Response of intractable pain to continuous intrathecal morphine: a retrospective study

Safety and Efficacy of Surgical Implantation of Intrathecal Drug Delivery Pumps in Patients With Cancer With Refractory Pain

BACKGROUND AND OBJECTIVES

Pain management in patients with cancer is a critical issue in oncology palliative care as clinicians aim to enhance quality of life and mitigate suffering. Most patients with cancer experience cancer-related pain, and 30%-40% of patients experience intractable pain despite maximal medical therapy. Intrathecal pain pumps (ITPs) have emerged as an option for achieving pain control in patients with cancer. Owing to the potential benefits of ITPs, we sought to study the long-term outcomes of this form of pain management at a cancer center.

METHODS

We retrospectively reviewed medical records of all adult patients with cancer who underwent ITP placement at a tertiary comprehensive cancer center between 2013 and 2021. Baseline characteristics, preoperative and postoperative pain control, and postoperative complication rate data were collected.

RESULTS

A total of 193 patients were included. We found that the average Numerical Rating Scale (NRS) score decreased significantly by 4.08 points (SD = 2.13, P < .01), from an average NRS of 7.38 (SD = 1.64) to an average NRS of 3.27 (SD = 1.66). Of 185 patients with preoperative and follow-up NRS pain scores, all but 9 experienced a decrease in NRS (95.1%). The median overall survival from time of pump placement was 3.62 months (95% CI: 2.73-4.54). A total of 42 adverse events in 33 patients were reported during the study period. The 1-year cumulative incidence of any complication was 15.6% (95% CI: 10.9%-21.1%) and for severe complication was 5.7% (95% CI: 3.0%-9.7%). Eleven patients required reoperation during the study period, with a 1-year cumulative incidence of 4.2% (95% CI: 2.0%-7.7%).

CONCLUSION

Our study demonstrates that ITP implantation for the treatment of cancer-related pain is a safe and effective method of pain palliation with a low complication rate. Future prospective studies are required to determine the optimal timing of ITP implantation.

Interventional Therapies for Pain in Cancer Patients: a Narrative Review

PURPOSE OF REVIEW

Pain is a prevalent symptom in the lives of patients with cancer. In light of the ongoing opioid epidemic and increasing awareness of the potential for opioid abuse and addiction, clinicians are progressively turning to interventional therapies. This article reviews the interventional techniques available to mitigate the debilitating effects that untreated or poorly treated pain have in this population.

RECENT FINDINGS

A range of interventional therapies and technical approaches are available for the treatment of cancer-related pain. Many of the techniques described may offer effective analgesia with less systemic toxicity and dependency than first- and second-line oral and parenteral agents. Neuromodulatory techniques including dorsal root ganglion stimulation and peripheral nerve stimulation are increasingly finding roles in the management of oncologic pain. The goal of this pragmatic narrative review is to discuss interventional approaches to cancer-related pain and the potential of such therapies to improve the quality of life of cancer patients.

A safety review of approved intrathecal analgesics for chronic pain management

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

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

Objectives

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

Methods

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

Results

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

Conclusion

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

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.

ANALGESIC EFFICACY OF EPIDURAL MORPHINE AND CLONIDINEIN PATIENTS UNDERGOING DECOMPRESSION OF THE LUMBAR CANAL: A PROSPECTIVE RANDOMIZED TRIAL

ABSTRACT Objective: To evaluate the postoperative analgesic efficacy in patients undergoing lumbar canal decompression using epidural morphine and clonidine at the Hospital Santa Casa de Vitória - ES, Brazil. Methods: Prospective, randomized study of 60 patients with stenosis of the lumbar canal up to two levels with surgical indication, in which decompression of the canal was performed in association with lumbar arthrodesis. In group 1 we performed conventional postoperative analgesia and in group 2, in addition to conventional analgesia, we associated epidural morphine and clonidine. We used VAS as a means of analyzing pain intensity at 1, 12, and 36 hours after surgery. The statistical analysis was performed using Microsoft Office/Excel and the software GraphPad Prism (San Diego, CA, USA). Results: The mean age of patients was 47 years, and 52% were female. The mean VAS in the first hour, 12th, and 36th hours after surgery in the control group was 5.44, 2.13, and 0.55 respectively. In the morphine-clonidine group it was 6.96; 2.21 and 0.60. Comparing one group with another in its absolute values through the Mann-Whitney test, as well as comparing the pain variations between the 1st and 12th hour (1h X 12h) and between the 12th hour and 36th hour (12h x 36h ) through Student’s t test it became clear that there was no statistical difference between groups (p > 0.05). Conclusions: The addition of epidural morphine and clonidine to conventional analgesia is not beneficial to reduce postoperative pain in patients undergoing lumbar canal decompression.

Intrathecal Therapy for Cancer-Related Pain

Objective. The increasing incidence of cancer survivorship has shifted treatment of cancer-related pain from short-term analgesia to long-term chronic pain management. As a result, alternatives to oral analgesics, such as intrathecal therapy, may be beneficial for patients with cancer-related pain. The authors review the use of intrathecal therapy in the management of cancer-related pain.

