Intrathecal Granuloma in Patients Receiving High-dose Intrathecal Morphine Therapy: A Report of Two Cases

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

BACKGROUND

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

OBJECTIVE

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

STUDY DESIGN

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

RESULTS

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

CONCLUSION

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

Intrathecal Catheter Granuloma Associated with Isolated Baclofen Infusion

Intrathecal (IT) baclofen is an effective management strategy for controlling spasticity in patients unresponsive to maximal oral therapy. We present the case of a 57-yr-old woman who was rendered quadriplegic after a complete spinal cord transection at the C6 level. Her course was complicated by severe spasms, which were uncontrolled despite titrating orally administered baclofen to 80 mg/d. IT baclofen testing was performed with good response, and administration was commenced via an implanted intrathecal pump 6 mo after the injury at an initial dose of 200 microg/d. Catheter revision was required 2 wk later as a result of catheter displacement. The initial IT baclofen dose was gradually increased to achieve good control at a level of 400 microg/d. After a period of stability lasting 38 mo, her lower limb spasms dramatically increased in severity and remained poorly controlled despite repeated dose increases. Contrast pumpogram and computed tomography myelogram were performed to exclude a mechanical cause for this apparent increase in baclofen requirement. These investigations revealed neither catheter displacement nor fracture as suspected but, rather, displayed the presence of a catheter tip-associated mass. Catheter tip granuloma has not previously been described in a patient receiving IT baclofen alone. This suggests that although uncommon, the possibility of catheter-associated granuloma must be considered in all patients receiving IT baclofen presenting with altered neurological function or significant increase in drug requirement.

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.

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.

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.