Restoring sensation in breast reconstruction: a mini review

Introduction

Of the 310,000 women diagnosed with breast cancer annually in the United States, approximately one-sixth undergo mastectomy and breast reconstruction. Loss of cutaneous breast sensation following mastectomy increases the risk of accidental trauma, undermines intimacy, and erodes satisfaction even when aesthetic goals of reconstruction are achieved. Large studies estimate that approximately 70% of patients lose nipple sensitivity after nipple-sparing mastectomy, with wide variation in the speed and extent of recovery (1). To address this problem, plastic surgeons have developed microsurgical techniques for improving return of breast sensation, both in autologous and implant-based breast reconstruction.

Patient surveys consistently rank return of sensibility alongside symmetry as a top priority in breast reconstruction, and case reports of thermal injury to insensate breasts underscore the safety implications of post-mastectomy numbness. Contemporary analyses demonstrate that neurotized autologous flaps recover sensation faster and more completely than non-neurotized flaps (Table 1), with recent meta-analyses confirming superior objective sensation after neurorrhaphy compared with standard reconstruction. Concurrently, the literature on patient reported outcomes (PROs) after mastectomy emphasizes the psychosocial value of breast sensation to women who undergo reconstruction. Although professional societies increasingly recognize the value of breast neurotization, widespread adoption remains limited due to perceived time costs, lack of consensus on surgical technique, absence of standardized testing protocols, and modest reimbursement incentives.

This mini-review synthesizes historical advances, anatomic foundations, operative strategies, and reported outcomes of efforts to restore breast and nipple sensation after mastectomy. We describe our technical approach to neurotization of free abdominal flaps during autologous breast reconstruction and highlight the major contributions of landmark studies in the field.

Historical background

In 1992, Slezak et al. published the first study on transverse rectus abdominis myocutaneous (TRAM) flap neurotization to facilitate return of breast sensibility (6). The authors observed that while breasts reconstructed with pedicled TRAM flaps spontaneously developed some sensibility, the magnitude of recovery was markedly diminished compared to normal breasts. Multiple case reports also documented thermal injuries to numb reconstructed breasts, underscoring the functional importance of restoring protective sensation (7,8). To address this issue, Slezak proposed flap neurotization, describing transfer of lower intercostal nerves within the flap to lateral cutaneous branches of the 4th intercostal nerve (ICN) at the chest. At 2- to 7-year follow-up, the authors reported improved sensibility in three neurotized breasts relative to contralateral controls. Follow-up studies by Doncatto and Blondeel et al. supported the benefit of flap neurotization during breast reconstruction, demonstrating lower pressure thresholds, improved temperature discrimination, and the possibility of erogenous sensation when donor sensory branches were coapted to chest wall recipients (9,10).

More recently, studies have described various methods for directly reinnervating the nipple-areola complex (NAC) in implant-based breast reconstruction (Table 2), expanding the demographic of patients eligible for neurotization surgery. Alongside these advances, numerous primary studies and systematic reviews have documented improved sensory recovery and enhanced patient-reported quality of life after neurotization, establishing the technique’s value in breast reconstruction (14).

Relevant anatomy

Breast sensibility depends primarily on anterior and lateral cutaneous branches of the ICNs 2 through 6, with more minor contributions from the supraclavicular nerves. The lateral branch of the fourth ICN provides the dominant supply to the NAC in most individuals, but contributions from the third and fifth intercostal nerves can be substantial, and supraclavicular branches often influence upper pole sensibility.

The ICNs travel inferior to the ribs, dividing into lateral cutaneous branches, whose anterior rami traverse the breast parenchyma, and anterior cutaneous branches that emerge near the sternum to supply medial breast skin. The anterior and lateral cutaneous branches are sensory nerves with comparable axon counts, suggesting they are equally viable recipient targets for nerve coaptation (15,16).

The proximity of the anterior cutaneous branches to the internal mammary vessels facilitates nerve coaptation and vascular anastomosis within the same exposure. Just lateral to the sternum, the third ICN runs below the inferior margin of the third rib, passing anterior to the internal mammary vessels before issuing its anterior cutaneous branch. The lateral cutaneous branches are often divided during gland excision, but can be useful when preserved, particularly for direct NAC reinnervation (15). Use of the lateral branches for flap neurotization, however, creates a second anchor point in addition to the pedicle anastomosis, narrowing the options for flap orientation and increasing the risk of tension, on either the nerve or vessel repair.

The abdominal wall is innervated by the thoracic and lumbar ICNs, which enter the rectus sheath laterally, form plexiform networks with the deep inferior epigastric system, and bifurcate into motor and sensory components within the muscle. ICNs T10 through L1 supply the infraumbilical segment, traveling ventrally in a plane between the transversus abdominis and internal oblique muscles before piercing the rectus sheath laterally. Within the rectus, the nerves travel craniocaudally along the deep surface of the muscle with the lateral branch of the deep inferior epigastric artery, powering the muscle and intermittently sending off sensory branches that course toward the skin. These sensory branches superficialize primarily with the lateral row perforators as they pierce the anterior rectus sheath (17,18).

