Pain medicine basics: Overview

Neuromodulation: Technology at the Neural Interface is the preeminent journal in the area of neuromodulation, providing our readership with the state of the art clinical, translational and basic science research in our field and representing the needs of the broad neuromodulation community. For clinicians, engineers, scientists and members of the biotechnology industry alike, Neuromodulation provides timely and rigorously peer reviewed articles on the technology, science and clinical application of devices that interface with the nervous system to treat disease and improve function. Neuromodulation covers an ever expanding field including pain, headache, movement disorders, spasticity, paralysis, psychiatric disorders, epilepsy, sensory deprivation, gastric dysfunction, obesity and incontinence.

Regional Anesthesia & Pain Medicine, the official publication of the American Society of Regional Anesthesia and Pain Medicine (ASRA Pain Medicine), is a monthly journal that publishes peer-reviewed scientific and clinical studies to advance the understanding and clinical application of regional techniques for surgical anesthesia and postoperative analgesia. Coverage includes intraoperative regional techniques, perioperative pain, chronic pain, obstetric anesthesia, paediatric anesthesia, outcome studies, and complications.

Abstract in English, French
Purpose: We sought to analyze postoperative discharge opioid prescription, consumption, and pain over three months following total hip arthroplasty (THA) and total knee arthroplasty (TKA).

Methods: We conducted a prospective observational study in patients undergoing THA and TKA at two centres in Toronto, ON, Canada. We contacted study participants at two, six, and 12 weeks after discharge to collect data on analgesic satisfaction, pain relief, time point of stopping opioids, quantity of unconsumed opioid pills, quality of pain, and mental health. We also evaluated patient factors that may have contributed to a higher opioid consumption or dissatisfaction with the analgesic prescription at six weeks.

Results: The median [interquartile range] opioid pill count prescribed at the time of discharge for the 443 participants was 60 [50-80]. At 12 weeks after surgery, 33.9% of participants had more than one-third of their prescribed quantity remaining. Three-quarters of the cohort indicated that pain relief after arthroplasty was appropriate at all postoperative follow-ups. The incidence of neuropathic pain reduced from 24.1% before TKA or THA to 4.3% at 12 weeks after arthroplasty. Female sex (odds ratio [OR], 1.78; 95% confidence interval [CI], 1.08 to 2.95; P = 0.03), a history of preoperative opioid use (OR, 2.46; 95% CI, 1.25 to 5.1; P = 0.01), and TKA vs THA (OR, 2.46; 95% CI, 1.47 to 4.17; P = 0.001) were associated with higher opioid consumption at six weeks after arthroplasty.

Conclusion: A discharge prescription of 60 opioid pills may be excessive for patients undergoing THA or TKA. Identifying patients with risk factors for higher postoperative opioid consumption may result in more appropriate analgesic regimens.

Abstract
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.

Keywords: Chronic pain; IT opioid; intrathecal; pain pump; targeted drug delivery.