Cite as: Nanda M, Rayaz H, Blessing M. Literature review - May 2026. ASRA Pain Medicine News 2026;51. https://doi.org/10.52211/asra050126.016.

Literature Review

Acute Pain

Intrathecal Morphine for Enhanced Recovery After Laparoscopic Colorectal Surgery: A Randomized Clinical Trial

Zheng L et al. JAMA Surg 2026;161(2):124-31. https://doi.org/10.1001/jamasurg.2025.5699

Summary by Monika Nanda, MBBS, MPH

Introduction: Postoperative pain remains a major barrier to recovery after laparoscopic colorectal surgery, even within enhanced recovery pathways. The transversus abdominis plane block (TAPB) can reduce somatic incisional pain but may not address visceral pain. Intrathecal morphine (ITM) may improve analgesia, but concerns about adverse effects have limited its routine use. This trial evaluated whether adding ITM to TAPB improves the quality of early postoperative recovery.

Methods: This was a prospective, single-center, double-blind, placebo-controlled randomized clinical trial conducted at Sun Yat-sen University Cancer Center. Adults aged 18 years or older with ASA physical status I to III scheduled for elective laparoscopic colorectal surgery were randomized 1:1 to receive intrathecal morphine 3 μg/kg or intrathecal saline placebo. Both groups received bilateral 4-quadrant TAPB with liposomal bupivacaine and otherwise standardized enhanced recovery after surgery (ERAS) care, anesthesia, and postoperative analgesia. The primary outcome was the QoR-15 score at 24 hours. Secondary outcomes included pain scores, opioid consumption, time to ambulation, time to first flatus, adverse effects, and hospital length of stay (LOS). Intention-to-treat analysis was performed.

Results: A total of 252 patients were randomized with 126 patients in each group. At 24 hours, the ITM group had higher QoR-15 scores than controls (114.95 vs 102.22; 95% CI 9.91-14.51; P < .001). Postoperative morphine consumption at 24 hours was lower with ITM (4.4 vs 10.4 MME; 95% CI -8.88 to -4.31; P < .001). The ITM group also had less nausea and vomiting, earlier ambulation and first flatus, but more pruritus. LOS was not significantly different.

Key Point: In laparoscopic colorectal surgery, adding low-dose intrathecal morphine to TAP block improved early recovery and reduced opioid use, with pruritus as the main tradeoff.

Analgesic Efficacy and Safety of Lidocaine Administered by Intravenous Route vs Erector Spinae Plane Blocks Following Open Heart Surgery: An Open-Label, Randomized Clinical Trial

Selvamani BJ et al. J Clin Anesth 2026;111:112166. https://doi.org/10.1016/j.jclinane.2026.112166

Summary by Hassan Rayaz, MD

Introduction: This is a randomized, non-blinded study comparing the efficacy of continuous erector spinae plane (ESP) block to IV lidocaine for primary open cardiac surgery. Previous studies have shown ESP blocks to be superior to placebo, but there have been mixed results when they have been compared with other analgesic modalities. To date, there have not been any comparisons between continuous ESP blocks and IV lidocaine infusion. This study also adds to the discussion of a proposed mechanism of action of ESP blocks, consisting of systemic absorption of local anesthetics.

Methods: Adult patients undergoing primary open cardiac surgery were randomized into either a continuous ESP lidocaine group or a continuous IV lidocaine group. The study was not blinded. Lidocaine infusions (same dose for both groups) were started postoperatively in the ICU in addition to a standardized multimodal ERAS protocol. Arterial blood samples were taken at multiple time intervals up to 24 hours postoperatively to measure plasma lidocaine concentrations.

Results: 30 patients were included in each arm of the study. Primary endpoints were opioid consumption and pain scores within the first 48 hours after surgery. There was no statistically significant difference in either primary endpoint between groups (p>0.05). There was no significant difference between plasma lidocaine concentrations between groups after 30 minutes of starting the lidocaine infusion. One patient in the ESP lidocaine group developed perioral tingling, but no other complications were noted.

