary predictor of interest was dose of intrathecal opioids, with ziconotide, bupivacaine, and clonidine characterized as binary secondary predictors.

RESULTS

Of the 1,653 IDDS identified, 62 were implanted primarily for CRPS-related pain. Of these, 26 had four or more years of complete follow-up data. Pain scores did not significantly decrease over time, and we observed no correlation between pain intensity and use of any intrathecal medication. Although oral opioid intake decreased over time, intrathecal opioid dose did not affect oral opioid consumption. Ziconotide was associated with a hastening of the decrease in oral opioid intake, whereas the presence of bupivacaine paradoxically increased oral opioid intake.

CONCLUSIONS

Our study demonstrates that intrathecal opioid dose was not associated with long-term decreases in oral opioid intake. Additionally, ziconotide was associated with a decrease in oral opioid intake over the four-year follow-up, and bupivacaine was associated with an increase in oral opioid intake. Our study examines the long-term effectiveness of intrathecal medications in managing pain in patients with complex regional pain syndrome. We present a detailed follow-up over four years for 26 patients, tracking oral opiate intake, pain scores, and intrathecal pump settings. Our findings suggest that intrathecal opiates may not be effective in reducing oral opiate intake, ziconotide may hasten a decrease in intake, and bupivacaine may lead to an increase in intake.

Altered Activity of SK Channel Underpins Morphine Withdrawal Relevant Psychiatric Deficiency in Infralimbic to Accumbens Shell Pathway

Drug addiction can be viewed as a chronic psychiatric disorder that is related to dysfunction of neural circuits, including reward deficits, stress surfeits, craving changes, and compromised executive function. The nucleus accumbens (NAc) plays a crucial role in regulating craving and relapse, while the medial prefrontal cortex (mPFC) represents a higher cortex projecting into the NAc that is active in the management of executive function. In this study, we investigated the role of the small conductance calcium-activated potassium channels (SK channels) in NAc and mPFC after morphine withdrawal. Action potential (AP) firing of neurons in the NAc shell was enhanced via the downregulations of the SK channels after morphine withdrawal. Furthermore, the expression of SK2 and SK3 subunits in the NAc was significantly reduced after 3 weeks of morphine withdrawal, but was not altered in the dorsal striatum. In mPFC, the SK channel subunits were differentially expressed. To be specific, the expression of SK3 was upregulated, while the expression of SK2 was unchanged. Furthermore, the AP firing in layer 5 pyramidal neurons of the infralimbic (IL) cortex was decreased via the upregulations of the SK channel-related tail current after 3 weeks of morphine withdrawal. These results suggest that the SK channel plays a specific role in reward circuits following morphine exposure and a period of drug withdrawal, making it a potential target for the prevention of relapse.

Retrospective analysis of the financial break-even point for intrathecal morphine pump use in Korea

Background

The high cost of intrathecal morphine pump (ITMP) implantation may be the main obstacle to its use. Since July 2014, the Korean national health insurance (NHI) program began paying 50% of the ITMP implantation cost in select refractory chronic pain patients. The aims of this study were to investigate the financial break-even point and patients' satisfaction in patients with ITMP treatment after the initiation of the NHI reimbursement.

Methods

We collected data retrospectively or via direct phone calls to patients who underwent ITMP implantation at a single university-based tertiary hospital between July 2014 and May 2016. Pain severity, changes in the morphine equivalent daily dosage (MEDD), any adverse events, and patients' satisfaction were determined. We calculated the financial break-even point of ITMP implantation via investigating the patient's actual medical costs and insurance information.

Results

During the studied period, 23 patients received ITMP implantation, and 20 patients were included in our study. Scores on an 11-point numeric rating scale (NRS) for pain were significantly reduced compared to the baseline value (P < 0.001). The MEDD before ITMP implantation was 0.59 [IQR: 0.55–0.82]. The total MEDD increased steadily to 0.77 [IQR: 0.53–1.08] at 1 year, which was 126% of the baseline (P < 0.001). More than a half (60%) responded that the ITMP therapy was somewhat satisfying. The financial break-even point was 28 months for ITMP treatment after the NHI reimbursement policy.

