Inflammatory mass lesions associated with intrathecal drug infusion catheters: report and observations on 41 patients

A Rare Intrathecal Pump Complication Caused by Prolonged Seroma Leading to a Potential Pump Pocket Fill: A Near Miss

Intrathecal drug delivery systems have been used with increasing frequency in patients with chronic intractable pain. Common complications of intrathecal drug delivery systems include surgical bleeding, spinal cord injury, fractured or migrated catheter, meningitis, pump failure, granuloma formation, cerebral spinal fluid leak, and hygroma formation. We present a rare near-miss case that could have led to the inadvertent filling of an intrathecal pump pocket with a high concentration of narcotic and local anesthetic. This situation arose due to the discovery of a prolonged intrathecal pump pocket seroma during a routine maintenance and refill procedure.

Restoration of rostral cerebrospinal fluid flow to solve treatment failure caused by obstruction in long-term intrathecal baclofen administration

Objects: We describe five traumatic spinal cord injury (SCI) patients with an intrathecal baclofen administration (ITB) failure caused by a rostral CSF flow obstruction referred to our expert center between January 2014 and January 2019. We discuss the diagnostic workup, rostral CSF flow obstruction as the cause of the ITB failure and treatment.Methods: When we could not determine the cause of the ITB failure through the patient's history, physical spasticity examination, pump readout, absence of fluid in the pump reservoir during aspiration, or plain radiography, we performed pump catheter access port (computed tomography [CT]) myelography. When CT myelography did not reveal the diagnosis, we used scintigraphy. In an obstruction, we aimed for CSF flow restoration. In three cases, we conducted a laminectomy with microsurgical adhesiolysis. In two of these patients, we could not achieve CSF flow restoration; thus, we placed an intradural catheter bypass. Recently, in three patients, we applied a less invasive technique of percutaneous fenestration of the obstruction.Results: In one case, we performed a successful catheter replacement. In another case using surgical adhesiolysis, spasticity control was complete. In two cases, we could obtain improvement with an additional intradural bypass, followed by a percutaneous fenestration of the obstruction, resulting in further improved CSF flow restoration. In one case, percutaneous fenestration was the first line of treatment. In all cases with percutaneous fenestration, we experienced spasticity control.Conclusion: Preliminary results showed that the restoration of rostral CSF flow might result in an effective ITB treatment in patients with an intrathecal obstruction.

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.

Eleven years' experience with Intrathecal Baclofen - Complications, risk factors

OBJECTIVE

Treatment with intrathecal baclofen (ITB) is commonly used in patients with severe spasticity. However, complications may occur after implantation of the ITB-device, albeit mainly procedure- and device-related problems. The aim of the study was to assess surgical- as well as catheter- and pump-related complications and define their risk factors.

METHODS

We retrospectively evaluated all patients with an implanted ITB-device who were treated at the Department of Neurology, Hochzirl Hospital, Zirl, Austria, between 2006 and 2016.

RESULTS

Twenty-nine of 116 (25%) patients experienced 32 complications: 5 procedure- and 27 device-related (4 pump- and 23 catheter-associated) problems occurred. Risk factors for sustaining any complication were a spinal localization of lesion (odds ratio [OR] OR 2.71, p = .021), other catheter types than an Ascenda^® catheter (OR 3.87, p = .041), a lower modified Rankin Scale (median 4 vs. 5; OR 2.86, p = .015) and a higher Barthel Index (median 53 vs. 0; OR 2.84, p = .006). The median time from the last ITB-related surgery to the first complication was 18 (IQR 1-57) months. Overall, 47% complications occurred within the first year after any surgical procedure regarding the ITB-device, thereof 25% within the first month.

CONCLUSIONS

Procedure- and device-related complications are frequent after implantation of an ITB-device with catheter-associated complications as the most frequently encountered problems. Patients with a spinal origin of spasticity, a lower modified Rankin Scale and a higher Barthel Index have a higher risk to sustain a complication.

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.

