Anatomical basis for sensory preservation in robotic mastectomy

Sensory preservation of the nipple-areolar complex (NAC) is crucial for physical, psychological, and sexual health after mastectomy. Robotic-assisted nipple-sparing mastectomy (rNSM) techniques have shown promise in preserving NAC sensation, but there is limited detailed anatomical evidence supporting this observation. The aim of this study was to characterize the anatomical pathways and variability of sensory nerves innervating the NAC, particularly focusing on implications for the development of improved nerve-preserving techniques during breast surgery.

A cadaveric anatomical study on three adult female cadaveric donors (six breasts) was undertaken, which was complemented by a systematic review of the existing literature using a modified PRISMA approach.

The anterior cutaneous branch (ACB) and the lateral cutaneous branch (LCB) of the fourth intercostal nerve (ICN) were consistently the primary cutaneous nerves innervating the NAC. The ACB of the fourth ICN, particularly its lateral division, followed a superficial and consistent subdermal route bypassing breast tissue in all cadavers. Conversely, the LCB of the fourth ICN, specifically its anterior division, traversed deeper breast tissue to reach the NAC. Variable supplementary contributions were observed from the second, third, and fifth ICNs, and previously undocumented ancillary branches. Significant inter-individual anatomical variability was noted.

The consistent superficial pathway of the ACB of the fourth ICN provides a clear anatomical rationale for improved sensory preservation observed in rNSM, given the procedure's lateral incision and precise dissection capabilities. Recognition of anatomical variability and detailed nerve trajectories should guide surgical planning to optimize sensory outcomes in breast cancer surgery and reconstruction.