Rozen and colleagues used nerve stimulation to define two types of motor nerves that innervate the rectus abdominis muscle (17,18). Type I nerves supply narrow, vertically oriented sections of muscle that receive redundant innervation from collateral branches; type II nerves are larger and innervate large transverse segments of rectus without significant redundancy. Therefore, certain (type II) motor branches are critical to abdominal wall integrity and cannot be harvested without significant risk of abdominal wall denervation and laxity (17,18). Given that type I and type II nerve branches are not easily differentiated intra-operatively, it is crucial to preserve motor nerves during abdominal flap elevation by harvesting only sensory segments of the ICNs, distal to where the afferent component has branched from its motor sibling.

Restoring sensation in autologous breast reconstruction

The literature on restoring breast sensation is dominated by variations on Slezak et al.’s foundational report on neurotization of TRAM flaps. In that paper, a 6cm length of abdominal ICN was preserved during flap harvest and coapted directly to the lateral cutaneous branch of the fourth ICN at the chest (6). Given that pedicled TRAM flaps dominated autologous breast reconstruction in 1992, concerns about abdominal wall denervation were not yet relevant. Similarly, debate over the optimal recipient nerve at the chest was not yet pertinent as orientation of the pedicled flap on inset mandated use of a lateral cutaneous branch.

As free abdominal flaps rapidly replaced pedicled TRAM flaps in breast reconstruction, plastic surgeons took advantage of the increased spatial flexibility to refine their approach to flap neurotization. Neurorrhaphy to the lateral cutaneous branch at the chest imposes several limitations, including restriction of flap mobility on inset and reliance on the oncologic surgeon to preserve a viable stump. To circumvent these challenges, Spiegel and colleagues introduced a technique for deep inferior epigastric artery perforator (DIEP) flap neurotization using the anterior branch of the third ICN, adjacent to the vascular anastomoses to the internal mammary vessels (19). Neurorrhaphy to the anterior cutaneous branch confined all microsurgical connections to a single point, facilitating flexibility on flap inset and improving surgical efficiency.

Despite performing a sensory-only nerve transfer, the requirement for a sufficiently long donor nerve segment compelled surgeons to divide the abdominal ICN branch upstream of its motor-sensory bifurcation. As a result, efforts to neurotize the breast almost certainly increased the risk of abdominal wall denervation (18). To overcome this obstacle, in 2018, the senior author (A.M.) introduced a technique in which only the sensory portion of the abdominal ICN is harvested, using nerve allograft to bridge the gap between the short donor segment and the anterior cutaneous branch of ICN 3 at the chest (20,21). This technique has been previously described in detail (20,21), but involves identification of sensory nerves traveling with lateral row perforators during abdominal flap elevation. Retrograde dissection proceeds to the sensory-motor-Y-junction of either ICN 11 or ICN 12. The sensory branch is transected immediately distal to the bifurcation, sparing the motor fibers that supply the rectus muscle. The resulting donor nerve is consequently only about 3cm long and, therefore, too short to reach recipients at the chest. To bridge this gap, an interpositional nerve allograft is used to facilitate tensionless neurorrhaphy to the anterior cutaneous branch of ICN 3. Importantly, the proximal neurorrhaphy is completed before pedicle division and the distal coaptation deferred until after vascular anastomoses are complete, so that neurotization has no effect on the length of flap ischemia. The flap is subsequently inset after dermis and epidermis have been removed, to bring regenerating axons into closer contact with native breast skin (3,16,20,21).

Efforts to coapt the short, sensory-only component of the abdominal nerve to the anterior ICN branch at the chest often result in 35–50 mm gaps (3,20,21). While nerve allograft remains our preferred bridging material (3,20), other spanning solutions have been proposed, including hollow nerve conduits (4,22) and ICN autograft (13). The use of nerve allograft has been studied most extensively in the upper extremity literature, where its reinnervation potential appears noninferior to nerve autograft for gaps of 70 mm or less (23). While research comparing the use of interpositional nerve allograft to primary nerve coaptation in the context of breast reconstruction is limited, early studies have not shown significant differences in terms of sensory outcomes (24).

Outcomes of neurotization in autologous breast reconstruction have been overwhelmingly positive, both in terms of objective results and PROs. Numerous studies have demonstrated clinically meaningful recovery of pressure sensitivity—measured using Semmes-Weinstein monofilaments (SWMs)—sooner (typically within 6–12 months), more uniformly, and to a greater ultimate magnitude in neurotized breasts compared with non-neurotized controls (2,3,5,6,10,25-27). Individual studies confirm superior reinnervation of neurotized flaps in terms of 2-point discrimination (6,25-27), vibration sensitivity (6,10,26,27), and sharp/blunt differentiation (26,27). A recent meta-analysis found that neurotized breast flaps achieved mean SWM score improvements of −0.67 overall, with a DIEP-specific subgroup analysis showing an even greater benefit at −0.86 (14). That article concluded that while neurotization in autologous breast reconstruction is associated with significant improvements in tactile sensory recovery, a lack of randomized control trials and standardized testing methodology precludes final clinical recommendations (14).

