Literature Review: May 2025
Cite as: Nanda M, Meng H. Literature review - May 2025. ASRA Pain Medicine News 2025;50. https://doi.org/10.52211/asra050125.017.
Literature Review
Chronic Pain
The Efficacy of Botulinum Toxin A Injection in Pelvic Floor Muscles in Chronic Pelvic Pain Patients: A Double-Blinded Randomised Controlled Trial
Spruijt MA, Klerkx WM, Notten K, et al.. BJOG 2025;132(3):297-305. https://doi.org/10.1111/1471-0528.17991
Summary by Vinita Singh, MD, MS
Introduction: Elevated pelvic floor muscle tone is often associated with chronic pelvic pain (CPP), and while pelvic floor muscle therapy (PFMT) is a common treatment, its efficacy varies. Botulinum Toxin A (BTA) injections have been proposed as a potential treatment to reduce muscle over-activity and alleviate pain in these patients by inducing temporary chemical denervation of the muscles.
Methods: This multicenter, double-blinded, randomized controlled trial was conducted across four hospitals in the Netherlands between January 2020 and April 2023. Ninety-four women with CPP and increased pelvic floor muscle tone, unresponsive to previous PFMT, were enrolled. Participants were randomized to receive either 100 units of BTA or placebo injections into the pelvic floor muscles, followed by four PFMT sessions. Primary outcomes were the proportion of women achieving at least a 33% reduction in pain (measured on painDETECT) and those reporting (very) much improvement in their pain (measured on Patient Global Impression of Improvement). Secondary outcomes included assessments of quality of life and pelvic floor function. Follow-up evaluations occurred at 4, 8, 12, and 26 weeks post-treatment.
Results: Of the participants, 33% in the BTA group and 20% in the placebo group reported at least a 33% reduction in average pain scores (odds ratio [OR] placebo/BTA 1.88; 95% CI 0.72–4.90; p=0.19). Additionally, 17% of women in both groups reported their improvement as (very) much better (OR placebo/BTA 0.947; 95% CI 0.32–2.80; p=0.92). Notably, pelvic floor resting activity decreased significantly in the BTA group compared to placebo (p=0.001).
Key Point: BTA injections did not demonstrate a significant clinical benefit over placebo in reducing pain for women with CPP despite a reduction in pelvic floor muscle activity.
Effectiveness of Lumbar Segmental Stabilization Exercises in Managing Disability and Pain Intensity Among Patients With Lumbar Spondylolysis and Spondylolisthesis: A Systematic Review and Meta-analysis of Randomized Controlled Trials
Lin LH, Lin TY, Chang KV, et al. Spine (Phila Pa 1976) 2024; 49(21) 1512-20. https://doi.org/10.1097/BRS.0000000000004989
Summary by Mohammad R. Rasouli, MD
Introduction: Lumbar spondylolysis and spondylolisthesis are spinal disorders characterized by lumbar segmental instability. The complex muscular structures in the lumbar region play a vital role in maintaining stability. Recent evidence suggests that lumbar segmental stabilization exercises (LSSE) may be effective in managing lumbar instability. This systematic review and meta-analysis aims to evaluate the effectiveness of LSSE in treating lumbar spondylolysis and spondylolisthesis.
Methods: A systematic literature search was conducted across multiple databases until January 2024. Randomized controlled trials (RCTs) that assessed the impact of LSSE on lumbar spondylolysis and spondylolisthesis were identified and included. The primary outcome was disability measured using the Oswestry Disability Index and the Quebec Back Pain Disability Scale. The secondary outcome was pain level assessed using the visual analog scale and the McGill Pain Questionnaire. Data extraction was performed by two independent reviewers, and data pooling was conducted using a random-effects model.
Results: A total of five RCTs involving 198 patients were included in the final analysis. When LSSE was employed as a single treatment, there was a significant improvement in disability scores (95% CI: -2.598 to -0.053, P = 0.041). In cases where LSSE was combined with other treatments, no significant improvement in disability was observed (95% CI: -0.460 to 0.213, P=0.471). LSSE did not significantly reduce pain scores (95% CI: -1.082 to 0.090, P = 0.097).
