Nipple-areolar complex neurotization in implant-based breast reconstruction: a narrative review

Introduction

Nipple-sparing mastectomy (NSM) with immediate implant-based breast reconstruction (IBBR) preserves the native skin envelope and nipple-areolar complex (NAC) while providing oncologically acceptable treatment for appropriately selected patients (1). Preservation of appearance, however, does not preserve innervation. Mastectomy divides medial and lateral intercostal sensory pathways, and implant reconstruction is associated with substantial loss of breast and NAC sensation (2-4). Consequences extend beyond numbness: patients may experience impaired protective touch, reduced thermal warning, dysesthesia, itching, altered breast awareness, and changes in sexual function (5,6). Protective, tactile, thermal, and erogenous sensation are distinct domains, and recovery in one domain should not be assumed to predict recovery in another (6,7).

Sensory restoration developed initially within autologous breast reconstruction, where flap neurotization and nerve coaptation were investigated as methods to accelerate or improve reinnervation. Reviews of that literature describe heterogeneous donor and recipient nerves, flap types, testing methods, and outcomes, but established the broader premise that breast reconstruction can include a functional sensory objective (8-12). Implant-based NAC neurotization subsequently adapted peripheral nerve preservation, direct coaptation, processed allograft, and targeted reinnervation concepts to the preserved skin envelope and nipple. Early implant-based reports demonstrated technical feasibility, followed by prospective cohorts, a randomized open-label study, and systematic reviews that suggest a sensory benefit signal while confirming substantial methodological heterogeneity (13-18).

The implant-based setting is not a simple extension of autologous neurotization. The donor and recipient must be connected around a prosthetic pocket rather than through vascularized flap tissue; implant base width and projection, reconstruction plane, donor length, and operative sequencing may determine whether coaptation is feasible. Acellular dermal matrix (ADM) or capsule interfaces, tissue expansion, later exchange, and route compression are plausible technical concerns, but breast-specific outcome thresholds have not been validated. Endoscopic and robotic NSM may alter visualization and access to sensory pathways, although current evidence does not establish superior sensory recovery or remove the need to consider reconstruction of divided nerves (3,19).

The clinical question is therefore not simply whether sensation can be detected after reconstruction, but whether a procedure can restore function that is meaningful to an individual patient without compromising cancer treatment. Published studies rarely use a common definition of protective recovery, and erogenous or thermal outcomes are usually secondary, inconsistently measured, or absent. At the same time, techniques now differ in donor preservation, recipient field, bridge material, and prosthetic setting. A decision-oriented synthesis is needed to prevent technical feasibility from being interpreted as established effectiveness or routine candidacy.

This review addresses four clinical questions: which sensory branches can be preserved or used after NSM; which recipient targets and bridge strategies are supported by direct implant-based evidence; how prosthetic reconstruction modifies route and tension feasibility; and when neurotization should be modified, abandoned, or replaced by deliberate stump management. The variability of donors, targets, implant planes, grafts, testing instruments, anatomical zones, and follow-up makes a pooled estimate poorly suited to these questions. A narrative design permits critical comparison of direct and indirect evidence without implying systematic-review completeness or guideline-level certainty. We present this article in accordance with the Narrative Review reporting checklist (available at https://gs.amegroups.com/article/view/10.21037/gs-2026-0298/rc).

Methods

Review design and objectives

This narrative review was designed to synthesize evidence relevant to surgical anatomy, nerve preservation, donor usability, recipient targeting, bridge selection, implant-specific constraints, sensory outcomes, pain and denervation symptoms, complications, oncologic safety, cost, and reporting standards for NAC neurotization in NSM-IBBR. The review was not designed as a systematic review, meta-analysis, clinical guideline, or consensus process.

Information sources and search strategy

PubMed was the primary indexed database. Google Scholar and backward and forward reference chaining were used as supplementary discovery methods to identify potentially relevant peer-reviewed publications and citation links. The documented search period extended from database inception through 15 May 2026. Term families included NSM, IBBR, NAC neurotization or reinnervation, intercostal nerve anatomy and preservation, recipient targets, allograft and autograft, sensory testing, pain, neuroma, TMR, RPNI, complications, and cost. Table 1 summarizes the approach. Table S1 provides example PubMed strategies that illustrate the search approach used for this narrative review; S1-S5 are not presented as a prospectively archived systematic-search history, and exact result counts are not reported because they were not previously recorded.

