Disclaimer: This article is intended solely for informational and educational purposes only. It does not constitute medical advice.
Breast surgery is associated with substantial acute pain and a considerable risk of persistent postsurgical pain, with rates of chronic pain after mastectomy reported as high as 55% (Woodworth et al., 2017). Because acute pain severity is one of the strongest predictors of chronic pain, perioperative analgesia in breast surgery is critical, and peripheral nerve blocks have emerged as attractive alternatives to thoracic epidural and paravertebral techniques, which carry risks of hypotension, pneumothorax, and inadvertent neuraxial spread.
An accurate understanding of chest wall innervation underlies rational block selection. The breast receives cutaneous innervation predominantly from the anterior and lateral cutaneous branches of the T2–T6 intercostal nerves, with a variable contribution from the supraclavicular nerves superiorly (Woodworth et al., 2017). The pectoral muscles, in contrast, are supplied by the lateral and medial pectoral nerves arising from the brachial plexus, while the long thoracic and thoracodorsal nerves innervate the serratus anterior and latissimus dorsi, respectively. This complex innervation map explains why no single interfascial block reliably anesthetizes the entire operative field (Woodworth et al., 2017).
The pectoral nerve (PECS) blocks, as first described by Blanco, were designed to address the myofascial component. The PECS I block targets the lateral and medial pectoral nerves via injection between pectoralis major and minor, while the modified PECS II block adds a deeper injection between pectoralis minor and serratus anterior to capture the intercostal lateral cutaneous branches, long thoracic nerve, and thoracodorsal nerve (Woodworth et al., 2017).
Clinical trials have supported its efficacy: in a randomized comparison with paravertebral block for modified radical mastectomy, PECS block reduced 24-hour morphine consumption and produced lower pain scores in the first 12 postoperative hours, although paravertebral block provided better analgesia later in the recovery period (Wahba & Kamal, 2014). Other trials have similarly demonstrated reduced opioid consumption, less postoperative nausea and vomiting, and shorter recovery times with PECS II block compared with no block (Woodworth et al., 2017).
Comparative data situate the peripheral nerve blocks within a broader hierarchy of regional techniques for breast surgery. The PROSPECT guideline for oncological breast surgery concludes that paravertebral block remains the first-choice regional technique for major breast surgery, with PECS block recommended as an alternative when paravertebral block is contraindicated or axillary dissection is not planned (Jacobs et al., 2020). A systematic review and meta-analysis of the erector spinae plane (ESP) block similarly found that, while ESP block reduced opioid consumption and pain scores compared with no block, its analgesic efficacy was inferior to pectoral nerve block and only comparable to paravertebral block, though with a notably lower complication profile than paravertebral techniques (Leong et al., 2021).
Overall, the evidence base supports peripheral nerve blocks as valuable components of multimodal analgesia for breast surgery. PECS blocks appear particularly useful when axillary or myofascial pain is anticipated, while paravertebral block remains preferred for more extensive procedures. Given the relative technical simplicity and favorable safety profile of ultrasound-guided nerve blocks, they are likely to see expanding use, though further high-quality randomized trials comparing these techniques head-to-head, particularly with attention to chronic pain outcomes, are still needed.
References
- Jacobs, A., Lemoine, A., Joshi, G. P., Van de Velde, M., & Bonnet, F. (2020). PROSPECT guideline for oncological breast surgery: A systematic review and procedure-specific postoperative pain management recommendations. Anaesthesia, 75(5), 664–673. https://doi.org/10.1111/anae.14964
- Leong, R. W., Tan, E. S. J., Wong, S. N., Tan, K. H., & Liu, C. W. (2021). Efficacy of erector spinae plane block for analgesia in breast surgery: A systematic review and meta-analysis. Anaesthesia, 76(3), 404–413. https://doi.org/10.1111/anae.15164
- Wahba, S. S., & Kamal, S. M. (2014). Thoracic paravertebral block versus pectoral nerve block for analgesia after breast surgery. Egyptian Journal of Anaesthesia, 30(2), 129–135. https://doi.org/10.1016/j.egja.2013.10.006
- Woodworth, G. E., Ivie, R. M. J., Nelson, S. M., Walker, C. M., & Maniker, R. B. (2017). Perioperative breast analgesia: A qualitative review of anatomy and regional techniques. Regional Anesthesia and Pain Medicine, 42(5), 609–631. https://doi.org/10.1097/AAP.0000000000000641