Polyanalgesic Consensus Conference 2012: recommendations for the management of pain by intrathecal (intraspinal) drug delivery: report of an interdisciplinary expert panel

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.

The Polyanalgesic Consensus Conference (PACC)®: Updates on Clinical Pharmacology and Comorbidity Management in Intrathecal Drug Delivery for Cancer Pain

INTRODUCTION

The International Neuromodulation Society convened a multispecialty group of physicians based on expertise with international representation to establish evidence-based guidance on using intrathecal drug delivery in chronic pain treatment. This Polyanalgesic Consensus Conference (PACC)® project's scope is to provide evidence-based guidance for clinical pharmacology and best practices for intrathecal drug delivery for cancer pain.

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 using Medline, EMBASE, Cochrane CENTRAL, BioMed Central, Web of Science, Google Scholar, PubMed, Current Contents Connect, Meeting Abstracts, and Scopus from 2017 (when the 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 were based on the strength of evidence, and when evidence was scant, recommendations were based on expert consensus.

RESULTS

The PACC evaluated the published literature and established evidence- and consensus-based expert opinion recommendations to guide best practices in treating cancer pain. Additional guidance will occur as new evidence is developed in future iterations of this process.

CONCLUSIONS

The PACC recommends best practices regarding the use of intrathecal drug delivery in cancer pain, with an emphasis on managing the unique disease and patient characteristics encountered in oncology. These evidence- and consensus-based expert opinion recommendations should be used as a guide to assist decision-making when clinically appropriate.

Intrathecal drug delivery systems for cancer pain: A retrospective analysis at a single tertiary medical center in China

Objective

Intrathecal drug delivery systems (IDDS) have been clinically applied to treat refractory cancer-related pain for years. In this study, we demonstrate the current clinical practice and outcomes of IDDS for cancer pain management over a 3-year period at a single tertiary medical center in China.

Methods

Patients who received IDDS implantation for cancer-related pain from 2021 to 2023 were identified. The electronic medical records of all eligible patients were retrospectively reviewed for study data including baseline characteristics, IDDS variables and postoperative clinical outcomes.

Results

A total of 96 consecutive individuals were identified for analysis and complete follow-up information was available in 72 patients with a follow-up rate of 75 %. Patients were 49.0 % female with a mean age of 62 ± 10 years. The top five cancer types in IDDS population were lung (34.4 %), colorectal (17.7 %), pancreatic (11.5 %), breast (5.2 %) and liver (4.2 %) cancer. The median duration from cancer diagnosis to IDDS implantation was 24 months (interquartile range [IQR] 12-48 months) and from pain onset to IDDS implantation was 6 months (IQR 2-12 months). In addition, the median oral morphine equivalents (OME) daily dose was 290 mg (IQR 100-632 mg). Mean NRS was 7.5 ± 0.8 before implantation and decreased to an average of 3.0 ± 1.1 after IDDS (p < 0.001). Median overall survival after IDDS implantation was 3 months (IQR 2-6 months). Overall, 75 % family members of cancer patients were satisfied with IDDS in relieving cancer pain.

Conclusion

IDDS therapy is a valuable option for patients suffering from cancer pain. More and more cancer pain patients receive IDDS to treat pain during the 3-year study period.

A comprehensive review on ziconotide

Managing severe chronic pain is a challenging task, given the limited effectiveness of available pharmacological and non-pharmacological treatments. This issue continues to be a significant public health concern, requiring a substantial therapeutic response. Ziconotide, a synthetic peptide initially isolated from Conus magus in 1982 and approved by the US Food and Drug Administration and the European Medicines Agency in 2004, is the first-line intrathecal method for individuals experiencing severe chronic pain refractory to other therapeutic measures. Ziconotide produces powerful analgesia by blocking N-type calcium channels in the spinal cord, which inhibits the release of pain-relevant neurotransmitters from the central terminals of primary afferent neurons. However, despite possessing many favorable qualities, including the absence of tolerance development, respiratory depression, and withdrawal symptoms (largely due to the absence of a G-protein mediation mechanism), ziconotide's application is limited due to factors such as intrathecal administration and a narrow therapeutic window resulting from significant dose-related undesired effects of the central nervous system. This review aims to provide a comprehensive and clinically relevant summary of the literatures concerning the pharmacokinetics and metabolism of intrathecal ziconotide. It will also describe strategies intended to enhance clinical efficacy while reducing the incidence of side effects. Additionally, the review will explore the current efforts to refine the structure of ziconotide for better clinical outcomes. Lastly, it will prospect potential developments in the new class of selective N-type voltage-sensitive calcium-channel blockers.

Treatment of Intrathecal Drug Pump Flipping Using Fascial Flaps: A Technical Description and Case Series

BACKGROUND AND OBJECTIVES

Intrathecal drug therapy is a common treatment for dystonia, pain, and spasticity using implanted pump and catheter systems. Standardized management of intrathecal drug pump (ITDP) migration and flipping has not been well established in the literature. This study reports the use of soft tissue to address less common pump complications such as pump flipping, migration, and difficulty in medication refill.

METHODS

A retrospective chart review of intrathecal pump cases performed by two surgeons between February 2020 and August 2022 was conducted. Patients with complications such as pump flipping, migration, or challenges in medication refill treated with soft tissue flaps were included. Patient demographics, comorbidities, and perioperative data were collected.

RESULTS

A total of five patients with ITDP complicated by pump flipping, migration, malposition, or difficulty in medication refill that were treated using fascial flaps were included in the study. Three technical considerations when revising ITDP complications are secure pump anchoring, reliable wound closure, and ease of pump medication refill. Cases 1 and 2 demonstrate the technique of secure pump anchoring with a rectus fascial flap. Cases 3 and 4 show a technique to achieve reliable vascularized wound closure, and case 5 describes a technique to solve an uncommon problem of a thick subcutaneous abdominal tissue preventing the refill of the ITDP medication.

