A Scoping Review of Innervated Breast Reconstruction.

BACKGROUND: After breast surgery, patients experience significant alterations to breast sensation, which can diminish quality of life. Nerve coaptation technique, introduced in the 1990s, has gained traction in recent years. We performed a scoping review of the literature to determine the available outcomes in sensate breast reconstruction. METHODS: The review was conducted using Preferred Reporting Items for Systematic Reviews and Meta-Analyses Extension for Scoping Reviews statement guidelines. EMBASE and PubMed databases were queried using standardized terminology. Studies were included if they reported original sensory outcomes following innervation techniques during breast reconstruction and were published from January 1, 1990, to April 18, 2022. Data extraction and analyses were performed on Microsoft Excel. RESULTS: From 602 screened articles, 27 studies met the inclusion criteria. Innervated autologous reconstructive procedures were described in 24, whereas the remaining 3 (all published after 2019) described direct reinnervation of the nipple-areola complex. Most (88.9%) of the studies comparing innervated versus noninnervated reconstruction reported improved sensory outcomes in at least 1 modality. Two studies investigated patient-reported outcomes using validated questionnaires, both of which reported improvement with innervated reconstruction. CONCLUSIONS: Sensate breast reconstruction has the potential to improve outcomes for patients. There is a recent progressive increase in studies involving direct nipple-areolar reinnervation. Larger, prospective studies are needed to better characterize the quality-of-life outcome using validated scales, as well as evaluate sensory and patient-reported outcomes with implant and autologous reconstruction.

Direct neurotization of free nipple grafts with cadaveric nerve grafts following mastectomy for gender affirming surgery.

BACKGROUND: Free nipple grafting makes sensory recovery challenging. Permanent decreased sensation to touch and temperature in skin-grafted skin is common. Direct neurotization of the nipple-areolar complex (NAC) graft has been described. However, quantitative data regarding degree of nipple reinnervation possible is unknown. This study aims to quantify and qualify sensation recovery following nerve coaptation to reinnervate the NAC. METHODS: Patients undergoing mastectomy for gender dysphoria from 2020 to 2022 were offered nerve allograft to restore nipple sensation. A lateral intercostal nerve was selected and coapted to allograft which was embedded beneath the nipple graft. Semmes Weinstein testing was used to assess nipple sensation. Assessments were made at visits <1 year and >1 year from surgery. Filaments used represented normal sensation, minor diminished sensation, diminished sensation, loss of protective sensation, and deep pressure sensation only. RESULTS: A total of 115 patients elected for direct neurotization. Semmes Weinstein testing was limited to 46 patients representing 46 encounters and 92 nipples in the <1 year group and 24 encounters and 48 nipples in the >1 year group. Of the 92 nipples in the <1 year group, 17 (18.5%) noted return of normal sensation and 37 (40.2%) noted minor diminished or diminished sensation, indicating nerve reinnervation. There were 38 (41%) nipples with loss of protective sensation or deep sensation only. There were 48 nipples included in the >1 year group. Of the 48 nipples, 4 (8.3%) noted normal sensation and 30 (62.5%) noted minor diminished or diminished sensation, indicating nerve reinnervation. For the remaining 14 nipples, 14 (29%) noted loss of protective sensation or deep sensation only. CONCLUSION: Sensory outcomes in NAC grafts used for reconstruction in patients undergoing double incision mastectomy remain poor. Sensation restoration beyond that expected from full thickness skin grafts can be achieved in the majority of patients with nerve allograft via direct neurotization.

Comparison of Sensory Changes Following Superomedial and Inferior Pedicle Breast Reduction.

