Literature Review: August 2024
Cite as: Nanda M, Meng H. Literature review - August 2024. ASRA Pain Medicine News 2024;49. https://doi.org/10.52211/asra080124.013.
Acute Pain
By Jeffrey Grzybowski, MD, Monika Nanda, MBBS, MPH, FASA, and Marcelle Blessing, MD
Evaluation of the Erector Spinae Plane Block for Postoperative Analgesia in Laparoscopic Ventral Hernia Repair: A Randomized Placebo-Controlled Trial
Sørenstua M et al. BMC Anesthesiol 2024;24(1):192. https://doi.org/10.1186/s12871-024-02566-x
Summary by Jeffrey Grzybowski, MD
Introduction: The erector spinae plane block (ESPB) has been adopted as a low-risk intervention for many surgeries. Despite being minimally invasive, laparoscopic ventral hernia repair patients often require an overnight stay due to severe postoperative pain and significant opioid consumption in the first 24 hours. This study assessed the analgesic efficacy of thoracic ESPB in these patients.
Methods: This prospective, double-blind, randomized controlled trial enrolled patients scheduled for elective laparoscopic ventral hernia repair. All received paracetamol and diclofenac preoperatively and underwent bilateral ultrasound-guided ESPB with catheter placement at the T7 level. Thirty milliliters of study medication (2.5 mg/ml ropivacaine or saline) were injected through each catheter. In the post-anesthesia care unit, all patients received a patient-controlled analgesia programmed with 0.03 mg/kg IV oxycodone boluses with a 5-minute lockout and a maximum of eight boluses per hour. Postoperative bolus doses (30 ml in both ESP catheters) of the study medication were administered by ward nurses every 6 hours for 4 total times in each patient.
Results: Seventy patients were included and randomized, with 64 completing the study protocol. There was no significant difference in the primary outcome of total opioid consumption during the first hour postoperatively. Oral morphine equivalent consumption was 26.9±17.1 mg in the ESPB group versus 32.4±24.3 mg (mean±SD) in the placebo group (p=0.27, 95% CI [-16.3, 4.66]). No significant differences were found in secondary outcomes during a seven-day follow-up.
Key Point: Without a significant difference in one-hour postoperative opioid consumption, this study suggests that ESPB does not provide more efficacious analgesia compared to placebo in laparoscopic ventral hernia repair.
A Randomized Controlled Trial Using Epidural Analgesia for Pain Relief After Lumbar Interlaminar Decompressive Spine Surgery: The RAPID trial
Hermans SMM et al. Spine 2024;49(7):456-62. https://doi.org/10.1097/BRS.0000000000004921
Summary by Monika Nanda, MBBS, MPH, FASA
Introduction: Adequate postoperative pain management following lumbar spinal decompression surgery is crucial for early mobilization, reducing complications, and shortening hospital stay. During the final phase of lumbar decompression surgery, the surgeon can easily access the epidural space, providing an ideal opportunity for administering an epidural dose of local anesthetic. This study investigates the efficacy of a single intraoperative bolus of epidural bupivacaine in reducing postoperative pain.
Methods: This prospective, double-blind, randomized controlled trial included 40 patients undergoing lumbar decompression surgery. They were randomized to receive either an intraoperative epidural bolus of 5 ml of 0.25% bupivacaine or a placebo (NaCl 0.9%) via an intraoperative epidural catheter placed by the surgeon during the last stage of the laminectomy procedure. The medication was blinded to the clinicians, researchers, and patients. The primary outcome measured was the Numeric Pain Rating Scale (NRS) scores at recovery entry, recovery exit, 2, 4, 6, 24, and 48 hours postoperatively. Secondary outcomes included cumulative opioid use up to 48 hours, health-related quality of life (measured by EuroQol-5D), and patient satisfaction (measured by the General Surgery Recovery Index).
Results: The intervention group exhibited significantly lower mean NRS pain scores than the placebo group, with a main effect group difference of -2.35±0.77 (P=0.004). No significant differences in opioid consumption, EQ-5D, or GSRI scores were observed between groups. The intervention did not affect the length of hospital stay. No study-related complications were reported.