CONCLUSION

Soft tissue flaps may serve as a treatment option for patients with uncommon ITDP complications. De-epithelialized dermal fasciocutaneous or fascial flaps may be developed to anchor the pump more securely. Cross-discipline collaboration may further delineate the technique, benefits, and outcomes of this approach.

Utilizing combination intrathecal baclofen and analgesic medication to manage spasticity and pain in patients with pediatric-onset disability: Case series

PURPOSE

The use of intrathecal medications for the management of spasticity and various pain syndromes in the adult population has been previously reported. However, no evidence-based guidelines currently exist in the pediatric population. This case series presents patients (n = 8) with pediatric-onset disability who underwent placement of intrathecal baclofen pumps initially for management of severe spasticity. Despite titration of dose and use of oral analgesia, their uncontrolled pain persisted. Each patient was transitioned to a combination of baclofen and analgesic intrathecal therapy. The outcome in pain improvement and quality of life, as reported by patients and/or caregivers, were retrospectively reviewed.

METHODS

Retrospective review of the background and decision-making process regarding transition to combination intrathecal therapy identified patient selection characteristics. Each patient and/or their caregivers completed a survey regarding improvements in pain, spasticity, function, and quality of life following initiation of combination intrathecal medications.

RESULTS

Survey results revealed improvements in functional and pain assessments after initiation of combination baclofen and analgesic intrathecal medication. Patients and caregivers reported decreases in pain and oral spasticity medications.

CONCLUSION

Use of pumps with antispasmodic and analgesic medication for combination intrathecal medication delivery should be considered in the management of patients with childhood-onset disabilities who have both severe spasticity and pain.

Multidisciplinary Approaches: Cingulotomy in an Adult With Refractory Neuropathic Cancer-Related Pain

Background: Oral medications, intravenous medications, and invasive interventions are effective means of neuropathic pain control. In patients with pain refractory to more conventional approaches, cingulum bundle ablation is an alternative treatment modality not routinely considered by providers. Case Description: A 42-year-old woman with history of cervical cancer in remission presented with intractable left lower extremity pain. Workup revealed radiation-induced left iliopsoas osteosarcoma complicated by deep venous occlusion and thrombosis. Her pain remained intractable to pharmacologic therapies and more invasive pain control interventions. A multidisciplinary decision was made to pursue bilateral subcortical cingulum bundle radiofrequency ablation. After a technically successful surgery, the patient exhibited improved pain control as evidenced by a decline in her numerical rating scale of pain and analgesic medication requirements. Conclusion: Cancer-related neuropathic pain often requires treatment with multiple modalities involving multidisciplinary teams. In select refractory cases, cingulum bundle ablation may be an effective alternative treatment modality.

Oral corticosteroid use and sarcopenia-related traits in older people with chronic airway disease: a population-based study

Background

Sarcopenia is characterised by two major phenotypic components: low handgrip strength (HGS) and appendicular skeletal muscle index (ASMI). Oral corticosteroid (OCS) use is an important medication for acute respiratory exacerbations in patients with COPD and asthma. However, the association of OCS and sarcopenia components in older people is largely unexplored. The aim of this study was to examine the association between OCS use and HGS or ASMI in the general population and explore interactions with chronic airway diseases.

Methods

From the population-based Rotterdam Study, 5054 participants (age 69.0±8.8 years; 56% females) were included in the cross-sectional analysis and 1324 in the longitudinal analysis. Associations between OCS and muscle strength and mass were analysed using linear regression models adjusted for age, sex, fat %, height, kidney function, smoking and comorbidities.

Results

At baseline, ever-OCS users had lower handgrip strength (β= -0.48, 95% CI -0.84- -0.12) than never-OCS users, with cumulative frequency (≥10 OCS prescriptions)-dependent effects (β= -1.25, 95% CI -2.16- -0.33). COPD ever-OCS users, but not asthma, had lower handgrip strength (β= -0.98, 95% CI -1.91- -0.06) and lower lean mass (β= -0.14, 95% CI -0.27- -0.01) than never-OCS users. After 5.6 years of follow-up in those free of sarcopenia traits at baseline, COPD ever-OCS users developed lower handgrip strength (β= -1.64, 95% CI -2.87- -0.40) with frequency (β= -3.64, 95% CI -6.57- -0.72) and duration (β= -1.51, 95% CI -2.87- -0.15) association compared to never-OCS users.

Conclusions

OCS use is associated with a decline in handgrip strength in people with COPD in a cumulative frequency and duration-dependent manner. Routine muscle examination may be necessary for patients with COPD.

Spinal cord and brain concentrations of riluzole after oral and intrathecal administration: A potential new treatment route for amyotrophic lateral sclerosis

Riluzole is the only treatment known to improve survival in patients with Amyotrophic Lateral Sclerosis (ALS). However, oral riluzole efficacy is modest at best, further it is known to have large inter-individual variability of serum concentration and clearance, is formulated as an oral drug in a patient population plagued with dysphagia, and has known systemic side-effects like asthenia (limiting patient compliance) and elevated liver enzymes. In this context, we postulated that continuous intrathecal (IT) infusion of low doses of riluzole could provide consistent elevations of the drug spinal cord (SC) concentrations at or above those achieved with oral dosing, without increasing the risk for adverse events associated with systemic drug exposure or off-target side effects in the brain. We developed a formulation of riluzole for IT delivery and conducted our studies in purpose-bred hound dogs. Our non-GLP studies revealed that IT infusion alone was able to increase SC concentrations above those provided by oral administration, without increasing plasma concentrations. We then conducted two GLP studies that combined IT infusion with oral administration at human equivalent dose, to evaluate SC and brain concentrations of riluzole along with assessments of safety and tolerability. In the 6-week study, the highest IT dose (0.2 mg/hr) was well tolerated by the animals and increased SC concentrations above those achieved with oral riluzole alone, without increasing brain concentrations. In the 6-month study, the highest dose tested (0.4 mg/hr) was not tolerated and yielded SC significantly above those achieved in all previous studies. Our data show the feasibility and safety profile of continuous IT riluzole delivery to the spinal cord, without concurrent elevated liver enzymes, and minimal brain concentrations creating another potential therapeutic route of delivery to be used in isolation or in combination with other therapeutics."

