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

Intrathecal morphine delivered via subcutaneous pump for intractable pain in pancreatic cancer

BACKGROUND

Pain secondary to unresectable pancreatic cancer is frequently severe and extremely difficult to control with traditional methods of analgesia. This retrospective study reports the analgesic effects of intrathecal morphine sulfate by implanted infusion pumps in nine patients with unresectable adenocarcinoma of the pancreas.

METHODS

Nine patients were implanted over a 2-year period. Preoperative morphine i.v. equivalents were a mean of 81.51 mg/day, with a range of 20-140 mg/day. Patients were hospitalized for a trial dose of 1-2 mg of intrathecal Duramorph, 1 mg/ml, via lumbar puncture to assess whether adequate pain relief could be achieved and whether there would be drug-related side effects.

RESULTS

All patients who received a trial dose experienced excellent pain relief, and subsequently underwent implantation of a lumbar subarachnoid catheter and infusion pump during the same hospitalization. The mean number of days from diagnosis to pump implant was 119, with a range of 3-587 days. The mean maximum daily dose was 21.28 mg, with a range of 3-73.10 mg. No patient experienced respiratory depression or excess sedation which prevented achievement of pain control. Minor supplemental narcotic use was documented in three of the nine patients. Assessment of pain control was made by the level of activity and the analog pain scale, with 0 being no pain and 10 being the worst pain imaginable. All of the patients experienced good to excellent relief of pain. The mean duration of intrathecal morphine sulfate use until death was 137.3 days, with a range of 52-354 days.

CONCLUSIONS

This series of nine patients indicates that long-term administration of intrathecal morphine via implanted infusion pump in patients with pancreatic cancer is both efficacious and safe. All patients and their families reported an improved quality of life with an increased level of activity.

Distribution, tolerability and tissue compatibility of intrathecal tizanidine in the sheep

BACKGROUND

Tizanidine (TZD) is an alpha-2-adrenergic drug with potential spinal analgesic action and could be a substitute or additive for intrathecal (i.t.) opiates in chronic pain treatment. However, long-term tolerability and tissue compatibility are not yet established.

METHODS

Three sheep were infused intrathecally with TZD up to 4000 micrograms/d over a time period of up to 440 d using implantable drug administration devices; one control animal was infused with vehicle only; standard values were collected from untreated sheep. CSF samples and blood samples were analyzed to determine pharmacokinetics and systemic redistribution. Behavioral effects were studied. The spinal cord tissue was investigated using standard laboratory histology.

RESULTS

Bolus kinetics after i.t. injection of TZD are best described by a two-phase model. Elimination half-lives of TZD in CSF were 15 min and 152 min, respectively. Clearance of TZD from lumbar CSF was 0.48 ml/min. Doses higher than 500 microgram i.t. caused dose-dependent motor inactivity and sleepiness. Continuous i.t. TZD up to 4 micrograms/d was well tolerated regarding behavioral, physical activity, heart rate, muscle counts and total protein were detected both in saline and TZD-treated animals, presumably due to local irritation by the catheter and repeated sampling procedures. Histological evaluation of the spinal cord and adjacent tissues showed no abnormalities.

CONCLUSION

The long-term intrathecal infusion of TZD is well tolerated and non-toxic in the sheep. The data favor clinical trials in patients with chronic pain.

Epileptic seizure associated with intracerebroventricular and intrathecal morphine bolus

We report on two patients with morphine-related seizures associated with either intrathecal or intracerebroventricular administration. Both patients had a history of malignant tumor and both experienced the seizures following bolus application of morphine, while even higher dosages were well tolerated when continuously infused. Seizures occurred without signs of intoxication. Initiation of intrathecal morphine therapy and bolus application should be performed carefully and only when constant monitoring is provided for at least 12 h. Animal data and possible mechanisms for morphine-related seizures are discussed.