Key Point: In this randomized controlled trial, intraoperative surgeon-administered epidural bupivacaine improved postoperative pain scores after lumbar decompressive surgery.
Comparison of the Effect of Pericapsular Nerve Group Block Combined with Lateral Femoral Cutaneous Nerve Block and Fascia Iliaca Compartment Block in Patients Undergoing Hip Arthroscopy Under General Anesthesia: A Randomized, Double-Blind Trial
Liu M et al. J Pain Res2024;17:1651-61. https://doi.org/10.2147/JPR.S456880
Summary by Marcelle Blessing, MD
Introduction: Pain management after arthroscopic hip surgery (AHS) is crucial, but the optimal block for analgesia and preservation of quadriceps function is unclear.
Methods: Eighty patients undergoing AHS were randomized into two groups. Group P received a preoperative pericapsular nerve group (PENG) and lateral femoral cutaneous nerve (LFCN) block. Group F received a fascia iliaca compartment block (FICB). All patients received general anesthesia. All blocks were ultrasound-guided. The primary outcomes were the incidence of quadricep weakness, muscle strength on the blocked side, pain scores, and the quality of recovery on the second postoperative day. Secondary outcomes included a number of rescue analgesics, duration of sensory blockade, time until patients were mobilized out of bed, and the Richards-Campbell Sleepiness Scale assessment of sleep quality.
Results: 78 patients completed the study and were included in the final statistical analysis. Group P had a lower incidence of quadriceps weakness than Group F during the first 48 hours after the block was placed (28.2% vs 76.9%, p<0.001). Group P also had lower static pain scores at 6,12,18,24,36, and 48 hours after block (p<0.001) and lower dynamic pain scores at 6 and 12 hours after block (p<0.05), with a higher quality of recovery on the second postoperative day (p<0.05). Patients in group P were mobilized earlier, used less ketorolac, and received fewer PCA demand doses (p<0.05).
Key Point: The combination of PENG and LFCN blocks was superior to FICB for AHS in preserving quadriceps function and providing better analgesia postoperatively.
Chronic Pain
By Howard Meng, MD, Mohammad R. Rasouli, MD, and Vinita Singh, MD, MS
Stellate Ganglion Destruction With Alcohol Versus Thermal Ablation for Chronic Post-Mastectomy Pain: A Randomized Trial
Thabet T et al. Pain Phys 2024; 27(2):E231-E38.
Summary by Howard Meng, MD
Introduction: Post-mastectomy pain syndrome (PMPS) is a prevalent pain concern that occurs in 25%-60% of patients after surgery for breast cancer. Stellate ganglion block (SGB) has emerged as a treatment option for PMPS. This study evaluates the efficacy of SG modulation with alcohol versus thermal ablation for PMPS.
Methods: A double-blinded RCT was performed involving 70 female patients aged 20-65 who underwent breast cancer surgery with moderate to severe pain between 6 months and 2 years. Patients included those with a grading system for neuropathic pain score of 3 or 4 and who experienced pain relief after diagnostic SBG. Then SGB with ultrasound guidance and C7 confirmation by fluoroscopy was performed by alcohol injection involving 2 ml 1% lidocaine and 1.5 ml 50% ethanol (group A) or thermal ablation—twice 0.5 cm apart for 60 seconds at 80°C (group B). Participants and outcome assessors were blinded for grouping. VAS, pregabalin, and oxycodone consumption were assessed at 1, 4, 8, and 12 weeks after the intervention.
Results: VAS measurements were significantly lower at all time points than pre-procedure in both groups (p<0.001). VAS measurements were lower at 4 and 8 weeks in Group A than in Group B (P<0.05). Oxycodone and pregabalin consumption were significantly lower at 4 and 8 weeks in Group A than in Group B (P<0.05). There were no significant differences in SF-36 and satisfaction scores between the groups. No significant complications were encountered in either group after a short follow-up period.
Key Point: Ultrasound-guided SG destruction with alcohol was more effective than thermal RF for managing PMPS by decreasing pain, opioids, and pregabalin consumption.
