Comparing the analgesic effect of the erector spinae plane block to the paravertebral block in breast cancer surgery

Post operative pain associated with breast surgery, particularly mastectomy, axillary lymph node staging and breast reconstruction, is well recognized (1,2). Opioid pain medications are used effectively in reducing post-operative pain but have significant associated problems, including the risk of persistent use. Over 10% of opioid-naïve patients undergoing curative oncologic surgery are at risk (3). More significantly, in one study, 37% of opioid-naïve patients had persistent opioid use after mastectomy. Higher opioid dose prescriptions at discharge predicted persistent opioid use (4). Many opioid sparing protocols have been developed, which include multimodal analgesia regimens (acetaminophen, non steroidal anti-inflammatory drugs (NSAIDS), gabapentinoids and glucocorticoids), local and regional analgesia (RA), non-pharmacologic approaches and patient education (5). The American Society of Breast Surgeons (ASBrS) has recommended RA as part of any multimodal opioid-sparing analgesic regimen for breast surgery (6). The PROSPECT (PROcedure SPECific postoperative pain management) guideline for analgesia for oncologic breast surgery, used a systematic review of the highest quality data available (7). In their review of RA techniques for breast cancer surgery, this group of European experts found that the paravertebral block (PVB) had the most reproducible and best studied effects (4 meta-analysis of 32 studies). PVB is associated with low postoperative pain scores, opioid consumption and incidence of nausea and vomiting, when compared to systemic analgesia (SA) alone. The ASBrS guideline, which was based on the PROSPECT review, endorsed the PVB as the first choice for major breast surgery. When RA modalities are evaluated, the PVB could be used as the standard to which others could be compared to, as it has been extensively evaluated (8).

A 2025 prospective, multicenter, double blinded, randomized controlled trial (RCT) by Raft et al., randomized 292 patients to receive erector spinae plane block (ESPB) or thoracic PVB (9). The trial had several key findings: (I) Analgesia: PVB was more effective, with higher pain scores (specifically during movement) observed with ESPB. (II) Coverage: complete or partial dermatomal coverage (T2–T6) at 15 minutes was significantly higher in the PVB group (79.6%) compared to the ESPB group (44.1%). (III) Opioid use: patients with ESPB had higher rates of morphine use in the post-anesthesia care unit (PACU) within 2 hours of surgery (75.2% vs. 50.3%), but no differences in intraoperative or oral opioid use at 24 hours. (IV) Satisfaction: both techniques reported similarly high satisfaction levels from patients and anesthesiologists. The trial concluded that the ESPB did not meet noninferiority criteria compared to the PVB regarding opioid requirements for major breast cancer surgery. Additionally, PVB provided superior, more consistent analgesic coverage for the anterior chest wall. Per the authors, PVB “remains the preferred technique for major breast surgery” (9). This large and well executed RCT provides valuable data regarding these 2 RA techniques. Further analyzing the key findings of the study can assist clinicians when selecting the appropriate analgesic modality for major breast surgical procedures.

Several RCTs have looked at the analgesic effectiveness of ESPB compared to PVB, utilizing either a numeric rating scale (NRS) or a visual analog scale (VAS), and analgesic consumption. A randomized trial of 100 patients undergoing non-mastectomy breast surgery found that PVB provided improved analgesia and lower pain scores (median NRS 0 vs. 3) and reduced opioid consumption compared to ESPB (10). A 2023 meta-analysis of four RCTs (310 patients) found comparable analgesic effects between ESPB and PVB, with no significant differences in perioperative pain scores or analgesic consumption, except when looking at recovery room scores, where ESPB had significantly higher NRS scores (11). A more recent RCT, found PVB is better than ESPB in acute postoperative pain management (less total morphine consumption, lower VAS scores and longer time to request of first analgesic) (12). Another RCT, attempting to increase ESPB’ efficacy, did not find significant differences in VAS between ESPB injected with ropivacaine and hydromorphone and ESPB with ropivacaine alone, despite the former having a decrease in interleukin-6, a proinflammatory marker whose serum concentration correlates with patients’ symptoms and quality of life (13). These high level evidence, including Raft et al.’s trial, suggests that ESPB may be inferior to PVB, and only comparable under certain circumstances, specifically when patients have returned to the ward and likely received multimodal SA. As described in a recent review article, the evidence comparing pain scores between these 2 RA techniques is mixed, with 3 RCT suggesting greater reduction in pain with PVB, 1 RCT suggesting ESPB superiority and 2 showing similar results between the 2 (14). When interpreting results from RA comparative studies, readers should carefully analyze the data and rely only on the highest level of evidence.