BACKGROUND: More attention is focused on sensory outcomes following breast reduction operations. We conducted this prospective, non-randomized study to compare two commonly used breast reduction techniques, superomedial pedicle and inferior pedicle, regarding sensation of the nipple-areolar complex. METHODS: We prospectively assigned 60 patients with macromastia into the superomedial pedicle group (SMP group, n = 30) or the inferior pedicle (IP group, n = 30) group. Six patients who withdrew from the study and another six patients who did not attend return visits were excluded. Algometry was used to measure the sensation of breast skin, cardinal points of the areola and the nipple. Two-point discrimination was also measured on the areola. Measurements were performed before surgery, at 3 weeks, and 6 months postoperatively. RESULTS: There were 20 patients in the SMP group and 28 patients in the IP group. The mean ages of the patients were 43.2 ± 12.7 and 45.9 ± 10.8 years, respectively (p = 0.438). The mean BMI of the patients were 32.4 ± 6.7 and 30.4 ± 5.3 kg/m2, respectively (p = 0.257). The mean weights of resected tissues were 802.5 (280-2180) versus 773.7 (349.5-1425.0) g, respectively (p = 0.900). Although breast sensation did not change in the SMP group, sensation in the upper medial and lower lateral portions of breast skin was reduced in the IP group. Two-point discrimination test results did not change in either group. The amount of changes in algometry and two-point discrimination tests were similar in both groups. CONCLUSION: Both superomedial and inferior pedicle breast reduction techniques are safe and reliable in terms of sensory changes. LEVEL OF EVIDENCE III: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Septum-Inferior-Medial (SIM)-Based Pedicle: A Safe Pedicle with Well-Preserved Nipple Sensation for Reduction in Gigantomastia.

BACKGROUND: Reduction in breasts with well-preserved nipple sensation and a viable nipple-areola complex (NAC) is one of the basic core concepts of reduction mammoplasty. Many techniques have been described with enthusiasm advocating full achievement of the aforementioned goals. The goal of this study is to introduce a novel technique that provides an intact neurovascular source to the nipple-areola complex for reduction in gigantic breasts. PATIENTS AND METHODS: Twenty-six patients operated on from December 2010 through April 2015 were included in the study. The reduction was performed by isolating Wuringer's septum and the inferior pedicle in continuity with the medial pedicle to save the neurovascular supply to the NAC and its accompanying breast parenchyma. This pedicle is called as septum-inferior-medial-based pedicle. Inclusion criteria, marking and planning with detailed description of the surgical procedure are presented. RESULTS: The overall satisfaction rate was high. Eighty percent of the patients rated their results. The results were as follows: 81% rated as 'very satisfied'; 19% rated as 'somewhat satisfied.' NAC sensation was intact in all cases at all time intervals even immediately after surgery. CONCLUSION: The united pedicle technique provides an intact neurovascular source to the nipple-areola complex. Reduction with this pedicle is a safe procedure. Remodeling the gigantic breast can be accomplished without any restriction because of the flexibility of this pedicle. The very early results are promising, but long-term results needed to be evaluated. LEVEL OF EVIDENCE IV: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

"Toward Breast Reinnervation- What is our Endpoint" A systematic review of normal breast sensibility.

BACKGROUND: To restore breast sensibility, some centers are offering nerve reconstruction as a component of implant and flap-based breast reconstruction. To interpret and contextualize the results of these procedures, it is necessary to understand the normal range of breast sensibility, the factors that affect it, and the best methods for its objective measurement. METHODS: We conducted systematic and comprehensive searches across PubMed, Web of Science, and Cochrane Library databases using keywords and controlled vocabulary for the concepts of the breast, nipple, areola, and measurement. The search results were imported into Rayyan QCRI for a blinded screening of titles and abstracts. Studies were evaluated for bias using RevMan 5 software. The results of sensory measurements were pooled, and a quantitative summary of breast sensibility was generated. RESULTS: A total of 36 articles were identified, including retrospective, cross-sectional, and prospective studies. Although there were some consistent findings across studies, such that breast sensibility is inversely related to breast volume, there was wide variability in the following parameters: population, breast condition, measurement modality, anatomic areas of measurement, and sensibility findings. This heterogeneity precluded the generation of normative breast sensibility measurements. Furthermore, we detected a high degree of bias in most studies, due to self-selection of participants and failure to record patient characteristics that may alter sensibility. CONCLUSIONS: The literature lacks consistent data delineating normative values for breast sensibility. Standardized measurements of healthy volunteers with various breast characteristics are necessary to elucidate normative values and interpret efforts to restore sensibility in breast reconstruction.

