Presynaptic Gαo (GOA-1) signals to depress command neuron excitability and allow stretch-dependent modulation of egg laying in Caenorhabditis elegans.

Egg laying in the nematode worm Caenorhabditis elegans is a two-state behavior modulated by internal and external sensory input. We have previously shown that homeostatic feedback of embryo accumulation in the uterus regulates bursting activity of the serotonergic HSN command neurons that sustains the egg-laying active state. How sensory feedback of egg release signals to terminate the egg-laying active state is less understood. We find that Gαo, a conserved Pertussis Toxin-sensitive G protein, signals within HSN to inhibit egg-laying circuit activity and prevent entry into the active state. Gαo signaling hyperpolarizes HSN, reducing HSN Ca2+ activity and input onto the postsynaptic vulval muscles. Loss of inhibitory Gαo signaling uncouples presynaptic HSN activity from a postsynaptic, stretch-dependent homeostat, causing precocious entry into the egg-laying active state when only a few eggs are present in the uterus. Feedback of vulval opening and egg release activates the uv1 neuroendocrine cells which release NLP-7 neuropeptides which signal to inhibit egg laying through Gαo-independent mechanisms in the HSNs and Gαo-dependent mechanisms in cells other than the HSNs. Thus, neuropeptide and inhibitory Gαo signaling maintain a bi-stable state of electrical excitability that dynamically controls circuit activity in response to both external and internal sensory input to drive a two-state behavior output.

Reduction of Hypertrophic Labia Minora by Posterior-Lateral Wedge Resection with Preservation of the Central Blood Vessels and Nerve Bundle.

OBJECTIVE: The aim of this study was to introduce a new method of labiaplasty. Here, we describe the surgical procedure, outcomes and the advantages of this method. METHOD: The medical records of 21 patients aged between 20 and 45 years who underwent reduction of the labia minora from February 2015 to June 2017 were reviewed. The procedures performed in these studies used posterior-lateral wedge resection with preservation of the central blood vessels and nerve bundle. RESULTS: All the surgeries were performed successfully, and 21 patients experienced an uneventful postoperative period. A minor dehiscence occurred in one patient, who recovered with no requirement for additional treatment. All of the patients were satisfied with the eventual esthetic appearance. CONCLUSION: The posterior-lateral wedge resection with preservation of the central blood vessels and nerve bundle is a simple and safe method that is associated with satisfactory outcomes. 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 .

Intraepidermal nerve fiber density in vulvar lichen sclerosus and normal vulvar tissues.

Lichen sclerosus (LS) is a chronic and inflammatory disease causing sensory symptoms such as itch and pain and affecting most frequently genital skin of women. Intraepidermal nerve fiber density (IENFD) was examined immunohistologically in 20 vulvar skin biopsies of patients affected by LS and in 20 control vulvar skin biopsies, in order to determine if these sensory sensations originate in changes in the epidermal innervation. Obtained results show fewer protein gene product 9.5 (PGP 9.5) positive intraepidermal nerve fibers (IENF) in LS tissues compared to controls (P = 0.004), while the number of calcitonin gene-related peptide (CGRP) positive IENF in LS was increased compared to normal vulvar tissue (P = 0.03). No differences in the number of vasoactive intestinal peptide (VIP) expressing IENF could be observed. To our best knowledge, this is the first study to describe intraepidermal nerve fiber density in vulvar LS. Significant differences in IENFD between LS and control skin samples, which have been found, point to the damage to the small nerve fibers in the disease process of LS, which may contribute to pathogenesis of LS sensory symptoms.

Injury to Perineal Branch of Pudendal Nerve in Women: Outcome from Resection of the Perineal Branches.

