FormalPara Key Summary Points

This article is in response to the recently published article entitled “Research Progress on Serratus Anterior Plane Block in Breast Surgery: A Narrative Review” aiming to add a few more insights on this topic.

Serratus anterior plane block (SAPB) is one of the commonly administered interfascial plane blocks in breast surgeries following its description a decade ago.

SAPB, like all interfascial plane blocks applied for breast surgeries, has to be applied based on its sensory coverage as discussed here.

SAPB does not block the pectoral nerves; hence, it cannot provide adequate analgesia in procedures where pectoral muscles are disrupted, such as breast augmentation, breast reconstruction with insertion of prostheses, etc.

Dear Editor

I read with great interest the recently published review about the serratus anterior plane block (SAPB) in breast surgeries [1]. I congratulate Chai et al. for their comprehensive review on the anatomical considerations of breast surgeries and clinical applications of SAPB [1] and wish to present my insights on this topic.

In Table 1 of their article, Chai et al. mention that a randomized controlled trial (RCT) is available for breast augmentation procedures, with a superscript C indicating this [1]. However, to the best of my knowledge, no RCT is available in this regard. Rather, we must note that SAPB does not block the medial and lateral pectoral nerves, which play a major role in preventing the myofascial pain associated with disruption of pectoral muscles; hence, it cannot provide analgesia for these procedures. Chai et al. incorrectly attribute this aspect of pain to medial and lateral thoracic nerves instead of pectoral nerves under the heading “Nerve Block Requirements for Different Types of Breast Surgery” [1]. Even in the subpectoral pocket creation, pectoral nerves might be directly disrupted in addition to the possibility of involving the lateral cutaneous branches of the intercostal nerves [2]. Furthermore, Chai et al. [1] also cited the study by Hidalgo et al. (Ref. 19 in Chai et al. [1]) regarding that statement. However, that study concluded that intercostal nerve blocks did not reduce the pain in breast augmentation procedures [3], which further corroborates the fact that thoracic nerves do not play much of a role in the pain associated with this procedure. It is important to note that this study was published in 2005 [3], well before various fascial plane blocks including SAPB were introduced for breast surgeries. Hence, it is not surprising that SAPB is not studied in breast augmentation procedures.

Chai et al. state that “PECS I block involves the medial and lateral thoracic nerves, and the PECS II block involves the lateral cutaneous branch of the intercostals nerve, the intercostal brachial nerve, and the long thoracic nerve”. However, we must note that PECS II block is inclusive of PECS I [2], thus also covering the medial and lateral pectoral nerves (again, not thoracic nerves as stated by Chai et al. [1]). Indeed, PECS I block was introduced to reduce the pain of breast reconstruction procedures with insertion of prostheses, and PECS II block (inclusive of PECS I) was introduced to provide additional sensory coverage over the lateral chest wall and axilla. We must note here that SAPB was introduced as a replacement for the subpectoral component (deep injection) of PECS II and not for the interpectoral component (superficial injection) of PECS II [2]. These components are also called “pectoserratus plane block” and “interpectoral plane block” respectively as per the recent nomenclature [4].