Polyanalgesic Consensus Conference-2012: Consensus on Diagnosis, Detection, and Treatment of Catheter-Tip Granulomas (Inflammatory Masses)

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.

Catheter Tip-Associated Mass With Continuous Infusion of Sufentanil for Persistent Spinal Pain Syndrome Type 2: A Case Report Including Histopathologic Examination and Review of the Associated Basic and Clinical Research

OBJECTIVES

Intrathecal opioids delivered by implanted pumps are used to treat malignant or nonmalignant chronic pain. In this study, we 1) review a case in which intrathecal infusions of sufentanil along with other adjuvants were used and after an extended period led to an intrathecal mass and 2) compared and contrasted the potential mechanisms for these phenomena.

MATERIALS AND METHODS

A woman aged 66 years with a history of scoliosis and multiple spine surgeries was treated with an implantable drug delivery system for treating persistent pain after laminectomy. The patient received intrathecal medication comprising sufentanil, bupivacaine, and clonidine.

RESULTS

Intrathecal therapy over approximately ten years served to reduce pain and improve function over the treatment period. After the extended treatment interval, the patient developed an intrathecal mass that was associated with impairment. The mass was surgically removed. Systematic histopathology revealed the space-occupying mass to largely comprise fibroblasts and some inflammatory cells embedded in a collagen mass located proximally to the catheter tip.

CONCLUSIONS

To our knowledge, this is the first published case report of sufentanil causing this complication. The science and mechanism of intrathecal catheter tip-associated mass formation and associated clinical research correlates are reviewed in detail, and explanations for this phenomenon are proposed based on histochemical analysis of the patient's pathology findings.

Dorsal Versus Ventral Intrathecal Catheter Tip Location and Effect on Dose Escalation and Opioid Use in Patients With Cancer Pain

OBJECTIVES

In the practice of intrathecal drug delivery, consensus exists regarding the cephalad to caudad location of the catheter tip relative to dermatomal distribution of pain. However, data are lacking on the importance of dorsal vs ventral tip location relative to the spinal cord. We hypothesize that a dorsally placed catheter tip improves efficacy because of closer proximity to nociceptive pathways.

MATERIALS AND METHODS

A retrospective review of 298 patients with cancer with intrathecal drug delivery systems implanted at the Huntsman Cancer Institute from May 2014 to June 2020 was performed. Patients were stratified by catheter tip location zones based on available radiographic studies. Patient-controlled intrathecal medication dose requirements and rate of change were compared with catheter zone and other variables, including the presence of adjuncts such as bupivacaine and ziconotide.

RESULTS

A total of 158 patients were suitable for analysis demonstrating a dorsal tip in 63.9% (n = 101) and ventral tip in 36.1% (n = 57), with a median follow-up of 17 days (interquartile range [IQR], 10-24). There was no difference in daily dose change from implant to discharge between the dorsal group 8.2% (IQR, 0.0-41.5) and ventral group 20.8% (IQR, 0.0-66.7; p = 0.12). Daily dose change from discharge to follow-up was 2.6% (IQR, 0.0-7.1) in the dorsal group and 1.8% (IQR, 0.0-5.7) in the ventral group (p = 0.92). Catheter tip location had no impact on systemic opioid use.

CONCLUSIONS

We did not find significant associations between dorsal vs ventral catheter tip location and measures of pain relief, including change in intrathecal dose or systemic opioid use.

Neuraxial drug delivery in pain management: An overview of past, present, and future

Activation of neuraxial nociceptive linkages leads to a high level of encoding of the message that is transmitted to the brain and that can initiate a pain state with its attendant emotive covariates. As we review here, the encoding of this message is subject to a profound regulation by pharmacological targeting of dorsal root ganglion and dorsal horn systems. Though first shown with the robust and selective modulation by spinal opiates, subsequent work has revealed the pharmacological and biological complexity of these neuraxial systems and points to several regulatory targets. Novel therapeutic delivery platforms, such as viral transfection, antisense and targeted neurotoxins, point to disease-modifying approaches that can selectively address the acute and chronic pain phenotype. Further developments are called for in delivery devices to enhance local distribution and to minimize concentration gradients, as frequently occurs with the poorly mixed intrathecal space. The field has advanced remarkably since the mid-1970s, but these advances must always address the issues of safety and tolerability of neuraxial therapy.