Methods. The Medline database was searched for English-language articles that included “ziconotide” or “morphine” AND (“cancer” OR “malignant”) AND “intrathecal” in title or abstract. Available abstracts from scientific congresses in the areas of neuromodulation and oncology were also reviewed.

Results. Intrathecal therapy provides pain relief with reduced systemic concerns in patients with cancer-related pain. Patients should undergo multidisciplinary evaluation and, in most cases, drug trialing before intrathecal pump implantation. Morphine, an opioid (µ-opioid receptor antagonist), and ziconotide, a nonopioid (selective N-type calcium channel inhibitor), are both approved for intrathecal analgesia; however, tolerance and safety concerns may deter the use of intrathecal morphine. Ziconotide has also shown efficacy for reduction of cancer-related pain; however, proper dosing and titration must be used to prevent adverse events. There is little information available on use of intrathecal therapies specifically in cancer survivors.

Conclusions. Treatment of cancer-related pain has shifted toward chronic pain management strategies, especially among cancer survivors. Intrathecal therapy provides an alternate route of administration of chronic pain medications (e.g., morphine and ziconotide) for cancer patients with and without active disease, although additional research is needed to support effectiveness in cancer survivors.

Efficacy and Safety of Ropivacaine Addition to Intrathecal Morphine for Pain Management in Intractable Cancer

Objective. Although intrathecal drug infusion has been commonly adopted for terminal cancer pain relief, its adverse effects have made many clinicians reluctant to employ it for intractable cancer pain. The objective of this study is to compare the efficacy and security of an intrathecal continuous infusion of morphine and ropivacaine versus intrathecal morphine alone for cancer pain. Methods. Thirty-six cancer patients received either a continuous morphine (n = 19) or morphine and ropivacaine (n = 17) infusion using an intrathecal catheter through a subcutaneous port. Numerical Rating Scale (NRS) scores and the Barthel Index were analyzed. Adverse effects and complications on postoperative days 1, 3, 7, and 15 were also analyzed. Results. All patients experienced pain relief. Compared to those who received morphine alone, patients receiving morphine and ropivacaine had significantly lower postoperative morphine requirements and higher Barthel Index scores on the 15th postsurgical day (P < 0.05). Patients receiving morphine and ropivacaine had lower NRS scores than patients receiving morphine alone on postoperative days 1, 3, 7, and 15 (P < 0.05). Negative postsurgical effects were similar in both groups. Conclusions. Morphine and ropivacaine administration through intrathecal access ports is efficacious and safe and significantly improves quality of life.

Acute and subchronic antinociceptive effects of nociceptin/orphanin FQ receptor agonists infused by intrathecal route in rats

Severe pain occurs in the context of many diseases and conditions and is a leading cause of disability. Nociceptin/orphanin FQ (N/OFQ) is the endogenous ligand of the N/OFQ peptide (NOP) receptor. This peptidergic system controls pain transmission and in particular spinally administered N/OFQ has robust antinociceptive properties. The aim of this study was to investigate the spinal antinociceptive properties of NOP peptide agonists after acute and subchronic treatment in rats. Doses unable to alter motor coordination were selected. UFP-112 (full NOP agonist) and UFP-113 (partial NOP agonist) were administered intrathecally (i.t.) by spinal catheterization. Acute injection of UFP-112 induced antinociceptive response at lower dosages (0.03-1nmol i.t.) compared to morphine and similar to N/OFQ. UFP-113 was effective in a 0.001-1nmol i.t. dose range. The antinociceptive effects of NOP ligands were no longer evident in rats knockout for the NOP gene, while those of morphine were maintained. The continuous spinal infusion (by osmotic pumps) of 0.1nmol/h UFP-112 and UFP-113 showed antinociceptive action comparable to 1-3nmol/h morphine or N/OFQ. The antinociceptive effect of morphine progressively decreased and was no longer significant after 6 days of treatment. Similar results were obtained with N/OFQ, UFP-112, and UFP-113. The acute i.t. injection of morphine in animals tolerant to N/OFQ and UFP-112 evoked analgesic effects. Neither morphine nor N/OFQ induced antinociceptive effects in morphine- and UFP-113-tolerant rats. In conclusion this study highlights the analgesic efficacy and potency of UFP-112 and UFP-113 underlining the relevance of NOP system in analgesia.

WITHDRAWN: Comparative efficacy of epidural, subarachnoid, and intracerebroventricular opioids in patients with pain due to cancer

2013: This review is now being updated by a new author team. The publication of the protocol is expected in late 2013.

October 2015: after discussion with the authors and PaPaS editors, the decision was made to halt the development of the protocol that was being planned to replace and update this review. It was felt that the review question was no longer a priority.

The editorial group responsible for this previously published document have withdrawn it from publication.

Characteristics of distribution of morphine and metabolites in cerebrospinal fluid and plasma with chronic intrathecal morphine infusion in humans

BACKGROUND

Despite widespread use of chronic intrathecal (IT) infusions of morphine, there is little systematic human work evaluating the steady state morphine concentrations or cerebrospinal (CSF) chemistry after long-term IT morphine delivery. We sought to address these issues in patients receiving chronic IT morphine infusion.