Conclusions

ITMP provided effective chronic pain management with improved satisfaction and reasonable financial break-even point of 28 months with 50% financial coverage by NHI program.

The Pharmacology of Spinal Opioids and Ziconotide for the Treatment of Non-Cancer Pain

Background

Intrathecal drug delivery has undergone a revitalization following a better understanding of this delivery route and its pharmacokinetics. Driven by patient safety and outcomes, clinicians are motivated to rethink the traditional spinal infusion pump patient selection criteria and indications. We review the current understanding of the pharmacology of commonly employed intrathecal agents and the clinical relevance.

Methods

Search strategies for data acquisition included Medline database, PubMed, Google scholar, along with international and national professional meeting content, with key words including pharmacology of opioids, intrathecal therapy, ziconotide, pharmacokinetics, and intrathecal drug delivery. The search results were limited to the English language.

Results

Over 300 papers were identified. The literature was condensed and digested to evaluate the most commonly used medications in practice, sto serve as a foundation for review. We review on-label medications: ziconotide and morphine, and off label medications including fentanyl, sufentail, and hydromorphine.

Conclusion

Intrathecal therapy has level-one evidence for use for malignant pain and nonmalignant pain, with continued cost savings and improved safety. To most effectively serve our patients, a clear appreciation for the pharmacology of these commonly employed medication is paramount..

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.

Treatment of Refractory Postdural Puncture Headache after Intrathecal Drug Delivery System Implantation with Epidural Blood Patch Procedures: A 20-Year Experience

A recent publication reported the incidence of postdural puncture headache (PDPH) in conjunction with intrathecal drug delivery system (IDDS) implantation to be nearly 23 percent. Many patients responded to conservative measures but a percentage needed invasive treatment with an epidural blood patch (EBP). There is limited data to describe the technical details, success rates, and complications associated with EBP in this population. This study aims to provide a retrospective report of EBP for patients suffering from PDPH related to IDDS implantation. A chart review established a cohort of patients that required EBP in relation to a PDPH after IDDS implantation. This cohort was evaluated for demographic data as well as details of the EBP including technical procedural data, success rates, and complications. All patients received a trial of conservative therapy. Standard sterile technique and skin preparation were utilized with no infectious complications. The EBP was placed below the level of the IDDS catheter in 94% of procedures. Fluoroscopy was utilized in each case. The mean EBP volume was 18.6 cc and median time of EBP was day 7 after implant. There were no complications associated with EBP. EBP appears to be an effective intervention in this subset of PDPH patients.

Brain Reward Circuits in Morphine Addiction

Morphine is the most potent analgesic for chronic pain, but its clinical use has been limited by the opiate's innate tendency to produce tolerance, severe withdrawal symptoms and rewarding properties with a high risk of relapse. To understand the addictive properties of morphine, past studies have focused on relevant molecular and cellular changes in the brain, highlighting the functional roles of reward-related brain regions. Given the accumulated findings, a recent, emerging trend in morphine research is that of examining the dynamics of neuronal interactions in brain reward circuits under the influence of morphine action. In this review, we highlight recent findings on the roles of several reward circuits involved in morphine addiction based on pharmacological, molecular and physiological evidences.

Total pancreatectomy with islet cell transplantation vs intrathecal narcotic pump infusion for pain control in chronic pancreatitis

AIM: To evaluate pain control in chronic pancreatitis patients who underwent total pancreatectomy with islet cell transplantation or intrathecal narcotic pump infusion.