Interventional Pain Procedures: A Narrative Review Focusing On Safety and Complications. PART 2 Interventional Procedures For Back Pain

In patients where conservative approaches have failed to relieve from chronic pain, interventional procedures may be an option in well selected patients. In recent years there has been an increase in the use and development of invasive procedures. Concomitantly, there has also been an increase in the complications associated with these procedures. Taken this into consideration, it is important for healthcare providers to take a cautious and vigilant approach, with a focus on patient safety, in order to minimize the risk of adverse events and ensure the best possible outcome for the patient. This may include careful selection of patients for procedures, use of proper techniques and equipment, and close monitoring and follow-up after the procedure. The aim of this narrative review is to summarize the primary complications associated with commonly performed image-guided (fluoroscopy or ultrasound-guided) interventional procedures and provide strategies to reduce the risk of these complications. We conclude that although complications from interventional pain procedures can be mitigated to a certain degree, they cannot be eliminated altogether. In order to avoid adverse events, patient safety should be given considerable attention and physicians should be constantly aware of the possibility of developing complications.

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.

Intrathecal Baclofen Monotherapy and Polyanalgesia for Treating Chronic Pain in Patients with Severe Spasticity

PURPOSE OF REVIEW

Intrathecal drug delivery is a well evidenced strategy for the treatment of many chronic pain syndromes. While opioids, anesthetics, and ziconotide are the most commonly used agents, intrathecal baclofen (ITB), which is indicated to treat spasticity, is also thought to have some analgesic properties that are poorly understood. These analgesic benefits have been reported with ITB use in treating patients with central neurological disorders who suffer from severe spasticity and chronic pain. Our review aims to characterize ITB's effects on pain, function, and quality of life in patients with severe spasticity. We performed a systematic review based on the Preferred Reporting Items for Systematic Reviews and Meta Analyses (PRISMA) guidelines. The primary outcome parameters were analgesic relief and functional improvements. Secondarily, quality of life and adverse effects were also recorded.

RECENT FINDINGS

After an initial survey identified 393 studies, 20 studies met final inclusion criteria. Of these, 16 utilized ITB monotherapy and 4 utilized ITB polyanalgesia. Overall, there was a paucity of high-powered studies. Mean titrated ITB doses ranged from 140 to 627.9 μg daily. Nineteen studies reported improved pain and spasticity. Seven studies reported improved functional outcomes and quality of life. Our results show that ITB may be an effective agent in treatingfor the treatment of chronic pain in patients with severe spasticity independent of its spasmolytic effects. Although this evidence was largely derived from studies lacking clearly defined outcomes of pain relief, ITB is reasonable to consider for concurrent spasticity and pain management. Well-designed studies are still needed to characterize ITB's analgesic efficacy when used in patients with severe spasticity.

Intrathecal Analgesia in Cancer Pain

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

Narrative review of intrathecal drug delivery (IDD): indications, devices and potential complications

The management of chronic refractory pain (non-neoplastic and cancer-related pain) remains a therapeutic challenge. The continuous intrathecal (IT) administration of drugs may play an important role in the possible management options. Intrathecal drug delivery devices (IDDDs) may be effective for patients with refractory chronic pain. Therefore, they may be adopted for non-oncologic pain in patients with compression fractures, spondylolisthesis, spondylosis, back surgery failure syndrome and spinal stenosis. Oncologic patients can benefit from these treatments in a variable way according to tumor characteristics, prognosis, periprocedural imaging and risk of disease progression. In this review, we describe the most commonly used drugs (opioids and non-opioids), their pharmacokinetic and pharmacodynamic features and indications of use. The most used drugs are morphine, hydromorphone, fentanyl, methadone, bupivacaine, clonidine, and ketamine. Patient evaluation before the device implantation should be based on clinical examination, medical records assessment and psychometric evaluation. The infusion pumps available on the market are both non-programmable (with continuous IT deliver of drugs) and programmable (with variable deliver of drugs according to their flow rate). Moreover, we describe the procedure of implantation and the potential complications of IT drug delivery (such as bleeding, infection, loss of cerebrospinal fluid, wound seroma, loss of catheter pump propellant).

Intrathecal pump catheter-tip granuloma recurrence with associated myelomalacia - How safe is intrathecal analgesic infusion therapy? A case report

Background:

A serious complication of intrathecal (IT) infusion therapy for pain management is catheter-tip-associated granuloma. Catheter-tip granulomas can lead to permanent severe neurological sequelae if not promptly detected.

Case Description:

We report a patient with a recurrence of a catheter-tip granuloma causing a high-grade paresis of the lower extremities and we review briefly the literature.