Pilot study of breast sensation after breast reconstruction: evaluating the effects of radiation therapy and perforator flap neurotization on sensory recovery.

BACKGROUND: Some sensation to the breast returns after breast reconstruction, but recovery is variable and unpredictable. We primarily sought to assess the impact of different types of breast reconstruction [deep inferior epigastric artery perforator (DIEP) flaps versus implants] and radiation therapy on the return of sensation. METHODS: Thirty-seven patients who had unilateral or bilateral breast reconstruction via a DIEP flap or implant-based reconstruction, with or without radiation therapy (minimum follow-up, 18 months; range, 18-61 months) were studied. Of the 74 breasts, 27 had DIEP flaps, 29 had implants, and 18 were nonreconstructed. Eleven breasts with implants and 10 with DIEP flaps had had prereconstruction radiation therapy. The primary outcome was mean patient-perceived static and moving cutaneous pressure threshold in nine areas. We used univariate and multivariate analyses to assess what independent factors affected the return of sensation (significance, P < 0.05). RESULTS: Implants provided better static (P = 0.071) and moving sensation (P = 0.041) than did DIEP flaps. However, among irradiated breasts, skin over DIEP flaps had significantly better sensation than did that over implants (static, P = 0.019; moving, P = 0.028). Implant reconstructions with irradiated skin had significantly worse static (P = 0.002) and moving sensation (P = 0.014) than did nonirradiated implant reconstructions. CONCLUSIONS: Without irradiation, skin overlying implants is associated with better sensation recovery than DIEP flap skin. However, with irradiation, DIEP flap skin had better sensation recovery than did skin over implants. Neurotization trended toward improvement in sensation in DIEP flaps.

Female orgasm(s): one, two, several.

INTRODUCTION: There is general agreement that it is possible to have an orgasm thru the direct simulation of the external clitoris. In contrast, the possibility of achieving climax during penetration has been controversial. METHODS: Six scientists with different experimental evidence debate the existence of the vaginally activated orgasm (VAO). MAIN OUTCOME MEASURE: To give reader of The Journal of Sexual Medicine sufficient data to form her/his own opinion on an important topic of female sexuality. RESULTS: Expert #1, the Controversy's section Editor, together with Expert #2, reviewed data from the literature demonstrating the anatomical possibility for the VAO. Expert #3 presents validating women's reports of pleasurable sexual responses and adaptive significance of the VAO. Echographic dynamic evidence induced Expert # 4 to describe one single orgasm, obtained from stimulation of either the external or internal clitoris, during penetration. Expert #5 reviewed his elegant experiments showing the uniquely different sensory responses to clitoral, vaginal, and cervical stimulation. Finally, the last Expert presented findings on the psychological scenario behind VAO. CONCLUSION: The assumption that women may experience only the clitoral, external orgasm is not based on the best available scientific evidence.

A superior vertical dermal pedicle for the nipple-areola: an alternative for severe breast hypertrophy and ptosis.

BACKGROUND: Nipple-areola nourishment and sensation have been the main concern in reduction mammaplasty for severe breast hypertrophy and ptosis. Free grafting for the nipple-areola can cause flatness and loss of sensation. These complications can be improved by pedicle techniques for the nipple-areola, no matter the pedicle orientation. The aesthetic outcomes and complications are similar for the inferior and superior pedicle techniques. The pedicle length has been crucial to nipple-areola viability and sensation. METHODS: Using a keyhole pattern, a vertical flap with a superior pedicle was outlined for nipple-areola transposition. The mammary tissue under the flap was removed, creating a vertical dermal flap 7-14 cm long, and the superior pedicle was located on the new site of the areola marked by the pattern. Sensation was evaluated monthly by subjective contact testing of the four quadrants of the nipple-areola. RESULTS: The Pearson product-moment correlation coefficient was used to correlate the return of sensation with the length of the dermal flap and the amount of breast tissue removed. Sensation was achieved for the four quadrants 6 months after the breast reduction for all the patients of this series. Recovery of sensation was significantly greater for the superior quadrants than for the inferior quadrants in the first 3 months. CONCLUSIONS: The vertical dermal flap with the superior pedicle preserves nipple-areola nourishment and sensation. It is an alternative option for pedicle techniques in surgical correction of severe breast hypertrophy and ptosis.