METHODS: We recognized 13 patients who underwent intrathecal narcotic pump (ITNP) infusion and 57 patients who underwent total pancreatectomy with autologous islet cell transplantation (TP + ICT) for chronic pancreatitis (CP) pain control between 1998 and 2008 at Indiana University Hospital. All patients had already failed multiple other modalities for pain control and the decision to proceed with either intervention was made at the discretion of the patients and their treating physicians. All patients were evaluated retrospectively using a questionnaire inquiring about their pain control (using a 0-10 pain scale), daily narcotic dose usage, and hospital admission days for pain control before each intervention and during their last follow-up.

RESULTS: All 13 ITNP patients and 30 available TP + ICT patients were evaluated. The mean age was approximately 40 years in both groups. The median duration of pain before intervention was 6 years and 7 years in the ITNP and TP + ICT groups, respectively. The median pain score dropped from 8 to 2.5 (on a scale of 0-10) in both groups on their last follow up. The median daily dose of narcotics also decreased from 393 mg equivalent of morphine sulfate to 8 mg in the ITNP group and from 300 mg to 40 mg in the TP + ICT group. No patient had diabetes mellitus (DM) before either procedure whereas 85% of those who underwent pancreatectomy were insulin dependent on their last evaluation despite ICT.

CONCLUSION: ITNP and TP + ICT are comparable for pain control in patients with CP however with high incidence of DM among those who underwent TP + ICT. Prospective comparative studies and longer follow up are needed to better define treatment outcomes.

Trialing and Maintenance Dosing Using a Low-Dose Intrathecal Opioid Method for Chronic Nonmalignant Pain: A Prospective 36-Month Study

OBJECTIVE

To evaluate low-dose intrathecal opioid trialing and maintenance with regard to analgesia and psychometric functional capacity.

MATERIALS AND METHODS

Prospective cohort of subjects offered, trialed and maintained using low-dose opioid therapy via an intrathecal drug delivery system. Analgesia, measured by visual analog scale and the Global Pain Scale, and function, measured by Multidimensional Pain Inventory and Global Pain Scale, are evaluated. Population analysis by age, gender, oral opioid dose, diagnosis, and pain type is reported.

RESULTS

Fifty-eight subjects enrolled in the 36-month evaluation period with mean opioid intrathecal opioid dose less than 350 μg per day of morphine equivalent utilized. Primary nociceptive pain type were associated with lower intrathecal opioid doses and improved visual analog scale pain rating and improved pain severity and interference on the Multidimensional Pain Inventory.

CONCLUSIONS

This study adds to the growing body of literature suggesting that low-dose intrathecal analgesia without oral opioid supplementation can be efficacious. It appears that this approach may achieve analgesia with lower doses in those with primary nociceptive pain type.

A Prospective, Randomized, Single-Blinded, Head-to-Head Long-Term Outcome Study, Comparing Intrathecal (IT) Boluses With Continuous Infusion Trialing Techniques Prior to Implantation of Drug Delivery Systems (DDS) for the Treatment of Severe Intractable Chronic Nonmalignant Pain

OBJECTIVE

The study aims to compare intrathecal (IT) boluses to continuous infusion trialing techniques prior to implantation of drug delivery systems (DDS) for the treatment of severe intractable chronic nonmalignant pain.

DESIGN

This is a prospective, randomized, head-to-head long-term outcome study.

MATERIALS AND METHODS

Forty patients with comparable patient demographics were randomly assigned to two cohorts. Cohort A trialed with intermittent boluses; Cohort B trialed with continuous infusion. One patient failed trial in each group. Nineteen patients were implanted in each group. Follow-up was for 36 months with intervals at 6, 12, 18, 24, 36 months. The Brief Pain Inventory was used was used for assessment.

OUTCOME MEASURES

We used the Brief Pain Inventory to measure pain (worst and average), physical function (walking, normal work, and general activity), behavioral function (mood, sleep, and relations with others), IT dose, and oral opioid use.

