Pelvic Floor Nerves Research Articles

Pelvic Nerve Blocks

<h3>Study Objective</h3> To demonstrate nerve block techniques for the obturator nerve, pudendal nerve, and uterine nerves (paracervical block). <h3>Design</h3> Procedural video. <h3>Setting</h3> Academic medical center. <h3>Patients or Participants</h3> Patients with chronic pelvic pain. <h3>Interventions</h3> This video demonstrates how to perform obturator, pudendal, and paracervical nerve blocks. This video highlights the techniques of these pelvic floor nerve blocks and includes general management and follow-up principles for these patients. <h3>Measurements and Main Results</h3> Pain scores, on a scale of 0-10, are measured prior to and after nerve blocks to gauge response. <h3>Conclusion</h3> Determining the source of chronic pelvic pain can be difficult for gynecologists. Nerve blocks can be an effective strategy to help evaluate and possibly treat pelvic pain. Pelvic floor nerve blocks can delineate whether or not pain is originating from the pelvic floor, uterus, or other source. Nerve blocks can also potentially be therapeutic in instances of nerve entrapment, muscle spasms, neuralgia, or myofascial pain. These instructional videos on administering pelvic floor nerve blocks can help gynecologists provide an additional source of therapy for their patients.

Targeted neuromodulation of pelvic floor nerves in aging and multiparous rabbits improves continence

Pelvic floor muscle stretch injury during pregnancy and birth is associated with the incidence of stress urinary incontinence (SUI), a condition that affects 30–60% of the female population and is characterized by involuntary urine leakage during physical activity, further exacerbated by aging. Aging and multiparous rabbits suffer pelvic nerve and muscle damage, resulting in alterations in pelvic floor muscular contraction and low urethral pressure, resembling SUI. However, the extent of nerve injury is not fully understood. Here, we used electron microscopy analysis of pelvic and perineal nerves in multiparous rabbits to describe the extent of stretch nerve injury based on axon count, axon size, myelin-to-axon ratio, and elliptical ratio. Compared to young nulliparous controls, mid-age multiparous animals showed an increase in the density of unmyelinated axons and in myelin thickness in both nerves, albeit more significant in the bulbospongiosus nerve. This revealed a partial but sustained damage to these nerves, and the presence of some regenerated axons. Additionally, we tested whether electrical stimulation of the bulbospongiosus nerve would induce muscle contraction and urethral closure. Using a miniature wireless stimulator implanted on this perineal nerve in young nulliparous and middle age multiparous female rabbits, we confirmed that these partially damaged nerves can be acutely depolarized, either at low (2–5 Hz) or medium (10–20 Hz) frequencies, to induce a proportional increase in urethral pressure. Evaluation of micturition volume in the mid-age multiparous animals after perineal nerve stimulation, effectively reversed a baseline deficit, increasing it 2-fold (p = 0.02). These results support the notion that selective neuromodulation of pelvic floor muscles might serve as a potential treatment for SUI.

Progress in studies on pathological changes and future treatment strategies of obesity-associated female stress urinary incontinence: a narrative review.

With the increasing prevalence of obesity worldwide, obesity-related female stress urinary incontinence (FSUI) has become a key health problem. Recent studies indicated that FSUI is primarily caused by obesity-related pathological changes, such as fat droplet deposition, and results in pelvic floor nerve, vascular, and urethral striated muscle injury. Meanwhile, treatments for obesity-associated FSUI (OA-FSUI) have garnered much attention. Although existing OA-FSUI management strategies, including weight loss, pelvic floor muscle exercise, and urethral sling operation, could play a role in symptomatic relief; they cannot reverse the pathological changes in OA-FSUI. The continued exploration of safe and reliable treatments has led to regenerative therapy becoming a particularly promising area of researches. Specifically, micro-energy, such as low-intensity pulsed ultrasound (LIPUS), low-intensity extracorporeal shock wave therapy (Li-ESWT), and pulsed electromagnetic field (PEMF), have been shown to restore the underlying pathological changes of OA-FSUI, which might be related by regulation endogenous stem cells (ESCs) to restore urine control function ultimately in animal experiments. Therefore, ESCs may be a target for repairing pathological changes of OA-FSUI. The aim of this review was to summarize the OA-FSUI-related pathogenesis, current treatments, and to discuss potential therapeutic options. In particular, this review is focused on the effects and related mechanisms of micro-energy therapy for OA-FSUI to provide a reference for future basically and clinical researches.

Multiparity affects conduction properties of pelvic floor nerves in rabbits.