Vertical reduction mammaplasty utilizing the superomedial pedicle: is it really for everyone?

BACKGROUND: Classically, the vertical-style reduction mammaplasty utilizing a superomedial pedicle has been limited to smaller reductions secondary to concerns for poor wound healing and nipple necrosis. OBJECTIVES: The authors reviewed a large cohort of patients who underwent a vertical-style superomedial pedicle reduction mammaplasty in an attempt to demonstrate its safety and efficacy in treating symptomatic macromastia. METHODS: A retrospective review was performed of 290 patients (558 breasts) who underwent a vertical-style superomedial pedicle reduction mammaplasty. All procedures were conducted by one of 4 plastic surgeons over 6 years (JDR, MAA, DLV, DRA). RESULTS: The average resection weight was 551.7 g (range, 176-1827 g), with 4.6% of resections greater than 1000 g. A majority of patients (55.2%) concomitantly underwent liposuction of the breast. The total complication rate was 22.7%, with superficial dehiscence (8.8%) and hypertrophic scarring (8.8%) comprising the majority. Nipple sensory changes occurred in 1.6% of breasts, with no episodes of nipple necrosis. The revision rate was 2.2%. Patients with complications had significantly higher resection volumes and nipple-to-fold distances (P = .014 and .010, respectively). CONCLUSIONS: The vertical-style superomedial pedicle reduction mammaplasty is safe and effective for a wide range of symptomatic macromastia. The nipple-areola complex can be safely transposed, even in patients with larger degrees of macromastia, with no episodes of nipple necrosis. The adjunctive use of liposuction should be considered safe. Last, revision rates were low, correlating with a high level of patient satisfaction.

Innervation of the Female Breast and Nipple: A Systematic Review and Meta-Analysis of Anatomical Dissection Studies.

BACKGROUND: Primary cadaveric studies were reviewed to give a contemporary overview of what is known about innervation of the female breast and nipple/nipple-areola complex. METHODS: The authors performed a Preferred Reporting Items for Systematic Reviews and Meta-Analyses-compliant systematic review and meta-analysis. The authors searched four electronic databases for studies investigating which nerve branches supply the female breast and nipple/nipple-areola complex or describing the trajectory and other anatomical features of these nerves. Inclusion criteria for meta-analysis were at least five studies of known sample size and with numerical observed values. Pooled prevalence estimates of nerve branches supplying the nipple/nipple-areola complex were calculated using random-effects meta-analyses; the remaining results were structured using qualitative synthesis. Risk of bias within individual studies was assessed with the Anatomical Quality Assurance checklist. RESULTS: Of 3653 studies identified, 19 were eligible for qualitative synthesis and seven for meta-analysis. The breast skin is innervated by anterior cutaneous branches and lateral cutaneous branches of the second through sixth and the nipple/nipple-areola complex primarily by anterior cutaneous branches and lateral cutaneous branches of the third through fifth intercostal nerves. The anterior cutaneous branch and lateral cutaneous branch of the fourth intercostal nerve supply the largest surface area of the breast skin and nipple/nipple-areola complex. The lateral cutaneous branch of the fourth intercostal nerve is the most consistent contributory nerve to the nipple/nipple-areola complex (pooled prevalence, 89.0 percent; 95 percent CI, 0.80 to 0.94). CONCLUSIONS: The anterior cutaneous branch and lateral cutaneous branch of the fourth intercostal nerve are the most important nerves to spare or repair during reconstructive and cosmetic breast surgery. Future studies are required to elicit the course of dominant nerves through the breast tissue.

Immediate targeted nipple-areolar complex re-innervation: Improving outcomes in immediate autologous breast reconstruction.