METHODS

Pain patients with implanted catheters and pumps (range: 127 to 2165 days), receiving a stable dosing (>1 week) of IT morphine by infusion, were entered into the study. The following sequence was performed: (1) estimation of pain score; (2) radiograph localization of catheter tip; (3) percutaneous sampling of lumbar CSF at the L4 to 5 or L5-S1 space. CSF/plasma samples were assayed for chemistry, and morphine and its 3/6 glucuronide metabolites (M3G, M6G) by liquid chromatography mass spectrometry.

RESULTS

Nineteen patients were enrolled. CSF samples were obtained from 16 subjects. Three patients were not included in the primary analysis because 1 catheter was epidural, 1 catheter was fractured, and 1 had a granuloma at the catheter tip. Of the 13 sampled patients, the range of daily doses, rates, and concentrations were 1.6 to 25 mg/d and 0.1 to 1 mL/d, 5 to 50 mg/mL, respectively. The principal observations were as follows: (i) morphine, M3G, and M6G were present in the CSF and plasma and showed a significant regression slope when plotted versus daily dose; (ii) in contrast, the regression slope of the group ratio morphine:M3G:M6G plotted versus daily dose in CSF or plasma was not different from zero; (iii) plotting "normalized" CSF analyte concentration (e.g., concentration at site/daily IT morphine dose) against the segmental distance of the sampling site from the catheter tip revealed a significant decline in concentration of morphine, but not of conjugates as a function of distance from the catheter tip; (iv) plotting CSF protein, glucose, and red and white cell counts versus daily morphine dose or morphine concentration at the sampling site revealed no significant regression; and (v) patients with a catheter failure or a granuloma showed reduced concentrations of morphine in their CSF.

CONCLUSION

Chronic infusion of morphine shows high concentrations, which correlate with the infusion dose and the proximity of the sampling site to the infusion site with no effects on CSF chemistry.

Intrathecal drug delivery system (IDDS) for cancer pain management: a review and updates

Cancer pain remains undertreated and a significant number of patients with cancer pain die from severe untreated pain. With increasing survival rate in cancer, the prevalence of cancer pain is also increasing in number. Though majority of patients with cancer pain can be effectively treated with conventional medical management, still a significant portion of patients required some form of interventional pain management techniques. Among the interventional techniques, intrathecal drug delivery is increasingly used in cancer pain management. Our objective of this article is to review literatures and clinical studies on intrathecal drug delivery system (IDDS) in cancer pain management and to provide updates on its use, precautions, contraindications, side effects and its management, socioeconomic consideration, and management of IDDS in difficult or uncommon situations.

Role of pretrial systemic opioid requirements, intrathecal trial dose, and non-psychological factors as predictors of outcome for intrathecal pump therapy: one clinician's experience with lumbar postlaminectomy pain

OBJECTIVE

Non-psychological parameters may predict pump success.

METHODS

Review was performed on 35 implants for gender, age, pretrial/trial dose, baseline visual analog scale (VAS), and pain location. One-year outcomes were % change VAS/intrathecal dose and medication change. Spearman coefficients correlated pretrial/trial dose, age, baseline VAS, and % change in VAS/intrathecal dose. Wilcoxon Rank-Sum tests correlated gender/pain location and % change in VAS/intrathecal dose. Pretrial/trial dose, baseline VAS, and medication change was tested using Wilcoxon Rank-Sums. Chi-square was used to correlate medication change with gender/pain location. A two-sample t-test compared age and medication change.

RESULTS

Positive correlation between % change VAS and trial dose was noted. Greater age correlated with lower VAS and % dose change. Marginally significant difference in % dose change by pain location was present with higher doses for leg pain.

CONCLUSION

Trial dose, age, and partially pain location are good predictors of pain relief.

Ultrasound-guided transversus abdominis plane block for spinal infusion and neurostimulation implantation in two patients with chronic pain

OBJECTIVE

This case report describes an ultrasound approach to the transversus abdominis plane (TAP) local anesthetic block. This block induces sensory blockade in the lower half of the abdomen where the pulse generator or the infusion pump is to be housed in a subcutaneous pocket, and therefore provides an alternate to general anesthesia or administration of high-dose local anesthetics.

CASE REPORT

We report two cases of neuromodulation procedures-implantation of an internal morphine pump for severe somatic pain refractory to other therapies and placement of a double-stimulator generator for dorsal column stimulation in a patient diagnosed with postoperative failed-back syndrome. We successfully used ultrasound-guided TAP block to achieve ipsilateral sensory block of dermatomes T9-L1 in the context of a monitored anesthesia care multimodal approach.

CONCLUSION

TAP block can be a potentially useful substitute to general anesthesia or local anesthesia for the pocket formation in neuromodulation techniques, and it provides adequate anesthesia of the abdominal wall. This block is potentially an important addition to the monitored anesthesia care protocol.

Intrathecal drug therapy for long-term pain management

PURPOSE

The use, safety, and efficacy of intrathecal medication administration with implantable pumps for cancer and chronic pain management are reviewed.