Background This study describes outcomes from a new surgical approach to treat "anterior" pudendal nerve symptoms in women by resecting the perineal branches of the pudendal nerve (PBPN). Methods Sixteen consecutive female patients with pain in the labia, vestibule, and perineum, who had positive diagnostic pudendal nerve blocks from 2012 through 2015, are included. The PBPN were resected and implanted into the obturator internus muscle through a paralabial incision. The mean age at surgery was 49.5 years (standard deviation [SD] = 11.6 years) and the mean body mass index was 25.7 (SD = 5.8). Out of the 16 patients, mechanisms of injury were episiotomy in 5 (31%), athletic injury in 4 (25%), vulvar vestibulectomy in 5 (31%), and falls in 2 (13%). Of these 16 patients, 4 (25%) experienced urethral symptoms. Outcome measures included Female Sexual Function Index (FSFI), Vulvar Pain Functional Questionnaire (VQ), and Numeric Pain Rating Scale (NPRS). Results Fourteen patients reported their condition pre- and postoperatively. Mean postoperative follow-up was 15 months. The overall FSFI, and arousal, lubrication, orgasm, satisfaction, and pain domains significantly improved (p < 0.05). The VQ also significantly improved (p < 0.001) in 13 (93%) of 14 patients. The NPRS score decreased on average from 8 to 3 (p < 0.0001). All four patients with urethral symptoms were relieved of these symptoms. Conclusion Resection of the PBPN with implantation of the nerve into the obturator internus muscle significantly reduced pain and improved sexual function in women who sustained injury to the PBPN.

Does Degree of Vulvar Sensitivity Predict Vulvodynia Characteristics and Prognosis?

Although women with vulvodynia typically have increased vulvar sensitivity, data on characteristics associated with the degree of vulvar sensitivity are lacking. We measured vulvar sensitivity using cotton swab test and vulvodolorimeter among a subset of 335 women, aged younger than 70 years, in the longitudinal Woman to Woman Health Study. Comparing the vulvodynia screening results from their online/paper survey to that at the time of the examination, 42 women had ongoing vulvodynia, 66 had a recent remission, 22 control participants had a recent onset of vulvodynia, and 205 control participants remained asymptomatic. Vulvar sensitivity was greater in each vulvodynia group compared with the control group (P < .001), and was associated with younger age at first onset of pain (P = .025), pain after intercourse (P = .008), describing the pain as a "pressure," "burning," or "irritating" (P = .015, P = .005, and P = .006, respectively), with increased severity of pain ever (P = .012), and with subsequent persistent or relapsing vulvodynia (P < .001 for each). A score of >1 for the cotton swab summary score best differentiated case from control participants (sensitivity 71.9%; specificity 72.0%). Although 13.8% of women with vulvodynia had no increased sensitivity on cotton swab testing, they did not differ in most clinical characteristics or clinical course from those with increased vulvar sensitivity. PERSPECTIVE: This study showed that women with vulvodynia have more vulvar sensitivity than control women, but the spectrum of sensitivity is broad. Furthermore, those with and without vulvar sensitivity did not differ in most vulvar pain characteristics or in prognosis, suggesting a positive swab test is not required to substantiate the diagnosis.

Immune activation enhances epithelial nerve growth in provoked vestibulodynia.

BACKGROUND: Provoked vestibulodynia manifests as allodynia of the vulvar vestibular mucosa. The exact mechanisms that result in altered pain sensation are unknown. Recently, we demonstrated the presence of secondary lymphoid tissue, which is the vestibule-associated lymphoid tissue in the vestibular mucosa, and showed that this tissue becomes activated in provoked vestibulodynia. OBJECTIVE: The purpose of this study was to examine whether expression of intraepithelial nerve fibers and nerve growth factor are related to immune activation in provoked vestibulodynia. STUDY DESIGN: Vestibular mucosal specimens were obtained from 27 patients with severe provoked vestibulodynia that was treated by vestibulectomy and from 15 control subjects. We used antibodies against the protein gene product 9.5, the neuron specific neurofilament, and nerve growth factor for immunohistochemistry to detect intraepithelial nerve fibers and nerve growth factor expressing immune cells in the vestibular mucosa. For intraepithelial nerve fibers, we determined their linear density (fiber counts per millimeter of the outer epithelial surface, protein gene product 9.5) or presence (neuron specific neurofilament). Nerve growth factor was analyzed by counting the staining-positive immune cells. Antibodies against CD20 (B lymphocytes) and CD3 (T lymphocytes) were used to identify and locate mucosal areas with increased density of lymphocytes and the presence of germinal centers (ie, signs of immune activation). B-cell activation index was used to describe the overall intensity of B-cell infiltration. RESULTS: We found more protein gene product 9.5-positive intraepithelial fibers in vestibulodynia than in the control samples (6.3/mm [range, 0.0-15.8] vs 2.0/mm [range, 0.0-12.0]; P=.006). Neuron specific neurofilament -positive intraepithelial fibers were found in 17 of 27 vestibulodynia cases (63.0%) and in none of the control cases. Protein gene product 9.5-positive intraepithelial fibers were more common in samples with more pronounced immune activation. The density of these fibers was higher in samples with than without germinal centers (6.1/mm [range, 4.3-15.8] vs 3.0/mm [range, 0.0-13.4]; P=.020). A positive correlation between the fiber density and B-cell activation index score of the sample was found (Spearman's Rho, 0.400; P=.004; R2=0.128). No significant difference, however, was found in the density or presence of nerve fibers between samples with high and low T-cell densities. We identified areas of minor and major vestibular glands in 16 of the patient samples and in 1 control sample. Protein gene product 9.5-positive nerve fibers were found more often in glandular epithelium surrounded by B-cell infiltration than in glands without B cells (P=.013). Also, the presence of neuron specific neurofilament-positive fibers in glandular epithelium was associated with B-cell infiltrates (P=.053). Nerve growth factor-positive immune cells were more common in mucosal areas with than without B-cell infiltration and intraepithelial nerve fibers. CONCLUSION: Excessive epithelial nerve growth in provoked vestibulodynia is associated with increased B-cell infiltration and the presence of germinal centers. This supports the fundamental role of immune activation in provoked vestibulodynia.