Key Point: This systematic review demonstrates that LSSE is more effective in improving disability than in alleviating pain for patients with lumbar segmental instability.
A Randomized Double-Blind Trial of 5% Dextrose Versus Corticosteroid Hydrodissection for Meralgia Paresthetica
Shi X, Xu H, Zhu J, et al.. Pain Physician 2024;27(8):E835-42.
Summary by Wee How Tan, MBBS, MMed (Anaes)
Introduction: Meralgia paresthetica (MP) caused by compression of the lateral femoral cutaneous nerve (LFCN) is often treated with corticosteroid injections, which provide short-term relief but carry risks of adverse effects. Although comparative studies are limited, ultrasound-guided 5% dextrose (D5W) hydrodissection has emerged as a safer alternative. This randomized, double-blind trial aimed to compare the efficacy and safety of D5W versus corticosteroid hydrodissection.
Methods: This single-center, double-blinded study of 56 patients with MP was randomized to either the D5W group (10 mL of 5% dextrose) or the steroid group (betamethasone sodium phosphate 5mg and betamethasone dipropionate 2mg + 5 mL 2% lidocaine + 4 mL 0.9% saline). Both groups received single ultrasound-guided perineural injections targeting the LFCN. Primary outcomes included changes in the Visual Analog Scale (VAS) for pain and paresthesia and global quality of life. Evaluations were conducted at baseline and at 1, 3, 4, and 6 months post-treatment.
Results: The D5W group demonstrated significant improvement in VAS pain and paresthesia scores at 3, 4, and 6 months compared to baseline (p<0.001) with no adverse effects reported. In contrast, the steroid group demonstrated statistically significant improvement in VAS pain and paraesthesia at 1, 3, and 4 months compared to baseline (p<0.001) with six patients reporting adverse effects. At 6 months, there was an intergroup VAS difference of -2.4 (-3.1 to -1.6, p<0.001) favoring the D5W group.
Key Points: D5W hydro dissection is more effective and safer than corticosteroid injection for MP in the 4-6 month range, offering sustained symptom relief without adverse effects.
Acute Pain
Effect of the Ultrasound-Guided Interscalene and Supraclavicular Blocks on the C4 Dermatome
Qiu Y, Cady C, Rosario BL, et al. Local Reg Anesth 2024;17:107-15. https://doi.org/10.2147/LRA.S495105
Summary by Marcelle Blessing, MD
Introduction: This study looks at the efficacy of a lower volume interscalene block (ISB) and supraclavicular block (SCB) for providing analgesia in the C4 dermatome. Incisions for arthroscopic shoulder surgery are often in this area, so the ability to provide C4 coverage could affect whether a block will provide surgical anesthesia.
Methods: Patients having shoulder, hand, or wrist surgeries received either ultrasound-guided ISB (for shoulder surgeries) with 12-15 mL of 0.5% bupivacaine or ultrasound-guided SCB (for hand and wrist surgeries) with 20-24 mL of 0.5% bupivacaine. The primary outcome studied was the sensory effect on the C4 dermatome after ISB and SCB. The secondary outcomes included the sensory effect on the C5 dermatome after performing ISB and SCB, pain scores upon arrival at the post-anesthesia care unit, and the incidence of adverse effects.
Results: This was a prospective, observational, single-center study. Sixty-one patients were recruited: 30 for ISB and 31 for SCB. C4 dermatome coverage was achieved in 53% and 29% of patients in the ISB and SCB groups, respectively (p=0.0268). Additionally, C5 dermatome coverage was achieved in 97% and 68% of patients in the ISB and SCB groups, respectively (p=0.0034). A moderate correlation coefficient (r=0.47) was observed between C4 sensory scores and postoperative pain scores.
Key Point: ISB of lower volume is almost twice as effective as SCB at providing C4 dermatomal coverage, but it is only effective about half of the time. Supplementation with local anesthetic for the C4 distribution may be needed when attempting to use lower-volume ISB for surgical anesthesia.