SUMMARY

Implanted intrathecal drug-delivery systems (IDDSs) are used for long-term management of persistent, severe pain despite a multimodal approach with conventional pain treatment options. Currently, consensus papers published in the literature are used as guidelines for determining patient selection and medication administration, because there is a lack of supporting evidence from randomized, controlled, clinical trials. Pharmacists have a critical role in the safe use of intrathecal medication. Most of the medication concentrations and combinations administered through IDDSs are not commercially available and therefore must be compounded in a pharmacy. Medications commonly administered through IDDSs include opioids, local anesthetics, clonidine, baclofen, and ziconotide. It is important for pharmacists who prepare products for IDDSs to understand the pharmacology, adverse effects, and concentration limitations of each medication in order to prevent adverse events related to postoperative subarachnoid hemorrhage, infection, catheter-tip inflammatory masses, withdrawal, and overdose. Pharmacists play an important role in maintaining quality assurance of intrathecal drug use, including the use of standard procedures for ordering and compounding medications, documentation of patient education, and monitoring of patient outcomes.

CONCLUSION

The use of long-term intrathecal drug delivery for the treatment of intractable pain or intolerable medication adverse effects has expanded to include the treatment of patients with chronic or cancer-related pain. Important considerations for the use of intrathecal drug therapy include the appropriate selection of patients, delivery systems, and medications, as well as potential complications of therapy and quality-assurance measures necessary to ensure patient safety.

Neuraxial pain relief for intractable cancer pain

Most patients with cancer pain achieve good analgesia using traditional analgesics and adjuvant medications; however, an important minority of patients (2% to 5%) suffers from severe and refractory cancer pain. For these individuals, spinal analgesics (intrathecal or epidural) provide significant hope for pain relief over months or years of treatment to help improve quality of life. Spinal analgesics have been suggested as the fourth step in the World Health Organization guidelines in the management of cancer pain, and thus the pain physician should be familiar with principles of use. Most patients achieve pain relief using spinal analgesics, with a minimum of complications that are easily managed at home. A variety of opioids, local anesthetics, clonidine, ketamine, and other analgesics are available for the spinal route of administration and should be titrated to clinical effect or intolerable side effect. This article discusses the appropriate selection of patients for spinal analgesics, reviews current recommended infusion systems and current spinal analgesics, discusses possible complications, and includes practical suggestions for patient management.

Continuous Intrathecal Morphine Infusion in Patients With Vertebral Fractures Due to Osteoporosis

OBJECTIVES

Vertebral fractures are the most common consequences of severe osteoporosis. The chronic pain from collapse of osteoporotic vertebrae affects quality of life (QOL) and autonomy of patients. The management of pain with oral or transdermal opiates can cause severe side effects. Continuous intrathecal administration of morphine via an implantable pump might represent an alternative therapy to conventional oral or transdermal administration of opioids and has some advantages and disadvantages for pain relief and improvement in QOL when compared with conventional opioid delivery. It is our objective to report our experience using intrathecal delivery of analgesics in a population of patients with refractory pain due to vertebral fractures.

MATERIALS AND METHODS

In 24 patients, refractory to conventional delivery of opioids, we used intrathecal analgesic therapy. To test for efficacy and improvement in QOL, we administered the visual analog scale for pain and the Questionnaire of the European Foundation of Osteoporosis (QUALEFFO). Before patients were selected for pump implantation, an intraspinal drug delivery trial was performed to monitor side effects and responses to intrathecal therapy.

RESULTS

Significant pain relief was obtained in all implanted patients. Using the QUALEFFO, we observed significant improvement of all variables such as quality of daily life, domestic work, ambulation, and perception of health status, before and after 1 year after pump implantation. With intrathecal morphine infusion, none of the 24 patients required additional systemic analgesic medication. The mean morphine dose during the spinal trial was 11.28 mg/d, 7.92 mg/d at pump implantation, and 16.32 mg/d at 1-year follow-up.

CONCLUSIONS

Our results show that intrathecal administration of morphine efficiently relieves the symptoms of pain and improves QOL. Continuous intrathecal administration of morphine appears to be an alternative therapy to conventional analgesic drug delivery and has advantages in those patients who have severe side effects with systemic administration of analgesics.

Programmable intrathecal opioid delivery systems for chronic noncancer pain: a systematic review of effectiveness and complications

OBJECTIVES

We conducted a systematic review of the literature on the effectiveness and complications of programmable intrathecal opioid and ziconotide drug delivery systems (IDDS) for patients with chronic noncancer pain.

METHODS

We searched MEDLINE, Cochrane, and other bibliographic databases to identify English-language journal articles reporting programmable IDDS complications or effects on pain or functioning. Additional study methodology criteria were applied for the effectiveness review. Two authors independently abstracted data from each included article.

RESULTS

Six articles met the inclusion criteria for the effectiveness and complications reviews, and 4 others met the criteria only for the complications review; none were randomized trials or of ziconotide. All 6 articles reviewed for effectiveness reported improvement in pain and functioning on average among patients who received a permanent IDDS. Two articles reported the proportion of patients with > or =50% improvement in pain at 6 months (38%, 56%) and 2 at longer follow-ups (30%, 44%). Intrathecal morphine-equivalent doses increased over time. The most commonly reported permanent IDDS drug side effects were nausea/vomiting (mean rate weighted by sample size=33%), urinary retention (24%), and pruritus (26%). Catheter problems were also reported commonly. Rare but serious complications included intrathecal catheter tip granulomas.