Conclusion:

Patients with IT pump therapy presenting new neurological findings need prompt imaging of the spinal axis to rule out a catheter-tip granuloma. In case of catheter-tip granuloma, early surgical decompression is important.

Characterization of Effect of Repeated Bolus or Continuous Intrathecal Infusion of Morphine on Spinal Mass Formation in the Dog

BACKGROUND

We determined whether intrathecally delivering the same daily dose of morphine (MS) at a fixed concentration of 25 mg/mL by periodic boluses versus continuous infusion would reduce intrathecal mass (IMs) formation in dogs.

METHODS

Adult dogs (hound cross, n = 32) were implanted with intrathecal catheters connected to SynchroMed II infusion pumps. Animals were randomly assigned to receive infusion of 0.48 mL/day of saline or MS dosing (12 mg/day at 25 mg/mL) as boluses: x1 (q24hour), x2 (q12hour), x4 (q6hour), or x8 (q3hour) given at the rate of 1000 μL/hour, or as a continuous infusion (25 mg/mL/20 μL/hour).

RESULTS

With IT saline, minimal pathology was noted. In contrast, animals receiving morphine displayed spinally compressing durally derived masses with the maximal cross-sectional area being greatest near the catheter tip. Histopathology showed that IMs consisted of fibroblasts in a collagen (type 1) matrix comprised of newly formed collagen near the catheter and mature collagen on the periphery of the mass. The rank order of median cross-sectional mass area (mm² ) was: Saline: 0.7 mm² ; x2: 1.8 mm² ; x4: 2.7 mm² ; x1: 2.7 mm² ; x8: 4.2 mm² ; Continuous: 8.1 mm² , with statistical difference from saline being seen with continuous (p < 0.0001) and x8 (p < 0.05). Bench studies with a 2D diffusion chamber confirmed an increase in dye distribution and lower peak concentrations after bolus delivery versus continuous infusion of dye.

CONCLUSIONS

Using multiple bolus dosing, IMs were reduced as compared to continuous infusion, suggesting relevance of bolus delivery in yielding reduced intrathecal masses.

An overview of interventional strategies for the management of oncologic pain

Pain is a ubiquitous part of the cancer experience. Often the presenting symptom of malignancy, pain becomes more prevalent in advanced or metastatic disease and often persists despite curative treatment. Although management of cancer pain improved following publication of the WHO's analgesic ladder, when used in isolation, conservative approaches often fail to control pain and are limited by intolerable side effects. Interventional strategies provide an option for managing cancer pain that remains refractory to pharmacologic therapy. The purpose of this review is to investigate these strategies and discuss the risks and benefits which must be weighed when considering their use. Therapies anticipated to have an increasingly important role in the future of cancer pain management are also discussed.

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.

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

OBJECTIVES

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

Intrathecal catheter-associated inflammatory mass in a neurofibromatosis type-1 patient receiving fentanyl and bupivacaine

Background:

Catheter-associated inflammatory masses (CIMs) are a rare but serious complication of intrathecal drug delivery devices. CIM formation is influenced by local medication concentration, which is determined in part by flow dynamics at the catheter tip. Underlying spinal pathologies, such as neoplasms, may alter flow at the catheter tip, thereby contributing to CIM formation. Moreover, they may also complicate the clinical and radiologic diagnosis of a CIM.

Case Description:

A 36-year-old man with neurofibromatosis type 1 presented to our emergency department with complaints of increased back pain and leg weakness. To treat pain secondary to his multiple spinal masses, he had previously undergone placement of an implantable drug delivery system, which infused a compounded drug of fentanyl and bupivacaine. Imaging studies depicted numerous masses consistent with neurofibromatosis, including a compressive mass located circumferentially at the porous catheter terminus and proximal to the catheter tip. Surgical removal of this mass was performed; pathologic findings were consistent with a catheter tip granuloma.

Conclusions:

In the described case, CIM formation likely resulted from a combination of, 1) an unusually high fentanyl concentration, and, 2) altered infusate flow due to spinal neurofibromas. Consideration of underlying spinal pathologies, particularly mass lesions, is critical to the management of intrathecal drug delivery devices.

Injury and Liability Associated with Implantable Devices for Chronic Pain

BACKGROUND

Due to an increase in implantable device-related anesthesia pain medicine claims, the authors investigated anesthesia liability associated with these devices.