Eligibility criteria

English-language, peer-reviewed anatomical studies, technical reports, clinical series, comparative or randomized studies, systematic or scoping reviews, and focused scholarly reviews were eligible when relevant to the predefined clinical questions. Direct evidence concerned oncologic NSM-IBBR or implant-based NAC neurotization. Supportive evidence included mixed breast-reconstruction cohorts, autologous neurotization, and gender-affirming targeted NAC reinnervation when the technical or measurement principle was transferable. Adjacent peripheral nerve and neuroma literature was retained only for clearly labelled biological or nerve-end-management context. Non-peer-reviewed media, unsupported opinion, and sources without transferable relevance were excluded from substantive synthesis.

Source selection and full-text assessment

Sources were selected according to relevance to the predefined clinical questions rather than to an exhaustive systematic-search denominator. Candidate publications identified through PubMed, supplementary discovery, or reference chaining were assessed for topical relevance; publications substantively relied upon for anatomical, technical, outcome, safety, cost, or biological claims were assessed in full text. W.S. and D.M. jointly selected publications for inclusion. Disagreements regarding relevance or interpretation were resolved through discussion and consensus. The process did not use dual independent systematic-review screening, formal adjudication, or a PRISMA-style flow.

Data extraction

For included sources, the synthesis recorded, when reported, study design, population and reconstructive setting, number of centers, comparator, donor nerve, preservation status, recipient target, bridge or graft, reconstruction plane, sensory instruments and anatomical testing zones, patient-reported outcomes, pain and denervation symptoms, complications, follow-up, and principal limitations. Attempted, completed, modified, and abandoned procedures were noted when authors reported them. W.S. extracted the study characteristics and findings used in the synthesis, and D.M. checked the extracted information for accuracy, completeness, and clinical interpretation. Extraction was not performed independently in duplicate.

Evidence appraisal and prioritization

Evidence was appraised narratively according to study design, sample and center context, directness to oncologic IBBR, consistency, applicability, comparator quality, participant or assessor blinding, outcome methodology, anatomical specificity, and duration of follow-up. Direct implant-based evidence received greatest weight for clinical statements. Supportive and adjacent evidence was used to explain anatomy, biological plausibility, measurement, or nerve-end management, but was not treated as proof of effectiveness in NSM-IBBR. No formal risk-of-bias instrument or numerical evidence grade was applied.

Narrative synthesis

Sources were synthesized around the operative sequence: oncologic and flap-safety conditions, native nerve preservation, donor usability, recipient target, route and tension feasibility, direct or graft-based repair, management of an unused stump, and postoperative outcome assessment. Conclusions were framed as supported by direct evidence, uncertain because evidence was insufficient or inconsistent, or technically plausible but not clinically validated. Quantitative pooling was not attempted because of heterogeneity in operative techniques, denominators, comparators, sensory tests, anatomical zones, patient-reported outcomes, and follow-up.

Handling of overlapping and recent evidence

When multiple publications addressed the same technique or cohort, the most informative full-text report was used for the specific claim, while systematic and scoping reviews were used to characterize consistency and methodological gaps rather than to duplicate primary-study findings. Recent publications already contained in the verified evidence set were assessed for direct relevance to the clinical questions. Broad oncologic standards were considered where applicable; the evidence set did not support a neurotization-specific guideline or consensus statement.

Methodological limitations

The approach is less reproducible than a prospectively registered systematic review. Supplementary Google Scholar discovery and reference chaining do not provide a stable denominator; English-language eligibility may have omitted relevant evidence; and the absence of dual independent screening, duplicate extraction, and formal risk-of-bias scoring increases susceptibility to selection and interpretation bias. These limitations were addressed by explicit evidence-directness labels, full-text assessment of substantively relied-upon sources, conservative claim boundaries, and separation of direct findings from author synthesis.

Evidence-base overview

The evidence base is clinically suggestive but methodologically immature. Direct implant-based literature includes technical descriptions, small case series, prospective and retrospective observational cohorts, and limited randomized evidence. The randomized evidence comprises an open-label study of posterior areolar tissue anastomosis and a double-blind pilot focused principally on postoperative pain; neither resolves comparative questions across donor levels, recipient targets, reconstruction planes, or graft types (13-18,20). Broader systematic and scoping reviews include mixed reconstructive settings and repeatedly identify small samples, single-center concentration, inconsistent comparators, variable sensory instruments, and short or uneven follow-up (8-12,17,18,21).