In order to understand the possible differences in coverage between these two RA techniques, one should first understand what nerves are blocked by each. The PVB deposits local anesthetic in the paravertebral space, which blocks the thoracic spinal nerves as they leave the intervertebral foramina, and can spread to multiple levels superiorly and inferiorly, the intercostal space laterally, the contralateral paravertebral space, the epidural space medially and to somatic and sympathetic nerves (15). ESPB blocks the dorsal and ventral rami of the thoracic spinal nerves, as well as sympathetic fibers. Additionally, it provides analgesia at several dermatomes adjacent to the level of injection, as the anesthetic agent travels in a cranial and caudal direction along the tissue compartment deep to the erector spinae muscle group, particularly the paravertebral space (16). PVB or ESPB do not cover the cervical plexus (supraclavicular nerves) innervating the cranial aspect of the breast or any of the brachial plexus nerves responsible not only for muscle innervation but myofascial pain (covered by the interpectoral plain block provided by the pectoralis nerve block II or PECS II) (15). Compared to PVB, which consistently stains the ventral rami (origin of the intercostal nerve which gives off the lateral and anterior cutaneous branches), the ESPB shows unreliable spread to these structures in clinical and cadaveric studies. Thus the primary mechanism of ESPB analgesia likely involves dorsal rami blockade with possible secondary effects from variable paravertebral diffusion, rather than consistent ventral ramus blockade (16). This could explain ESPB inferiority with regards to anterior chest wall coverage. To better understand dermatomal coverage, its assessment should not be only at 15 minutes, but at longer intervals, as these blocks require more than 30 minutes to reach its full effect, especially when extended T2–T6 coverage is desired (17).

As stated initially, decreasing perioperative opioid consumption is an important goal of any analgesic protocol. Perioperative opioid use is a metric frequently studied to determine the efficacy of RA techniques. In 2020 RCT, for example, patients undergoing breast conserving surgery as well as mastectomy were randomized to PVB, ESPB, or SA; all patients received a morphine PCA. At 24 hours, the study found statistically significant differences in morphine use between RA groups and SA, but none between PVB and ESPB (P<0.001 for ESPB vs. SA and PVB vs. SA, P>0.05 for ESPB vs. PVB) (18). In Raft et al.’s study, a significantly lower percentage of study subjects required morphine in the first two hours; this criterion was used to declare that non inferiority was not met. Two letters to the editor commented on potential limitations of this particular metric. Huang noted that for those that required morphine, the amounts were similar for both groups, suggesting that patient specific factors that could predict higher analgesic requirements could be present in each group (19). Bao reflected that, despite the first 2 hours difference, likely consistent with a better initial coverage by PVB, there were no differences in total opioid consumption, satisfaction and pain scores at 24 hours. “This more nuanced temporal pattern”, Bao argues, “suggests waning of the postoperative pain phase and transitioning into a multimodal pain regimen, rather than RA technique analgesic equivalency”. More importantly, the lack of differences at 24 hours should caution readers against concluding that ESPB is not effective; instead, it should be considered as an alternative when PVB is contraindicated or there is a lack of expertise for its application (20). Caution should be exercised when interpreting the results of different studies looking at opioid consumption, as significant variability in morphine equivalent conversion methods can limit their external validation (21).

Ultimately, patient centered outcomes, like satisfaction, provide invaluable insights into the effectiveness of a particular intervention. A 2024 RCT showed ESPB had lower satisfaction than PVB (12). 2 RCT found increased satisfaction, quality of recovery, and lower VAS pain scores and opioid use with ESPB compared to a control group treated with SA (22,23). As Raft et al. state in the study’s discussion, despite significant differences in VAS scores, these may not be significant enough to impact clinical outcomes, especially in light of similar patient and provider satisfaction scores between groups. The authors state that ESPB is still a useful intervention, despite its less effective pain relief (9).

The 2026 American Society of Anesthesiologist Practice Guideline on Perioperative Pain management Using Local and Regional Analgesia for major operations (including mastectomy), evaluated the available evidence from systematic reviews and meta-analyses (24). The guideline found that PVB and fascial plane blocks (including ESPB) are effective analgesic modalities after mastectomy, without major differences between the two, and are superior to control groups without RA or surgical site local anesthetic infiltration for reducing postoperative pain and opioid use. Raft et al.’s study provides important additional knowledge regarding the analgesic effectiveness of the ESPB compared to the PVB, considered the standard RA to which others should be compared. A clear mechanistic action could explain PVB’s superior coverage of the anterior chest dermatomes that provide the majority of the sensory innervation to the breast. But when looking at other metrics, including patient satisfaction and perioperative opioid consumption, in the context of a multimodal pain management strategy, ESPB is clearly superior to SA alone and the superiority of PVB may not be clinically significant in all situations. Additionally, the safety profile and relative technical ease of performance of ESPB makes it an attractive alternative to PVB (25). Ultimately, while the PVB continues to be the RA procedure of choice for major breast surgery, ESPB and other fascial plane blocks are good alternatives, and their success may depend on the technical expertise available (6). Further studies could explore the specific indications for each of these RA techniques.

Acknowledgments

None.

Footnote

Provenance and Peer Review: This article was commissioned by the editorial office, Gland Surgery. The article has undergone external peer review.

Peer Review File: Available at https://gs.amegroups.com/article/view/10.21037/gs-2026-1-0121/prf

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Conflicts of Interest: The author has completed the ICMJE uniform disclosure form (available at https://gs.amegroups.com/article/view/10.21037/gs-2026-1-0121/coif). The author has no conflicts of interest to declare.

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