Efficacy and technical complications of long-term continuous intraspinal infusions of opioid and/or bupivacaine in refractory nonmalignant pain: a comparison between the epidural and the intrathecal approach with externalized or implanted catheters and infusion pumps

OBJECTIVE

To compare efficacies, failure rates, and technical complication rates of intraspinal treatments in patients with "refractory" nonmalignant pain conditions in relation to the approach (epidural/intrathecal), the drug (opioid/opioid-bupivacaine or bupivacaine), and the type of system used (externalized/internalized). In these comparisons, recent data from a companion paper (Nitescu et al., Clin J Pain 1998;14:17-28) were used as a reference to be compared with data from a literature review of different intraspinal treatment modalities in nonmalignant pain.

DESIGN

Prospective, cohort, nonrandomized, consecutive trial.

SETTING

Tertiary care center, institutional practice, hospitalized, and ambulatory care.

PATIENTS

Five groups according to treatment modality: (a) externalized, long-term intrathecal nylon catheters, connected to external, electronic infusion pumps (companion paper), n = 90; (b) internalized, long-term intrathecal catheters (Silastic) connected to implanted SynchroMed pumps, n = 330 (literature review); (c) externalized, "short-term" epidural catheters for "temporary" infusions, n = 565 (literature review); (d) externalized, long-term epidural catheters, n = 50 (literature review); (e) internalized, long-term epidural catheters, n = 111, connected to implanted systems: Port-A-Cath injection ports, n = 58; Infusaid pumps, n = 46; and SynchroMed pumps, n = 7 (literature review).

INTERVENTIONS

In reviewing the literature, we found 21 studies that reported on the intraspinal (epidural or intrathecal) administration of opioids with or without local anesthetics (usually bupivacaine). These studies were analyzed with respect to the rates of the variables satisfactory pain relief (efficacy), failures, and technical complications. A rate is the number of observations of a variable divided by the number of patients or the number of catheters or infusion systems, as logically indicated (e.g., the numbers of complications, such as epidural abscess and meningitis, were related to the number of patients and those of catheter occlusion or leakage to the number of the catheters). The variables were expressed as the means of the rates of a variable from studies belonging to various treatment modalities: approach (epidural vs. intrathecal), duration (short vs. long term), drugs administered intraspinally (opioid vs. opioid and/or local anesthetic), and type of infusion system (externalized vs. internalized). Further, the sums of all observations of one variable in different studies with various treatment modalities were related to the corresponding sums of the patients (alternatively, catheters or implanted devices). The proportions of these sums were tested for significance in relation to treatment modality.

MAIN OUTCOME MEASURES

Comparative rates of successful intraspinal treatment and its failures and complications.

RESULTS

(a) The intrathecal approach, compared with the epidural approach, was associated with higher rates of satisfactory pain relief for both externalized (86/90, 95% vs. 17/40, 42.5%, p < .0001) and internalized (295/336, 89% vs. 33/56, 59%, p < .0001) catheters; higher rates of treatment failures with externalized epidural catheters than with internalized intrathecal catheters (24/47, 51%, vs. 36/338, 11%, p < .0001); lower rates of treatment failures with internalized intrathecal catheters than with internalized epidural catheters (36/338, 11% vs. 29/76, 38%, p < .0001); higher rates of system replacement with internalized epidural catheters than with internalized intrathecal catheters (23/32, 72% vs. 6/49, 12%, p < .0001; higher rates of system removal with internalized epidural catheters than with internalized intrathecal catheters (22/49, 45% vs. 5/49, 10%, p < .001); higher rates of catheter-related complications with epidural than with intrathecal catheters (dislodgement 13/126, approximately 10% vs. 6/150, 4%, p < .05; leakage 5/51, approximately 10% vs. 1/116, 0.9%, p < .05; obstruction 2

Clinical realities and economic considerations: patient selection in intrathecal therapy