Breast reconstruction often renders the chest skin and nipple areolar complex (NAC) insensate. We propose a new technique of preserving the intercostal nerves during mastectomy and using them to reinnervate the NAC following mastectomy and immediate autologous tissue reconstruction. The technique involves preservation of the lateral intercostal nerves during mastectomy, dissection of the lateral intercostal nerves to length, coaptation of the intercostal nerves to a nerve graft which is then tunneled through the free flap and the distal nerve graft is then coapted to the nerve stumps at the base of the NAC. We performed a retrospective analysis of 14 breasts, which underwent nipple reinnervation during immediate autologous breast reconstruction. Mean age was 49 years (range: 32-61 years). Sensory outcomes, as tested with Semmes-Weinstein monofilaments, were compared to a cohort of breasts that underwent nipple sparing mastectomy without neurotization. Compared to control patients, there was no statistically significant difference (p = 0.0969) in sensation between pre-operative and post-operative nipple sensation at final follow-up. This proof-of-concept study suggests that immediate re-innervation of the NAC in the setting of immediate breast reconstruction enhances recovery of the NAC sensation.

Nipple Sparing Mastectomy as a Risk-Reducing Procedure for BRCA-Mutated Patients.

Growing numbers of asymptomatic women who become aware of carrying a breast cancer gene mutation (BRCA) mutation are choosing to undergo risk-reducing bilateral mastectomies with immediate breast reconstruction. We reviewed the literature with the aim of assessing the oncological safety of nipple-sparing mastectomy (NSM) as a risk-reduction procedure in BRCA-mutated patients. Nine studies reporting on the incidence of primary breast cancer post NSM in asymptomatic BRCA mutated patients undergoing risk-reducing bilateral procedures met the inclusion criteria. NSM appears to be a safe option for BRCA mutation carriers from an oncological point of view, with low reported rates of new breast cancers, low rates of postoperative complications, and high levels of satisfaction and postoperative quality of life. However, larger multi-institutional studies with longer follow-up are needed to establish this procedure as the best surgical option in this setting.

Craniomedial pedicled mammaplasty based on Würinger's horizontal septum.

BACKGROUND: During 30 months, 40 "septum-based" mammaplasties with a craniomedial pedicle were performed. This report aims to demonstrate the anatomic basics of the horizontal septum and the authors' experience with the septum-based mammaplasty technique. METHODS: A series of 40 consecutive patients underwent a "septum-based" mammaplasty. This technique uses a medial pedicle based on Würinger;s horizontal septum, which is the main plain for the neural and vascular supply of the nipple-areolar complex (NAC). RESULTS: The mean nipple-to-sternal-notch distance was 32 cm (range, 24-43 cm). The mean resection weight was 648 g (range, 484-1,320 g), and the mean nipple elevation was 9.5 cm (range, 5-18 cm). There were no hematomas and no partial or complete NAC necroses. Minimal wound dehiscence at the T-junction was present in three cases (7.5%). The pre- and postoperative NAC sensibilities were comparable in all the patients. CONCLUSION: Based on Würinger;s horizontal septum, a safe and well-vascularized mammaplasty is possible even with large resection weights and long nipple-areola distances, and NAC sensibility can be preserved. The reported technique combining excellent pedicle perfusion with a wide variety of breast shaping proved to be safe.

Neurotization of the Nipple-Areola Complex during Implant-Based Reconstruction: Evaluation of Early Sensation Recovery.

The concept of sensate autologous breast reconstruction is not novel, and prior literature has focused mainly on sensate abdominally based breast reconstruction. The goal of this article is to present the authors' results with a novel technique performing sensate implant-based reconstruction. A database was prospectively maintained for patients who underwent implant-based sensate breast reconstruction. The anterior branch of the lateral fourth intercostal is identified and preserved during the mastectomy by the breast surgeon. A processed nerve allograft is used as an interpositional graft connecting the donor nerve to the targeted nipple-areola complex. The sensory recovery process was objectively monitored using a pressure-specified sensory device. Thirteen patients underwent the proposed technique. Eight patients with 15 breasts were monitored for sensory recovery. For sensory measurement, the nipple had a mean threshold of 67.33 ± 34.48 g/nm. The upper inner (29 ± 26.75 g/nm) and upper outer (46.82 ± 32.72 g/nm) nipple-areola complex quadrants demonstrated better scores during the moving test compared with the static test. Mean time between the test and surgery was 4.18 ± 2.3 months, and mean time between the second test and surgery was 10.59 ± 3.57 months. Threshold improvements were documented after the second test for all nipple-areola complex areas evaluated. This is the first study to report on early results obtained after performing sensate implant-based breast reconstruction. More studies are required to determine the long-term outcomes and impact on quality of life and to assess whether patient or breast characteristics impact the success of this procedure.