A Review of Chronic Pain and Device Interventions: Benefits and Future Directions

Chronic pain is a debilitating condition with a growing prevalence both in the USA and globally. The complex nature of this condition necessitates a multimodal approach to pain management that extends beyond the established pharmaceutical interventions currently employed. A variety of devices comprising both invasive and noninvasive approaches are available to patients, serving as adjuvants to existing regimens. The benefits of these interventions are notable for their lack of addiction potential, potential for patient autonomy regarding self-administration, minimal to no drug interaction, and overall relative safety. However, there remains a need for further research and more robust clinical trials to assess the true efficacy of these interventions and elucidate if there is an underlying physiological mechanism to their benefit in treating chronic pain or if their effect is predominantly placebo in nature. Regardless, the field of device-based intervention and treatment remains an evolving field with much promise for the future chronic pain management.

Intrathecal drug delivery for cancer pain at the end of life: a case study

Two-thirds of patients with advanced cancer have pain and, of these, approximately 10-20% do not respond to conventional pain management approaches. This case study concerns a hospice patient who received intrathecal drug delivery for intractable cancer pain at the end of life. This involved working in partnership with a hospital-based interventional pain team. Despite side-effects and complications associated with intrathecal drug delivery and the requirement for inpatient nursing care, intrathecal drug delivery was the best option for the patient. The case identifies the importance of a patient-centred approach to decision-making, effective partnerships between hospice and acute hospital teams, and nurse education as key factors contributing to the provision of safe and effective intrathecal drug delivery.

Marine Natural Products in Clinical Use

Marine natural products are potent and promising sources of drugs among other natural products of plant, animal, and microbial origin. To date, 20 drugs from marine sources are in clinical use. Most approved marine compounds are antineoplastic, but some are also used for chronic neuropathic pain, for heparin overdosage, as haptens and vaccine carriers, and for omega-3 fatty-acid supplementation in the diet. Marine drugs have diverse structural characteristics and mechanisms of action. A considerable increase in the number of marine drugs approved for clinical use has occurred in the past few decades, which may be attributed to increasing research on marine compounds in laboratories across the world. In the present manuscript, we comprehensively studied all marine drugs that have been successfully used in the clinic. Researchers and clinicians are hopeful to discover many more drugs, as a large number of marine natural compounds are being investigated in preclinical and clinical studies.

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.

The State-of-the-art Pharmacotherapeutic Options for the Treatment of Chronic Non-Cancer Pain

INTRODUCTION

Pharmacotherapeutic options continue to expand for the treatment of chronic non-cancer pain. There has been an increasing emphasis on multimodal analgesia. This strategy employs use of multiple analgesic medications each with a distinct mechanism of action, which when administered concomitantly may provide profound analgesia.

AREAS COVERED

The authors describe evidence from randomized controlled trials and systematic reviews on a variety of established medications including anti-inflammatory agents, opioids, anti-convulsants, anti-depressants, N-methyl-D-aspartate receptor antagonists, sodium channel blockers, cannabinoids, and alpha-2-receptor blockers. Furthermore, they provide developing evidence on more novel pharmacotherapeutics including alpha lipoic acid, acetyl-L-carnitine, low dose naltrexone, calcitonin gene-related peptide antagonists, targeted toxin therapy, Nav1.7 inhibitors, neurotensin agonists, purinoceptor antagonists, and sigma-1 receptor antagonists. Furthermore, the authors review the safety and adverse effect profile for these agents.

EXPERT OPINION

In this era of the opioid epidemic, clinicians should first offer non-opioid analgesics and employ a multimodal analgesic strategy. Current guidelines recommend a personalized approach to the chronic pain treatment, in each case accounting for type, location, severity, and chronicity of pain. Clinicians should also carefully consider the risk-to-benefit ratio to the patient based on the drug side effect profile, patient age, and comorbidities.

Intrathecal Morphine Infusion for Trigeminal Deafferentation Pain Following Percutaneous Intervention for Unexplained Facial Pain: A Case Report

Chronic pain in painful post-traumatic trigeminal neuropathy, formerly called trigeminal deafferentation pain (TDP) or anesthesia dolorosa, is virtually incurable neuropathic pain. In severe cases, no effective method has yet been established. A 58-year-old woman presented with chronic dysesthetic pain in the right side of her face that had persisted for 8 years. It was caused by percutaneous balloon compression for an unexplained, persistent right gingival pain. The TDP did not respond to any medications or radiosurgery. Considering the typical occipital neuralgia that occurred later, the incomprehensible gum pain was interpreted as referred trigeminal pain from occipital neuralgia. Decompression of the greater occipital nerve improved occipital neuralgia; however, TDP did not respond to internal neurolysis or invasive brain stimulation. The last attempt was made to administer an intrathecal opioid because of pain sufficiently severe to cause suicidal ideation. Trial administration of intrathecal opioids had some effect on pain relief. Although incomplete, the effects of intrathecal morphine infusion were maintained up to 1 year later. Invasive neurosurgical interventions should be cautiously performed for continuous pain in persistent idiopathic facial pain and referred facial pain cases that do not show typical neuralgic pain in primary trigeminal neuralgia because of the risk of TDP.