PRO studies on autologous breast reconstruction consistently reinforce the quality-of-life advantages of neurotization. In 2009, Temple et al. used three validated quality-of-life surveys to show that patients with neurotized free TRAM flaps scored significantly higher than non-neurotized controls across physical function, physical role, general health, social function, and emotional role domains (25). Subsequent studies have linked breast neurotization with marked improvements in multiple BREAST-Q domains, including psychosocial well-being, sexual well-being, physical well-being of the chest, and satisfaction with the medical team (13). Despite considerable variability in the instruments used to evaluate PROs, studies consistently associate neurotization with improved patient satisfaction and quality-of-life benefits. Importantly, the strength of existing PRO data is attenuated by the underrepresentation of high-risk neurosensory cohorts including elderly patients, those requiring radiation therapy, and those undergoing delayed reconstruction.

Restoring sensation in alloplastic breast reconstruction

Compared to the robust history of flap neurotization in autologous breast reconstruction, sensory restoration in implant-based reconstruction is a relatively novel concept with few examples in the literature. Since Peled and Peled’s initial description in 2019, six primary studies including 212 patients have discussed NAC neurotization in implant-based breast reconstruction (11-13,28-30). In each report, lateral cutaneous branches of the third, fourth, or fifth ICN are coapted via nerve graft to the undersurface of the NAC following nipple-sparing mastectomy. In most cases, nerve allograft is used to bridge the gap between a lateral cutaneous branch stump and the NAC, though Shyu et al. used segments of ICN autograft instead (13). While Peled and Peled suture the nerve graft to a subareolar nerve preserved during mastectomy, most authors secure the graft directly to the underside of the NAC (11,29). Proximal neurorrhaphy to the ICN at the chest wall is typically performed first, followed by standard prepectoral implant placement, and then distal coaptation proceeds after draping the nerve graft directly over the prosthesis. Neurotization via the lateral cutaneous ICN branches has been described for both prepectoral and subpectoral implant-based reconstructions.

Limitations and future directions

Widespread adoption of breast neurotization has been tempered by concerns about additional costs, increased operative time, and modest reimbursement. While one recent study reported that NAC neurotization added a mean cost of $7,839 per breast in implant-based reconstruction (30), the literature lacks a cost-effectiveness analysis comparing these expenses to the outcomes achieved. From an operative efficiency perspective, the additional time required for nerve coaptation is marginal, ranging from 8 to 38 minutes in various studies (24). There is no published guidance specifically addressing reimbursement for breast neurotization, resulting in bundling and undervaluation of neurorrhaphy procedures in breast reconstruction.

Overall, the current evidence for breast neurotization in autologous breast reconstruction is moderate-quality and limited by predominantly observational study designs. Heterogeneity in testing methodology and follow-up timing undermines the reliability and replicability of results. Divergent technical approaches similarly limit the reproducibility of outcomes reported in the literature, which is dominated by small, single-center, non-randomized studies. Confidence in the value and technical feasibility of neurotization in breast reconstruction would be bolstered significantly by a robust, multi-center, randomized trial.

Mirroring the limitations of the autologous reconstruction literature, conclusions regarding alloplastic neurotization are constrained by inconsistent testing protocols and compounded by even smaller patient cohorts. In general, results are encouraging, with Peled and Peled reporting that 87% of neurotized breasts achieved complete return of pre-operative NAC sensation at 3 month follow-up (11). Other studies convey more modest findings but consistently demonstrate expedited sensory recovery among neurotized NACs with few complications.

Conclusions

Restoration of breast and nipple sensation has become an increasingly central goal of modern breast reconstruction. Three decades of incremental refinements, including sensory-only abdominal nerve harvest, allograft-bridged coaptation, and direct NAC reinnervation in implant-based reconstruction, have resulted in improved sensory recovery while minimizing donor-site morbidity. Objective measures of pressure sensitivity, two-point discrimination, and vibratory detection, together with patient-reported gains across multiple BREAST-Q domains, converge on the same conclusion: neurotized breasts consistently outperform their non-neurotized counterparts. Broader adoption depends on standardized sensory testing protocols, robust cost-effectiveness data, and adequately powered multicenter randomized trials. Until higher-quality evidence emerges, neurotization will remain a niche technique performed by a limited subset of plastic surgeons.

Acknowledgments

None.

Footnote

Provenance and Peer Review: This article was commissioned by the Guest Editor (Ayush Kapila) for the series “Innovations in Breast Surgery” published in Annals of Breast Surgery. The article has undergone external peer review.

Peer Review File: Available at https://abs.amegroups.com/article/view/10.21037/abs-2025-1-63/prf

Funding: None.

Conflicts of Interest: Both authors have completed the ICMJE uniform disclosure form (available at https://abs.amegroups.com/article/view/10.21037/abs-2025-1-63/coif). The series “Innovations in Breast Surgery” was commissioned by the editorial office without any funding or sponsorship. A.M. reports consulting fees from AxoGen, Evergen, Gore, and Tiger Aesthetics. The authors have no other conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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