The sensory innervation of the human nipple.

Nipples represent a highly specialized skin with capital importance in mammals for breastfeeding and additionally in humans due to sexuality. The histological studies regarding this region are scarce, so 42 human nipples were studied to describe the morphology of the nipple innervation. Our results exclude the presence of a rich innervation on nipple's skin or superficial dermis, thus definitely excluding nipple skin from the concept glabrous skin. The presence of mechanoreceptors is limited to scarce Merkel cells on the epidermis and some corpuscular capsulated and non-capsulated structures in the dermis; Merkel cells progressively decrease with ageing. No Meissner corpuscles were found and the rare Pacinian corpuscles identified were close to vascular structures and embroidered in the mammary fatty tissue. The great sensitivity observed functionally on the breast and especially in the nipple can be morphologically explained by two elements; on the one hand there is a rich smooth muscle innervation present in the deep dermis; on the other hand the mammary gland demonstrate Piezo2 expression in many glandular cells, with two differentiated patterns in the ductal and in the acinar tissue of the breast. The role of Piezo2 in the normal mammary gland is discussed.

Novel topical formulation applied to the nipple-areola complex improves female orgasm.

BACKGROUND: The nipple-areola complex (NAC) is an often overlooked but important erogenous zone in the female sexual response and sexual functional repertoire. Research suggests that nipple stimulation is significant to female sexual satisfaction in as many as 80% of women. Previously, we have reported that stimulation of the arrector pili muscle in the NAC increases nipple sensitivity and has a positive impact on female sexual function. AIMS: To study the effect of RJ-101 on female orgasm. METHODS: A randomized double-blinded placebo-controlled study of RJ101, a novel topical formulation that stimulates the arrector pili muscle of the NAC, in 59 women. Each subject completed a survey composed of Likert scale questions in order to identify changes in orgasm after topical application of RJ101 or placebo. RESULTS: We demonstrated a positive increase in the perceived intensity of orgasm and orgasmic satisfaction/pleasure in women using RJ101 vs those in the placebo group. After 4 weeks of treatment, 76% of the women in the RJ101 arm reported a positive improvement in satisfaction with orgasm versus 47% in the placebo cohort. The mean change in score for overall satisfaction with orgasm in the RJ101 group was statistically significant (P = .007) compared to placebo. CONCLUSION: The application of RJ101 to the NAC 30 minutes prior to sexual activity can improve orgasmic strength, pleasure, and satisfaction.

Objective Methods for Breast Sensibility Testing.

BACKGROUND: The breast and the factors that affect the sensitivity of the nipple-areola complex have been a significant subject of study in recent years. The main purpose of this study was to provide an objective assessment of the effect of volumetric differences on nipple-areola complex sensitivity. METHODS: Data were collected examining the right breast of 34 female volunteers. The mechanosensitive Aß-fiber and mechanoinsensitive C-fiber function of the nipple-areola complex was assessed after mechanical and chemical stimulation, respectively. Flare responses were elicited chemically by the application of histamine by means of iontophoresis and recorded by laser Doppler imaging. The correlation of the maximum flare area responses with the breast volume and nipple-areola complex and the response from the von Frey fiber test was estimated using linear regression analysis. RESULTS: Nipple-areola complex area increased with breast volume and, similarly, the area of histamine-induced axon reflex flare response follows the larger nipple-areola complex. However, a larger nipple-areola complex correlated with higher local mechanical thresholds. Higher mechanical thresholds were linked to smaller axon reflex area, suggesting combined small- and thick-fiber neuropathy. CONCLUSIONS: Objective small-fiber assessment using laser Doppler imaging and subjective mechanical threshold tests were used successfully to quantify function of Aß and C fibers in the nipple-areola complex. Increased breast volume was linked to larger nipples, but also to impairment of Aß and C fibers. Sensory testing can be incorporated into preoperative and postoperative management of patients undergoing breast operations to assess changes of neuronal function of the nipple-areola complex after surgery.