Clinical Uses of Intrathecal Therapy and Its Placement in the Pain Care Algorithm

Intrathecal drug delivery is an effective treatment option for patients with severe chronic pain who have not obtained adequate analgesia from more conservative therapies (eg, physical therapy, systemic opioids, nonsteroidal anti-inflammatory drugs, antidepressants, and anticonvulsants). This review focuses on, but is not limited to, the 2 agents currently approved by the U.S. Food and Drug Administration for intrathecal analgesia: preservative-free morphine and ziconotide (a nonopioid, selective N-type calcium channel blocker). We describe the appropriate use of intrathecal therapy in the management of severe chronic pain, based on current best practices. Topics addressed here include patient selection, trialing, dosing and titration, adverse event profiles, long-term management, intrathecal therapy for cancer-related pain, and the placement of intrathecal therapy in the pain care algorithm. In appropriately selected patients with chronic pain, intrathecal therapy can provide substantial pain relief with improved functioning and quality of life. Successful long-term management requires ongoing patient monitoring for changes in efficacy and the occurrence of adverse events, with subsequent changes in intrathecal dosing and titration, the addition of adjuvant intrathecal agents, and the use of concomitant oral medications to address side effects, as needed. Based on an infrequent but clinically concerning risk of overdose, granuloma, and other opioid-induced complications, nonopioid therapy with ziconotide may be preferred as a first-line intrathecal therapy in patients without a history of psychosis or allergy.

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.

Role of meningeal mast cells in intrathecal morphine-evoked granuloma formation

BACKGROUND

Intrathecal morphine forms granulomas that arise from the adjacent arachnoid membrane. The authors propose that these inflammatory cells exit the meningeal vasculature secondary to meningeal mast cell degranulation.

METHODS

Three sets of experiments were accomplished in dogs: (1) ex vivo meningeal mast cell degranulation (histamine release was measured ex vivo from canine dura incubated with opiates); (2) in vivo cutaneous mast cell degranulation (flare areas on the dog abdomen were measured after subcutaneous opiates); and (3) in vivo granuloma pharmacology. Dogs with lumbar intrathecal catheters received infusion of intrathecal saline or intrathecal morphine. Intrathecal morphine dogs received (1) no other treatment (control); (2) twice-daily subcutaneous naltrexone; (3) intrathecal co-infusion of cromolyn; or (4) twice-daily subcutaneous cromolyn for the 24- to 28-day study course.

RESULTS

Morphine but not fentanyl evoked dural histamine release, which was blocked by cromolyn but not naloxone. Wheal/flare was produced by subcutaneous morphine, methadone, hydromorphone, but not fentanyl, and was unaffected by naltrexone but prevented by cromolyn. Granulomas occurred in all dogs receiving intrathecal morphine (15 of 15); subcutaneous naltrexone had no effect on granulomas (six of six) but was reduced by concurrent intrathecal cromolyn (zero of five) or twice-daily subcutaneous cromolyn (one of five).

CONCLUSIONS

The pharmacology of cutaneous/dural mast cell degranulation and intrathecal granulomas are comparable, not mediated by opioid receptors, and reduced by agents preventing mast cell degranulation. If an agent produces cutaneous mast cell degranulation at concentrations produced by intrathecal delivery, the agent may initiate granulomas.

Alfentanil: correlations between absence of effect upon subcutaneous mast cells and absence of granuloma formation after intrathecal infusion in the dog

BACKGROUND

We hypothesize that intrathecal (IT) granulomas arising from the IT infusion of several opiates may result from the degranulation of meningeal mast cells (MC). Given functional covariance between cutaneous and meningeal MC, we propose that opioids that do not degranulate cutaneous MC will not produce a granuloma. An opioid meeting this criteria is the phenylpiperadine alfentanil HCl.

METHODS

Three experiments were accomplished in dogs. 1) Cutaneous MC degranulation. Flare areas on the dog abdomen were measured after intradermal alfentanil, morphine, or compound 48-80. 2) Dose ranging of analgesic effects of IT alfentanil infusion. Dogs with lumbar IT catheters received continuous infusion for 24 hours of different concentrations (1-20 mg/mL/d) of alfentanil and analgesic effects were assessed. 3) Granuloma inducing effects. Dogs received IT alfentanil (20 mg/mL/d; N = 5; 22-28 days) or morphine (12 mg/mL/d; N = 3; 22-30 days) and spinal cord harvested for histopathology after 22-30 days of infusion.