CONCLUSIONS

The studies reviewed found improvement in pain and functioning on average among patients with chronic noncancer pain who received permanent IDDS. However, their methodologic limitations preclude conclusions concerning the effectiveness of this technology long-term and as compared with other treatments. Drug side effects and hardware complications were common. Suggestions are made for methodologic improvements in future studies.

Management of chronic severe pain: spinal neuromodulatory and neuroablative approaches

The spinal cord is the target of many neurosurgical procedures used to treat pain. Compactness and well-defined tract separation in addition to well understood dermatomal cord organization make the spinal cord an ideal target for pain procedures. Moreover, the presence of opioid and other receptors involved in pain modulation at the level of the dorsal horn increases the suitability of the spinal cord. Neuromodulative approaches of the spinal cord are either electrical or pharmacological. Electrical spinal cord modulation is used on a large scale for various pain syndromes including; failed back surgery syndrome (FBSS), complex regional pain syndrome (CRPS), neuropathic pain, angina, and ischemic limb pain. Intraspinal delivery of medications e.g. opioids is used to treat nociceptive and neuropathic pains due to malignant and cancer pain etiologies. Neuroablation of the spinal cord pain pathway is mainly used to treat cancer pain. Targets involved include; the spinothalamic tract, the midline dorsal column visceral pain pathway and the trigeminal tract in the upper spinal cord. Spinal neuroablation can also involve cellular elements such as with trigeminal nucleotomy and the dorsal root entry zone (DREZ) operation. The DREZ operation is indicated for phantom type pain and root avulsion injuries. Due to its reversible nature spinal neuromodulation prevails, and spinal neuroablation is performed in a few select cases.

Adverse effects of gabapentin and lack of anti-allodynic efficacy of amitriptyline in the streptozotocin model of painful diabetic neuropathy

Amitriptyline and gabapentin are the primary treatments for painful diabetic neuropathy (PDN), and it is clear that they produce beneficial effects, but there are questions about these treatments that have not been adequately addressed. For example, although there is a growing consensus that the therapeutic effects of amitriptyline in pain patients are independent of its effects on mood, it is not clear that amitriptyline has specific and direct effects on pain. There is also a fairly broad consensus that gabapentin is safe and well tolerated, but the side-effect profile of gabapentin has not been adequately assessed in pain populations. The rat streptozotocin (STZ) model of PDN was used (a) to assess the effects of amitriptyline on objective, quantitative measures of tactile allodynia, a common type of pain in PDN patients, and (b) to assess the side effects of gabapentin using measures of motor/ambulatory and cognitive function. Amitriptyline did not attenuate STZ-induced mechanical allodynia, even after chronic administration of high doses. Gabapentin produced robust anti-allodynic effects but also produced deficits in tests of motor/ambulatory and cognitive functions. The present experiments suggest that the beneficial effects of amitriptyline in PDN may not be a result of anti-allodynic efficacy and that gabapentin produces robust anti-allodynic effects but may also produce significant motor and cognitive deficits even at or near the lowest effective doses. These findings challenge the consensus opinions about these primary treatments for PDN and suggest that their therapeutic and adverse effects should be explored further in pain patients.

Comparative efficacy of epidural, subarachnoid, and intracerebroventricular opioids in patients with pain due to cancer

BACKGROUND

Since the 1970s, when endogenous opioids and opioid receptors were first isolated in the central nervous system, attempts have been made to optimize opioid therapy by delivering the medication centrally rather than systemically. Although the vast majority of cancer patients obtain satisfactory pain relief from individualized systemic treatment, there remain the few whose pain is refractory to systemic treatments. These patients may obtain relief from neuraxial opioid therapy: intracerebroventricular, epidural or subarachnoid.

OBJECTIVES

To compare intracerebroventricular therapy with other neuraxial treatments and to determine whether intracerebroventricular (ICV) has anything to offer over epidural (EPI) and subarachnoid (SA) catheters in terms of efficacy, adverse effects, and complications.

SEARCH STRATEGY

A number of electronic databases were searched to retrieve information for inclusion in this review. Non-English language reports are awaiting assessment. Unpublished data were not sought.

SELECTION CRITERIA

Randomised studies of intracerebroventricular therapy for patients with intractable cancer pain were sought. However, this level of evidence was not available so data from uncontrolled trials, retrospective case series and uncontrolled prospective cohort studies were assessed.

DATA COLLECTION AND ANALYSIS

Our search did not retrieve any controlled trials. We therefore used data from uncontrolled studies to compare incidences of analgesic efficacy, adverse effects, and complications. We found 72 uncontrolled trials assessing ICV (13 trials, 337 patients), EPI (31 trials, 1343 patients), and SA (28 trials, 722 patients) in cancer patients. From these we extracted data on analgesic efficacy, common pharmacologic adverse effects, and complications.

