Regional Anesthesia and Pain Medicine最新文献

The role of differential nerve block in the development of analgesia after erector spinae plane block has been questioned. While highly myelinated nerves are more sensitive to local anesthetics than unmyelinated ones in vitro, factors influencing drug diffusion, particularly pKa, are more relevant in the clinical setting. Bupivacaine (the drug most used for an 'analgesic' effect) has a relatively high pKa (8.1), and only 15% of it is present in the lipid permeant, unionized form at pH 7.4 so it will penetrate unmyelinated C fibers relatively easily, but the myelin sheaths around other fiber types are a significant barrier to drug diffusion. The greater sensitivity of myelinated axons to local anesthetic action will only be apparent if the drug can reach their membranes in significant concentrations. In the very dynamic situation pertaining to a local anesthetic injection (no matter the site), diffusion factors mean that the concentration of the drug around the axons is likely to be very low and may result in an effect on unmyelinated fibers only.

Objective: The study's primary objective was to compare the effectiveness of intra-articular platelet-rich plasma injections versus corticosteroid injections for the treatment of cervical facetogenic pain. Secondary aims were to compare self-rated disability, pain self-efficacy, and the safety of the procedure between groups.

Methods: A single-site randomized double-blind controlled trial with 40 participants assigned to receive either leucocyte-poor, low-concentrate platelet-rich plasma injections or corticosteroid injection without local anesthetic into the cervical facet joint under fluoroscopy. Outcomes were collected via telephone at 1, 3, and 6 months to determine treatment effectiveness.

Results: Low-concentrate platelet-rich plasma and corticosteroid injections had similar effects on cervical facetogenic pain intensity over a 6-month period post injection as demonstrated by a non-significant group-by-time interaction for Numeric Rating Scale scores (p>0.05). However, both groups showed a statistically significant decrease in cervical facetogenic pain intensity 1 month post treatment compared with baseline (p=0.02), while the platelet-rich plasma group also demonstrated a clinically significant decrease in pain intensity at the same time point. There was a significant interaction at 1 month post intervention for pain self-efficacy (p=0.04), with the platelet-rich plasma injection group showing a larger increase in pain self-efficacy compared with the corticosteroid injection group. No significant interaction was observed for self-rated disability; however, significant reductions were shown at 3 and 6 months post treatment compared with baseline in both groups (p<0.01). No significant differences between groups were reported for adverse events; however, those receiving platelet-rich plasma injection reported significantly less procedural pain (p=0.02).

Conclusion: Both platelet-rich plasma and corticosteroid injections induced similar improvements in cervical facetogenic pain intensity (1 month post) and self-rated disability (3 and 6 months post). Pain self-efficacy demonstrated a significant interaction with platelet-rich plasma injection showing greater improvement 1 month post. Additionally, both treatments exhibited a similar low prevalence of adverse events; however, those receiving platelet-rich plasma injection reported less procedural pain.

Background: Clinical studies suggest that long-term conventional spinal cord stimulation (LT-SCS) for painful diabetic peripheral neuropathy (PDPN) is initially effective but may decline in efficacy over time. Preclinical studies indicate that LT-SCS alleviates mechanical hypersensitivity and enhances hind paw blood flow in PDPN rats, suggesting nociceptive system plasticity. This study hypothesized that LT-SCS induces peripheral hind paw small-fiber sprouting and reduces central protein expression of glial and P2X4 brain-derived neurotrophic factor (BDNF) pathway markers.

Methods: Diabetes was induced via Streptozotocin injection in 32 rats, with 16 developing PDPN and receiving a quadrupolar lead implant. LT-SCS was applied for 4 weeks, 12 hours per day. Pain behavior was assessed using the Von Frey test for mechanical hypersensitivity and the mechanical conflict avoidance system for motivational aspects of pain. Fiber sprouting was assessed via immunohistochemical analysis of nerve fibers in the hind paw skin. Protein expression in the spinal cord was assessed using western blotting.

Results: LT-SCS increased the baseline threshold of mechanical hypersensitivity in PDPN animals, consistent with previous findings, but showed no effects on motivational aspects of pain. Hind paw tissue analysis revealed significantly increased intraepidermal nerve fiber density of PGP9.5 fibers in LT-SCS animals compared with Sham-SCS animals. Protein analysis showed significantly decreased pro-BDNF expression in LT-SCS animals compared with Sham-SCS animals.

Conclusion: LT-SCS induces structural changes in both peripheral and central components of the nociceptive system in PDPN animals. These changes may contribute to observed behavioral modifications, elucidating mechanisms underlying LT-SCS efficacy in PDPN management.

Background and objectives: The transversus abdominis plane (TAP) block is the most widely used abdominal field block in colorectal surgery with a postoperative enhanced recovery pathway. We aimed to determine whether the laparoscopic-assisted and ultrasound-guided TAP (US-TAP) blocks provide superior pain relief compared with placebo. We separately investigated whether the laparoscopic-assisted technique was non-inferior to the ultrasound-guided technique in providing pain relief, with a non-inferiority margin of 10 mg morphine dose equivalents.