Physicochemical Stability Study of the Morphine-Ropivacaine-Ziconotide Association in Implantable Pumps for Intrathecal Administration

PURPOSE

This study aimed to investigate the physicochemical stability of morphine-ropivacaine-ziconotide mixtures used in intrathecal analgesia.

MATERIALS AND METHODS

Eight mixtures were studied to assess their stability profiles according to the initial drug concentrations used. The solutions obtained were put in implantable pumps and stored at 37 °C over a period of 60 days. Assays were performed using ultra high-pressure liquid chromatography. Turbidity and pH were also measured throughout the study.

RESULTS

Results confirmed excellent physicochemical stability for morphine and ropivacaine. Concerning ziconotide, three of the eight mixtures did not show any sign of chemical instability: average concentrations remained constant throughout the 60 days. A decrease of the concentration was observed for the five other mixtures. Moreover, the appearance of a degradation product linked to oxidation confirmed the ziconotide degradation.

CONCLUSIONS

All these results are in favor of a physicochemical stable preparation for three of the mixture profiles when stored in implantable pumps at 37 °C up to 60 days. For the five others, the efficacy should decrease over time owing to the degradation of ziconotide. The decrease in kinetics of the ziconotide concentration depends on the mixing profile. One possibility is to adapt the filling intervals according to the profile of the mixture. Finally, the results show the period of stability ensuring maximum analgesic efficacy for the eight mixture profiles studied.

Intrathecal Analgesia in Cancer Pain

The number of new cancer cases has been increasing globally over the last several decades.

Intrathecal pain management with ziconotide: Time for consensus?

This article summarizes recommendations made by six pain specialists who discussed the rationale for ziconotide intrathecal analgesia (ITA) and the requirement for evidence-based guidance on its use, from a European perspective. Riemser Pharma GmbH (Greifswald, Germany), which holds the European marketing authorization for ziconotide, hosted the meeting. The group agreed that ITA is under-used in Europe, adding that ziconotide ITA has potential to be a first-line alternative to morphine; both are already first-line options in the USA. Ziconotide ITA (initiated using a low-dose, slow-titration approach) is suitable for many patients with noncancer- or cancer-related chronic refractory pain and no history of psychosis. Adopting ziconotide as first-line ITA could reduce opioid usage in these patient populations. The group advocated a risk-reduction strategy for all candidate patients, including compulsory prescreening for neuropsychosis, and requested US-European alignment of the licensed starting dose for ziconotide: the low-and-slow approach practiced in the USA has a better tolerability profile than the fixed high starting dose licensed in Europe. Of note, an update to the European Summary of Product Characteristics is anticipated in early 2021. The group acknowledged that the Polyanalgesic Consensus Conference (PACC) treatment algorithms for ziconotide ITA provide useful guidance, but recommendations tailored specifically for European settings are required. Before a consensus process can formally begin, the group called for additional European prospective studies to investigate ziconotide in low-and-slow dosing strategies, in different patient settings. Such data would enable European guidance to have the most appropriate evidence at its core.

Triple Intrathecal Combination Therapy for End-Stage Cancer-Related Refractory Pain: A Prospective Observational Study with Two-Month Follow-Up

INTRODUCTION

In cancer-related pain refractory to systemic opioids, intrathecal (IT) administration of morphine can be a useful strategy. In clinical practice, IT morphine is usually combined with other drugs with different mechanisms of action, in order to obtain a synergistic analgesic effect. However, the discussion on efficacy and safety of IT combination therapy is still ongoing. The aim of this observational study was to report the effects of an IT combination of low doses of ziconotide, morphine, and levobupivacaine in end-stage cancer refractory pain.

METHODS

Sixty adult patients, 21 females and 39 males, were enrolled to an IT device implant. The mean visual analogue scale of pain intensity (VASPI) score was 88 ± 20 mm. All patients started with a triple combination therapy: the initial IT dose of morphine was calculated for each patient based on the equivalent daily dose of morphine; an oral/IT ratio of 400/1 was used. For ziconotide, a standard slow titration schedule was started at 1.2 μg/day and the initial dose of levobupivacaine was 3 mg/day.

RESULTS

The initial IT mean doses of morphine, ziconotide, and levobupivacaine were 0.8 ± 0.3 mg/day, 1.2 mcg/day and 3 mg/day, respectively. At day 2, a significant reduction in VASPI score was registered (49 ± 17, p < 0.001), and this significant reduction persisted at 56 days (mean VASPI score 44 ± 9, p < 0.001), with mean doses of morphine 2 ± 1 mg/day, ziconotide 2.8 ± 1 mcg/day, and levobupivacaine 3.8 ± 2 mg/day. Very few adverse effects (AEs) were observed. Patients' satisfaction was very high during the entire study period.

CONCLUSIONS

Our results, within the limit of the study design, suggest that the IT combination of ziconotide, morphine, and levobupivacaine, at low doses, allows safe and rapid control of refractory cancer pain, with high levels of patient satisfaction.

The Management of Unresectable Intrathecal Catheter-Tip-Associated Granuloma Using Morphine Therapy Cessation and Spinal Cord Stimulation

Catheter-tip-associated granulomas (CTG) are a rare but serious complication of intrathecal analgesic delivery pumps (IADP), which interfere with pain modulation and can cause irreversible neurologic deficits. The treatment of symptomatic CTG generally involves surgical resection and catheter removal. We present a case of an unresectable CTG, which we managed using progressive lowering of the intrathecal morphine sulfate (ITMS) dosage as well as spinal cord stimulation (SCS). A 55-year-old female with failed back surgery syndrome (FBSS) presented with new-onset left-sided lumbar radiculopathy after five years of moderately successful ITMS therapy. An MRI study suggested an unknown mass associated with the tip of the catheter. The tumor’s adherence to nerve roots of the conus terminalis prevented a complete resection and only allowed for a biopsy. After the SCS implantation, we progressively lowered the ITMS dose. In a follow-up consultation, the patient reported the regression of the radiculopathy as well as satisfactory pain levels without oral opiates. In this case of CTG, cessation of intrathecal morphine prevented the further growth of the granuloma. SCS effectively addressed both the chronic lumbar back pain as well as the new-onset radicular pain caused by the CTG.