IntroductionWomen often develop pelvic floor dysfunction due to damage to the pelvic musculature during childbirth; however, the effect on pelvic floor nerves function is less understood. This study used adult rabbits to evaluate the electrophysiological and histological characteristics of the bulbospongiosus (Bsn) and pubococcygeus nerves (Pcn) in multiparity.MethodsCompound nerve action potentials (CNAP) were compared between age‐matched nulliparous and multiparous animals and associated to the histological characteristics of myelinated axons from the Bsn and Pcn nerves. The extensor digitorum longus nerve (EDLn) was used as negative control. Data were analyzed with unpaired two‐tailed Student's t test or Mann–Whitney U test to determine significant differences between groups.ResultsThe onset and peak latencies, duration, and conduction velocity of the motor fibers in these pelvic nerves were not significantly different between nulliparous and multiparous animals. However, the peak‐to‐peak amplitude and area of the CNAP in both Bsn and Pcn were reduced in multiparous rabbits. Histology showed a higher percentage of axons with myelin disorganization caused by multiparity in these pelvic nerves. Together, the data indicate a reduction in the number of functional pelvic axons due to multiparity. As expected, no effect of parity was observed in the EDLn controls.ConclusionsPresent findings demonstrated that multiparity affects myelination and consequently conduction properties in the small pelvic floor nerves.

Discharge patterns of abdominal and pudendal nerves during induced defecation in anesthetized cats

Defecation is thought to be achieved not only by contraction of the colon, but also by a rise in intra-abdominal pressure. In this study we recorded the discharges of nerves innervating the abdominal (Abd) muscles, diaphragm, external anal sphincter (EAS) muscle and pelvic floor (PF) muscles during induced defecation evoked by distention of an expellable balloon to reveal defecation-related muscle activities. The discharges of the Abd muscle and phrenic (Phr) nerves increased when rectal pressure increased. The discharges of the EAS and PF nerves usually increased in proportion to the pressure in the rectum and maintained a constant activity level, although some trials showed inhibition. The results suggest that activities of these muscles increase the intra-abdominal pressure.

Evaluating the effect of Tranilast for pelvic pain caused by endometriosis

The most commonly proposed mechanisms for pain production in endometriosis are: 1) production of substances such as cytokines and growth factors released from activated macrophages and other cells; 2) direct and indirect effects of active bleeding from endometriotic implants; and 3) irritation or direct invasion of pelvic floor nerves induced by infiltrating endometriotic implants with the mechanism of ‘epithelial to mesenchymal transition’ (EMT). The use of Tranilast, an anti-allergic drug, was approved in 1982 in Japan and South Korea for treatment of bronchial asthma.

Reference Lines in Dynamic Magnetic Resonance Imaging of the Pelvic Floor

: To compare the variability in two commonly used reference lines in pelvic magnetic resonance imaging (MRI), the pubococcygeal line (PCL) and the sacrococcygeal to inferior pubis (SCIPP) line, with respect to their distance from pelvic floor points of interest. : We obtained pelvic MR images of 20 asymptomatic nulliparous women who are part of an ongoing pelvic floor nerve injury postpartum study. The subjects underwent a high-resolution two-dimensional, T2-weighted sagittal pelvic MRI in the supine position using a GE Signa scanner with a body phased-array coil. We also obtained dynamic T2-weighted sagittal MR images in supine position during Kegel and Valsalva maneuvers. Using the midsagittal image, we measured the length of two reference lines: the PCL and the more cephalad SCIPP line. From each line, we then measured the perpendicular distance to the bladder neck and to the posterior margin of the anorectal angle (M-line). We compared the mean values of all measurements between the two reference lines with paired Student t tests. : The SCIPP line (mean [SD], 11.60 [0.91] cm) is longer than the PCL (mean [SD], 10.54 [0.85] cm) at rest (P < 0.001). There is no significant change in length from resting to Kegel maneuver or from resting to Valsalva maneuver in either reference line. Only the resting to Valsalva maneuver for the M-line was significantly different between the 2 reference lines (P = 0.02). The resting to Kegel for the perpendicular distance to the bladder neck and the M-line was not significantly different between the two lines. : Both reference lines remain stable during pelvic floor maneuvers.

Anatomic variations of the pelvic floor nerves adjacent to the sacrospinous ligament: a female cadaver study

Our objective was to document variations in the topography of pelvic floor nerves (PFN) and describe a nerve-free zone adjacent to the sacrospinous ligament (SSL). Pelvic floor dissections were performed on 15 female cadavers. The course of the PFN was described in relation to the ischial spine (IS) and the SSL. The pudendal nerve (PN) passed medial to the IS and posterior to the SSL at a mean distance of 0.6 cm (SD = +/-0.4) in 80% of cadavers. In 40% of cadavers, an inferior rectal nerve (IRN) variant pierced the SSL at a distance of 1.9 cm (SD = +/-0.7) medial to the IS. The levator ani nerve (LAN), coursed over the superior surface of the SSL-coccygeus muscle complex at a mean distance of 2.5 cm (SD = +/-0.7) medial to the IS. Anatomic variations were found which challenge the classic description of PFN. A nerve-free zone is situated in the medial third of the SSL.