Areola-nipple perception threshold to faradic electricity: a new measure of sensibility of the breasts.

BACKGROUND: We describe a new method to study the sensibility of the nipple-areola complex of the breast with faradic electricity delivered through an electromyographic device used to monitor peripheral nerve conduction. METHODS: The objective results of faradic pulses (2-50 mA per pulse) delivered to the nipple-areola complex of the breast through a Nihon-Kohden II machine (Evoked potential/Electromyographs, Nihon-Kohden Co., Japan) were evaluated in normal volunteers to get a basal measure that was defined by the patient as "a soft electric discharge." The measures were recorded and their output discharges averaged (at least 5 to each complex). RESULTS: Twenty-eight volunteers with normal breasts, 28 patients with breast hypertrophy before and after breast reduction, and 28 patients before and after breast augmentation were studied. The faradic pulses were perceived from 1.5 to 3.5 mA in the areola and from 3 to 5.5 mA in the nipple in the control group and from 4.5 to 7.0 mA in the areola and from 6.5 to 9.5 mA in the nipple in the breast hypertrophy group with no significant changes before and after surgery. In the breast augmentation group the faradic pulses were very similar to the volunteers that had normal breasts, but 13 months after breast augmentation with silicone gel prosthesis, a difference was found because all the patients had a higher threshold and three cases had lost sensibility of the nipple-areola complex. CONCLUSION: In normal breasts the areola had a lower threshold for faradic pulses compared to the nipple. Hypertrophic breasts had a higher threshold to the faradic stimulation than normal subjects in the pre- and postoperative period. Hypoplastic breasts before breast augmentation had a perception threshold similar to that of the normal volunteers but after breast augmentation this perception was much higher.

Afferent projections from the mammary glands to the spinal cord in the lactating rat--II. Electrophysiological responses of spinal neurons during stimulation of the nipples, including suckling.

In lactating rats, the milk ejection reflex is evoked and maintained by stimulation of the nipples by the suckling young. In order to understand the processing of the suckling stimulus within the spinal cord, urethane-anaesthetized lactating rats were prepared for electrophysiological recording from the thoraco-lumbar spinal cord during stimulation of the nipples. Single shocks to inguinal or abdominal nipples evoked a cord dorsum potential, consisting of an early (2.6 ms) afferent volley followed by a negative wave (100-200 microV; latency 5-7 ms, duration 5-10 ms). Evoked potentials were also recorded at various depths within the spinal cord, with a maximum amplitude (200-400 microV) at a depth of 400-800 microns, 400-800 microns lateral to the mid-line. At a given recording site, the response was maximal for one particular nipple but submaximal potentials could be evoked from adjacent nipples. Simultaneous stimulation of adjacent nipples caused summation of the response. Unit recordings were made from 35 spinal neurons. Upon electrical stimulation of the nipples, the cells responded with an early train of spikes (latency 5-15 ms), and in 6 cells, a later response (140-180 ms), with a higher stimulation threshold, was also observed. All cells examined showed convergence and summation from different nipples. Twenty out of 27 cells were also activated by stretching of the nipples, which evoked a rapidly adapting response; rhythmical stretching produced a more sustained increase in activity. The cells also responded to other natural stimuli such as touch and pressure or stroking the hair around the nipple and had large receptive fields. Six cells were tested with the suckling stimulus. There was a brisk increase in firing as the pup grasped the nipple and then intermittent (every 18-30 s) episodes of enhanced activity, which directly correlated with the suckling movements. These episodes continued for the duration of the suckling test and were enhanced when a second pup was placed on an adjacent nipple. Finally, from a few experiments when a stimulating electrode was placed within the contralateral antero-lateral funiculus at the level of C2-C3 for antidromic identification, it was seen that some of the cells activated from the nipples projected to higher levels. The short latency responses to nipple stimulation, including suckling, suggest that the suckling stimulus reaches the spinal cord ungated.(ABSTRACT TRUNCATED AT 400 WORDS)