Efficacy and Safety of High-Voltage Pulsed Radiofrequency versus Standard-Voltage Pulsed Radiofrequency for Patients with Neuropathic Pain: A Literature Review and Meta-Analysis
Wang Y, Jia Y, Wang Z, et al. J Pain Res2024:17:851-63. https://doi.org/10.2147/JPR.S439909
Summary by Mohammad R. Rasouli, MD
Introduction: Pulsed radiofrequency (PRF) is a neuromodulation technique for treating neuropathic pain. Accepted settings that permit modulation of neuronal activity without affecting the structural integrity of the nerve include an output voltage of 45 V, a pulse frequency of 2 Hz, an output frequency of 500kHz, an intermission of 480 ms, and a temperature limit of 42°C. However, recent studies indicate that increasing the output voltage may improve the efficacy of PRF. This systematic review and meta-analysis compared the efficacy and safety of standard and high-voltage PRF.
Methods: PubMed/MEDLINE, EMBASE, Web of Science, and the Cochrane Library were searched to identify randomized controlled trials (RCTs) comparing standard and high-voltage PRF for treating neuropathic pain from inception until March 15, 2022. The primary outcome was the proportion of patients with greater than 50% reduction in pain score after the procedure. Post-procedure pain score (numeric rating scale or visual analog scale), quality of life (SF-36), and complications were also compared between the two groups.
Results: The final analysis included six RCTs with 423 patients with trigeminal neuralgia, postherpetic neuralgia, and infraorbital neuralgia. The average output voltage of high-voltage PRF varied between 60 and 100 V. Compared to the standard PRF, high-voltage PRF was associated with a higher efficacy rate at 1 month (RR: 1.44, P = 0.004), 3 months (RR: 1.44, P =0.004), and 6 months (RR: 1.51, P = 0.0002) post-procedure. There was no significant difference at 12 months. High-voltage PRF was also superior to standard PRF regarding post-procedure pain scores and physical and mental components of SF-36. The rate of adverse effects between the two groups was not statistically different.
Key Point: Compared to standard PRF, a greater proportion of patients who had high-voltage PRF had effective treatment of neuropathic pain due to trigeminal neuralgia, postherpetic neuralgia, or infraorbital neuralgia.
Comparative Randomized Study Between Pulsed Radiofrequency and Suprascapular Nerve Block for the Treatment of Chronic Shoulder Pain
Bergamaschi ECQA et al. Clin J Pain2024;40(3):182-6. https://doi.org/10.1097/AJP.0000000000001184
Summary by Vinita Singh, MD, MS
Introduction: The suprascapular nerve is one of the primary nerves transmitting afferent nociceptive fibers from the shoulder. Pulsed radiofrequency (RF) may provide longer-lasting pain relief compared to a nerve block without the risk of motor damage and neuritis associated with continuous radiofrequency. This clinical trial compares the efficacy of suprascapular nerve block with pulsed RF for chronic shoulder pain treatment.
Methods: Adult patients with chronic shoulder pain and positive test block with 5 ml of lidocaine (>50 % pain relief for up to 4 hours) were eligible for the study. Forty patients were randomized to the RF group or nerve block group. In the RF group, pulsed RF was done for 180 seconds at 50V and 42°C at 2 locations (medial and lateral to the suprascapular artery). In the block group, ultrasound-guided nerve block was done using 5 ml of 0.25% bupivacaine with epinephrine. The following outcomes were recorded 12 weeks after the procedure: pain intensity, analgesia supplementation, shoulder range of motion, and side effects.
Results: Both groups evaluated pain at all times lower than before the procedure. With movement, pain was significantly lower in the RF group after 2, 4, and 8 weeks but not at 12 weeks. Pain at rest was significantly lower in group RF at 4 and 12 weeks but not after 1, 2, and 8 weeks. Adverse effects were minimal, and no treatment was required.
Key Point: Suprascapular nerve block and pulsed RF can potentially provide analgesia for up to 12 weeks for chronic shoulder pain. There was a trend toward improved pain after pulsed RF relative to just nerve block that was statistically significant at only certain time points.
Howard Meng, MD, is an assistant professor in the department of anesthesiology and pain medicine at the University of Toronto. He practices as an anesthesiologist and pain physician at Sunnybrook Health Sciences Centre.