MAIN RESULTS

Data from uncontrolled studies reported excellent pain relief among 73% of ICV patients compared with 72% EPI and 62% SA. Unsatisfactory pain relief was low in all treatment groups. Persistent nausea, persistent and transient urinary retention, transient pruritus, and constipation occurred more frequently with EPI and SA. Respiratory depression, sedation and confusion were most common with ICV. The incidence of major infection when pumps were used with EPI and SA was zero. There was a lower incidence of other complications with ICV therapy than with EPI or SA.

AUTHORS' CONCLUSIONS

Neuraxial opioid therapy is often effective for treating cancer pain that has not been adequately controlled by systemic treatment. However, long-term use of neuraxial therapy can be complicated by problems associated with the catheters. The data from uncontrolled studies suggests that ICV is at least as effective against pain as other neuraxial treatments and may be a successful treatment for patients whose cancer pain is resistant to other treatments.

Evolving spinal analgesia practice in palliative care

Intraspinal analgesia can be helpful in some patients with intractable pain. Over 15 years palliative care professionals evolved their spinals policy through a repeated series of evaluations, discussions and literature reviews. One hundred intraspinal lines were then reviewed. Notable changes in policy were the switch from epidurals to intrathecals, and the insertion of lines during working hours rather than as emergencies. Our efficacy, and frequency of adverse effects, is equal or better to published studies. Key issues in reducing adverse effects were the improved care of the spinal line exit site, a change from bolus administration to continuous infusions, and modifying line insertion techniques. Current policy is to use continuous infusions of diamorphine and bupivacaine in a 1:5 ratio through externalized intrathecal lines. The lines are effective in approximately two thirds of patients and can be kept in place for up to 18 months. The policy continues to be updated and common documentation is now in place.

Mechanisms of action of intrathecal medications

Intrathecal delivery of medications for the management of chronic pain syndromes reflects a modern targeted delivery system with the potential for even greater efficacy than is outlined in Tables 1 and 2. The twentieth century ushered in the development of parenteral approaches of medical therapy for chronic pain and other diseases that were superior to the traditional oral delivery methods known in the preceding century. Targeted drug delivery represents a significant advancement in the treatment of patients with chronic pain and is likely be the method of choice for the twenty-first century. This method of delivery is best represented by current drug delivery systems, such as the intrathecal drug pump. Traditional pharmacologic agents will still be used in the twenty-first century; however, the development of novel compounds, transplanted tissues, and genetic engineering will likely usher in a new era of pain management, including their use as analgesics for intraspinal infusion.

Long-term intrathecal opioid therapy with a patient-activated, implanted delivery system for the treatment of refractory cancer pain

The present study evaluated the safety and efficacy of patient-activated delivery of intrathecal morphine sulfate boluses delivered by way of a novel internalized intrathecal delivery system. Patients with refractory cancer pain or uncontrollable side effects were enrolled at 17 US and international sites in this prospective, open-label study. Pain relief, reduction in systemic opioid use, and reduction in opioid-related complications were analyzed both individually and together as a measure of overall success. One hundred forty-nine patients were enrolled and 119 were implanted. Average numeric analog scale pain decreased from 6.1 to 4.2 at 1 month and was maintained through month 7 (P <.01) and through month 13 (P <.05). Systemic opioid use was significantly decreased throughout the study (P <.01). Significant reduction in the opioid complication severity index was demonstrated at all 4 follow-up visits (P <.01). Overall success (>/=50% reduction in numeric analog scale pain, use of systemic opioids, or opioid complication severity index) was reported in 83%, 90%, 85%, and 91% of patients at months 1, 2, 3, and 4, respectively. This study demonstrated that patients with refractory cancer pain or intolerable side effects achieved better analgesia when managed with patient-activated intrathecal delivery of morphine sulfate via an implanted delivery system.

Encapsulation of an intrathecal catheter

A 47-year-old patient with cancer pain underwent implantation of an intrathecal drug delivery device. When the patient suffered from an infection with fever, pain on injection into the catheter and an elevated number of granulocytes in the cerebrospinal fluid 7 weeks later, radiologic examination showed an encapsulation of the catheter tip. Concentrations of morphine and morphine-6-glucuronide in the cerebrospinal fluid suggested transport of morphine into the systemic circulation via the vascularisation of the encapsulating membrane. After antibiotic therapy and removal of the catheter, morphine was administered intravenously with a one to one conversion ratio.

Intrathecal therapy for chronic pain

With the improved utilisation and widespread availability of opiates, the oral treatment of pain due to malignancy has changed radically, so that the expected need for intrathecal (IT) delivery systems for this pain has largely failed to materialise. Instead, the lack of equal progress in the design and production of non-opiates for treating non-malignant pain, in the long term, has resulted in a greater interest in the development of these IT systems in this non-malignant area.

Epidural and intrathecal analgesia for cancer pain

The three-step analgesic ladder approach developed by the World Health Organization works well in treating the vast majority (70-90%) of patients suffering from pain related to cancer. In those patients who do not get pain relief by this three-step approach, intraspinal agents can be a fourth step in managing pain of malignant origin. Although morphine is the only opioid approved by the US Food and Drug Administration for intraspinal use, many different opioid analgesics are used intraspinally, including hydromorphone, fentanyl, sufentanil, meperidine and methadone in the treatment of cancer pain. Many non-opioid agents have also been used intraspinally either alone or in combination with opioids in the treatment of intractable cancer pain. This chapter summarizes the clinical use of these agents with some practical points.