Interpretation is further limited by outcome and denominator bias. Studies use different units of analysis, NAC and breast testing zones, monofilaments or pressure devices, threshold definitions, and patient-reported measures. Participant and assessor blinding is often absent or incompletely reported, which is especially relevant to examiner-dependent testing and subjective outcomes. Many reports describe patients or breasts in which neurotization was completed without reporting all cases in which it was planned, attempted, modified, or abandoned. Consequently, published feasibility may overrepresent favorable anatomy and cannot establish pathway-specific success rates or universal candidacy (17,21).

The strongest inferences are therefore limited. Direct evidence supports technical feasibility in selected anatomy and a reproducible signal of measurable sensory recovery. It does not establish the incremental benefit of neurotization over spontaneous reinnervation for every reconstruction, the durability of recovery beyond the reported follow-up, or comparative superiority among donors, targets, and bridges. Technical reports are valuable for defining operative possibilities, but cannot provide unbiased candidacy rates. Observational comparisons may be confounded by surgeon selection, flap quality, implant strategy, treatment indication, and willingness to undergo added procedures. Randomized findings should be interpreted within their specific target and outcome rather than generalized to all NAC neurotization.

Surgical anatomy and preservation

Breast and NAC sensation is supplied by medial anterior cutaneous and lateral cutaneous intercostal pathways. Anterior cutaneous branches from approximately T2-T6 contribute to the medial breast, whereas anatomical studies consistently identify T3-T5 contributions to the NAC (22,23). In implant reconstruction, the lateral corridor is usually more accessible for a lateral-to-central route. The T4 lateral cutaneous branch is the most consistently identified contributor, but T3 and T5 participation is variable; current evidence does not establish superior clinical performance for one usable level over another (22-24). Table 2 translates these findings into neutral operative implications.

Depth and relationship to the oncologic specimen are more important than level alone. A superficial sensory branch already outside glandular tissue may remain in continuity when preservation does not compromise skin-flap perfusion, retroareolar clearance, or extirpative quality. A branch that traverses breast tissue, remains adherent to the specimen, or follows a deep course generally cannot be preserved without weakening the mastectomy. Nerve preservation therefore means retaining a safely separable structure, not leaving breast tissue to protect a sensory pathway (25).

The lateral pectoral border and anterior-to-midaxillary region are practical identification zones. Deliberate dissection, limited thermal spread, and controlled management of accompanying vessels may reduce avoidable nerve injury (24,25). Robotic exposure may improve visualization of relevant pathways, but its effect on sensory outcomes is not established (19). Deeper dissection toward the main intercostal trunk can provide length or autologous graft material, although it increases complexity and pleural proximity; pleural rupture was reported in two patients in one series of intercostal branch elongation (26). Deeper harvest is therefore a selective option rather than a default response to an unfavorable superficial branch.

Anatomical consistency should not be equated with a deterministic sensory map. Intercostal branching, fascicular caliber, and the relative contribution of anterior and lateral pathways vary, and clinical testing does not reliably identify which donor generated a recovered sensory territory. The operative value of the T3-T5 corridor is therefore its reproducible accessibility and documented relationship to the NAC, not proof that a particular branch will restore a particular sensory domain. Studies should report all exposed donor levels, not only the branch ultimately selected, so that anatomical availability can be separated from surgeon preference and completed-procedure reporting.

Implant-specific biological and mechanical constraints

Implant reconstruction imposes a geometric constraint that is less prominent in free-flap neurotization. Direct implant-based technical evidence supports consideration of implant pocket or base width, available donor length, access to the lateral donor zone, and sequencing of coaptation when the device may cover the donor site (28). The relevant clinical question is whether a usable donor and credible target can be connected without tension through the anticipated reconstruction. Route assessment may be repeated after pocket definition or device placement, but no evidence establishes a mandatory device-in-place measurement protocol.

Other concerns remain biologically plausible rather than clinically validated. ADM or capsule transitions, device-related compression, kinking, tissue expansion, later exchange, and route vascularity could influence a regenerating construct, yet no breast-specific thresholds or outcome-based routing rules have been demonstrated (17,21). A technical report recommends documenting the graft course so that it can be identified and avoided at expander-to-implant exchange (28); evidence does not define required protected slack or a superior exchange-incision pathway.