Efficacy of transcranial direct-current stimulation (tDCS) in women with provoked vestibulodynia: study protocol for a randomized controlled trial.

BACKGROUND: Provoked vestibulodynia is the most common form of vulvodynia. Despite its high prevalence and deleterious sexual, conjugal, and psychological repercussions, effective evidence-based interventions for provoked vestibulodynia remain limited. For a high proportion of women, significant pain persists despite the currently available treatments. Growing evidence suggests that the central nervous system (CNS) could play a key role in provoked vestibulodynia; thus, treatment targeting the CNS, rather than localized dysfunctions, may be beneficial for women suffering from provoked vestibulodynia. In this study, we aim to build on the promising results of a previous case report and evaluate whether transcranial direct-current stimulation, a non-invasive brain stimulation technique targeting the CNS, could be an effective treatment option for women with provoked vestibulodynia. METHODS/DESIGN: This single-center, triple-blind, parallel group, randomized, controlled trial aims to compare the efficacy of transcranial direct-current stimulation with sham transcranial direct-current stimulation in women with provoked vestibulodynia. Forty women diagnosed with provoked vestibulodynia by a gynecologist, following a standardized treatment protocol, are randomized to either active transcranial direct-current stimulation treatment for ten sessions of 20 minutes at an intensity of 2 mA or sham transcranial direct-current stimulation over a 2-week period. Outcome measures are collected at baseline, 2 weeks after treatment and at 3-month follow-up. The primary outcome is pain during intercourse, assessed with a numerical rating scale. Secondary measurements focus on the sexual function, vestibular pain sensitivity, psychological distress, treatment satisfaction, and the patient's global impression of change. DISCUSSION: To our knowledge, this study is the first randomized controlled trial to examine the efficacy of transcranial direct-current stimulation in women with provoked vestibulodynia. Findings from this trial are expected to provide significant information about a promising intervention targeting the centralization of pain in women with provoked vestibulodynia. TRIAL REGISTRATION: Clinicaltrials.gov, NCT02543593 . Registered on September 4, 2015.

The Safe Labiaplasty: A Study of Nerve Density in Labia Minora and Its Implications.

BACKGROUND: Surgical techniques to alleviate labia minora hypertrophy are gaining popularity. Due to the rapidly growing number of labiaplasties performed around the world, there is concern for the safety of these procedures with respect to maintaining sensitivity to the genitalia and/or implications for sexual arousal. OBJECTIVES: An anatomic study aimed at identifying the nerve density distribution of the labia minora was performed to provide unique insight into performing labiaplasty while preserving sensation. METHODS: Four fresh tissue cadaver labia minora were analyzed. Each labia minora was divided into 6 anatomic areas. The samples from each of the 6 anatomic locations were analyzed for presence of nerve bundles using both a routine hematoxylin and eosin (H&E) stain and a confirmatory immunohistochemical staining for S100 protein. Nerve density was analyzed under light microscopy, counted, and then expressed as percentage nerve density as well as number of bundles per square millimeter. RESULTS: Upon gross analysis, the raw data reveal that labia minora have a heterogeneous population of sensory nerves. When looking at percent nerve density, the data do not reveal any statistical differences between the anatomic locations. CONCLUSIONS: Most labiaplasty techniques can be performed safely and are unlikely to cause loss of sensation as the nerve density distribution in labia minora is heterogeneous.