METHODS

After institutional review board approval, the authors identified 148 pain medicine device claims from 1990 or later in the Anesthesia Closed Claims Project Database. Device-related damaging events included medication administration events, infections, hematomas, retained catheter fragments, cerebrospinal fluid leaks, cord or cauda equina trauma, device placed at wrong level, stimulator incorrectly programmed, delay in recognition of granuloma formation, and other issues.

RESULTS

The most common devices were implantable drug delivery systems (IDDS; 64%) and spinal cord stimulators (29%). Device-related care consisted of surgical device procedures (n = 107) and IDDS maintenance (n = 41). Severity of injury was greater in IDDS maintenance claims (56% death or severe permanent injury) than in surgical device procedures (26%, P < 0.001). Death and brain damage in IDDS maintenance claims resulted from medication administration errors (n = 13; 32%); spinal cord injury resulted from delayed recognition of granuloma formation (n = 9; 22%). The most common damaging events for surgical device procedures were infections, inadequate pain relief, cord trauma, retained catheter fragments, and subcutaneous hygroma. Care was more commonly assessed as less than appropriate (78%) and payments more common (63%) in IDDS maintenance than in surgical device procedure claims (P < 0.001).

CONCLUSIONS

Half of IDDS maintenance claims were associated with death or permanent severe injury, most commonly from medication errors or failure to recognize progressive neurologic deterioration. Practitioners implanting or managing devices for chronic pain should exercise caution in these areas to minimize patient harm.

Current and Future Issues in the Development of Spinal Agents for the Management of Pain

Targeting analgesic drugs for spinal delivery reflects the fact that while the conscious experience of pain is mediated supraspinally, input initiated by high intensity stimuli, tissue injury and/or nerve injury is encoded at the level of the spinal dorsal horn and this output informs the brain as to the peripheral environment. This encoding process is subject to strong upregulation resulting in hyperesthetic states and downregulation reducing the ongoing processing of nociceptive stimuli reversing the hyperesthesia and pain processing. The present review addresses the biology of spinal nociceptive processing as relevant to the effects of intrathecally-delivered drugs in altering pain processing following acute stimulation, tissue inflammation/injury and nerve injury. The review covers i) the major classes of spinal agents currently employed as intrathecal analgesics (opioid agonists, alpha 2 agonists; sodium channel blockers; calcium channel blockers; NMDA blockers; GABA A/B agonists; COX inhibitors; ii) ongoing developments in the pharmacology of spinal therapeutics focusing on less studied agents/targets (cholinesterase inhibition; Adenosine agonists; iii) novel intrathecal targeting methodologies including gene-based approaches (viral vectors, plasmids, interfering RNAs); antisense, and toxins (botulinum toxins; resniferatoxin, substance P Saporin); and iv) issues relevant to intrathecal drug delivery (neuraxial drug distribution), infusate delivery profile, drug dosing, formulation and principals involved in the preclinical evaluation of intrathecal drug safety.

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

BACKGROUND

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

OBJECTIVE

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

STUDY DESIGN

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

RESULTS

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

CONCLUSION

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

Advances in intrathecal drug delivery

PURPOSE OF REVIEW

Targeted intrathecal drug delivery systems (IDDS) are an option in algorithms for the treatment of patients with moderate-to-severe chronic refractory pain. This article is intended to review the literature regarding IDDS published over the last year, with special attention to the Polyanalgesic Consensus Conference 2012.

RECENT FINDINGS

The recommendations made by the Polyanalgesic Consensus Conference 2012 are reviewed. Separate considerations of intrathecal drug therapy for neuropathic and nociceptive pain syndromes and the new concept of 'microdosing' are discussed in this article.

SUMMARY

This review includes the recommendations for the use of IDDS, trialing, and recent reports of complications (especially, the occurrence of granulomas). In addition, the latest documents on cerebrospinal fluid and potential lines of future development are discussed.

Minimally invasive procedures for neuropathic pain

Neuropathic pain is "pain arising as a direct consequence of a lesion or disease affecting the somatosensory system". The prevalence of neuropathic pain ranges from 7 to 11% of the population and minimally invasive procedures have been used to both diagnose and treat neuropathic pain. Diagnostic procedures consist of nerve blocks aimed to isolate the peripheral nerve implicated, whereas therapeutic interventions either modify or destroy nerve function. Procedures that modify how nerves function include epidural steroid injections, peripheral nerve blocks and sympathetic nerve blocks. Neuroablative procedures include radiofrequency ablation, cryoanalgesia and neurectomies. Currently, neuromodulation with peripheral nerve stimulators and spinal cord stimulators are the most evidence-based treatments of neuropathic pain.