RESULTS

1) Intradermal morphine (10 mg/mL) and compound 48-80 (1 mg/mL) but not alfentanil at concentrations up to 20 mg/mL produced a cutaneous flare. IT alfentanil infusion produced increases in thermal escape latency at concentrations as low as 2 mg/mL/day. A significant depression of arousal was noted in the dogs receiving 20 mg/mL. Over the 22- to 30-day infusion period, morphine (12 mg/mL/day) resulted in granulomas in all three animals examined whereas IT alfentanil at 20 mg/mL/day failed to initiate a granuloma in any animal.

CONCLUSIONS

These results support the hypothesis linking MC degranulation and IT granulomas.

Ephrin-B3 decreases the survival of adult rat spinal cord-derived neural stem/progenitor cells in vitro and after transplantation into the injured rat spinal cord

Although transplantation of neural stem/progenitor cells (NSPC) encourages regeneration and repair after spinal cord injury (SCI), the survival of transplanted NSPC is limited. Ephrin-B3 has been shown to reduce the death of endogenous NSPC in the subventricular zone of the mouse brain without inducing uncontrolled proliferation. Due to similarities in the environment of the brain and spinal cord, we hypothesized that ephrin-B3 might reduce the death of both transplanted and endogenous spinal cord-derived NSPC. Both normal and injured (26 g clip compression) spinal cords were examined. Ephrin-B3-Fc was tested, and Fc fragments and phosphate-buffered saline (PBS) were used as controls. We found that EphA4 receptors were expressed by spinal cord-derived NSPC and expressed in the normal and injured rat spinal cord (higher expression in the latter). In vitro, ephrin-B3-Fc did not significantly reduce the survival of NSPC except at 1 μg/mL (P<0.05), but Fc fragments alone reduced NSPC survival at all doses in a dose-dependent fashion. In vivo, intrathecal infusion of ephrin-B3-Fc increased the proliferation of endogenous ependymal cells and the proportion of proliferating cells that expressed the glial fibrillary acidic protein astrocytic marker in the injured spinal cord compared with the infusion of PBS (P<0.05). However, in the injured spinal cord, the infusion of either ephrin-B3-Fc or Fc fragments alone caused a 20-fold reduction in the survival of transplanted NSPC (P<0.001). Thus, after SCI, ephrin-B3-Fc and Fc fragments are toxic to transplanted NSPC.

Spinal cord compression secondary to intrathecal catheter-induced granuloma: a report of four cases

Objective: The management of nonmalignant pain by morphine pump implantation has become an effective and increasingly frequent strategy of care. We report a rare complication of intrathecal granuloma formation adjacent to the intrathecal catheter tip resulting in spinal cord compression in four patients undergoing intrathecal treatment for chronic pain.

Methods: Four patients presented with chronic back pain and lower extremity pain and weakness and were treated with morphine pump implantation (Fig 1). Each patient developed a mass at the level of the intrathecal catheter tip resulting in increased back pain and diminished neurological function. Following clinical examination and x-ray workup, the patients underwent surgical resection of the mass and removal of the intrathecal catheter. One patient received conservative saline therapy first, and another patient had granuloma resection first and removal of the intrathecal catheter at a later date. Pathological analysis showed granulation tissue with extensive necrosis and chronic inflammation, with negative culture results. No evidence of neoplasm was found.

Results: Patients showed varying degrees of improvement following removal of the intrathecal mass. Two patients had moderate pain reduction following resection of the granuloma; a third had minimal pain improvement; and a fourth had significant pain improvement but continued lower extremity weakness.

Conclusions: The formation of granulomas caused by intrathecal catheter implantation is a rare but serious complication. Imaging studies including magnetic resonance imaging with contrast and computed tomography with myelogram should be used to follow up a neurological examination consistent with spinal cord compression. Timely surgical intervention may result in marked improvement of symptoms.

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.

Catheter obstruction of intrathecal drug administration system -a case report-

Intrathecal drug administration system (ITDAS) can reduce the side effects while increasing the effectiveness of opioids compared to systemic opioid administration. Therefore, the use of ITDAS has increased in the management of cancer pain and chronic intractable pain. Catheter obstruction is a serious complication of ITDAS. Here, we present a case of catheter obstruction by a mass formed at the side hole and in the lumen. A 37-year-old man suffering from failed back surgery syndrome received an ITDAS implantation, and the ITDAS was refilled with morphine every 3 months. When the patient visited the hospital 18 months after ITDAS implantation for a refill, the amount of delivered morphine sulfate was much less than expected. Movement of the pump rotor was examined with fluoroscopy; however, it was normal. CSF aspiration through the catheter access port was impossible. When the intrathecal catheter was removed, we observed that the side hole and lumen of the catheter was plugged.