Chronic nonmalignant pain, persisting more than 6 months, affects 15%-30% of the United States population. The majority of chronic pain patients respond to a combination of physical modalities and non-opioid analgesics. However, approximately 20% do not derive sufficient pain relief from traditional measures (back surgery, oral drugs, etc.). An additional percentage of patients do not achieve a favorable balance between analgesia and side effects with systemic opioid therapy. For these patients, intraspinal delivery of opioids may improve pain relief, reduce suffering, and enhance quality of life and functional ability. Patient selection is a significant determinant of the success of this approach. Because pain is a biopsychosocial phenomenon, psychological and social assessment are essential along with adequate trials of opioid responsiveness. There are several valid approaches to conducting trials of intraspinal pain therapy including epidural and intrathecal trials. Other important issues concern trial length, the utility of placebo trials, and drug selection in cases where morphine alone provides insufficient analgesia.

Pain-related disability and effects of chronic morphine in the adjuvant-induced arthritis model of chronic pain

Functional disability has been identified as one of the most important aspects of chronic pain, yet modeling pain-related disability has received little attention. Adjuvant-induced arthritis was induced, and one group of arthritic rats was implanted with SC 75-mg morphine pellets 1 week postadjuvant, and reimplanted every 2 weeks thereafter. The results confirm that the rodent adjuvant-induced arthritis model of severe chronic pain can be used to model pain-related disability: spontaneous activity levels and ambulatory function were reduced in arthritic rats and they exhibited substantial weight loss. The results of the present study suggest that the operant delayed nonmatching-to-position task can be used as a measure of pain-related disability, which may be especially relevant to the effects of chronic pain on performance in a work setting. The delayed nonmatching-to-position operant bar-pressing task is an "apical" test that is sensitive to deficits across a wide range of behavioral functions: motor ability, attention, motivation, learning, and memory, and arthritic rats were severely impaired in this task. In addition, analgesic treatments that impair functional abilities in normal healthy rats may actually improve the performance of rats exhibiting pain-related disability. Previous work demonstrated that acute morphine injections of only 4 mg/kg impaired performance in the delayed matching-to-position task. The results of the present study demonstrate that chronic morphine attenuates the degree of pain-related disability exhibited by arthritic rats in the test of ambulatory function and the delayed nonmatching-to-position bar-pressing test. These results demonstrate that novel analgesic treatments can be screened preclinically, both with respect to their direct analgesic effects, and with respect to their ability to reduce pain-related disability.

Long-term intrathecal infusion of morphine in the home care of patients with advanced cancer

BACKGROUND

Fear of infections and other complications has made many clinicians avoid intrathecal application of morphine in chronic cancer pain. However, recent comparative studies show that, in long-term treatment, intrathecal morphine administration may give a more satisfactory pain relief with lower doses of morphine and fewer side-effects than epidural administration. In Montpellier Cancer Institute, first cancer pain patients received long-term intrathecal morphine as early as in 1979, and since then more than 400 patients have been treated.

METHODS

In 1991-1994, 50 patients having refractory cancer pain were treated with a continuous intrathecal infusion of morphine using an external pump with patient-controlled boluses. In this retrospective study, the outcome of these 5602 days of morphine therapy will be analysed. The treatment consisted of a lateral puncture technique, strictly aseptic conditions during catheter insertion and changes of pump reservoirs, and effective prevention of side-effects.

RESULTS

The average duration of intrathecal infusion was 142 (7-584) days. The mean starting dose, 2.5 (0.4-8.3) mg/day, increased to a mean final dose of 9.2 (1-94) mg/day, the average dose being 5.4 (1-23) mg/day. During the treatment period, no clinically detectable infections and no respiratory depression occurred. Leakage of cerebrospinal fluid followed by post-spinal headache occurred in only 6 patients who received a temporary external catheter: the lateral lumbar puncture technique seemed to protect from this complication in long-term treatment. The patients stayed at home, coming to agreed control visits only at 4-6 week intervals, using a telephone-telefax service for emergencies.

CONCLUSIONS

Long-term intrathecal morphine infusion seems to provide satisfactory analgesia, few side-effects and a high degree of patient autonomy.