Advanced Innovations for Pain

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

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Successful Management of Corneal Neuropathic Pain with Intrathecal Targeted Drug Delivery

OBJECTIVE

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

DESIGN

Single case report.

SETTING

Academic tertiary care center in the United States of America.

SUBJECT AND METHODS

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

RESULTS

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

CONCLUSIONS

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

The Relationship Between the Mechanisms of Action and Safety Profiles of Intrathecal Morphine and Ziconotide: A Review of the Literature

OBJECTIVE

To better characterize safety profiles associated with the intrathecal (IT) administration of morphine and ziconotide and discuss how they relate to mechanisms of action.

METHODS

Published data were evaluated to identify potential relationships between safety profiles of IT morphine and IT ziconotide and their mechanisms of action.

RESULTS

Potentially severe and clinically relevant adverse events (AEs) associated with IT morphine include respiratory depression, tolerance, and granuloma formulation, whereas IT ziconotide is associated with neuropsychiatric AEs, such as cognitive impairment, hallucinations, and changes in mood or consciousness, particularly with high doses and rapid titration. AEs associated with these IT therapies may result from spread of the medication out of the IT space into areas of the central and peripheral nervous systems and systemic circulation. AEs that occur usually can be managed and, in some cases, prevented. To mitigate risk, patients' histories should be reviewed to identify potential complicating factors (e.g., obesity or other risk factors for respiratory dysfunction in patients receiving IT morphine; a history of psychosis in patients receiving IT ziconotide). Also, treatment should be initiated at a low dose, titrated slowly, and patients should be closely monitored during treatment.

CONCLUSIONS

IT morphine and IT ziconotide are approved by the US Food and Drug Administration for patients who do not respond to less invasive treatments, but the safety profiles of each may make them more or less appropriate for certain patient populations.

Current perspectives on intrathecal drug delivery

Advances in intrathecal analgesia and intrathecal drug delivery systems have allowed for a range of medications to be used in the control of pain and spasticity. This technique allows for reduced medication doses that can decrease the side effects typically associated with oral or parenteral drug delivery. Recent expert panel consensus guidelines have provided care paths in the treatment of nociceptive, neuropathic, and mixed pain syndromes. While the data for pain relief, adverse effect reduction, and cost-effectiveness with cancer pain control are compelling, the evidence is less clear for noncancer pain, other than spasticity. Physicians should be aware of mechanical, pharmacological, surgical, and patient-specific complications, including possible granuloma formation. Newer intrathecal drug delivery systems may allow for better safety and quality of life outcomes.

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 delivery of analgesics

Targeted intrathecal (IT) drug delivery systems (IDDS) are an option in algorithms for the treatment of patients with moderate to severe chronic refractory pain when more conservative options fail. This therapy is well established and supported by several publications. It has shown efficacy and is an important tool for the treatment of spasticity, and both cancer and nonmalignant pain. Recent technological advances, new therapeutic applications, reported complications, and the costs as well as maintenance required for this therapy require the need to stay up-to-date about new recommendations that may improve outcomes. This chapter reviews all technological issues regarding IDDS implantation with follow-up, and pharmacological recommendations published during recent years that provide evidence-based decision making process in the management of chronic pain and spasticity in patients.

Brief review: Neuraxial analgesia in refractory malignant pain

PURPOSE

This narrative review aims to inform health care practitioners of the current literature surrounding the use of intrathecal (IT) and epidural analgesia in cancer patients with refractory pain at end of life. Topics discussed and reviewed include: patient selection, treatment planning, procedure, equipment, medications, complications, policies and procedures, as well as directions for future research.

PRINCIPAL FINDINGS

Cancer pain is inadequately treated in an estimated 10% of patients with malignant pain despite the implementation of the World Health Organization three-step analgesic ladder. This has prompted some to advocate for the addition of a fourth step that would include neuraxial interventions. There is moderate evidence supporting the safety and efficacy of IT drug therapy in cancer patients with refractory pain. A detailed assessment and interdisciplinary team approach is necessary to develop and implement care plans for patients requiring neuraxial analgesia. Neuraxial analgesia can significantly improve pain and reduce side effects, but this must be balanced against the increased complexity of care and the risk of uncommon but serious complications.

CONCLUSION

Neuraxial drug delivery gives clinicians more options to manage refractory pain at end of life and should be offered to patients with intractable cancer pain. Teams should be interprofessional with clear delineation of roles and responsibilities. They should discuss advanced discharge planning with the patient prior to implantation as well as provide on-call support.