Peripheral nerve studies provide mechanistic context but should not be converted into implant-specific rules. Experimental work associates long acellular grafts with Schwann-cell senescence, and other models demonstrate interactions among vascular remodeling, conduit vascularization, and regeneration (29-32). These studies support caution about regenerative distance and tissue environment, but they do not establish a clinical gap cutoff, compression threshold, vascularity requirement, or bridge hierarchy for NAC neurotization. Implant-pocket variables should therefore be documented as technical characteristics and candidate modifiers rather than validated predictors.

Prepectoral and subpectoral reconstruction may create different access, curvature, and tissue-interface conditions, while an expander introduces a later change in pocket volume and a second operation. These differences are clinically relevant to planning but have not been compared sufficiently to support plane-specific recommendations. Similarly, a route that appears visually protected may not be biologically superior, and a longer route does not have a validated point at which repair becomes futile. The appropriate evidence-based position is to document plane, device stage, anticipated route, coaptation sequence, and later exchange handling, while avoiding claims that any one configuration guarantees or precludes regeneration.

Donor-state decision-making

Donor-state assessment follows oncologic resection. If a superficial sensory branch can safely remain in continuity, preservation avoids transection and an interposition graft, although comparative superiority has not been proven (25). When preservation is not possible, the proximal stump should be assessed for identity, integrity, caliber, orientation, available length, and morbidity of further dissection. T4 is commonly used, but a usable T3 or T5 branch may also be considered; donor level alone does not determine outcome (17,21-24).

A transected donor is reconstructively useful only when it can be paired with an anatomically credible target through a tension-free anticipated route. An identifiable donor does not justify repair if the target is absent, the stump is damaged, access is unsafe, or implant geometry makes coaptation technically non-credible. Direct implant-based reports most often describe a lateral intercostal donor connected to the NAC with processed allograft, while direct repair, branch elongation, and autograft have been reported in selected settings (13-17,26-28,33). The literature rarely reports all intraoperative donor states, so the relative frequency of preservation, reconstruction, modification, and non-use remains unknown.

Selective non-use should be recorded as an operative outcome rather than treated as procedural failure. Reasons may include oncologic or perfusion concerns, no usable donor, no meaningful target, inability to obtain a tension-free route, or disproportionate operative burden. No validated escalation sequence requires progression from direct repair to allograft, autograft, branch elongation, or deeper harvest.

Donor quality should also be distinguished from donor presence. A branch may be visible but thermally injured, crushed, excessively short, poorly aligned, or associated with morbidity that outweighs the expected sensory objective. Conversely, an anatomically less typical branch may be usable if it is intact and provides a credible route. These judgments are intraoperative and have not been converted into validated scoring criteria. Describing the observed donor state and the reason for selection or rejection is therefore more informative than reporting only the final donor level.

Recipient-target strategies

Recipient targets represent distinct interventions and should not be pooled under a single label. A discrete subareolar nerve stump provides the most anatomically specific nerve-to-nerve endpoint when it is identifiable, viable, appropriately oriented, and oncologically acceptable. Implant-based reports support technical feasibility, but the stump may be absent, damaged, very small, or difficult to distinguish from ducts and scar (13,15,28). Evidence does not establish that stump coaptation is superior to other targets.

When no discrete stump is available, targeted reinnervation of a viable retroareolar or subdermal NAC field distributes donor fascicles or graft ends toward a defined sensory field (28). Direct anastomosis to posterior areolar tissue has randomized open-label support for improved early Semmes-Weinstein testing in a specific subpectoral prosthetic setting (16). Direct implantation or coaptation at the nipple base has also been described, including autograft and adjacent reconstructive contexts, but quantitative oncologic IBBR evidence remains limited (27,33-36). Gender-affirming studies contribute technical and measurement information, yet differ in mastectomy purpose, nipple handling, patient characteristics, and adjuvant treatment and therefore remain supportive rather than directly generalizable evidence (34-37).

Reports should identify the exact endpoint—subareolar stump, retroareolar or subdermal field, posterior areolar tissue, nipple base, or mixed strategy—and describe fixation, coaptation, and testing zones. Table 3 summarizes reported use, technical implications, and limitations without assigning a preferred target.

The choice among these targets reflects different assumptions about how regenerating axons will reach cutaneous end organs. Nerve-to-nerve coaptation offers a discrete distal pathway; field or tissue targeting relies on dispersion within viable recipient tissue; direct nipple-base strategies seek proximity to nipple sensory structures. The literature does not yet show whether these biological distinctions translate into different recovery speed, topographic accuracy, protective function, or erogenous sensation. Comparative studies must therefore preserve the target taxonomy rather than aggregate all procedures as NAC neurotization.