The Rate of Infectious Complications After Intrathecal Drug Delivery System Implant for Cancer-Related Pain Is Low Despite Frequent Concurrent Anticancer Treatment or Leukopenia

BACKGROUND

The efficacy of intrathecal drug delivery (IDD) for cancer-related pain is well established. Cancer therapies are often associated with immunosuppression and increased risk of infection, and the rate of infection after intrathecal drug delivery system (IDDS) implant in cancer patients has been reported as 2.4%-6.3%. Our objective is to report on the rate of surgical site infections (SSI) in patients implanted with IDDS for cancer-related pain and to provide a data-driven discussion on the relationship between antineoplastic treatment, leukopenia, and other clinical or demographic characteristics and SSI.

METHODS

Following local institutional review board approval, we conducted a retrospective chart review of IDDS implants from May 2014 through December 2018. Data collected included demographic data, health status, prophylactic antibiotic administration, surgery duration, presence of leukopenia (white blood cell [WBC] count of <4.0 K/µL) or moderate neutropenia (absolute neutrophil count [ANC] of <1000/μL) within the 30 days before IDDS implant, and details of antineoplastic treatment or systemic corticosteroid use in the perioperative period. This information was assessed in relation to SSI incidence up to 6 months following implant.

RESULTS

Two hundred seventeen IDDS implants were identified. A majority of patients (79.3%) received ≥1 form of antineoplastic therapy within 30 days before or after implant, and 42.4% received multiple forms of antineoplastic therapy. Therapies included chemotherapy in 46.5%, immunotherapy in 28.6%, systemic steroids in 32.3%, and radiation therapy in 28.1%. One-quarter of patients (25.8%) were leukopenic within 30 days before implant, with 3.2% having moderate neutropenia. There were 2 infectious complications representing an infection rate of 0.9% (95% CI, 0.1%-3.3%), with limited shared characteristics between those experiencing SSI.

CONCLUSIONS

SSI risk after IDDS placement for cancer pain is low, despite frequent concurrent antineoplastic therapy and leukopenia in the perioperative period. Concomitant cancer therapies should not be a barrier to the implementation of IDD for cancer pain.

Evaluation of an Intrathecal Drug Delivery Protocol Leads to Rapid Reduction of Systemic Opioids in the Oncological Population

Objective: The article that follows is purposed at demonstrating how IT opioid plus bupivacaine achieves sustained acceptable pain relief while simultaneously rapidly reducing oral morphine equivalents (OME). Background: Cancer patients represent a population with significant morbidity, pain, and limited life expectancy. It is, therefore, vital to achieve satisfactory analgesia quickly and safely. To date, there is limited data in the literature that discusses efficacy of combined intrathecal (IT) medication therapy in reducing systemic opioids in the oncological population. Methods: This was a retrospective analysis that reviewed cancer pain patients from day of IT pump implantation through the six-month postoperative time point. A cohort of 50 oncological patients who had intrathecal drug delivery systems (IDDSs) implanted at Memorial Sloan Kettering Cancer Center between 2017 and 2019 were studied. Median OMEs were the primary modality of analysis for this review. Mean visual analogue scale scores were secondarily reviewed. Results: Median OMEs decreased from 503 preoperative to 105 at six months postoperative time point. Median time to discharge was 6.5 days. Unfortunately, due to malignant mortality, 27 patients did not make it to the 6-month postoperative time point. Discussion: IDDSs with opioid plus bupivacaine represent a safe and efficient route toward expeditious pain relief and decreased OMEs in the cancer pain population.

Evaluation of Fixed Intrathecal Bupivacaine Infusion Doses in the Oncologic Population

OBJECTIVES

Intrathecal drug delivery systems (IDDS) are an important method of pain control for patients with refractory oncologic pain. Local anesthetics such as bupivacaine have been infused either alone or with opioids. While effective, bupivacaine can cause adverse effects such as numbness, weakness, and urinary retention. This study looks to establish a safe and efficacious fixed bupivacaine dosing algorithm in intrathecal pumps for cancer patients.

MATERIALS AND METHODS

A bupivacaine dosing algorithm was developed using data from 120 previous patients who underwent IDDS placement at Memorial Sloan Kettering Cancer Center. The outcomes were then evaluated for 43 subsequent patients who were treated with bupivacaine IDDS according to our aforementioned algorithm.

RESULTS

Our data show that in patients treated with our bupivacaine guideline, visual analog pain scale scores decreased by 59% and oral morphine equivalence decreased by 70% from the period between IDDS implantation until discharge from the MSKCC hospital. However, 16.3% of our patients had bupivacaine-related side effects.

CONCLUSIONS

For oncological patients, our data and experience support the initiation of intrathecal bupivacaine at the following doses: 5 mg/day for catheter tips in the cervical spine, 8 mg/day for catheter tips at T1-4, and 10 mg/day for catheter tips at T5-8. Given the higher likelihood of adverse effects in catheters at T9-12 and the lumbar spine, we start at 8 mg/day with close follow-up of the patient. Initiating these doses allow our patients to safely reach adequate analgesia faster, with a shorter hospitalization and quicker return to anti-cancer therapy.