Intrathecal opioid therapy for chronic nonmalignant pain: a retrospective cohort study with 3-year follow-up

OBJECTIVE

The objective of this study was the analysis of outcomes after intrathecal opioid treatment. Design. Retrospective chart review cohort study. Setting. Tertiary care university hospital and clinic. Patients. Adults of both sexes were included. Interventions. The intervention consisted of the implantation of intrathecal catheter and subcutaneous programmable pump to deliver opioids.

OUTCOME MEASURES

These included intrathecal and oral opioid consumption, self-reported pain levels, and complications.

RESULTS

We observed reduction of visual analog scale scores, decrease in oral opioid consumption. Stable long-term (3 year) pain reports. We also noted gradual increases in intrathecal opioid consumption. Pre-implant opioid consumption was inversely correlated with treatment success. The complication rate was approximately 20%.

CONCLUSIONS

We conclude that intrathecal opioids without adjunctive intrathecal medications have a favorable outcome. Some patients are able to eliminate oral opioids. Results seem stable for prolonged periods, although some increase in intrathecal opioids dosing may be required.

Intrathecal catheter granuloma associated with continuous sufentanil infusion

Intrathecal sufentanil is a minimally utilized opioid for patients with intractable pain refractory to traditional intrathecal medications. We present an 86-year-old female with a history of multiple spine surgeries who eventually progressed to having chronic, intractable, and diffuse low back pain. After failing medical management, she underwent a successful intrathecal trial of opioid therapy and was subsequently treated with an implantable drug delivery system (IDDS) or intrathecal pump. We describe the first reported case of formation of a catheter tip granuloma associated with intrathecal infusion of sufentanil. Due to increasing opioid requirements and gradually escalating pain, a computed tomography myelogram was performed to explore neuraxial etiologies of her symptoms. This investigation revealed the presence of a catheter tip-associated inflammatory mass (granuloma). All patients receiving intrathecal medications, including sufentanil, must be considered for the possibility of catheter-associated granuloma, particularly with symptoms of altered neurological function and/or increasing medication requirements associated with worsening pain.

Intrathecal morphine attenuates recovery of function after a spinal cord injury

Prior work has shown that a high dose (20 mg/kg) of systemic morphine, required to produce significant analgesia in the acute phase of a contusion injury, undermines the long-term health of treated subjects and increases lesion size. Moreover, a single dose of systemic morphine in the early stage of injury (24 h post-injury) led to symptoms of neuropathic pain 3 weeks later, in the chronic phase. The present study examines the locus of the effects using intrathecal morphine administration. Subjects were treated with one of three doses (0, 30, or 90 microg) of intrathecal morphine 24 h after a moderate contusion injury. The 90-microg dose produced significant analgesia when subjects were exposed to noxious stimuli (thermal and incremented shock) below the level of injury. Yet, despite analgesic efficacy, intrathecal morphine significantly attenuated the recovery of locomotor function and increased lesion size rostral to the injury site. A single dose of 30 or 90 microg of intrathecal morphine also decreased weight gain, and more than doubled the incidence of mortality and autophagia when compared to vehicle-treated controls. Morphine is one of the most effective pharmacological agents for the treatment of neuropathic pain and, therefore, is indispensable for the spinally injured. Treatment can, however, adversely affect the recovery process. A morphine-induced attenuation of recovery may result from increases in immune cell activation and, subsequently, pro-inflammatory cytokine concentrations in the contused spinal cord.

Optimizing pain control through the use of implantable pumps

Intrathecal therapy represents an effective and well established treatment of nonmalignant as well as malignant pain. Devices available include mechanical constant flow pumps as well as electronic variable flow pumps with patient-controlled bolus release. The latter provide faster dose finding, individual pain control, and good acceptance by patients. New technologies such as membrane pumps and rechargeable devices are expected to be developed to clinical perfection. The available drugs for intrathecal therapy are listed according to the polyanalgesic consensus on intrathecal therapy. The integration of remote patient-controlled analgesia into electronic implantable devices, and the peptide analgesic ziconotide, have significantly improved intrathecal therapy. Complications include infections, catheter ruptures or disconnections, catheter granulomas, and technical dysfunctions. Further possibilities for optimizing intrathecal therapy include development of new drugs, drug side effects, catheter and pump technologies, and surgical techniques.