Spinal opioid infusions in the treatment of chronic pain of nonmalignant origin

OBJECTIVE

To review the published literature on the use of spinal opioids in the treatment of chronic pain due to nonmalignant diseases.

DESIGN

Literature review.

RESULTS

Ten studies describing 146 patients have been located and reviewed. The data are insufficient to permit formal analysis.

CONCLUSION

The proper role of intraspinal opioids in the treatment of chronic pain not due to cancer cannot be determined from the existing literature. Intraspinal opioids should be considered an experimental procedure for chronic pains not due to cancer until better data can be obtained; all patients who receive such therapy should be part of a clinical protocol whose results are published. The development of standardized clinical trial methodology and case reporting protocols would facilitate this process.

Intraspinal opioid therapy for chronic nonmalignant pain: current practice and clinical guidelines

The multidimensional nature of chronic nonmalignant pain lends itself to numerous treatment options, which vary in cost and invasiveness. Based on the principle that less invasive and less costly interventions for pain treatment should be attempted first, a continuum of interventions for chronic pain states is presented. Although intraspinal opioid therapy is a relatively invasive and costly modality for pain treatment, it has a rational place in the treatment continuum for some chronic nonmalignant pain patients. A thorough review of the literature, supplemented by clinical experience, provides a foundation for the development of management guidelines.

Intraspinal morphine for chronic pain: a retrospective, multicenter study

Intraspinal opioids are frequently used in the treatment of cancer and noncancer pain, but few studies have evaluated the efficacy of this technique. This multicenter, retrospective study surveyed physicians in the United States regarding their standard practices when using intraspinal opioids delivered via an implanted drug administration device. Thirty-five physicians (50.0%) responded, providing 429 usable patient forms (52.4%), which sought information about screening, outcomes, dosing, and adverse effects. Patients with malignant (32.7%) and noncancer (67.3%) pain had been treated for an average of 14.6 +/- 0.57 months (range, 8-94 months) at the time of form completion. For all patients, the mean percent relief was 61.0% +/- 1.35%. Patients with somatic pain tended to have greater relief, as measured by a global rating of pain relief, than did patients with other types of pain (Mann-Whitney test, P = 0.0003). After titration during the first 3 months, intrathecal morphine doses increased only twofold from 6.84 +/- 0.65 mg/day at 3 months to 13.19 +/- 1.76 mg/day at 24 months. Compared to those with noncancer pain, malignant pain patients had a higher average initial dose. The average dose used by cancer patients escalated quickly and then stabilized, whereas the average doses used by noncancer pain patients exhibited a more gradual, linear increase in dose. Long-term adverse drug effects were uncommon, but system malfunction, usually catheter related, occurred in 21.6% of patients. Prospective, randomized, controlled clinical studies of long-term efficacy and adverse effects are warranted.

Outcomes of epidural morphine treatment in cancer pain: nine years of clinical experience

The outcome of epidural morphine therapy is described in 146 consecutive cancer patients who were treated by a community hospital-based pain service. The routine procedure used a standard epidural catheter that was tunneled subcutaneously. One hundred and twenty-one patients improved and stayed on lifelong or chronic epidural opioids. Mean treatment time was 92 days (median, 47; range, 2-2040); 49% of the time was spent as outpatients. Twenty-five patients failed to respond to the treatment. The oral daily morphine-equivalent dose prior to inclusion was 164 mg. The mean daily epidural start dose of morphine was 18 mg (range, 6-120), and the mean daily dose at termination was 69 mg (range, 2-540). The dose escalations, described as the ratio of the maximum dose to the minimum maintenance start dose, were moderate, with a mean of 4.1 (median, 2.5), which corresponded to a percent increase of 5.1 (median, 2.7) per patient per day. Lack of effect due to the character of the original symptoms or progression of pain was the main reason for withdrawal from epidural opioid therapy (N = 27), followed by catheter-related problems (N = 9) and drug-related complications (N = 5). Also due to drug-related complications, epidural morphine therapy was changed to buprenorphine or methadone in 19 patients. Adjuvant systemic opioids were given to ten patients and epidural local anesthetics were administered to 17 of the subjects. Neuropathic pain, certain visceral pain types, incident pain on movement, and pain from cutaneous ulcerations were characteristics of poor responders.(ABSTRACT TRUNCATED AT 250 WORDS)