Intrathecal Drug Delivery Systems for Cancer Pain: An Analysis of a Prospective, Multicenter Product Surveillance Registry

BACKGROUND

The safety and efficacy of intrathecal drug delivery systems (IDDSs) for the treatment of cancer-related pain have been demonstrated in randomized controlled clinical trials (RCTs). Despite positive evidence for this therapy, IDDS remains underutilized to treat cancer pain. Real-world registry data augment existing safety and effectiveness data and are presented here to broaden awareness of this therapeutic option, needed for adequate cancer-related pain treatment, and as a viable tool addressing concerns with systemic opioid use.

METHODS

This prospective, long-term, multicenter (United States, Western Europe, and Latin America) registry started in 2003 to monitor the performance of SynchroMed Infusion Systems. Patient-reported outcomes were added in 2013. Before data acquisition, all sites obtained Ethics Committee/Institutional Review Board approval and written patient consent. The study was registered (NCT01524276 at clinicaltrials.gov) before patients were enrolled. Patients who provided informed consent were enrolled in the registry at initial IDDS implant or replacement.

RESULTS

Through July 2017, 1403 patients with cancer pain were enrolled and implanted. The average (minimum/maximum) age of patients was 59 years (13/93 years), with 56.6% female. The most frequent cancer types were lung, breast, colon/rectal, pancreatic, and prostate. The majority of patients whose registry follow-up ended (87%; 1141/1311) were followed through death, with 4.3% (n = 57) exiting due to device explant or therapy discontinuation; the remaining 113 (8.6%) discontinued for reasons such as transfer of care, lost to follow-up, and site closure. Pain scores within the cohort of patients providing baseline and follow-up data improved significantly at 6 (P = .0007; n = 103) and 12 (P = .0026; n = 55) months compared to baseline, with EuroQol with 5 dimensions (EuroQol-5D) scores showing significant improvement at 6 months (P = .0016; n = 41). Infection requiring surgical intervention (IDDS explant, replacement, pocket revision, irrigation and debridement, etc) was reported in 3.2% of patients.

CONCLUSIONS

Adequate and improved pain control in patients with cancer, even in advanced stages, with concurrent quality of life maintenance is attainable. Results from this large-scale, multicenter, single-group cohort supplement existing RCT data that support IDDS as a safe and effective therapeutic option with a positive benefit-risk ratio in the treatment of cancer pain.

[Pain treatment, assessment and reassessment]

Treating the pain is essential. It requires knowledge, assessment and reassessment by trained professionals. Communication is essential between the different professionals involved for the benefit of the patient.

Intrathecal Baclofen for Severe Spasticity: Longitudinal Data From the Product Surveillance Registry

Objective

To assist in the assessment of intrathecal baclofen (ITB) therapy risks and benefits by providing surgical intervention rate, safety, and elective device replacement rate data.

Materials and Methods

An ongoing prospective, long‐term, multicenter Product Surveillance Registry (PSR) (NCT01524276) enrolled consented patients implanted with the SynchroMed II infusion system. Pump and catheter performance data were collected, with patients followed prospectively for events related to the device, procedure, and therapy. Investigators provided event descriptions, patient symptoms, and patient outcomes.

Results

We analyzed registry data from 1743 patients (77% adult, 46.8% female) treated with ITB for severe spasticity at 53 registry sites between August 2003 and October 2017, for an accumulated 6481 patient‐years. Discontinuation from the registry was largely (58.6% of discontinued patients) due to study site closure and patient relocation; exit due to an adverse event was limited to 0.3%. After 10 years, 87.2% of adult and 76.3% of pediatric patients continued with ITB. Overall, 99.1% of pumps reaching end of battery life were replaced at the time of explant.

Conclusions

ITB therapy for the treatment of severe spasticity requires surgical implantation of a programmable infusion system for chronic drug delivery. If complications arise, many necessitate surgical intervention for correction. For spinal and cerebral spasticity in pediatric and adult patients, discontinuation rates due to an adverse event were low (0.3%), and there was high acceptance (99.1%) of surgical intervention for therapy continuation. Patient/caregiver willingness to accept surgical and other risks for therapy continuation was extremely high.

Choice of spinal cord stimulation versus targeted drug delivery in the management of chronic pain: a predictive formula for outcomes

Contemporary nonmalignant pain treatment algorithms commence with conservative non-invasive strategies, later progressing from minimally invasive interventions to invasive techniques or implantable devices. The most commonly used implantable devices are spinal cord stimulation (SCS) systems or targeted drug delivery (TDD) devices. Historically, SCS had been considered in advance of TDD, positioning TDD behind SCS failures. Following Institutional Review Board approval, data were extracted from electronic medical records of patients who underwent SCS trial in the Department of Pain Management at Cleveland Clinic from 1994 to 2013. The sample size was analyzed in two cohorts: those who succeeded with SCS and those who failed SCS and consequently proceeded to TDD. Univariate and multivariate analyses were performed and a predictive formula for successful outcomes was created. 945 patients were included in the cohort of which 119 (12.6%) subjects achieved adequate pain relief with TDD after failure of SCS. Gender, age, depression and primary pain diagnosis were significantly different in this subgroup. Males were 52% less likely to experience pain relief with SCS. The odds of SCS success decreased as age increased by 6% per year. Patients with comorbid depression, interestingly, were 63% more likely to succeed with SCS. A logistic model was created to predict SCS success which was used to create a predictive formula. Older male patients diagnosed with spine-related pain were more likely to benefit from TDD than SCS. This observation potentially identifies a subgroup in whom consideration for TDD in advance of SCS failure could prove more efficient and cost effective. These retrospective findings warrant prospective comparative studies to validate this derived predictive formula.