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.

Management of chronic back and leg pain by intrathecal drug delivery

Intrathecal delivery of analgesic drugs by implantable pump systems has been recognized as a treatment option for patients with chronic pain of benign or malignant origin that is resistant to oral or parenteral medication. Patients with chronic back and leg pain (CBLP), a benign but severely disabling condition of the lumbar spine with multifactorial genesis, have been demonstrated in a number of retrospective and in some prospective clinical studies to benefit from intrathecal delivery of opioid and/or non-opioid substances, either as single drugs or in combinations. In addition, intrathecal therapy for CBLP has been proven safe and less expensive that conventional medical therapy. This chapter summarizes the clinical and experimental evidence and the personal experience of the authors with long-term intrathecal infusion therapy for CBLP. It discusses important clinical issues such as drug selection, drug combinations, and side effects and complications of intrathecal infusion. It is concluded that further clinical research is needed in order to provide stronger evidence for the usefulness of a number of drugs currently used for intrathecal therapy on a mostly empirical basis.

Inflammatory mass of an intrathecal catheter in patients receiving baclofen as a sole agent: a report of two cases and a review of the identification and treatment of the complication

INTRODUCTION

Intrathecal inflammatory masses or granuloma have been described extensively in the literature in patients receiving chronic spinal infusions for pain. After an extensive literature review, no reported cases of baclofen causing this disorder when administered as a sole agent were identified. Intrathecal baclofen has been used to treat spasticity secondary to stroke, multiple sclerosis, cerebral palsy, spinal cord injury, and other neurological disease.

CASES

Two patients who received intrathecal infusions of baclofen to treat spasticity developed catheter failure. Magnetic resonance imaging analysis showed the presence of an inflammatory mass at the tip of each catheter causing the dysfunction. The catheters were removed and replaced by a percutaneous technique.

DISCUSSION

Inflammatory mass on an intrathecal catheter can result in a variety of symptoms. These problems range from the patient being asymptomatic to flaccid paraplegia. Animal studies have shown an association with high concentrations of morphine and hydromorphone theorized to be related to a mast cell degranulation response. Presence of this lesion in these two patients should heighten the suspicion for inflammatory mass in any patient treated for spasticity. The diagnosis of intrathecal catheter tip inflammatory mass is made after an initial suspicion of a catheter occlusion or failure. The gold standard of diagnosis is T2-weighted magnetic resonance imaging. A computerized tomography myelogram is acceptable if a magnetic resonance imaging is not feasible.

CONCLUSION

We report two cases of inflammatory mass in patients receiving baclofen as a sole intrathecal agent. The authors would recommend vigilance in any patient receiving intrathecal baclofen. If the suspicion arises of this problem, a magnetic resonance imaging or computerized tomography myelogram should be obtained with a focus on the catheter tip.

Update in Cancer Pain Syndromes

Cancer pain assessment and management are integral to palliative medicine. This paper reviews recent publications in the period 1999-2004 in the broad categories of epidemiology, pain assessment, nonpharmacologic approaches to cancer pain (radiation therapy, anesthetic blocks, palliative surgery and chemotherapy, complementary and alternative medicine), and in nociceptive pain, neuropathic pain, visceral pain, and bone pain.

Intrathecal therapy for the management of cancer pain

Inadequately managed cancer pain continues to be a significant problem despite increased awareness, improved knowledge and understanding of pain pathophysiology, and standardized treatment guidelines of this distressing and debilitating symptom complex. Small subsets of patients who are refractory to optimal medical management because of drug toxicity or unsatisfactory analgesia may be candidates for exteriorized or implantable intrathecal drug delivery systems. By delivering opioids and other agents directly to the central nervous system, intrathecal drug administration can offer superior pain relief with less toxicity at a fraction of the systemic dose. With adjuncts such as local anesthetics and clonidine, intrathecal therapy also allows for broader therapeutic options in the most difficult of cases. In general, intrathecal therapy is underused despite evidence of its efficacy, safety, and cost-effectiveness.