Bridge and graft strategies

Bridge selection begins only after donor, target, and anticipated route are defined. Direct repair is technically attractive when donor and target meet without tension because it avoids an interposition graft. This condition is anatomy-dependent and should not be achieved by compromising donor integrity, target quality, or oncologic dissection. No comparative IBBR study demonstrates that direct repair is universally superior.

Coaptation technique is another source of heterogeneity. Reports describe microsutures, connectors or wraps, fascicular distribution, and different distal fixation methods. Such adjuncts may facilitate handling or protect a coaptation, but available breast evidence does not establish that one interface improves sensory outcomes. Conduit-like devices should not be assumed to solve a long interposition gap unless the construct and distance are supported by appropriate evidence. The number and location of coaptations, caliber mismatch, and fixation method should be documented because they may influence interpretation even when the same graft material is used.

Processed acellular nerve allograft has the strongest implant-based clinical precedent. Early reports and later cohorts used allograft to connect lateral intercostal donors to NAC targets and documented measurable early sensory recovery in selected patients (13-15). Its practical advantages are availability, avoidance of a second donor site, and compatibility with immediate reconstruction. The evidence does not define a validated gap-length cutoff, acceptable curvature or compression, required vascular environment, or economic threshold for use (17,21). Experimental long-graft biology warrants caution but does not prove clinical failure in the breast (29).

Autologous approaches include intercostal branch elongation, local intercostal autograft, adjacent branch transfer, and distant sural grafting (26,27,33). They avoid processed allograft material but require additional dissection and create donor-site or donor-stump considerations; deeper intercostal harvest also introduces pleural proximity (26,27,33). The available breast studies demonstrate technical feasibility and, in selected cohorts, favorable sensory findings, but they do not directly compare autograft with allograft in oncologic IBBR. Avoiding the purchase price of allograft does not establish lower total procedural cost because operative time, expertise, instruments, and donor morbidity also contribute.

Accordingly, allograft versus autograft is not a validated hierarchy. Allograft has greater direct implant-based precedent; autograft and elongation provide reported alternatives when anatomy, donor availability, and operative context support them. Clinical selection remains individualized, and comparative biological or economic superiority is unestablished. Table 4 presents each strategy by reported use, technical considerations, and evidence limitations.

Unused transected stump management

A transected sensory donor that is not used for NAC reconstruction remains a potential source of disorganized axonal growth and neuropathic symptoms. Targeted muscle reinnervation (TMR) and regenerative peripheral nerve interface (RPNI) are distinct active nerve-end strategies supported principally by limb-amputation literature, whereas simple implantation into muscle is a separate method with less consistent evidence (38,39). Breast reports establish technical feasibility of intercostal TMR and provide preliminary uncontrolled data for prophylactic intercostal RPNI (40,41). Their effectiveness for unused sensory stumps during NSM-IBBR is not established.

Possible breast-adapted approaches include documented intramuscular placement, TMR or RPNI in appropriately selected anatomy, other deliberate nerve-end management, or no additional procedure. No technique can be recommended as mandatory. Future reports should state whether a stump was left free, buried, transferred, incorporated into an active nerve-end procedure, or otherwise managed, and should link that information to pain, dysesthesia, and neuroma outcomes.

Symptoms attributed to an unused stump are also difficult to distinguish from broader postmastectomy pain, scar sensitivity, implant discomfort, or intercostal injury elsewhere in the field. Studies evaluating stump management should use predefined anatomical examination, symptom mapping, and longitudinal assessment rather than rely only on unplanned reoperation or a diagnosis of clinical neuroma. Reporting negative findings is important because the absence of a recorded neuroma in a small cohort is not equivalent to a validated preventive effect.

Clinical outcomes and evidence limitations

Outcome interpretation should begin with methodology. Most direct studies are small and frequently single-center, use selected completed procedures, and differ in reconstruction plane, donor, target, bridge, testing device, anatomical zone, and follow-up (8-12,17,18,21). In observational cohorts, participant and assessor blinding is commonly absent or incompletely described. Open-label testing is vulnerable to expectation and examiner effects, while objective thresholds still depend on standardized application, zone selection, and prespecified definitions. These limitations preclude a firm estimate of effect magnitude or a reliable comparison among techniques.