High-Voltage-Activated Calcium Channel in the Afferent Pain Pathway: An Important Target of Pain Therapies

High-voltage-activated (HVA) Ca2+ channels are widely expressed in the nervous system. They play an important role in pain conduction by participating in various physiological processes such as synaptic transmission, changes in synaptic plasticity, and neuronal excitability. Available evidence suggests that the HVA channel is an important therapeutic target for pain management. In this review, we summarize the changes in different subtypes of HVA channel during pain and present the currently available evidence from the clinical application of HVA channel blockers. We also review novel drugs in various phases of development. Moreover, we discuss the future prospects of HVA channel blockers in order to promote "bench-to-bedside" translation.

Cancer- and Non-cancer Related Chronic Pain: From the Physiopathological Basics to Management

The prevalence of chronic pain is between 33% to 64% and is due to cancer pain, but it has also been observed in non-cancer patients. Chronic pain is associated with lower quality of life and higher psychological distress and depressive/anxiety disorders in patients without a history of disorder. In this study we evaluated in clinical practice the effectiveness of the intrathecal pump in 140 patients who underwent pain therapy at our Center. These patients were consecutively enrolled from January 2010 to July 2018. Follow-up was carried out over these eight years regarding the infusion modalities. Pain relief was obtained in 71 (50,7%) patients out of the 140 that experienced satisfactory pain control globally. Intrathecal therapy is one of the best options for chronic severe refractory pain. The greatest advantage of this therapy is due to the possibility of treating the pain with minimal dosages of the drug, avoiding the appearance of troublesome side effects.

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.

Adult Cancer Pain, Version 3.2019, NCCN Clinical Practice Guidelines in Oncology

In recent years, the NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines) for Adult Cancer Pain have undergone substantial revisions focusing on the appropriate and safe prescription of opioid analgesics, optimization of nonopioid analgesics and adjuvant medications, and integration of nonpharmacologic methods of cancer pain management. This selection highlights some of these changes, covering topics on management of adult cancer pain including pharmacologic interventions, nonpharmacologic interventions, and treatment of specific cancer pain syndromes. The complete version of the NCCN Guidelines for Adult Cancer Pain addresses additional aspects of this topic, including pathophysiologic classification of cancer pain syndromes, comprehensive pain assessment, management of pain crisis, ongoing care for cancer pain, pain in cancer survivors, and specialty consultations.

Intrathecal drug delivery for pain management: recent advances and future developments

Introduction: Chronic pain conditions of malignant and non-malignant etiology afflict a large group of the population and pose a vast economic burden on society. Intrathecal drug therapy is a viable treatment option in such patients who have failed conservative medical measures and less invasive pain management procedures. However, the clinical growth of intrathecal therapy in managing intractable chronic pain conditions continues to face many challenges and is likely underutilized secondary to its high-complexity and lack of understanding. Areas covered: This review will briefly discuss the history of intrathecal drug delivery systems (IDDS), cerebrospinal fluid (CSF) flow dynamics, types of IDDS, indications and patient profile suitable for this therapy, and risks and complications related to IDDS. We will also discuss challenges faced by physicians utilizing this therapy and the future changes that are needed for making this treatment modality more efficacious. Expert opinion: IDDS offer an effective therapy for pain control in patients suffering from chronic intractable pain conditions. These devices provide a safer alternative to oral opioid medications with reduced systemic side effects. Adherence to best practices and continued clinical and basic science research is important to ensure continuing success of this therapy.

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.

Strategies for interventional therapies in cancer-related pain-a crossroad in cancer pain management

PURPOSE

Interventional therapies are important to consider when facing cancer pain refractory to conventional therapies. The objective of the current review is to introduce these effective strategies into dynamic interdisciplinary pain management, leading to an exhaustive approach to supportive oncology.

METHODS

Critical reflection based on literature analysis and clinical practice.

RESULTS

Interventional therapies act on the nervous system via neuromodulation or surgical approaches, or on primitive or metastatic lesions via interventional radiotherapy, percutaneous ablation, or surgery. Interventional therapies such as neuromodulations are constantly evolving with new technical works still in development. Nowadays, their usage is better defined, depending on clinical situations, and their impact on quality of life is proven. Nevertheless their availability and acceptability still need to be improved. To start with, a patient's interdisciplinary evaluation should cover a wide range of items such as patient's performance and psychological status, ethical considerations, and physiochemical and pharmacological properties of the cerebrospinal fluid for intrathecal neuromodulation. This will help to define the most appropriate strategy. In addition to determining the pros and cons of highly specialized interventional therapies, their relevance should be debated within interdisciplinary teams in order to select the best strategy for the right patient, at the right time.

CONCLUSIONS

Ultimately, the use of the interventional therapies can be limited by the requirement of specific trained healthcare teams and technical support, or the lack of health policies. However, these interventional strategies need to be proposed as soon as possible to each patient requiring them, as they can greatly improve quality of life.

Optimizing Initial Intrathecal Drug Ratio for Refractory Cancer-Related Pain for Early Pain Relief. A Retrospective Monocentric Study

Objective

Intrathecal (IT) drug delivery has shown its efficiency in treating refractory cancer pain, but switching opioids from the systemic to the intrathecal route is a challenging phase. Moreover, associations are widely used and recommended. Few data deal with the initial dosage of each drug. Analyzing conversion factors and initial dosages used in intrathecal therapy seems essential to decreasing the length of titration and to delivering quick pain relief to patients.

Methods

We retrospectively analyzed data from consecutive adult patients implanted with an intrathecal device for cancer pain and treated at the Institut de Cancérologie de l’Ouest, in Angers, France, for four years. The main goal was to identify factors associated with early pain relief after intrathecal drug delivery system (IDDS) implantation.