Quantitative electromyography of the anal sphincter after uncomplicated vaginal delivery.

Fecal incontinence in women is thought to be associated with sphincter laceration or pudendal nerve damage. A prolonged pudendal nerve terminal motor latency is evidence of profound nerve damage, but pudendal nerve terminal motor latency can be normal even when nerve injury has been sustained. We performed quantitative electromyography (EMG) to compare multiple motor unit action potential parameters between recently postpartum women and nulliparous women. Standardized examinations were prospectively performed on 2 groups: 1) healthy nulliparous women without pelvic floor disorders (n = 28) and 2) asymptomatic women who were postpartum following vaginal delivery of their first child (n = 23). The examinations included pelvic organ prolapse quantification measurements, endoanal ultrasonography, pudendal nerve terminal motor latency, sacral reflexes, and concentric needle EMG using multiple motor unit action potential analysis. A mean of 11.5 (standard deviation [sd] 1.1) weeks had elapsed since first vaginal deliveries in the postpartum group. The mean fetal weight at delivery was 3,495 (sd 458) grams. There were no sphincter defects seen by ultrasonography. Compared with the nulliparous women, pudendal nerve terminal motor latency and sacral reflexes (clitoral-anal reflex, urethral-anal reflex) were not increased in the postpartum group. Each of the quantitative parameters (duration, amplitude, area, turns, and phases), measured from motor unit action potentials in the postpartum group, were larger than in the nulliparous group (P < or =.004, nested analysis of variance [ANOVA]). Quantitative EMG using multiple motor unit action potential analysis can detect the presence after vaginal childbirth of subtle nerve injury not demonstrable by pudendal nerve terminal motor latency. Even asymptomatic women show evidence of pelvic floor nerve injury after uncomplicated deliveries.

Innervation of the levator ani and coccygeus muscles of the female rat.

In humans, the pelvic floor skeletal muscles support the viscera. Damage to innervation of these muscles during parturition may contribute to pelvic organ prolapse and urinary incontinence. Unfortunately, animal models that are suitable for studying parturition-induced pelvic floor neuropathy and its treatment are rare. The present study describes the intrapelvic skeletal muscles (i.e., the iliocaudalis, pubocaudalis, and coccygeus) and their innervation in the rat to assess its usefulness as a model for studies of pelvic floor nerve damage and repair. Dissection of rat intrapelvic skeletal muscles demonstrated a general similarity with human pelvic floor muscles. Innervation of the iliocaudalis and pubocaudalis muscles (which together constitute the levator ani muscles) was provided by a nerve (the "levator ani nerve") that entered the pelvic cavity alongside the pelvic nerve, and then branched and penetrated the ventromedial (i.e., intrapelvic) surface of these muscles. Innervation of the rat coccygeus muscle (the "coccygeal nerve") was derived from two adjacent branches of the L6-S1 trunk that penetrated the muscle on its rostral edge. Acetylcholinesterase staining revealed a single motor endplate zone in each muscle, closely adjacent to the point of nerve penetration. Transection of the levator ani or coccygeal nerves (with a 2-week survival time) reduced muscle mass and myocyte diameter in the iliocaudalis and pubocaudalis or coccygeus muscles, respectively. The pudendal nerve did not innervate the intrapelvic skeletal muscles. We conclude that the intrapelvic skeletal muscles in the rat are similar to those described in our previous studies of humans and that they have a distinct innervation with no contribution from the pudendal nerve.

Pelvic floor nerve conduction studies: establishing clinically relevant normative data

Objective The purpose of this study was to establish data for normative distributions for pudendal and perineal nerve compound muscle action potential data in healthy women across a wide age range and varied history of vaginal deliveries. Study design We studied 42 continent women, aged 20 to 67 years, including 29% nulliparous women with a disposable St. Mark's electrode to stimulate the pudendal nerve at the ischial spine by a transvaginal approach. The pudendal terminal motor latency and amplitude were detected with the use of surface patch electrodes overlying the external anal sphincter; the perineal responses were measured with the use of a surface ring electrode at the proximal urethra. Results None of the data were distributed normally and required the use of negative inverse and cube root transformations to create a normal distribution. Clinical correlations were found with advancing age and vaginal delivery. Conclusion The collection of these data allows for the definition of normal limits and begins the study of clinically important variables on test results and clinical outcomes.