Selection bias operates at several levels. Surgeons may offer neurotization to patients with favorable flaps, identifiable donors, and reliable follow-up; patients may self-select according to sensory priorities and willingness to accept additional cost or time; and published series may exclude cases in which the plan was abandoned. Contralateral-breast or historical controls do not fully address these differences. Without consecutive eligibility and attempted-procedure denominators, apparent feasibility, complication rates, and sensory recovery may be inflated relative to routine practice.

Objective sensory findings nevertheless provide a consistent signal that neurotization can produce measurable recovery in selected patients. Early implant-based series documented return of NAC or breast sensibility after nerve preservation and allograft reconstruction (13,14). A larger prospective series reported good-to-excellent one-point moving and static sensibility in more than 80% of patients at 6 months, although the selected cohort, short follow-up, and absence of a contemporaneous randomized comparator limit inference (15). The randomized open-label posterior areolar tissue study found improved Semmes-Weinstein results at 3 and 6 months in a defined subpectoral setting (16). Systematic reviews generally support a possible benefit but cannot identify a superior donor, target, graft, or reconstruction plane (8-12,17,18,21).

Objective thresholds and patient-reported outcomes should be separated. Monofilament testing, pressure-specified sensory devices, two-point discrimination, vibration, temperature, and pain thresholds measure different constructs. Studies also vary in whether they test the nipple, areola, central breast, quadrants, or an average of multiple zones. A change in one zone or modality does not establish restoration of normal protective function. Baseline testing is important because preoperative breast and NAC sensation may already differ between patients or sides (2-4,42).

Patient-reported breast awareness, nipple sensation, satisfaction, psychosocial well-being, and sexual well-being provide complementary information but are not interchangeable with sensory thresholds. A prospective mixed-reconstruction cohort reported higher nipple sensation scores, improved BREAST-Q psychosocial and sexual well-being domains, and fewer denervation symptoms with neurotization (43). Other literature emphasizes that erogenous sensation, nipple erection, body ownership, and thermal safety are incompletely and inconsistently measured (7,18,21,35,42). The current evidence therefore supports discussing possible domain-specific recovery, not promising normal or erogenous sensation.

Clinically meaningful recovery has not been standardized. A lower monofilament threshold may represent statistical improvement without restoring protective warning, and an average breast score may obscure persistent NAC anesthesia. Conversely, a patient may value modest recovery in breast awareness or sexual well-being even when threshold testing remains abnormal. Future analyses should define responder thresholds for each domain, report absolute values and change from baseline, and avoid combining objective and subjective endpoints into a single success label. Time-to-recovery curves may be more informative than one isolated postoperative assessment.

Pain and dysesthesia require separate analysis. A double-blind randomized pilot of intercostal nerve coaptation reported a lower Short-Form McGill Pain Questionnaire score at 6 months, while other pain measures and 12-month differences were less consistent (20). Observational reports describe low rates of persistent dysesthesia or clinical neuroma, but selected samples and limited follow-up reduce confidence (15,17). These findings do not establish prevention of postmastectomy pain syndrome. Future studies should prespecify pain, itch, numbness, dysesthesia, neuroma symptoms, and analgesic use rather than treating absence of reported complications as absence of symptoms.

Early safety findings are reassuring but incomplete. Available cohorts have not demonstrated a clear increase in implant loss or perioperative complications, and a matched-paired analysis found no significant perioperative complication increase with NAC neurotization (44). Rare complications, late implant events, reoperations, effects of radiotherapy, oncologic outcomes, and nerve-specific adverse events require larger denominators and longer follow-up. Safety claims should therefore remain limited to early selected cohorts.

Oncologic safety, patient selection, consent, economics and logistics

Oncologic resection is the overriding constraint. Neurotization does not change NSM eligibility, imaging assessment, retroareolar evaluation, margin management, or treatment of a positive nipple margin. NSM is oncologically acceptable in appropriately selected patients, but sensory preservation cannot justify retained glandular tissue, inadequate exposure, delayed cancer treatment, or compromise of flap perfusion (1,45,46). When oncologic assessment, donor integrity, target reliability, or flap safety is unfavorable, the planned sensory procedure should be modified or abandoned.