RESULTS

We observed statistically significant reduction in pain and improvement of function in both cohorts following DDS implantation throughout the observation period. The IT dose remained virtually unchanged throughout as well, with overall limited dose escalation. Oral opioid use was significantly reduced. There was no statistically significant difference in prediction of trial success or long-term outcomes between the two cohorts.

CONCLUSION

Low-dose IT opioids via DDS can provide significant and long-lasting reduction in pain, and improvement in function (physical and behavioral) for patients with chronic nonmalignant pain. The two trialing techniques tested, intermittent boluses, and continuous infusion delivered intrathecally showed no clinical significance difference in terms of predicting trial success or long-term outcomes.

Interventional Therapies for Chronic Low Back Pain: A Focused Review (Efficacy and Outcomes)

CONTEXT

Lower back pain is considered to be one of the most common complaints that brings a patient to a pain specialist. Several modalities in interventional pain management are known to be helpful to a patient with chronic low back pain. Proper diagnosis is required for appropriate intervention to provide optimal benefits. From simple trigger point injections for muscular pain to a highly complex intervention such as a spinal cord stimulator are very effective if chosen properly. The aim of this article is to provide the reader with a comprehensive reading for treatment of lower back pain using interventional modalities.

EVIDENCE ACQUISITION

Extensive search for published literature was carried out online using PubMed, Cochrane database and Embase for the material used in this manuscript. This article describes the most common modalities available to an interventional pain physician along with the most relevant current and past references for the treatment of lower back pain. All the graphics and images were prepared by and belong to the author.

RESULTS

This review article describes the most common modalities available to an interventional pain physician along with the most relevant current and past references for the treatment of lower back pain. All the graphics and images belong to the author. Although it is beyond the scope of this review article to include a very detailed description of each procedure along with complete references, a sincere attempt has been made to comprehensively cover this very complex and perplexing topic.

CONCLUSION

Lower back pain is a major healthcare issue and this review article will help educate the pain practitioners about the current evidence based treatment options.

Programmable intrathecal pumps for the management of chronic pain: recommendations for improved efficiency

The management of chronic pain can be very challenging. Often, physicians employ intrathecal (IT) drug delivery systems as a last resort to relieve intractable pain. The system consists of an implantable pump that stores and delivers medication through a catheter to the IT space. Programmability is achieved by positioning an external devise over the implanted pump to change the mode of drug delivery. The innovations in programmable IT drug delivery systems are expanding more rapidly than ever before. Unfortunately, the rapid expansion is accompanied by a lack of prospective randomized trials examining these new options. In an effort to improve results and reduce side effects, publications by experts or expert consensus panels provide guidance for the community. The purpose of this article is to provide a summary of high interest topics in recent publications.

Intrathecal pain pumps: indications, patient selection, techniques, and outcomes

Intrathecal drug delivery represents an advanced modality for refractory chronic pain patients as well as intractable spasticity. This article reviews the advantages and indications for intrathecal therapy, as well as recommendations for proper patient selection using a multidisciplinary team to provide a global assessment of the impact of chronic pain on the patient's well-being. The goals and expectations of trialing are discussed alongside advantages and disadvantages of several trialing techniques. A discussion of outcomes is presented for patients with chronic pain due to both malignant and nonmalignant causes.

The use of combined spinal-epidural technique to compare intrathecal ziconotide and epidural opioids for trialing intrathecal drug delivery

SUMMARY Choosing the initial medications for intrathecal delivery is often confusing and not standardized. We describe a novel way for using a combined spinal-epidural technique to compare two first-line medications for intrathecal delivery; ziconotide and morphine (or hydromorphone). Five patients with intractable chronic or cancer pain were elected to have an intrathecal drug delivery system implanted for pain management. Each patient was given a 3-day inpatient trial with the combined spinal-epidural technique. The Visual Analog Scale, Numerical Rating Scale, short-term McGill questionnaire and opioid consumption were monitored daily. The results were used to develop a paradigm to describe how ziconotide can be used in practice.