Key Point: Bilateral continuous lidocaine ESP blocks did not provide superior analgesia to IV lidocaine for primary open cardiac surgery.

Ultrasound-Guided Thoracic Paravertebral Block Versus Erector Spinae Plane Block Analgesia for Cardiac Surgery with Median Sternotomy: A Noninferiority Randomized Controlled Trial

Montandrau O et al. Br J Anaesth 2026;136(2):687-94. https://doi.org/10.1016/j.bja.2025.10.039

Summary by Marcelle Blessing, MD

Introduction: Enhanced recovery protocols for cardiac surgery by median sternotomy need effective analgesia. Thoracic paravertebral block (TPVB) has excellent outcomes but is technically challenging and not without risks. The authors hypothesized that the erector spinae plane block (ESPB) would provide noninferior analgesia with fewer complications.

Methods: This was a prospective, double-blinded, noninferiority, randomized controlled trial for adults undergoing median sternotomy for cardiac surgery. Patients received either an ultrasound-guided single-shot ESPB or a TPVB with 20 mL of 0.375% ropivacaine per side. Blocks were performed under general anesthesia in the left lateral decubitus position. Pain during forced expiration was the primary outcome.

Results: 74 patients were included in the primary analysis of the 96 randomized patients. No serious block complications occurred. The mean time to perform the block was significantly shorter for ESP than for TPVB: 360 (102) vs 438 (132) s (P<.001). For the primary outcome, mean NRS scores on forced expiration at 6 hours after surgery were 3.5 (2.6) in the ESPB group and 3.0 (2.1) in the TPVB group. The upper limit of the 95% CI exceeded the prespecified noninferiority margin of 1 point, so noninferiority of ESPB could not be established. Opioid consumption, NRS scores at 24 hr and 48 hr, and ICU or hospital length of stay were comparable between the two groups. ESPB recipients had more intraoperative hypertension than TPVB recipients.

Key Point: ESPB was not noninferior to PVB for early dynamic analgesia after median sternotomy.

Chronic Pain

Duloxetine and Cognitive Behavioral Therapy with Phone-Based Support for the Treatment of Chronic Musculoskeletal Pain: A Randomized Controlled Trial

Ang D, Kaplan S, Keefe F, et al. Pain 2026;167(3):577-88. https://doi.org/10.1097/j.pain.0000000000003861

Summary by Mamta Chura, MD

Introduction: Duloxetine, a serotonin-norepinephrine reuptake inhibitor, has demonstrated analgesic efficacy, while cognitive behavioral therapy (CBT) addresses maladaptive pain coping mechanisms. This study protocol evaluates whether combining duloxetine with web-based CBT, augmented by motivational interviewing, improves outcomes compared to pharmacologic therapy alone in participants with chronic musculoskeletal pain (CMP)

Methods: This is a three-arm randomized controlled trial involving adults with CMP recruited from primary care clinics. Participants received duloxetine 30 mg for 1 week prior to randomization to ensure tolerability of the medication. Participants were then randomized to (1) duloxetine monotherapy, (2) duloxetine and web-based CBT, and (3) duloxetine and web-based CBT with phone-based motivational interviewing. The primary outcome was the Brief Pain Inventory total pain score (BPI TPS) at 24 weeks.

Results: A total of 281 participants were randomized. Compared to baseline across all treatment arms, there was a 2.2 point (SE [standard error] =0.2) reduction in BPI TPS scores, a 2.1 point (SE=0.2) reduction in BPI pain intensity scores, and a 2.2 point (SE=0.2) reduction in BPI pain interference scores at 24 weeks, which represent clinically significant differences. There was no significant difference between treatment groups at 24 weeks for BPI TPS, BPI pain severity, and BPI pain interference. Secondary outcomes using PROMIS, GAD-7, PHQ-9, and Pain Catastrophizing Scale measures at 12 and 24 weeks demonstrated no difference between groups but were significant improvements from baseline.

Key Point: Duloxetine use for CMP is effective in reducing BPI TPS, BPI pain intensity, and BPI pain interference. The addition of phone-based motivational interviews and web-based CBT did not result in additional pain-related improvements.

