Regional Nerve Blocks for Breast Surgery

Breast cancer is the most common cancer in women worldwide, and the incidence of breast cancer is climbing every year. One of the mainstay treatment approaches for breast cancer is surgery, including breast-sparing lumpectomies, mastectomies and lymph node biopsies, as well as breast implant and reconstruction after initial surgery. These are typically major surgeries however, and even though general outcomes have improved for breast cancer patients, many patients have significant post-operative pain. Regional nerve blocks have been shown to decrease postoperative pain after breast surgery, thus decreasing length of hospital stay, hospital cost, and perioperative morbidity [1]. 

One option for regional nerve block during breast surgery is the thoracic paravertebral block, in which local anesthetic is injected into the space adjacent to the spine in the same plane as the neurovascular bundles that supply the breast tissue [1]. This block has been shown to have significantly better pain control than general anesthesia alone, along with decreased nausea and vomiting [2]. These nerve blocks have been shown to provide most benefit for patients undergoing single or double mastectomies, resulting in decreased utilization of postoperative opioids and anti-emetics [2]. And even in patients who underwent bilateral mastectomies with immediate reconstruction, considered one of the most painful breast procedures, patients who received a thoracic paravertebral block used significantly less postoperative opioids than patients who did not receive the block [3]. Furthermore, this block has not only been shown to provide effective acute pain relief, but it also helps attenuate the intensity of chronic pain after surgery [1]. Patients who received the block reported fewer and less intense symptoms of chronic pain, including paresthesia, intercostobrachial neuralgia, and phantom breast pain, as well as improved mental health and quality of life scores [1].  

 Another form of regional block for breast surgery is the pectoral nerve block that targets the medial and lateral pectoral nerves and parts of the brachial plexus which provide innervation to the pectoralis muscles [1]. This block is particularly useful in procedures that require breast expanders or subpectoral implants, both of which are associated with significant pain [1]. This block helps to decrease postoperative muscle spasm and thus pain, and does a better job of reaching the nerve fibers associated with the pectoralis muscles than the thoracic paravertebral block [1]. One study that compared these two techniques found that at 12 hours postoperatively, patients who received the pectoral block were using significantly less morphine and self-reported lower pain intensity scores than patients who received the thoracic paravertebral block [1]. While patients actually reported better pain control with the thoracic paravertebral block at the 18- and 24-hour mark post-operatively, the pectoral nerve block has still been shown to be an effective pain control adjunct [1]. When these techniques are used in conjunction, they are associated with effective acute pain control and lower doses of intraoperative sedation [1].  

 In addition to pain control, a few studies have also shown an anti-tumor immune response associated with the thoracic paravertebral regional block. Clearly these regional nerve blocks have strong benefits and should be explored as pre-operative and intra-operative adjunct therapy options for patients undergoing breast surgery.  

References  

1. Calì Cassi L, Biffoli F, Francesconi D, Petrella G, Buonomo O. Anesthesia and analgesia in breast surgery: the benefits of peripheral nerve block. Eur Rev Med Pharmacol Sci. 2017 Mar;21(6):1341-1345. PMID: 28387892. 
2. Fahy AS, Jakub JW, Dy BM, Eldin NS, Harmsen S, Sviggum H, Boughey JC. Paravertebral blocks in patients undergoing mastectomy with or without immediate reconstruction provide improved pain control and decreased postoperative nausea and vomiting. Ann Surg Oncol. 2014 Oct;21(10):3284-9. doi: 10.1245/s10434-014-3923-z. 
3. Klein SM, Bergh A, Steele SM, Georgiade GS, Greengrass RA. Thoracic paravertebral block for breast surgery. Anesth Analg. 2000 Jun;90(6):1402-5. doi: 10.1097/00000539-200006000-00026.