Candidate selection is individualized because validated predictors of sensory benefit are not available. Therapeutic versus risk-reducing indication, age, baseline sensation, incision and mastectomy approach, reconstruction plane, implant or expander strategy, systemic treatment, radiotherapy, wound-healing risk, and patient priorities are reasonable variables to record, but their independent predictive value is uncertain (3,4,17,21). Endoscopic or robotic access may improve visualization in selected cases, yet does not establish candidacy or superior sensory outcomes (3,19).

Consent should distinguish technical completion from clinical benefit. Patients should be informed that the final donor, target, and route may only be known intraoperatively; the plan may change from preservation to repair, from direct to graft-based reconstruction, or to non-use. Recovery is gradual, partial, and probabilistic. Protective touch, tactile threshold, thermal detection, nipple-specific sensation, pain, dysesthesia, erogenous sensation, nipple erection, and subjective breast awareness may recover differently (7,18,35,42). Neurotization can add operative time, material cost, and coordination requirements and does not guarantee normal sensation.

Logistical success requires coordination between breast and reconstructive teams. The donor zone should be recognized before avoidable thermal injury; device and pocket planning should preserve access for coaptation; and any graft course relevant to later expander exchange should be documented (25,28). These are technical planning considerations rather than validated outcome rules. Teams should also decide how sensory testing will be performed before and after surgery, because postoperative findings are difficult to interpret without defined baseline zones and instruments.

Applicability also depends on institutional capability. Nerve identification during mastectomy, microsurgical coaptation, sensory testing, and management at later exchange require coordinated workflows and documentation that may not be available in every setting. Added time should be evaluated in relation to bilateral surgery, immediate implant versus expander reconstruction, and competing reconstructive priorities. Adjuvant treatment should not be delayed for a sensory adjunct, and planned radiotherapy or reoperation should be recorded because they may alter both tissue conditions and follow-up. These factors affect implementation but are not validated exclusion criteria.

Economic evidence is limited. One matched-paired analysis reported an added mean cost of $7,839 per breast for NAC neurotization (44). Material price is only one component: operative time, microsurgical instruments, coordination, later procedures, and potential donor morbidity also affect cost. A relative-value model in gender-affirming surgery illustrates the influence of workflow and reimbursement context but is not directly transferable to oncologic IBBR (37). No current evidence establishes economic superiority of allograft, autograft, direct repair, or selective non-use.

Practical intraoperative decision framework

The proposed framework is a conditional sequence for clinical reasoning, not a validated guideline (Figure 1). Gate 0 is oncologic and flap safety: proceed with sensory reconstruction only when extirpation, retroareolar management, and perfusion remain uncompromised. Gate 1 asks whether a superficial sensory branch can safely remain in continuity. If not, Gate 2 evaluates whether the proximal donor is identifiable, intact, appropriately oriented, and usable. Gate 3 requires an anatomically credible recipient target: a subareolar stump, retroareolar or subdermal NAC field, posterior areolar tissue, or nipple-base target.

Figure 1 Conditional intraoperative decision framework for nipple-areolar complex neurotization in implant-based breast reconstruction. The sequence begins with oncologic and flap safety, followed by native nerve preservation, donor usability, recipient-target credibility, and route/tension feasibility. Direct repair is considered only when tension free; graft-based repair is conditional on anatomy, morbidity, operative burden, and resources, without a universal graft hierarchy or gap cutoff. Any unused transected stump is managed and documented according to the operative context. The final node records whether neurotization was planned, attempted, completed, modified, or abandoned and the reason. The framework supports clinical reasoning and reporting; it is not a validated clinical guideline. ADM, acellular dermal matrix; NAC, nipple-areolar complex.

Gate 4 assesses whether the anticipated route permits a technically credible, tension-free connection. This assessment considers donor length and implant geometry but does not apply mandatory device-in-place measurements or unvalidated compression, vascularity, ADM, capsule, or expansion thresholds. Gate 5 favors direct repair only when it is tension free. Gate 6 considers graft-based repair—processed allograft, local or distant autograft, or branch elongation—according to anatomy, donor morbidity, operative burden, and resources, without a universal hierarchy or gap cutoff.

Gate 7 addresses any unused transected stump; the selected management should be deliberate and documented, while acknowledging the indirect or preliminary evidence base. Gate 8 records whether neurotization was planned, attempted, completed, modified, or abandoned and why. Documentation of every pathway, including non-use, is necessary to reduce denominator bias and permit credible future estimates of feasibility and comparative effectiveness.