Efficacy and Safety of Bisphosphonates for Complex Regional Pain Syndrome: A Systematic Review and Meta-analysis

Ferraro MC, O’Connell NE, Goebel A, et al. Ann Intern Med 2026;179(2):256-69. https://doi.org/10.7326/ANNALS-25-03693

Summary by Vandana Sharma, MD, FASA

Introduction: Bisphosphonates are promoted as first-line treatment for complex regional pain syndrome (CRPS) despite a lack of evidence supporting efficacy. This systematic review summarizes the efficacy and safety of bisphosphonates in CRPS.

Methods: Data sources were searched through September 2025 for randomized controlled trials enrolling adults with CRPS who received bisphosphonate treatment. The primary outcomes were pain intensity and adverse events. Random-effects meta-analysis models were used to synthesize data. Continuous and dichotomous data were analyzed as mean differences (MDs) and risk ratios with 95% confidence intervals (CI), respectively.

Results: 953 records were identified, and 11 trials (754 participants) were included in the systematic review. CRPS was diagnosed according to the following criteria: Budapest (7 trials), IASP 1999 (1 trial), IASP 1994 (1 trial), and Kozin (2 trials). 97% of trial participants had CRPS type-1. The meta-analysis showed that bisphosphonates may result in little to no difference in pain intensity at immediate follow-up (<4 weeks) and may reduce pain intensity (MD = -10.0; CI, -18.9 to -1.1, low certainty) at short-term follow-up (4 weeks to 3 months). In medium-term (3-6 months) and long-term (> 6 months) follow-up, there was no difference in pain intensity (low- and very-low-certainty evidence). Bisphosphonate use probably increases the risk of adverse effects (RR 1.1; CI, 1.0-1.2) with increased risk for arthralgia (RR 1.7; CI, 1.0-2.9) and myalgia (RR 3.9; CI 1.5-9.8)

Key Point: Bisphosphonates may reduce CRPS pain intensity in the short term but are likely associated with certain adverse events.

Ultrasound-Guided Versus Conventional Fluoroscopy-Guided Epidural Injection for Radiculopathy: A Meta-Analysis of Randomized Controlled Trials

Ahmed M et al. World Neurosurg 2023;180:203-12. https://doi.org/10.1016/j.wneu.2023.09.088

Summary by Vinita Singh, MD, MSCR

Introduction: Fluoroscopy (FL) is the traditional guidance method for epidural steroid injections (ESIs) in patients with radiculopathy; however, it involves radiation exposure and risks of intravascular injection. Ultrasound (USG) has emerged as a potential alternative, offering real-time visualization without radiation. This meta-analysis aimed to test the non-inferiority of USG-guided ESIs compared with FL for the treatment of radiculopathy.

Methods: A systematic search of PubMed, Embase, ClinicalTrials.gov, and Cochrane databases was conducted to identify studies comparing USG and FL-guided ESIs. Primary outcomes included pain reduction at 1 and 3 months, while secondary outcomes included functional improvement, procedure time, multiple injections, and complications such as vascular puncture. Risk of bias was assessed using the Cochrane tool, and certainty of evidence was evaluated using GRADE (Grading of Recommendations Assessment, Development, and Evaluation).

Results: Seven randomized controlled trials, encompassing patients with both cervical and lumbosacral radiculopathy, met the inclusion criteria. Clinical efficacy was similar between USG and FL, with no significant differences in pain reduction at 1 month (mean difference [MD] −0.12; 95% CI −0.47 to 0.23) or 3 months (MD 0.73; 95% CI −1.49 to 2.96). Functional outcomes and reintervention rates were also comparable. Safety favored USG, with a lower risk of vascular puncture (odds ratio 0.21; 95% CI 0.07 to 0.64). Procedure time was shorter with USG, but definitions varied. GRADE certainty ranged from high (1-month disability) to very low (procedure time), warranting caution in interpreting time differences.

Key Point: Ultrasound guidance provides a radiation-free, safe, and clinically comparable alternative to fluoroscopy for epidural steroid injections, with particular advantages in reducing vascular complications.