Drug Delivery Systems

Intrathecal drug delivery (IDD) is a proven and effective treatment alternative in carefully selected patients with chronic pain that cannot be controlled by a well-tailored drug regime and/or spinal cord stimulation (SCS), and may be specifically trialed in patients who fail to respond to SCS. While the lack of randomized controlled trials is often perceived as a limitation of IDD, many studies attest to the efficacy of this therapy, and a number are large-scale and with follow-up periods of up to five years. Good to excellent pain relief is achieved in many patients who have failed more conservative therapies, and there is often a reduced need for analgesia. The advent of patient-controlled analgesia allows flexibility of dosing according to the patient's needs. Consequently, quality of life improves in many patients and the majority express satisfaction with treatment. Some patients are able to return to work. The benefits of IDD (including a potent analgesic response with a more stable therapeutic drug level, decreased latency, increased duration of action, and decreased pharmacological complications) mean that side effects such as nausea, vomiting, sedation, and constipation are reduced. In addition, IDD demonstrates long-term cost-effectiveness when compared to conventional pain therapies, addressing a concern that affects many physicians in clinical practice today.

Intrathecal Hydromorphone for Intractable Nonmalignant Pain: A Retrospective Study

BACKGROUND

Hydromorphone is often administered intrathecally for the treatment of cancer and nonmalignant chronic intractable pain. It is frequently utilized in combination with other analgesics in a multidrug intrathecal infusion; however, very little data are available documenting efficacy or safety of intrathecal hydromorphone as a solo analgesic.

OBJECTIVE

This study was conducted to examine pain and side effects in patients receiving intrathecal hydromorphone.

DESIGN

A retrospective review was conducted of all patients receiving intrathecal hydromorphone monotherapy in two large pain specialty practices in the Pacific Northwest. All data collected within 30 days of the patient's 3-month, 6-month, and 12-month anniversary of implant were analyzed.

PATIENTS

Twenty-four patients with noncancer-related chronic pain were included in the study. Thirteen patients had eligible pain data at 1 month, 10 patients had pain data at 3 months and seven patients had pain data available at 12 months after initiation of intrathecal hydromorphone.

RESULTS

Average pain scores decreased significantly (P = 0.03). Side-effect and pain-interference scores remained essentially unchanged in this small sample of patients.

Inflammatory masses associated with intrathecal drug infusion: a review of preclinical evidence and human data

OBJECTIVES

The phenomenon of inflammatory masses at the tips of intrathecal drug administration catheters was the subject of a recent case-compilation report and a number of animal studies. We sought to synthesize current clinical and preclinical data to formulate hypotheses about the etiology of catheter-tip masses.

METHODS

We reviewed the published human clinical data, new unpublished clinical data, and the results of preclinical studies in two mammalian species, beagle dogs and sheep.

RESULTS

Intrathecal morphine sulfate studies in beagle dogs suggested that the observed inflammatory reaction was dose or concentration dependent. Masses occurred after 28 days in one of three animals at 1.5 mg/day (the lowest morphine dose tested); in two of three animals at 3 and 9 mg/day; and in three of three animals at 12 mg/day. The addition of various amounts of clonidine to 1.5 mg/day of morphine revealed no mass formation when the clonidine dose was>0.25 mg/day. A morphine sulfate study that was performed in sheep using a commercially marketed drug administration system found catheter tip masses in two of three animals that received 12 or 18 mg/day of morphine, the highest doses tested. Human cases have occurred only in pain patients who received intrathecal opioids, alone or mixed with other drugs, or in patients who received investigational agents (such as superoxide dismutase or the partial micro-opioid-receptor agonist, tramadol) that were not labeled for long-term intrathecal use.

DISCUSSION/CONCLUSIONS

The evidence suggests that the long-term administration of opioids, especially morphine, caused the masses that were observed in humans and in two species of animals. A relationship probably exists between mass formation and intrathecal morphine doses or concentration. Other factors remain to be investigated.

Efficacy of Intrathecal Bupivacaine: How Important Is the Flow Rate?