Terminal innervation of female genitalia, cutaneous sensory receptors of the epithelium of the labia minora.

INTRODUCTION: Little information is available regarding the sensory nerve endings within the glabrous skin of the external female genitalia. The diversity of possible sensations suggests a variety of receptor types. Comprehensive knowledge of the sensory stimuli, including stimulus position, changes in temperature, pressure and pain, is critical for addressing pain and sexual function disorders clinically. The aim of this neuro-histological study is document the presence and characteristics of cutaneous sensory receptors in female genital tissue. MATERIALS AND METHODS: Labial skin samples were obtained from ten normal girls (aged 1-9 years). The specimens were waste tissue obtained during surgical intervention. They were all obtained by the senior investigator, a pediatric urologist, after the parent or legal guardian had given informed consent. The specimens were stained by Cajal-type silver impregnation and by immunocytochemistry against protein gene product (PGP) 9.5 and neuron-specific enolase (NSE). RESULTS: PGP 9.5 was the most sensitive neural marker for identifying cutaneous sensory receptors. Free nerve endings (FNEs) in the papillary dermis appeared as thin fibers, varicose, branched or single processed, straight or bent. In the labia minora, FNEs were identified in the strata basale, spinosum and granulosum of the epidermis. Non-capsulated (Meissner-like) corpuscles in the dermal papillae interdigitated with epidermal ridges of the skin. Capsulated corpuscles protruded from the deep dermis into the epidermis. Encapsulated corpuscles and cells located in the inner and outer cores were strongly positive for PGP 9.5. CONCLUSIONS: FNEs, Meissner's corpuscles and Pacinian corpuscles are present in the female labia minora and exhibit characteristic staining patterns.

Sexual function in adult life following Passerini-Glazel feminizing genitoplasty in patients with congenital adrenal hyperplasia.

PURPOSE: We assessed external genitalia sensitivity and sexual function in adults with congenital adrenal hyperplasia who had undergone Passerini-Glazel feminizing genitoplasty as children, and compared them to a control group of healthy counterparts. MATERIALS AND METHODS: Inclusion criteria were congenital adrenal hyperplasia, Passerini-Glazel feminizing genitoplasty, adult age and penetrative vaginal intercourse. Thermal and vibratory sensitivity of the clitoris, vagina and labia minora were analyzed using the Genito Sensory Analyzer (Medoc Ltd., Minnetonka, Minnesota). Psychosexual outcome was assessed with the Beck Depression Inventory, Zung Self-Rating Anxiety Scale, Female Sexual Distress Scale and Female Sexual Function Index. Matched analyses were performed to compare outcomes in patients to controls (healthy medical students). All statistical tests were performed using SPSS®, version 18.0 RESULTS: A total of 12 patients (10%) entered the study. Thermal and vibratory clitoral sensitivity was significantly decreased in all patients compared to healthy controls (p <0.01). There was no difference in thermal or vibratory vaginal sensitivity between patients and controls. On the Female Sexual Distress Scale 11 patients (91.6%) and 11 controls (91.6%) described a stable satisfactory relationship. All patients reported active sexual desire, good arousal, adequate lubrication and orgasm. No significant difference in Female Sexual Function Index global score or single domain scores was observed between patients and controls. CONCLUSIONS: Although clitoral sensitivity in sexually active patients with congenital adrenal hyperplasia treated with Passerini-Glazel feminizing genitoplasty is significantly reduced compared to controls, sexual function in those patients is not statistically or clinically significantly different from their healthy counterparts. Finally, 1-stage Passerini-Glazel feminizing genitoplasty seems to allow normal adult sexual function.

Cutaneous corpuscular receptors of the human glans clitoris: descriptive characteristics and comparison with the glans penis.