The framework deliberately avoids numerical cutoffs and mandatory techniques. A negative decision at any gate may lead to safe non-use, and a positive decision only permits consideration of the next step; it does not establish expected benefit. The gates should be revisited when new information emerges, particularly after pocket creation or device placement. Because several nodes rely on surgical judgment rather than comparative evidence, studies using the framework should record the observations underlying each decision rather than report the pathway alone.

Future research and reporting standards

Progress requires study designs that capture the full clinical pathway rather than only completed neurotizations. Multicenter prospective cohorts and registries should enroll consecutive eligible NSM-IBBR cases and report planned, attempted, completed, modified, and abandoned procedures with reasons for change. Pragmatic comparative studies could evaluate defined choices—such as coaptation versus no coaptation in a specified plane or one target strategy within standardized anatomy—while avoiding pooled comparisons of biologically different procedures.

Preoperative and postoperative assessment should use defined NAC and breast zones, prespecified instruments, consistent threshold definitions, and repeated time points extending beyond early recovery. Objective measures should be reported separately from patient-reported breast awareness, satisfaction, sexual well-being, pain, dysesthesia, itch, and thermal safety. Studies should define clinically meaningful recovery domains rather than equating any detectable threshold change with functional success (17,18,20,21,42,43). Sensory rehabilitation should also be described; breast-specific evidence for sensory re-education remains insufficient, but unreported rehabilitation may confound comparisons.

Technical reporting should include study design, number of centers, sample and comparator, blinding, baseline testing, donor level and condition, preserved versus transected status, target, bridge and length, reconstruction plane, implant or expander details, route and tension assessment, distal fixation, stump management, operative time, cost, adverse events, oncologic outcomes, and follow-up. ADM, capsule, compression, expansion, and route vascularity should be treated as exploratory variables unless outcome associations are demonstrated. Table 5 provides a minimum dataset for future studies; it is a reporting proposal, not a consensus standard.

Analytical plans should account for bilateral clustering, repeated sensory measurements, baseline asymmetry, missing follow-up, and confounding by indication. Core follow-up intervals should include early and later assessments sufficient to distinguish delayed axonal recovery from transient postoperative change. Comparative studies should prespecify the primary sensory domain and a clinically meaningful effect, while registries should permit exploratory evaluation of donor, target, route, and device variables. Complete reporting of negative, modified, and abandoned procedures will be as important as additional positive case series.

Strengths and limitations of the review

This review integrates direct implant-based evidence with clearly labelled supportive anatomy, autologous reconstruction, gender-affirming, peripheral nerve, and neuroma literature. Organizing the synthesis by operative decisions clarifies which statements are supported, which remain uncertain, and which represent technical plausibility. The recipient-target taxonomy, neutral bridge comparison, conditional framework, and proposed reporting dataset are intended to improve interpretation and study design rather than prescribe one technique.

The limitations are substantial. The review is narrative, uses PubMed as the primary indexed source with supplementary Google Scholar discovery and reference chaining, and is restricted to English-language peer-reviewed literature. It did not use dual independent systematic-review screening, duplicate extraction, formal risk-of-bias scoring, protocol registration, or quantitative pooling. The search examples were not a prospectively archived systematic-search history, and exact result counts were not available. Selection and interpretation bias therefore remain possible. In addition, the underlying studies are small, heterogeneous, often single-center, incompletely blinded, and limited by variable outcomes, follow-up, and attempted-versus-completed denominators. The framework should consequently be interpreted as structured clinical reasoning under uncertainty, not as a guideline or consensus recommendation.

Because no prospectively archived systematic-search record or exact result counts were available, the review cannot quantify search yield or guarantee comprehensive retrieval. The methodology also cannot support a formal certainty rating for each claim. These constraints do not prevent a critical narrative synthesis, but they require conservative language, explicit acknowledgement of indirect evidence, and avoidance of recommendations that exceed the underlying studies.

Conclusions

NAC neurotization is selectively feasible in NSM-IBBR and the available literature suggests a possible sensory benefit, but certainty is low because techniques, targets, outcome methods, denominators, and follow-up are heterogeneous. Current evidence does not support firm comparative recommendations for donor level, recipient target, bridge, or patient selection. Oncologic resection and flap safety remain primary, and decisions should be individualized according to usable anatomy and a tension-free credible route. Standardized reporting, complete attempted-procedure denominators, and prospective comparative research are required before the field can move from conditional decision support to validated clinical recommendations.

Acknowledgments

None.

Footnote

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