Results

Of the 220 IDDS-treated patients, 70 (32%) experienced early pain relief (EaPR) and 150 (68%) delayed pain relief (DePR). Performance Status stage and initial IT ropivacaine:IT morphine ratio were the variables independently associated with EaPR. The best IT ropivacaine:IT morphine ratio to predict EaPR was 5:1, with a 73% (95% confidence interval [CI] = 64.8% to 79.6%) sensitivity and a 67.1% (95% CI = 54.9% to 77.9%) specificity. EaPR subjects experienced better pain relief (–84% vs –60% from baseline pain score, P < 0.0001), shorter length of hospitalization (7 vs 10 days, P < 0.0001), and longer survival (155 vs 82 days, P = 0.004).

Conclusions

Local anesthetic:morphine ratio should be considered when starting IDDS treatment. EaPR during the IT analgesia titration phase was associated with better pain relief and outcomes in patients with refractory cancer-related pain.

Intrathecal morphine combined with ropivacaine induces spinal myoclonus in cancer patients with an implanted intrathecal drug delivery system: Three case reports

RATIONALE

Although intrathecal opioid infusion has been used for decades for the treatment of severe pain, myoclonus as one of the complications of this therapeutic modality is now beginning to be recognized more.

PATIENTS CONCERNS

Here, we report three patients who developed myoclonus after dose adjustment in intrathecal drug delivery system for the treatment of refractory cancer pain.

DIAGNOSIS

Spinal myoclonus is a sudden, brief, shock-like muscle contractions originating from the central nervous system. In our cases, it occurred after opioid administration via intrathecal delivery system with no abnormality found in laboratory or imaging examinations.

INTERVENTIONS

Spinal myoclonus can be treated effectively by reducing the dose or infusion rate as described in case 1, or changing from an intrathecal to systemic administration in case 2, or correcting infusion and bolus parameters mistakes in case 3.

OUTCOMES

All patients recovered quickly after stopping or decreasing the intrathecal drug infusion.

LESSONS

Prevention is more important than treatment as for spinal myoclonus. Pain management teams should be aware of this distressing complication. Dose of intrathecal drugs should not exceed the recommended maximal daily doses by guidelines and patient education is important for successful intrathecal analgesic therapy.

Determination of ED50 and time to effectiveness for intrathecal hydromorphone in laboring patients using Dixon's up-and-down sequential allocation method

Background

With the increasing occurrence of drug shortages, understanding the pharmacokinetics of alternative intrathecal opioid administration has gained importance. In particular, additional data are needed to comprehensively evaluate the analgesic properties of intrathecal hydromorphone in the laboring patient. In a phase 2 clinical trial, we set out to determine the median effective dose (ED₅₀) and time to effectiveness for this drug in this population.

Methods

Using Dixon’s up-and-down sequential allocation method, twenty women presenting for labor analgesia were prospectively enrolled. A combined spinal-epidural technique was used to deliver the determined dose of intrathecal hydromorphone. Visual analog pain scores were obtained assessing peak pain scores during serial uterine contractions. Effective pain relief was defined as achieving a pain score of less than or equal to 3 out of 10. The dose was deemed to be ineffective if the patient failed to achieve this level of relief after 30 min.

Results

The ED₅₀ of hydromorphone in our population was 10.9 μg (95% confidence interval 5.6–16.2 μg). Amongst patients for whom the dose was effective, the median time to pain relief was 24 min. One patient experienced both nausea and pruritus. No other complications were noted.

Conclusion

Due to the prolonged time to onset, hydromorphone cannot be recommended in favor of substantively better alternatives such as sufentanil and fentanyl.

Trial registration

Clinicaltrials.gov registration number: NCT01598506.

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

INTRODUCTION

The Neuromodulation Appropriateness Consensus Committee (NACC) is dedicated to improving the safety and efficacy of neuromodulation and thus improving the lives of patients undergoing neuromodulation therapies. With continued innovations in neuromodulation comes the need for evolving reviews of best practices. Dorsal root ganglion (DRG) stimulation has significantly improved the treatment of complex regional pain syndrome (CRPS), among other conditions. Through funding and organizational leadership by the International Neuromodulation Society (INS), the NACC reconvened to develop the best practices consensus document for the selection, implantation and use of DRG stimulation for the treatment of chronic pain syndromes.

METHODS

The NACC performed a comprehensive literature search of articles about DRG published from 1995 through June, 2017. A total of 2538 article abstracts were then reviewed, and selected articles graded for strength of evidence based on scoring criteria established by the US Preventive Services Task Force. Graded evidence was considered along with clinical experience to create the best practices consensus and recommendations.

RESULTS

The NACC achieved consensus based on peer-reviewed literature and experience to create consensus points to improve patient selection, guide surgical methods, improve post-operative care, and make recommendations for management of patients treated with DRG stimulation.

CONCLUSION

The NACC recommendations are intended to improve patient care in the use of this evolving therapy for chronic pain. Clinicians who choose to follow these recommendations may improve outcomes.

Ziconotide-induced psychosis: A case report and literature review

Ziconotide is an intrathecally administered medication indicated for the treatment of severe chronic pain in patients who are intolerant of or refractory to other treatment options. A black box warning is included in the packaging and states ziconotide is contraindicated in patients with a preexisting history of psychosis. Patients taking ziconotide should be monitored for evidence of cognitive impairment, hallucinations, or changes in mood, and ziconotide should be discontinued if neurological or psychiatric signs and symptoms appear. We present a case of a 49-year-old white male with no previous neuropsychiatric history who received ziconotide for several years before he developed command auditory hallucinations within 24 hours of a dose increase. Upon admission to the emergency room, the patient's pain management physician was contacted and the ziconotide dose was decreased and eventually discontinued. Because of a continuation of symptoms, the patient was transferred from the emergency room to an acute care psychiatric hospital where he was started on risperidone 1 mg orally at bedtime. At discharge, the patient was noted to be in good behavioral control without any hallucinations. The patient was encouraged to follow up with his pain management physician to determine if ziconotide should be reconsidered.