INTRODUCTION: The female genital sensory pathways that initiate sexual arousal reflexes begin with cutaneous corpuscular receptors in the glabrous genital skin, including those of the glans clitoris. AIM: The aim of this study is to characterize the corpuscular receptors of the glans clitoris. In addition, we compared basic features with the receptors of the glans penis. MAIN OUTCOME MEASURE: Number of stained receptors. METHODS: Five cadaveric vulvectomy specimens and four cadaveric penile specimens were used. They were serially sectioned and stained with hematoxylin and eosin. Selected blocks were stained with Masson's trichrome, and immunohistochemical staining was done with neuronal markers S-100 and neurofilament. RESULTS: Using the three stains, we identified an abundance of corpuscular receptors within the glans clitoris, as compared with the surrounding prepuce. These receptors were of varied arrangements, situated in the subepithelial tissues of the glans clitoris. They were indistinguishable from the receptors of the glans penis. The number of receptors per 100× high-powered field ranged from 1 to 14, whereas the receptor density in the glans penis ranged from 1 to 3. A second type of receptor, the Pacinian corpuscle, was identified within the suspensory ligament along the trunks of the dorsal nerve but not within the glans itself. CONCLUSIONS: The glans clitoris is densely innervated with cutaneous corpuscular receptors, and these receptors are morphologically similar to the corpuscular receptors of the glans penis. The glans clitoris has greater variability in receptor density compared with the glans penis.

Bilateral accessory breast tissue of the vulva: a case report introducing a novel labiaplasty technique.

INTRODUCTION: We present the case of a 23-year-old female with bilateral ectopic breast tissue of the vulva, the repair of which necessitated a novel labiaplasty technique. Labiaplasty is becoming an increasingly frequent cosmetic procedure, and the popularity of brief didactic labiaplasty courses has risen in response to consumer demand. There is a paucity of detailed anatomic description of female sensory innervation patterns to the clitoris and surrounding structures. This places patients at risk for denervation of clitoral structures during labiaplasty procedures. Our novel technique proposes a method of individualized patient neurosensory mapping preoperatively, which allows for surgical planning to avoid injury to the sensory branches of the dorsal clitoral nerve. METHODS: A 23-year-old female presented with bilateral vulvar masses that involved the clitoral complex, which had first become apparent during the second trimester of pregnancy, and failed to resolve in the postpartum period. We describe the preoperative planning and intraoperative approach and dissection to labiaplasty in this patient, which was complex given the size of the masses, and specifically designed to avoid injury to sensory branches of the dorsal clitoral nerve. DISCUSSION: As labiaplasty becomes more common, it is important to approach labiaplasty patients with a detailed understanding of the sensory innervation of the clitoris and surrounding structures, to avoid nerve injury and resultant sexual dysfunction. Traditional labiaplasty approaches may violate the sensory innervation patterns of the clitoral region, thus causing a sensory loss that affects patient sexual function. Our novel approach to preoperative clitoral nerve sensory mapping provides an alternative method of labiaplasty that may avoid denervation injury.

LIN-12/Notch signaling instructs postsynaptic muscle arm development by regulating UNC-40/DCC and MADD-2 in Caenorhabditis elegans.

The diverse cell types and the precise synaptic connectivity between them are the cardinal features of the nervous system. Little is known about how cell fate diversification is linked to synaptic target choices. Here we investigate how presynaptic neurons select one type of muscles, vm2, as a synaptic target and form synapses on its dendritic spine-like muscle arms. We found that the Notch-Delta pathway was required to distinguish target from non-target muscles. APX-1/Delta acts in surrounding cells including the non-target vm1 to activate LIN-12/Notch in the target vm2. LIN-12 functions cell-autonomously to up-regulate the expression of UNC-40/DCC and MADD-2 in vm2, which in turn function together to promote muscle arm formation and guidance. Ectopic expression of UNC-40/DCC in non-target vm1 muscle is sufficient to induce muscle arm extension from these cells. Therefore, the LIN-12/Notch signaling specifies target selection by selectively up-regulating guidance molecules and forming muscle arms in target cells. DOI:http://dx.doi.org/10.7554/eLife.00378.001.

Vulvar pain: Anatomic and recent pathophysiologic considerations.