A lack of supersensitivity to opioid receptor agonists following chronic spinal opioid receptor antagonist administration in the rat

1. Male Sprague-Dawley rats were chronically tested with intrathecal (i.t.) receptor selective opioid antagonists to determine if antinociceptive supersensitivity developed to selective i.t. opioid receptor agonists. 2. A subcutaneously implanted osmotic minipump was used to deliver the mu-opioid receptor antagonist CTOP (0.3 nmol) or the delta-opioid receptor antagonist naltrindole (5.5 nmol) for 7 days. 3. Following a 24 hr washout period, rats received a single i.t. dose (ED50) of either DAMPGO (for CTOP-treated animals) or DPDPE (for naltrindole-treated animals) and the antinociceptive effects of the agents were tested on the tail-flick test. 4. Our findings revealed that chronic spinal treatment with selective opioid receptor antagonists did not induce an antinociceptive supersensitivity to selective opioid receptor agonists. 5. Perhaps this lack of supersensitivity is reflective of difficulties inherent to opioid receptor antagonists that do not possess negative intrinsic activity.

Management of spinal infusions in palliative care

Spinal analgesia can provide excellent pain relief for a small group of patients in whom conventional modalities have failed. The role of spinal analgesia in the palliative care setting is discussed and illustrated by the experience at St Gemma's Hospice over a two-year period. Special emphasis is placed on the difficulties that may need to be overcome when using this form of analgesia. The management of spinal infusions can produce some unique problems to the hospice or home care team, but the benefits often far outweight the difficulties.

Intrathecal morphine and bupivacaine in advanced cancer pain patients implanted at home

Fifteen patients with pain due to advanced cancer who no longer obtained relief from conventional treatment using oral or parenteral opioids were administered morphine and bupivacaine by continuous intrathecal infusion. Thirteen patients were implanted at home due to poor medical condition or refusal to be hospitalized. A summary score was derived to monitor the effects of the treatment. Thirteen patients required low doses of intrathecal morphine and bupivacaine and all reported good pain relief until death. Only minor side effects were evidenced. Implantation at home of an intrathecal catheter to administer morphine and bupivacaine provided a degree of pain relief during the last days of life that would have otherwise been impossible and did so without producing important complications.

Autoradiographic localization of receptors for neuropeptide FF, FLFQPQRFamide, in human spinal sensory system

The regional distribution of FLFQPQRFamide binding sites on fresh unfixed cryostate sections from post mortem specimens of human spinal cord and lower medulla oblongata was studied by quantitative autoradiographic methods using [125I]YLFQPQRFamide as ligand. Samples were taken from five cases who had died with no history of neurological disease at ages ranging from 5 months to 66 years. The biochemical and pharmacological characteristics of [125I]YLFQPQRFamide binding to mounted tissue sections were comparable to those reported for the rat in a previous study. [125I]YLFQPQRFamide appeared to interact reversibly with high affinity binding sites (Kd = 0.06 nM), distinct from opiate receptors. Sites labelled with [125I]YLFQPQRFamide were distributed unevenly within the human spinal cord and lower medulla oblongata, with the highest density in the superficial layers of the dorsal horn and the spinal trigeminal nucleus. Although moderate labelling was observed in the ventral part of spinal grey matter, dense labelling appeared in the gracile and cuneate nuclei. No binding sites were detected in white matter. These results show that, as in the rat, FLFQPQRFamide receptors in the human spinal cord and lower medulla oblongata, are mainly concentrated within spinal areas implicated in the analgesic action of opiates. The possible role of these receptors in modulating spinal nociceptive information is discussed with respect to the pharmacological effects of substances acting on FLFQPQRFamide receptors in animals.