Predictive Value of Intrathecal Narcotic Trials for Long-Term Therapy with Implantable Drug Administration Systems in Chronic Non-Cancer Pain Patients

This study retrospectively investigated the predictive value of intrathecal narcotic trials for long-term drug utilization via implantable pumps in chronic non-cancer patients. Data were derived from 86 patients who were categorized according to the intrathecal narcotic dose that resulted in the optimal trial response. The response during the trial period and the pattern of long-term utilization of morphine was studied, as was the impact of age, gender and diagnosis. The analysis revealed that low dose responders had lower daily dose requirements at 18 months than standard dose and high dose responders. It also showed that women had lower total daily dose requirements at 18 and 24 months and that individuals over 65 years of age had lower total daily dose requirements at 18 months. A trend toward a disproportionately higher use of adjuvant drugs and narcotic substitutions was found among high dose responders, while a trend toward a disproportionately higher total daily dose was found among cervicalgia patients. The findings indicate that the responsiveness to an intrathecal narcotic during a trial, along with the diagnosis at the time of implantation, and the patient's age and gender can shed light on the long-term utilization of intrathecal analgesics in chronic non-cancer patients. This information may be used to better select patients and design trials that more closely reflect long-term drug utilization.

Implantable devices for pain control: spinal cord stimulation and intrathecal therapies

Untreated chronic pain is costly to society and to the individual suffering from it. The treatment of chronic pain, a multidimensional disease, should rely on the expertise of varying health care providers and should focus not only on the neurobiological mechanisms of the process but also on the psychosocial aspects of the disease. Implantable devices are costly and invasive, and such efficacious therapies should be used only when more conservative and less costly therapies have failed to provide relief of pain and suffering. Spinal cord stimulation provides neuromodulation of neuropathic, but not nociceptive, pain signals and when used for appropriate indications in the right individuals provides approximately 60-80% long-term pain relief in 60-80% of patients trialled for efficacy. Intrathecal therapies with opioids such as morphine, fentanyl, sufentanil or meperidine--or non-opioids such as clonidine or bupivacaine--provide analgesia in patients with nociceptive or neuropathic pain syndromes. Baclofen, intrathecally, provides profound relief of muscle spasticity due to multiple sclerosis, spinal cord injuries, brain injuries or cerebral palsy.

The significance of intrathecal opioid therapy for the treatment of neuropathic cancer pain conditions

The effectiveness of intrathecal opioid therapy when applied to different pain mechanisms, in particular neuropathic and nociceptive pain conditions, was studied retrospectively in 43 patients suffering from cancer pain. On the basis of clinical and radiological data, the pain mechanisms were categorized as nociceptive (n = 23) and neuropathic (n = 20). The average duration of treatment of nociceptive pain was 5 months, of neuropathic pain only 2.5 months. The initial median reduction of pain with intrathecal opioid therapy was 77.8% for nociceptive and 61.1% for neuropathic pain. Long-term results with patients suffering nociceptive pain showed a continuing good median pain reduction of 66.7%. Patients suffering from neuropathic pain showed poor long-term results (11.1% median pain reduction). Neuropathic pain in the extremities reacted least to the application of intrathecal opioids. Optimal results were obtained for nociceptive pain in the trunk area of the body.

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

BACKGROUND

To analyze, prospectively, the long-term effects of continuous intrathecal morphine infusion therapy in 16 patients with chronic nonmalignant pain syndromes.

METHODS

Twenty-five patients with severe, chronic, nonmalignant pain that had proven refractory to conservative management were considered candidates for trial of intrathecal spinal morphine. Sixteen patients achieved more than 50% pain relief after a trial period of intrathecal morphine infusion. They were implanted with fully implantable and programmable pumps through which morphine was delivered intrathecally on a continuous basis. These patients were followed prospectively and underwent careful evaluation of their functional and mental status, and pain intensity measurements using standardized techniques before treatment and every 6 months thereafter in the follow-up period. The follow-up period ranged from 13 months to 49 months (mean 29.14 months +/- 12.44 months) for the patients who had implanted morphine pumps.

RESULTS

The mean morphine dosage initially administered was 1.11 mg/day (range 0.2--6.5 mg/day); after 6 months, it was 3.1 mg/day (range 0.4--8.75 mg/day). In long-term observation, no patient had a constant dosage history. The patients who received intrathecal morphine for longer than 2 years all showed an increase in morphine dosage to more than 10 mg/day. The best long-term results were seen with deafferentation pain and mixed pain, with 75% and 61% pain reduction (visual analog scale), respectively. Nociceptive pain patients had best pain relief initially (78% pain reduction) but it tended to decrease over the follow-up period to 57% pain reduction at final follow-up. The average pain reduction for all groups after 6 months was 67.5% and at last follow-up, it was 57.5%. Ten patients were satisfied with the delivery system and eleven reported improvement in their quality of life. In two patients, morphine was not able to adequately control the pain without producing undesirable side effects requiring the addition of clonidine to their infusion medication. In this series, 12 patients were considered successes and 4 patients were considered failures. In two patients, the intrathecal opioid therapy was unable to produce satisfactory pain relief and in the other two patients the pumps had to be explanted because of intolerable side effects.