Methods: 340 patients undergoing elective minimally invasive colon surgery were randomly allocated to one of three groups: (1) US-TAP block, (2) laparoscopic-assisted TAP (L-TAP) block, or (3) placebo. Superiority and non-inferiority were tested for the primary outcome: 24-hour postoperative morphine equivalent consumption. Secondary outcomes, including patient-reported quality of recovery, were included in the superiority analysis.

Results: 127 patients were included in each block group and 86 in the placebo group. The US-TAP block was no different from placebo at -1.4 mg morphine (97.5% CI -6.8 to 4.0 mg; p=0.55). The L-TAP block was superior to placebo at -5.9 mg morphine (97.5% CI -11.3 to -0.5 mg; p=0.01) and non-inferior to the US-TAP block at -4.5 mg morphine (98.75% CI -10.0 to 1.1 mg).

Conclusion: The L-TAP block was superior to placebo and non-inferior to the US-TAP block. However, neither met our predetermined estimate of the minimal clinically important difference of 10 mg morphine.

Trial registration number: NCT04311099.

Background: Many patients with brachial plexus avulsion (BPA) suffer from neuropathic pain, but the mechanism remains elusive. Modifications of histones, the proteins responsible for organizing DNA, may play an important role in neuropathic pain. Lysine demethylase 4A (KDM4A), an essential component of histone demethylase, can modify the function of chromatin and thus regulate the vital gene expressions. However, the mechanism by which KDM4A regulates neuropathic pain following BPA remains unclear.

Methods: The pain model was developed in adult rats that received BPA surgery. Western blot, ELISA, and reverse transcription-PCR were used to examine the protein and mRNA levels of targeted genes. Immunofluorescence studies were conducted to analyze their cellular distribution in the spinal cord. Pharmacological and genetic methods were used to modulate the expression of KDM4A. Co-immunoprecipitation and chromatin immunoprecipitation PCR were used to assess the binding potential between KDM4A and the promoter of brain-derived neurotrophic factor (BDNF).

Results: KDM4A and BDNF levels were significantly upregulated in the ipsilateral spinal cord dorsal horn in the BPA group compared with the sham surgery group. Additionally, knockdown of KDM4A decreased BDNF expression and microgliosis and reduced neuropathic pain-like behaviors in BPA rats. Conversely, KDM4A overexpression increased BDNF expression and microgliosis and exacerbated neuropathic pain. BDNF inhibitors and activators also regulated the activation of spinal microglia and neuropathic pain. Importantly, we showed that KDM4A modulates BDNF expression by regulating the methylation of histone 3 lysine 9 and histone 3 lysine 36 in its promoter region.

Conclusion: Current findings suggest that the upregulation of KDM4A increases BDNF expression in the spinal cord in rats after BPA, contributing to microgliosis, neuroinflammation, and neuropathic pain.

Background/importance: Fibromyalgia is a complex chronic pain disorder that significantly impairs patient well-being. Evaluating the efficacy of muscle relaxants for treating fibromyalgia is crucial for improving patient care.

Objective: This study aimed to evaluate the analgesic efficacy of muscle relaxants in patients with fibromyalgia.

Evidence review: A comprehensive literature search was conducted using PubMed, EMBASE, Web of Science, ClinicalTrials.gov, and the Cochrane Library. The search included randomized controlled trials (RCTs) comparing skeletal muscle relaxants with placebo/active analgesics for fibromyalgia. The primary outcome was pain intensity, measured by standardized mean difference (SMD) in pain scores. The risk of bias of included RCTs was assessed using the Cochrane Risk of Bias Assessment Instrument for Randomized Controlled Trials.

Findings: 14 RCTs (1851 participants) were included. Muscle relaxants were associated with a small but statistically significant reduction in pain scores compared with placebo or active treatment (SMD=-0.24, 95% CI=-0.32 to -0.15, p<0.001, 95% prediction interval=-0.40 to -0.08), with no significant inconsistency (I²=0, 95% CI=0% to 50.79%) and a moderate Grading of Recommendation, Assessment, Development and Evaluation rating. Secondary outcomes showed small, but statistically significant improvements in depression, fatigue and sleep quality. Muscle relaxants were associated with increased incidence of overall adverse effects, fatigue, abnormal taste, and drug withdrawal due to adverse effects.

Conclusions: Moderate quality evidence showed that muscle relaxants were associated with a small reduction in pain intensity for patients with fibromyalgia.

Introduction: Postoperative pain after laparoscopic abdominal surgery remains complex. While lateral quadratus lumborum (QL) block and transversus abdominus plane (TAP) block are similar techniques, no studies have examined if one technique has greater dermatomal spread.

Methods: Laparoscopic colorectal surgical patients were randomized to lateral QL or TAP blocks. Dermatomal anesthetic spread, as measured by loss of sensation to temperature in the postanesthesia care unit, was the primary outcome. If a clear level of dermatomal anesthesia could not be defined, the block was categorized as "indeterminate." Secondary outcomes included opioid consumption, pain scores, and opioid-related side effects.