Randomised, double-blind controlled trial by dose reduction of implanted intrathecal morphine delivery in chronic non-cancer pain

OBJECTIVE

This study aimed to investigate the efficacy of intrathecal morphine in the long term by hypothesising that a reduction of the intrathecal opioid dose following long-term administration would increase the level of pain intensity.

DESIGN

Randomised, double-blind, controlled, parallel group trial.

SETTING

Department of Pain Management, Russells Hall Hospital, Dudley, UK.

PARTICIPANTS

24 patients with non-cancer pain implanted with morphine reservoirs were assessed for eligibility.

INTERVENTIONS

Participants were randomly allocated to one of two parallel groups in which one of the groups had no change in morphine dose and the other group had a small reduction (20%) in dosage every week during a 10-week follow-up.

OUTCOME

Primary outcomes were visual analogue scale (VAS) pain score change and withdrawal from the study due to lack of efficacy.

RESULTS

9 of the patients assessed for eligibility declined to participate in the study. 15 patients were randomised to control (n=5) or intervention (n=10) and included in an intention-to-treat analysis. Owing to worsening of pain, seven patients withdrew from the study prematurely. None knew prior to withdrawal which arm of the study they were in, but all turned out to be in the dose-reduction arm. The calculation of dropout rates between groups indicated a significant statistical difference (p=0.026) and recruitment was ceased. The VAS change between baseline and the last observation was smaller in the control group (median, Mdn=11) than in the intervention group (Mdn=30.5), although not statistically significant, Z=-1.839, p=0.070; r=-0.47. Within groups, VAS was significantly lower at baseline (Mdn=49.5) than at the last observation (Mdn=77.5) for the reduction group, Z=-2.805, p=0.002; r=-0.627 but not for the control group (p=0.188).

CONCLUSIONS

This double-blind randomised controlled trial of chronic intrathecal morphine administration suggests the effectiveness of this therapy for the management of chronic non-cancer pain. However, owing to the small number of patients completing the study (n=8), further studies are warranted.

TRIAL REGISTRATION

International Standard Randomised Controlled Trials Centre (ISRCTN 33733462).

Do implantable devices improve mood? Comparisons of chronic pain patients with or without an implantable device

Objective.  This descriptive study compares outcome measures of a computerized assessment of pain, emotional distress, and quality of life between chronic noncancer pain patients who have received an implantable device (spinal cord stimulator or intrathecal pump; N = 143) and those who have not received a device (N = 130). Methods.  Each patient marked the location of their pain on a body diagram and rated pain intensity, emotional distress, and impact of their pain on mood, sleep, and quality of life using a computerized pain assessment program. An electronic version of the Hospital Anxiety and Depression Scale (HADS) also was administered. Results.  No significant differences were found on the pain variables between the two groups. Patients with an implantable device gave lower ratings (less impact) on emotional distress (p < 0.05) and rated their health quality of life as better compared with control patients (p < 0.05). The patients with implantable devices also scored lower on the HADS Depression Subscale. Conclusion.  The results suggest that although patients with an implantable device seem to have more pathology and greater disability, they report less emotional distress and improved quality of life compared with patients with chronic pain without an implantable device. Future controlled trials are needed to establish the role that an implantable device plays in improving mood and quality of life.