CONCLUSIONS

In our experience, the administration of intrathecal opioid medications for nonmalignant pain is justified in carefully selected patients.

Subarachnoid Techniques for Cancer Pain Therapy: When, Why, and How?

For cancer patients who obtain inadequate pain relief with conservative treatment, there is a growing list of effective options for subarachnoid therapy. Morphine and bupivacaine have been the most frequently used drugs for intrathecal infusion, and their use has consistently yielded good results. Despite their effectiveness, however, a therapeutic deficit remains, primarily in the treatment of neuropathic cancer pain. Because of this limitation, more recent research has focused on novel compounds for intrathecal therapy such as clonidine, midazolam, ketamine, and SNX-111. In addition to new drug options, there are various catheter delivery systems from which to choose. In reviewing the literature and experience to date with these various medications and delivery systems, we hope to better aid the clinician in tailoring the best treatment for each patient.

Evidence-based review of the literature on intrathecal delivery of pain medication

Evidence-based medicine depends on the existence of controlled clinical trials that establish the safety and efficacy of specific therapeutic techniques. Many interventions in clinical practice have achieved widespread acceptance despite little evidence to support them in the scientific literature; the critical appraisal of these interventions based on accumulating experience is a goal of medicine. To clarify the current state of knowledge concerning the use of various drugs for intraspinal infusion in pain management, an expert panel conducted a thorough review of the published literature. The exhaustive review included 5 different groups of compounds, with morphine and bupivacaine yielding the most citations in the literature. The need for additional large published controlled studies was highlighted by this review, especially for promising agents that have been shown to be safe and efficacious in recent clinical studies.

Human chromaffin cell graft into the CSF for cancer pain management: a prospective phase II clinical study

A number of pre-clinical studies have demonstrated the value of adrenal medullary allografts in the management of chronic pain. The present longitudinal survey studied 15 patients transplanted for intractable cancer pain after failure of systemic opioids due to the persistence of undesirable side-effects. Before inclusion, all the patients had their pain controlled by daily intrathecal (I-Th) morphine administration. The main evaluation criteria of analgesic activity of the chromaffin cell allograft was the complementary requirement of analgesics and in particular the consumption of I-Th morphine required to maintain effective pain control. Out of the 12 patients who profited from enhanced analgesia with long-term follow-up (average 4.5 months), five no longer required the I-Th morphine (with prolonged interruption of systemic opioids as well), two durably decreased I-Th morphine intake and five were stabilized until the end of their follow-up. Durable decline and stabilization were interpreted as indicative of analgesic activity by comparison with the usual dose escalation observed during disease progression. In most cases, we noted a relationship between analgesic responses and CSF met-enkephalin levels. The results of this phase II open study demonstrate the feasibility and the safety of this approach using chromaffin cell grafts for long-term relief of intractable cancer pain. However, while analgesic efficacy was indicated by the reduction or stabilization in complementary opioid intake, these observations will need to be confirmed in a controlled trial in a larger series of patients.

A prospective study of long-term intrathecal morphine in the management of chronic nonmalignant pain

OBJECTIVE

To examine in a prospective manner the long-term safety and efficacy of chronic intrathecal morphine in patients with severe, nonmalignant pain refractory to less invasive modalities.

METHODS

Forty patients with severe, chronic nonmalignant pain poorly managed by systemic medications were identified as candidates for intraspinal trial of morphine. Thirty participants reported successful pain relief during trial and were implanted with an intraspinal delivery system. Standardized measures of pain and functional status were assessed before treatment was begun and at defined intervals during the subsequent 24 months. Intrathecal opioid use and pharmacological and device-related complications were also monitored.

RESULTS

The participants had a mean age of 58 +/- 13 years and a mean pain duration of 8 +/- 9 years. Fifty-three percent of the study participants were women. Pain type was characterized as mixed neuropathic-nociceptive (15 of 30 patients, 50%), peripheral neuropathic (10 of 30 patients, 33%), deafferentation (4 of 30 patients, 13%), or nociceptive (1 of 30 patients, 3%). Forty-seven percent of the patients were diagnosed with failed back surgery syndrome. Significant improvement over baseline levels of visual analog scale pain was measured at each follow-up examination after implant. Overall, 50% (11 of 22 patients) of the population reported at least a 25% reduction in visual analog scale pain after 24 months of treatment. In addition, the McGill Pain Questionnaire, visual analog scale measures of functional improvement and pain coping, and several subscales of the Chronic Illness Problem Inventory showed improvement throughout the follow-up period. Pharmacological side effects were managed medically by morphine dose reduction, addition of bupivacaine, or replacement of morphine with hydromorphone. Device-related complications requiring repeat operations were experienced by 20% of the patients.

CONCLUSION

Continuous intrathecal morphine can be a safe, effective therapy for the management of severe, nonmalignant pain among a carefully selected patient population and can result in long-term improvement in several areas of daily function.