Intrathecal Pump Refills, Pocket Fills, and Symptoms of Drug Overdose: A Prospective, Observational Study Comparing the Injected Drug Volume vs. the Drug Volume Effectively Measured Inside the Pump

Intrathecal Drug Delivery for Intractable Pain: Identified Patient Satisfaction Survey Study Comparing Intrathecal Dose With Satisfaction, Pain Relief, and Side Effects

OBJECTIVES

Past studies have shown the efficacy of spinal targeted drug delivery (TDD) in pain relief, reduction in opioid use, and cost-effectiveness in long-term management of complex chronic pain. We conducted a survey to determine treatment variables associated with patient satisfaction.

MATERIALS AND METHODS

Patients in a single pain clinic who were implanted with Medtronic pain pumps to relieve intractable pain were identified from our electronic health record. From November 2021 to February 2023, 973 patients with active TDD were identified; 564 completed the 23-question survey, and 560 were included in analyses. Most patients (96.4%) had intrathecal (IT) infusion admixtures containing bupivacaine and opioid. The survey compared satisfaction with IT medication dosages, pain relief, pain diagnosis, catheter tip location, side effects, mental clarity, physical functioning, and healthcare utilization. Outcomes were reported as proportions; p < 0.05 was considered significant.

RESULTS

Most respondents reported good-to-excellent pain relief (63.8%), high satisfaction with TDD (80.7%), improvement in physical functioning (75.0%), and better quality of life (89.7%); 78.5% of respondents reported complete discontinuation or substantial reductions in systemic opioid use. There was a statistically significant relationship between satisfaction and IT medication dose (p = 0.02), with the average dose increasing with higher satisfaction groups. We found that patients on higher doses of IT opioids did not have more bothersome side effects (p = 0.05).

CONCLUSIONS

Our data show that the most satisfied respondents had higher IT doses, fewer side effects, and longer duration of TDD therapy. This suggests that higher dose IT admixtures are safe and effective at relieving pain and improving quality of life in patients with complex chronic pain whose condition has failed to respond adequately to other treatments. TDD may be an effective alternative to long-term systemic opioids for well-selected patients willing to accept the risks of invasive procedures.

The Polyanalgesic Consensus Conference (PACC)®: Intrathecal Drug Delivery Guidance on Safety and Therapy Optimization When Treating Chronic Noncancer Pain

INTRODUCTION

The International Neuromodulation Society convened a multispecialty group of physicians and scientists based on expertise with international representation to establish evidence-based guidance on intrathecal drug delivery in treating chronic pain. This Polyanalgesic Consensus Conference (PACC)® project, created more than two decades ago, intends to provide evidence-based guidance for important safety and efficacy issues surrounding intrathecal drug delivery and its impact on the practice of neuromodulation.

MATERIALS AND METHODS

Authors were chosen on the basis of their clinical expertise, familiarity with the peer-reviewed literature, research productivity, and contributions to the neuromodulation literature. Section leaders supervised literature searches of MEDLINE, BioMed Central, Current Contents Connect, Embase, International Pharmaceutical Abstracts, Web of Science, Google Scholar, and PubMed from 2017 (when PACC® last published guidelines) to the present. Identified studies were graded using the United States Preventive Services Task Force criteria for evidence and certainty of net benefit. Recommendations are based on the strength of evidence or consensus when evidence is scant.

RESULTS

The PACC® examined the published literature and established evidence- and consensus-based recommendations to guide best practices. Additional guidance will occur as new evidence is developed in future iterations of this process.

CONCLUSIONS

The PACC® recommends best practices regarding intrathecal drug delivery to improve safety and efficacy. The evidence- and consensus-based recommendations should be used as a guide to assist decision-making when clinically appropriate.

Adverse Events and Complications Associated With Intrathecal Drug Delivery Systems: Insights From the Manufacturer and User Facility Device Experience (MAUDE) Database

BACKGROUND

Modern intrathecal drug delivery systems (IDDS) are technologically advanced to deliver medication through various automated and patient-controlled programs. They also are associated with unique complications ranging from post-operative complications, medication-related adverse events (AE), device malfunction, to refill associated AE.

OBJECTIVES

To systematically analyze real-world complications and AE reported on the Food and Drug Administration's Manufacturer and User Facility Device Experience database (MAUDE) associated with IDDS among patients predominantly with chronic pain disorders.

MATERIALS AND METHODS

MAUDE database was sampled for a month four times a year during the study period, February 2018 to February 2019. The database was resampled every six months till August 2020 to evaluate for any additional reported cases during the index months. The two FDA approved IDDS, were included. AE were broadly classified into causes related to catheter malfunction, pump malfunction, biologic, and medication-related AE.

RESULTS

A total of 1001 reports were included in the final analysis. The top three reasons for adverse report are infection/erosion (15.7%, n = 157), motor stall (12.4%, n = 125) and adverse medication reactions (11.8%, n = 119), respectively. There were five deaths among patients with IDDS. Epidural hematoma (n = 3) after IDDS surgery resulted in a death and residual neurological deficits after surgical evacuation. Programming errors, medication concentration discrepancy, and failure to turn on the pump after reprogramming are various preventable causes of medication-related IDDS AEs.

CONCLUSIONS

Analysis of AE associated with IDDS from the MAUDE database provided a real-world perspective different from reported registry complications. Awareness and vigilance of preventable IDDS-related complications is the first step toward mitigating risks to provide safe and effective intrathecal drug delivery for chronic pain management.

Intrathecal bupivacaine and morphine toxicity leading to transient hypotension and delayed status epilepticus

BACKGROUND

Local anesthetic systemic toxicity characteristically occurs after inadvertent intravascular injection of local anesthetics; however, it is unclear if similar symptoms arise after intrathecal adminstration. Intrathecal use of local anesthetics for chronic pain is increasing and carries a potential risk of toxicity. Experience with the presenting symptoms and appropriate treatment for intrathecal local anesthetic toxicity is limited.

CASE STUDY

A 74-year-old woman with an intrathecal bupivacaine/morphine pump developed lower extremity sensory neuropathy followed by obtundation, hypotension, and lower extremity flaccidity after an intrathecal pump refill. Her condition evolved to status epilepticus (SE) refractory to standard treatment. Intravenous fat emulsion (IFE) was administered, but was not immediately effective thus necessitating phenobarbital loading and propofol infusion. Despite significant bupivacaine neurotoxicity, no cardiotoxicity developed.

DISCUSSION

The patient developed intrathecal local anesthetic and opioid toxicity after a malfunction of her intrathecal pump during a refill. We hypothesize that no cardiotoxicity developed secondary to sequestration of bupivacaine within the central nervous system. Likewise, poor CNS penetration of intravenous lipid emulsion may have negated or delayed any antidotal effect.

CONCLUSION

We present a case of intrathecal toxicity leading to prolonged spinal anesthesia, progressive encephalopathy, and SE refractory to intravenous lipid emulsion. Management of SE with benzodiazepines and barbiturates may be more effective than lipids in cases of toxicity from intrathecal administration of bupivacaine.

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.