Guidance on the management of pain in older people

This guidance document reviews the epidemiology and management of pain in older people via a literature review of published research. The aim of this document is to inform health professionals in any care setting who work with older adults on best practice for the management of pain and to identify where there are gaps in the evidence that require further research. The assessment of pain in older people has not been covered within this guidance and can be found in a separate document (http://www.britishpainsociety.org/pub_professional.htm#assessmentpop). Substantial differences in the population, methods and definitions used in published research makes it difficult to compare across studies and impossible to determine the definitive prevalence of pain in older people. There are inconsistencies within the literature as to whether or not pain increases or decreases in this age group, and whether this is influenced by gender. There is, however, some evidence that the prevalence of pain is higher within residential care settings. The three most common sites of pain in older people are the back; leg/knee or hip and 'other' joints. In common with the working-age population, the attitudes and beliefs of older people influence all aspects of their pain experience. Stoicism is particularly evident within this cohort of people. Evidence from the literature search suggests that paracetamol should be considered as first-line treatment for the management of both acute and persistent pain, particularly that which is of musculoskeletal origin, due to its demonstrated efficacy and good safety profile. There are few absolute contraindications and relative cautions to prescribing paracetamol. It is, however, important that the maximum daily dose (4 g/24 h) is not exceeded. Non-selective non-steroidal anti-inflammatory drugs (NSAIDs) should be used with caution in older people after other safer treatments have not provided sufficient pain relief. The lowest dose should be provided, for the shortest duration. For older adults, an NSAID or cyclooxygenase-2 (COX-2) selective inhibitor should be co-prescribed with a proton pump inhibitor (PPI), and the one with the lowest acquisition cost should be chosen. All older people taking NSAIDs should be routinely monitored for gastrointestinal, renal and cardiovascular side effects, and drug–drug and drug–disease interactions. Opioid therapy may be considered for patients with moderate or severe pain, particularly if the pain is causing functional impairment or is reducing their quality of life. However, this must be individualised and carefully monitored. Opioid side effects including nausea and vomiting should be anticipated and suitable prophylaxis considered. Appropriate laxative therapy, such as the combination of a stool softener and a stimulant laxative, should be prescribed throughout treatment for all older people who are prescribed opioid therapy. Tricyclic antidepressants and anti-epileptic drugs have demonstrated efficacy in several types of neuropathic pain. But, tolerability and adverse effects limit their use in an older population. Intra-articular corticosteroid injections in osteoarthritis of the knee are effective in relieving pain in the short term, with little risk of complications and/or joint damage. Intra-articular hyaluronic acid is effective and free of systemic adverse effects. It should be considered in patients who are intolerant to systemic therapy. Intra-articular hyaluronic acid appears to have a slower onset of action than intra-articular steroids, but the effects seem to last longer. The current evidence for the use of epidural steroid injections in the management of sciatica is conflicting and, until further larger studies become available, no firm recommendations can be made. There is, however, a limited body of evidence to support the use of epidural injections in spinal stenosis. The literature review suggests that assistive devices are widely used and that the ownership of devices increases with age. Such devices enable older people with chronic pain to live in the community. However, they do not necessarily reduce pain and can increase pain if used incorrectly. Increasing activity by way of exercise should be considered. This should involve strengthening, flexibility, endurance and balance, along with a programme of education. Patient preference should be given serious consideration. A number of complementary therapies have been found to have some efficacy among the older population, including acupuncture, transcutaneous electrical nerve stimulation (TENS) and massage. Such approaches can affect pain and anxiety and are worth further investigation. Some psychological approaches have been found to be useful for the older population, including guided imagery, biofeedback training and relaxation. There is also some evidence supporting the use of cognitive behavioural therapy (CBT) among nursing home populations, but of course these approaches require training and time. There are many areas that require further research, including pharmacological management where approaches are often tested in younger populations and then translated across. Prevalence studies need consistency in terms of age, diagnosis and terminology, and further work needs to be done on evaluating non-pharmacological approaches.

Polyanalgesic Consensus Conference--2012: recommendations to reduce morbidity and mortality in intrathecal drug delivery in the treatment of chronic pain

INTRODUCTION

Targeted intrathecal drug infusion to treat moderate to severe chronic pain has become a standard part of treatment algorithms when more conservative options fail. This therapy is well established in the literature, has shown efficacy, and is an important tool for the treatment of both cancer and noncancer pain; however, it has become clear in recent years that intrathecal drug delivery is associated with risks for serious morbidity and mortality.

