Chronic pain after breast surgery – still many unanswered questions: a reply

Abstract

We thank Drs Hartopp and Kelly 1 for their keen interest and thoughtful comments pertaining to our recent article 2. We agree that the pectoral nerve (PECS-2) and serratus plane blocks do not affect the anterior cutaneous branch of the intercostal nerve. However, we observed that the sites of moderate-to-severe chronic pain 6 months postoperatively were the axilla in 13 cases, arm in nine cases and chest in five cases (where multiple answers were possible). The most common site of chronic pain was, therefore, the axilla. We believe that achieving adequate anaesthesia in the region of the axilla, rather than the medial side of the breast, is more important for prevention of chronic pain after mastectomy. According to reports by Versyck et al. 3 and Biswas et al. 4, our PECS-2 technique acts on the axilla and blocks the intercostobrachial nerve. In contrast, our serratus plane block shows a weak effect on the axilla because it is targeted to the area superficial to the serratus anterior muscle at the level of the fifth rib in the mid-axillary line. Our study showed that the PECS-2 block was more effective for chronic pain management after mastectomy than the serratus plane block 2. Postmastectomy chronic pain is usually associated with damage to the intercostobrachial nerve 5. Our study also suggested that the anaesthetic effect of the PECS-2 block on the intercostobrachial nerve could lead to a reduced incidence of chronic pain after mastectomy. We assessed the intensity of chronic pain 6 months after mastectomy in patients having axillary lymph node dissection. The proportion of patients with moderate-to-severe chronic pain was 14% (two) in those receiving the PECS-2 block and 44% (seven) in those receiving the serratus plane block. Furthermore, the proportion of patients without chronic pain was 64% (nine) in patients receiving the PECS-2 block and 25% (four) in patients receiving the serratus plane block (Table 1). In addition, multivariable logistic regression analysis was used to adjust for postoperative radiotherapy as a major risk factor for postmastectomy chronic pain. We found that the proportion of patients without chronic pain after adjusting for postoperative radiotherapy was statistically significant. Although the sample size for the analysis of this sub-group was small, we found the PECS-2 block more effective in preventing postoperative chronic pain after mastectomy with axillary lymph node dissection than the serratus plane block.