An Interventional Pain Algorithm for the Treatment of Postmastectomy Pain Syndrome: A Single-Center Retrospective Review.

OBJECTIVE: Breast cancer is the most common female malignancy worldwide. Breast surgery and adjuvant oncological therapies are often required to increase survival. Treatment-related pain may persist and evolve into postmastectomy pain syndrome (PMPS) in a significant subset of breast cancer survivors. In this retrospective investigation, we will present our experience in applying an interventional algorithmic approach to treat PMPS. DESIGN: A retrospective study. SETTING: An academic cancer hospital. SUBJECTS: Adult females with PMPS diagnosis. METHODS: We reviewed 169 records with the diagnosis of PMPS from 2015 to 2019 within our health system. Pre- and post-injection pain scores, relief duration, and medication usage changes were collected. The decision to perform each procedure was based on the anatomic location of the painful area with the corresponding peripheral sensory innervation. Decision-making flow diagrams were created to present our experience in managing PMPS beyond peripheral nerve blocks. RESULTS: Ultrasound-guided peripheral nerve block results (n=350) were analyzed. The mean baseline pain score was 7, compared with the post-treatment mean score of 3 (95% confidence interval: 3.58 to 3.98, P = 0.0001). Among the responders, the mean pain relief duration was 45 days, with a median of 84 days. Opioid medication consumption was reduced by 11% (t = 0.72, P = 0.47). CONCLUSIONS: Ultrasound-guided nerve blocks of this area could be performed safely and effectively after breast surgeries. We also present our proposed algorithm to provide a stepwise application for selecting the appropriate therapies in the management of more complex PMPS.

Recent Advances in Peripheral Opioid Receptor Therapeutics.

PURPOSE OF REVIEW: Although opioids are excellent analgesics, they are associated with severe short- and long-term side effects that are especially concerning for the treatment of chronic pain. Peripherally acting opioid receptor agonists promise to mitigate the more serious centrally mediated side effects of opioids, and the goal of this paper is to identify and elaborate on recent advances in these peripheral opioid receptor therapeutics. RECENT FINDINGS: Peripheral opioid receptor agonists are effective analgesics that at the same time circumvent the problem of centrally mediated opioid side effects by (1) preferentially targeting peripheral opioid receptors that are often the source of the pain and (2) their markedly diminished permeability or activity across the blood-brain barrier. Recent novel bottom-up approaches have been notable for the design of therapeutics that are either active only at inflamed tissue, as in the case of fentanyl-derived pH-sensitive opioid ligands, or too bulky or hydrophilic to cross the blood-brain barrier, as in the case of morphine covalently bound to hyperbranched polyglycerols. Recent innovations in peripheral opioid receptor therapeutics of pH-sensitive opioid ligands and limiting opioid permeability across the blood-brain barrier have had promising results in animal models. While this is grounds for optimism that some of these therapeutics will be efficacious in human subjects at a future date, each drug must undergo individualized testing for specific chronic pain syndromes to establish not only the nuances of each drug's therapeutic effect but also a comprehensive safety profile.

Intranasal ketamine for acute traumatic pain in the Emergency Department: a prospective, randomized clinical trial of efficacy and safety.

BACKGROUND: Ketamine has been well studied for its efficacy as an analgesic agent. However, intranasal (IN) administration of ketamine has only recently been studied in the emergency setting. The objective of this study was to elucidate the efficacy and adverse effects of a sub-dissociative dose of IN Ketamine compared to IV and IM morphine. METHODS: A single-center, randomized, prospective, parallel clinical trial of efficacy and safety of IN ketamine compared to IV and IM morphine for analgesia in the emergency department (ED). A convenience sample of 90 patients aged 18-70 experiencing moderate-severe acute traumatic pain (≥80 mm on 100 mm Visual Analog Scale [VAS]) were randomized to receive either 1.0 mg/kg IN ketamine, 0.1 mg/kg IV MO or 0.15 mg/kg IM MO. Pain relief and adverse effects were recorded for 1 h post-administration. The primary outcome was efficacy of IN ketamine compared to IV and IM MO, measured by "time-to-onset" (defined as a ≥15 mm pain decrease on VAS), as well as time to and degree of maximal pain reduction. RESULTS: The 3 study groups showed a highly significant, similar maximal pain reduction of 56 ± 26 mm for IN Ketamine, and 59 ± 22 and 48 ± 30 for IV MO and IM MO, respectively. IN Ketamine provided clinically-comparable results to those of IV MO with regards to time to onset (14.3 ± 11.2 v. 8.9 ± 5.6 min, respectively) as well as in time to maximal pain reduction (40.4 ± 16.3) versus (33.4 ± 18), respectively. CONCLUSIONS: IN ketamine shows efficacy and safety comparable to IV and IM MO. Given the benefits of this mode of analgesia in emergencies, it should be further studied for potential clinical applications. TRIAL REGISTRATION: Retrospectively registered on 27 June 2016. ClinicalTrials.gov ID: NCT02817477.

Ultrasound-guided caudal epidural steroid injection for successful treatment of radiculopathy during pregnancy.

Aim: The aim of this case report is to describe ultrasound guidance for caudal epidural steroid injection during pregnancy. Case report: A 29-year-old, 32-week parturient presented with severe back and leg pain with MRI demonstrating herniation of the L5-S1 level. The disabling pain was refractory to conservative therapy, and an ultrasound-guided caudal epidural steroid injection was performed. There was significant pain relief in the first week with an uneventful subsequent pregnancy. Following delivery, the patient had no further recurrence of her presenting symptoms. Conclusion: Severe radiculopathy may be encountered during pregnancy, complicated by a limited number of treatment options. Ultrasound guidance should be considered during performance of caudal epidural injections in feasible cases.