METHODS

The Polyanalgesic Consensus Conference is a meeting of experienced implanting physicians who strive to improve care in those receiving implantable devices. Employing data generated through an extensive literature search combined with clinical experience, this work group formulated recommendations regarding awareness, education, and mitigation of the morbidity and mortality associated with intrathecal therapy to establish best practices for targeted intrathecal drug delivery systems.

RESULTS

Best practices for improved patient care and outcomes with targeted intrathecal infusion are recommended to minimize the risk of morbidity and mortality. Areas of focus include respiratory depression, infection, granuloma, device-related complications, endocrinopathies, and human error. Specific guidance is given with each of these issues and the general use of the therapy.

CONCLUSIONS

Targeted intrathecal drug delivery systems are associated with risks for morbidity and mortality that can be devastating. The panel has given guidance to treating physicians and healthcare providers to reduce the incidence of these problems and to improve outcomes when problems occur.

Persistent hiccups with continuous intrathecal morphine infusion

OBJECTIVE

To report a case of hiccups secondary to intrathecal (IT) morphine infusion.

METHODS

Case report and discussion.

RESULTS

The hiccups in our patient resolved on substitution of IT morphine infusion with hydromorphone.

DISCUSSION

We report a case of a 44-year-old man who developed persistent hiccups with IT morphine infusion pump therapy. The hiccups persisted despite various nonpharmacological and pharmacological measures. The untoward symptom resolved after substitution of IT hydromorphone for IT morphine.

Polyanalgesic Consensus Conference--2012: recommendations on trialing for intrathecal (intraspinal) drug delivery: report of an interdisciplinary expert panel

INTRODUCTION

Trialing for intrathecal pump placement is an essential part of the decision-making process in placing a permanent device. In both the United States and the international community, the proper method for trialing is ill defined.

METHODS

The Polyanalgesic Consensus Conference (PACC) is a group of well-published experienced practitioners who meet to update the state of care for intrathecal therapies on the basis of current knowledge in the literature and clinical experience. Anexhaustive search is performed to create a base of information that the panel considers when making recommendations for best clinical practices. This literature, coupled with clinical experience, is the basis for recommendations and for identification of gaps in the base of knowledge regarding trialing for intrathecal pump placement.

RESULTS

The panel has made recommendations for the proper methods of trialing for long-term intrathecal drug delivery.

CONCLUSION

The use of intrathecal drug delivery is an important part of the treatment algorithm for moderate to severe chronic pain. It has become common practice to perform a temporary neuroaxial infusion before permanent device implantation. On the basis of current knowledge, the PACC has developed recommendations to improve care. The need to update these recommendations will be very important as new literature is published.

Neuraxial (epidural and intrathecal) opioids for intractable pain

1. Neuraxial opioids are considered for use in patients who have resistant intractable pain that fails to respond to other treatment options or pain that responds to analgesia but for which the doses required result in unacceptable side-effects. 2. Neuraxial opiods can be considered for both chronic non-malignant pain and chronic cancer-related pain. 3. Effectiveness in chronic non-malignant pain and cancer pain is exerted through the use of either single-agent drugs (opioids) or a combination of drugs: opioids, local anaesthetics and other drugs such as clonodine and ziconotide. 4. Complications of long-term continuous infusion therapy are related to the insertion process (haematoma), the mechanical device (both pump and catheter) and the long-term effects of the drugs. 5. Patients will require ongoing ambulatory monitoring and supportive care.

Safety and efficacy of intrathecal drug delivery for pain

SUMMARY The practice of delivering analgesic drugs into the intrathecal space has evolved over the past several decades from a ‘last-ditch’ therapy for intractable pain in patients with terminal cancer to a more widely applied strategy for treating patients with chronic nonmalignant pain as well. This review discusses the available safety and efficacy data of intrathecal drug delivery with a focus on device- and user-related safety issues.