Results: 153 patients completed the study (75 QL and 78 TAP). Mean (95% CI) number of dermatomes with loss of sensation to ice was greater in subjects randomized to QL (4.2 (3.7 to 4.8)) versus TAP (2.7 (2.2 to 3.2); p=0.0001), and the QL group was more likely to have loss of sensation above T8 (p=0.01) and T10 (p=0.02). Indeterminate block was more often noted with TAP blocks (p<0.0001). Opioid consumption at 24 hours, pain scores, and opioid-related side effects did not differ.

Discussion: Compared with TAP blocks, QL blocks had greater dermatomal anesthesia spread and lower rates of an indeterminate block. However, differences in pain and opioid consumption were not noted. The clinical importance of these findings should be investigated in future trials.

Trial registration number: NCT03490357.

Background and aims: Minimally invasive repair of pectus excavatum is associated with intense postoperative pain. We aimed to evaluate the effectiveness of percutaneous intercostal cryoanalgesia according to the different timing of its preoperative application. Outcome variables included pain, drug consumption, time to mobilization, and hospital length of stay.

Methods: Retrospective data analyzed from a single pediatric institution, involving a series of consecutive patients who underwent pectus surgery. Group 1: 18 patients received thoracic epidural analgesia. Group 2: 11 patients underwent cryoanalgesia on the same day of surgery and epidural analgesia as a bridge to cryoanalgesia onset. Group 3: 13 patients underwent earlier preoperative intercostal cryoanalgesia with a median of 6 days (IQR 3-6) before surgery. All groups received rescue systemic analgesia.

Results: Pain scores were similar among groups. The incidence of severe pain decreased in Group 3 versus Group 1 (38% vs 78%) (p<0.05). Ropivacaine epidural cumulative dose (mg/kg) decreased in Group 2 versus Group 1: 16 (IQR 12-23) versus 27 (IQR 22-35) (p<0.01). Cumulative oral morphine equivalent dose (mg/kg) decreased among groups: 12 (IQR 9.3-17), 8 (IQR 4.2-12), and 0.2 (IQR 0.0-0.3) (p<0.001) for Groups 1-3, respectively. Length of stay (days) also decreased among Groups 1-3, respectively: 7 (IQR 6-7), 6 (IQR 5-7), and 4 (IQR 4-5) (p<0.001).

Conclusions: This exploratory observational study suggests that the timing of cryoanalgesia may play a crucial role in its efficacy, with earlier placement being associated with improvements in pain, opioid utilization, and length of stay.

Background: While superficial parasternal intercostal plane blocks can improve analgesia after cardiac surgery, the optimal site and the number of injections remain uncertain. This study aimed to compare the efficacy of single versus double injections of superficial parasternal blocks, hypothesizing that double injections would achieve superior cutaneous sensory blockade.

Methods: 70 cardiac patients undergoing median sternotomy were randomly assigned to receive either single or double injections of superficial parasternal blocks bilaterally. Each patient received 40 mL of 0.25% bupivacaine with epinephrine 5 µg/mL and dexamethasone 10 mg. The single-injection group received 20 mL/side at the third costal cartilage, while the double-injection group received 10 mL/injection at the second and fourth costal cartilages. The primary outcome was a successful block, defined as sensory loss in the T2-T6 dermatomes. Secondary outcomes included sensory block of T1, T7, and T8 dermatomes, block-related complications, intraoperative hemodynamics, postoperative pain intensity, opioid consumption, and recovery quality.

Results: Double injections achieved an overall higher success rate compared with the single-injection technique (81% vs 51%, relative risk 1.6; 95% CI 1.2, 2.0; p<0.001). Additionally, higher blockade percentages were observed in dermatomes T1 (83% vs 59%, p=0.003), T7 (67% vs 46%, p=0.017), and T8 (61% vs 39%, p=0.011) with double injections. Other secondary outcomes did not differ significantly between groups.

Conclusions: Compared with single injection, double injections of superficial parasternal blocks provided more reliable coverage of the T2-T6 dermatomes, crucial for median sternotomy. However, no differences were observed in intraoperative hemodynamic effects or postoperative pain control after cardiac surgery.

Trial registration number: TCTR20230408004.

Chat Generative Pre-trained Transformer (ChatGPT), an artificial intelligence chatbot, produces detailed responses and human-like coherent answers, and has been used in the clinical and academic medicine. To evaluate its accuracy in regional anesthesia topics, we produced a ChatGPT review on the addition of dexamethasone to prolong peripheral nerve blocks. A group of experts in regional anesthesia and pain medicine were invited to help shape the topic to be studied, refine the questions entered in to the ChatGPT program, vet the manuscript for accuracy, and create a commentary on the article. Although ChatGPT produced an adequate summary of the topic for a general medical or lay audience, the review that were created appeared to be inadequate for a subspecialty audience as the expert authors. Major concerns raised by the authors included the poor search methodology, poor organization/lack of flow, inaccuracies/omissions of text or references, and lack of novelty. At this time, we do not believe ChatGPT is able to replace human experts and is extremely limited in providing original, creative solutions/ideas and interpreting data for a subspecialty medical review article.