We present two cases of cancer patients with intractable mechanical and visceral pain that was unrelieved with either comprehensive medical management or intrathecal morphine who received intrathecal bupivacaine. While the continuous administration of a seemingly significant daily dose neither relieved pain nor caused measurable clinical changes, the addition of small, presumably negligible bolus doses on top of the continuous infusion resulted in spectacular pain control, clear thermoanalgesic suspended block, and in one of the patients, significant hypotension. To the best of our knowledge, such an observation has neither been reported before nor can we provide a satisfactory explanation for it. However, we believe it may have significant implications for the treatment of some patients, in particular, cancer patients with mechanical pain that cannot be adequately relieved with morphine whatever the route of administration.

Continuous Intrathecal Infusion of Hydromorphone: Safety in the Sheep Model and Clinical Implications

OBJECTIVE

To determine the safety of hydromorphone delivered by continuous intrathecal infusion via implanted delivery systems in sheep.

DESIGN

Sheep implanted with intrathecal infusion systems were randomly assigned to receive either 1.5, 3, or 6 mg/day hydromorphone HCl or saline control (3 sheep/dose level) at a fixed infusion rate of 1.92 mL/day for 28-31 days. Infusions were initiated approximately 5 days after surgical implantation of the delivery systems (pumps and intrathecal catheters), and investigators were blinded to doses administered. An additional group of sheep (N=3) received hydromorphone (open label) at a dose of 12 mg/day. All animals were examined daily during drug infusion for changes in behavior and neurologic function. Cerebrospinal fluid was analyzed for protein, cytology, and hydromorphone concentration in samples collected prior to and at the end of drug infusion. The spinal cord with the catheter in situ was removed en bloc and fixed in formalin for microscopic analysis.

RESULTS

All sheep receiving intrathecal hydromorphone exhibited gaiting deficits and biting behavior over the caudal lumbar area above the infusion site. Animals treated with 12 mg/day were sedate and lethargic, and exhibited repeated biting behavior over the caudal lumbar area during the study. No lesions were noted in any animal upon gross evaluation of the spinal cord. Microscopic changes were comparable between hydromorphone- and saline-treated animals with one exception. Mild inflammation 5 cm cranial to the catheter tip was present in two of three sheep receiving 12 mg/day and in one of three sheep receiving 1.5 mg/day. Mild chronic inflammation hydromorphone in the vicinity of the catheter was also presented in saline-treated animals.

CONCLUSIONS

Hydromorphone was not associated with inflammatory mass formation in the sheep model. Further studies are necessary to determine whether hydromorphone is a safer alternative to morphine for continuous intrathecal infusion for the treatment of chronic pain.

Management of Intrathecal Catheter-Tip Inflammatory Masses: A Consensus Statement

OBJECTIVES

In a companion article, we synthesized current clinical and preclinical data to formulate hypotheses about the etiology of drug administration catheter-tip inflammatory masses. In this article, we communicate our recommendations for the detection, treatment, mitigation, and prevention of such masses.

METHODS

We reviewed published and unpublished case reports and our own experiences to find methods to diagnose and treat catheter-tip inflammatory masses in a manner that minimized adverse neurological sequelae. We also formulated hypotheses about theoretical ways to mitigate, and possibly, prevent the formation of such masses.

RESULTS

Human cases have occurred only in patients with chronic pain who received intrathecal opioid drugs, alone or mixed with other drugs, or in patients who received agents that were not labeled for long-term intrathecal use. Most patients had noncancer pain owing to their large representation among the population with implanted pumps. Such patients also had a longer life expectancy and exposure to intrathecal drugs, and they received higher daily doses than patients with cancer pain. Clues to diagnosis included the loss of analgesic drug effects accompanied by new, gradually progressive neurological symptoms and signs. When a mass was diagnosed before it filled the spinal canal or before it caused severe neurological symptoms, open surgery to remove the mass often was not required. Anecdotal reports and the authors' experiences suggest that cessation of drug administration through the affected catheter was followed by shrinkage or disappearance of the mass over a period of 2-5 months.

CONCLUSIONS

Attentive follow-up and maintenance of an index of suspicion should permit timely diagnosis, minimally invasive treatment, and avoidance of neurological injury from catheter-tip inflammatory masses. Whenever it is feasible, positioning the catheter in the lumbar thecal sac and/or keeping the daily intrathecal opioid dose as low as possible for as long possible may mitigate the seriousness, and perhaps, reduce the incidence of such inflammatory masses.