Vulvar pain syndrome or vulvodynia is a common multifactorial, heterogeneous, and chronic gynecological disorder with an estimated prevalence of up to 16%. This disorder seriously impacts the quality of life of women in several ways. The etiology of this condition is complex and remains elusive and requires an extensive differential diagnosis. A standard therapeutic approach for the management of vulvar pain is still under investigation and must be multidisciplinary. This review outlines the anatomic and pathophysiologic aspects of vulvar pain.

Genitofemoral and perineal neuralgia after transobturator midurethral sling.

BACKGROUND: Midurethral slings successfully treat stress urinary incontinence through a minimally invasive vaginal approach. Postoperative pain related to sling placement can occur and poses both diagnostic and treatment dilemmas. CASE: Four years after transobturator midurethral sling placement, the patient presented with complaints of left labial pain and dyspareunia since surgery. Using sensory mapping and a nerve stimulator, the problem was identified in the distribution of the genitofemoral nerve. Conservative therapy with a centrally acting neuromodulatory drug and nerve block relieved the pain. CONCLUSION: Postsling neuralgia diagnosis using sensory mapping and a nerve stimulator aids in indentifying the nerve involved and in successful conservative treatment with a nerve block.

Immunocytochemical characterization of pacinian-like corpuscles in the labia minora of prepubertal girls.

STUDY OBJECTIVE: To better understand the precise role of sensory corpuscles within the female external genitalia. DESIGN: After IRB approval, waste tissue samples were obtained from 10 normal girls (aged 2-9 years) who underwent surgery for labial fusion. Immunocytochemistry against protein gene product 9.5 (PGP 9.5), neuron-specific enolase (NSE), vasoactive intestinal peptide (VIP), 5-hydroxytryptamine transporter (5HTT), 5-hydroxytryptamine receptor 1A (5HT1A), Neuronal Peptide Y (NPY), neuronal nitric oxide synthase (nNOS), and estrogen receptors (ER) α and ß was performed. RESULTS: Pacinian-like corpuscles were identified in epithelium of labia minora of prepubertal girls. A central structure composed of an axon surrounded by a central core, outer core, external capsule, surrounded by encapsulated stroma, and a subsidiary innervation in the outer aspect of the corpuscle stroma stained for PGP 9.5 in the outer core and layers of the external capsule, NSE positive cells in layers of the outer core, 5HTT in stroma of the corpuscle and cells located in layers of the outer core, 5HT1A in cells of outer core, NPY in stroma of the corpuscle, and nNOS in external core and external capsule of the central structure. ERα was present in stroma, external core, and external capsule, and ERß in stroma of the corpuscle with subsidiary innervation in the stroma positive to PGP 9.5, VIP, and NPY. CONCLUSION: PGP 9.5, NSE, ERα, nNOS, and 5HTT immunoreaction detected in the outer core and external capsule could indicate these areas may play an important role in the functional aspects of the Pacinian-like corpuscle.

Repeated vulvovaginal fungal infections cause persistent pain in a mouse model of vulvodynia.

Provoked vestibulodynia, the most common form of vulvodynia (unexplained pain of the vulva), is a prevalent, idiopathic pain disorder associated with a history of recurrent candidiasis (yeast infections). It is characterized by vulvar allodynia (painful hypersensitivity to touch) and hyperinnervation. We tested whether repeated, localized exposure of the vulva to a common fungal pathogen can lead to the development of chronic pain. A subset of female mice subjected to recurrent Candida albicans infection developed mechanical allodynia localized to the vulva. The mice with allodynia also exhibited hyperinnervation with peptidergic nociceptor and sympathetic fibers (as indicated by increased protein gene product 9.5, calcitonin gene-related peptide, and vesicular monoamine transporter 2 immunoreactivity in the vaginal epithelium). Long-lasting behavioral allodynia in a subset of mice was also observed after a single, extended Candida infection, as well as after repeated vulvar (but not hind paw) inflammation induced with zymosan, a mixture of fungal antigens. The hypersensitivity and hyperinnervation were both present at least 3 weeks after the resolution of infection and inflammation. Our data show that infection can cause persistent pain long after its resolution and that recurrent yeast infection replicates important features of human provoked vulvodynia in the mouse.