Spread of Local Anaesthetic After Erector Spinae Plane Block: A Randomised, Three-Dimensional Reconstruction, Imaging Study
Shan T, Zhang X, Zhao Z, et al. Br J Anaesth 2025;134(3):830-8. https://doi.org/10.1016/j.bja.2024.10.046
Summary by Monika Nanda, MBBS, MPH, FASA
Introduction: The anterior spread of local anesthetic after erector spinae plane block (ESPB) is variable as demonstrated by anatomical and clinical studies.This study explores the effect of maintaining patient positioning (supine, lateral, or prone) on local anesthetic distribution after ESPB, which can greatly influence clinical analgesic efficacy.
Methods: In this randomized trial, 84 participants requiring thoracic imaging were assigned to three groups based on position after ESPB (N=28 each). Each group received a single-injection ESPB in the prone position at T7 with 30 ml of 0.375% ropivacaine mixed with radiocontrast. After injection, subjects were maintained in their assigned position, supine, lateral, or prone, for 30 minutes before CT scanning. The primary outcome was radiologic evidence of paravertebral spread. Secondary outcomes included neural foramina involvement, craniocaudal extent, intercostal spread, and epidural distribution. Cold testing assessed sensory changes, and imaging was used to reconstruct the three-dimensional injectate spread.
Results: Of 81 patients completing the study, the paravertebral space reached 96.5%, with prone positioning yielding 100% involvement. Prone positioning also achieved broader thoracic coverage vs supine (5.0 vs. 3.1 levels, P<0.001). Epidural spread occurred in 23.3% of patients overall. Loss of cold sensation similarly reached more lateral and anterior segments with prone positioning after ESPB.
Key Point: Prone positioning for 30 minutes after ESPB significantly enhanced local anesthetic-contrast spread to the paravertebral space, intercostal space, and neural foramina, suggesting that gravity plays a substantial role in the spread of injectate.
Trends in Opioid Prescribing and New Persistent Opioid Use After Surgery in the United States
Luby AO, Alessio-Bilowus D, Hu HM, et al. Ann Surg 2025;281(3):347-52. https://doi.org/10.1097/SLA.0000000000006461
Summary by Jeffrey Grzybowski, MD
Introduction: New persistent opioid use after surgery is associated with an increased long-term risk of complications, opioid use disorder, overdose, and death. Numerous strategies have been undertaken to optimize opioid stewardship and prevent opioid-related harms. This study attempts to assess how such public health initiatives have impacted national prescribing patterns and rates of new persistent opioid use between 2013 and 2021.
Methods: A retrospective study of opioid-naïve, privately insured adult patients undergoing 17 common surgical procedures between 2013 and 2021 was conducted utilizing data from the Health Care Cost Institute. Sociodemographic and clinical covariates, including use of one or more controlled substances in the prior year, tobacco use history, mental health diagnoses, and pain diagnoses, were included. Unadjusted rates of initial prescription fill, initial opioid prescription size, subsequent prescription refills, and new persistent opioid use were determined.
Results: Among 989,354 opioid-naïve individuals, the adjusted initial opioid prescription size decreased from 282 mg oral morphine equivalents (OME) to 164 mg OME, a reduction of 118 mg OME (95% CI: 116-120). The adjusted incidence of new persistent opioid use decreased from 2.7% in 2013 (95% CI: 2.6%-2.8%) to 1.1% in 2021 (95% CI: 1.0%-1.2%). More patients with new persistent opioid use filled a prescription for a non-opioid controlled substance in the year before surgery (33.2% vs 16.8%, P<0.001), had a history of tobacco use (8.6% vs. 5.7%, P <0.001), had preoperative pain disorders, had anxiety or mood disorders, or reported preoperative alcohol and drug use.
Key Point: Since 2013, initial opioid prescription sizes decreased by 41.8%, and the incidence of new persistent opioid use decreased by more than half from 2.7% to 1.1%.
