Accuracy of augmented reality-guided needle placement for pulsed radiofrequency treatment of pudendal neuralgia: a pilot study on a phantom model.

Background: Pudendal neuralgia (PN) is a chronic neuropathy that causes pain, numbness, and dysfunction in the pelvic region. The current state-of-the-art treatment is pulsed radiofrequency (PRF) in which a needle is supposed to be placed close to the pudendal nerve for neuromodulation. Given the effective range of PRF of 5 mm, the accuracy of needle placement is important. This study aimed to investigate the potential of augmented reality guidance for improving the accuracy of needle placement in pulsed radiofrequency treatment for pudendal neuralgia. Methods: In this pilot study, eight subjects performed needle placements onto an in-house developed phantom model of the pelvis using AR guidance. AR guidance is provided using an in-house developed application on the HoloLens 2. The accuracy of needle placement was calculated based on the virtual 3D models of the needle and targeted phantom nerve, derived from CBCT scans. Results: The median Euclidean distance between the tip of the needle and the target is found to be 4.37 (IQR 5.16) mm, the median lateral distance is 3.25 (IQR 4.62) mm and the median depth distance is 1.94 (IQR 7.07) mm. Conclusion: In this study, the first method is described in which the accuracy of patient-specific needle placement using AR guidance is determined. This method could potentially improve the accuracy of PRF needle placement for pudendal neuralgia, resulting in improved treatment outcomes.

Comparison of the effects of ring block and dorsal penile nerve block on parental satisfaction for circumcision operation in children: randomized controlled trial.

PURPOSE: In children, circumcision is a procedure associated with perioperative pain and parental satisfaction is an important parameter in the evaluation of anesthesia procedures. Inadequate dorsal penile nerve block (DPNB) for the ventral shaft of the penis might impact parental satisfaction negatively. To evaluate this hypothesis, we compared the effects of penile ring block (RB) and dorsal penile nerve block (DPNB) on parental satisfaction. Postoperative pain, need for additional analgesia, intraoperative hemodynamic data, recovery status, side effects, and postoperative complications were evaluated as secondary outcomes between the blocks. METHODS: Parental satisfaction and anesthetic effectiveness of RB and DPNB for circumcision in children were compared. 86 patients were randomized 1:1 to Group RB and Group DPNB, which were administered the same dose of anesthesia. Parental satisfaction was evaluated with the Pediatric Anesthesia Parental Satisfaction Questionnaire (PAPS). Postoperative pain evaluations were made with the Face, Legs, Activity, Crying, Consolability Pain Scale (FLACC). RESULTS: In terms of parent satisfaction, no differences were detected between the groups in the pre-anesthesia, pre-anesthesia and post-anesthesia, post-anesthesia, hospital team, and anesthesia team parameters (p > 0.05). The scores of Group DPNB patients were higher only in the "Q11" subparameter in the "anesthesia team" parameter, and this difference was significant (0.024). CONCLUSION: RB and DPNB were compared in circumcision, which is the most common surgical procedure for children. Parental satisfaction, anesthesia, and analgesic effects of both blocks were found to be similar. CLINICAL TRIALS: ACTRN12622001211752.

Contribution of pudendal nerve injury to stress urinary incontinence in a male rat model.

Urinary incontinence is a common complication following radical prostatectomy, as the surgery disturbs critical anatomical structures. This study explored how pudendal nerve (PN) injury affects urinary continence in male rats. In an acute study, leak point pressure (LPP) and external urethral sphincter electromyography (EMG) were performed on six male rats with an intact urethra, the urethra exposed (UE), the PN exposed (NE), and after PN transection (PNT). In a chronic study, LPP and EMG were tested in 67 rats 4 days, 3 weeks, or 6 weeks after sham PN injury, PN crush (PNC), or PNT. Urethras were assessed histologically. Acute PNT caused a significant decrease in LPP and EMG amplitude and firing rate compared to other groups. PNC resulted in a significant reduction in LPP and EMG firing rate 4 days, 3 weeks, and 6 weeks later. EMG amplitude was also significantly reduced 4 days and 6 weeks after PNC. Neuromuscular junctions were less organized and less innervated after PNC or PNT at all timepoints compared to sham injured animals. Collagen infiltration was significantly increased after PNC and PNT compared to sham at all timepoints. This rat model could facilitate preclinical testing of neuroregenerative therapies for post-prostatectomy incontinence.

Anatomy of the pudendal nerve in clinically important areas: a pictorial essay and narrative review.

PURPOSE: The pudendal nerve is an anatomical structure arising from the ventral branches of the spinal roots S2-S4. Its complex course may be affected by surrounding structures. This may result in irritation or entrapment of the nerve with subsequent clinical symptoms. Aim of this study is to review the anatomy of the pudendal nerve and to provide detailed photographic documentation of the areas with most frequent clinical impact which are essential for surgical approach. METHODS: Major medical databases were searched to identify all anatomical studies investigating pudendal nerve and its variability, and possible clinical outcome of these variants. Extracted data consisted of morphometric parameters, arrangement of the pudendal nerve at the level of roots, formation of pudendal nerve, position according to sacrospinal and sacrotuberal ligaments and its terminal branches. One female cadaver hemipelvis was dissected with common variability of separate course of inferior rectal nerve. During dissection photodocumentation was made to record course of pudendal nerve with focus on areas with recorded pathologies and areas exposed to iatrogenic damage during surgical procedures. RESULTS: Narrative review was done to provide background for photodocumentation. Unique photos of course of the pudendal nerve was made in areas with great clinical significance. CONCLUSION: Knowledge of anatomical variations and course of the pudendal nerve is important for examinations and surgical interventions. Surgically exposed areas may become a site for iatrogenic damage of pudendal nerve; therefore, unique picture was made to clarify topographic relations.

Swine Pudendal Nerve as a Model for Neuromodulation Studies to Restore Lower Urinary Tract Dysfunction.

Lower urinary tract dysfunction, such as incontinence or urinary retention, is one of the leading consequences of neurological diseases. This significantly impacts the quality of life for those affected, with implications extending not only to humans but also to clinical veterinary care. Having motor and sensory fibers, the pudendal nerve is an optimal candidate for neuromodulation therapies using bidirectional intraneural prostheses, paving the way towards the restoration of a more physiological urination cycle: bladder state can be detected from recorded neural signals, then an electrical current can be injected to the nerve based on the real-time need of the bladder. To develop such prostheses and investigate this novel approach, animal studies are still required since the morphology of the target nerve is fundamental to optimizing the prosthesis design. This study aims to describe the porcine pudendal nerve as a model for neuromodulation studies aiming at restoring lower urinary tract dysfunction. Five male farm pigs were involved in the study. First, a surgical procedure to access the porcine pudendal nerve without muscle resection was developed. Then, an intraneural interface was implanted to confirm the presence of fibers innervating the external urethral sphincter by measuring its electromyographic activity. Finally, the morphophysiology of the porcine pudendal nerve at the level of surgical exposure was described by using histological and immunohistochemical characterization. This analysis confirmed the fasciculate nature of the nerve and the presence of mixed fibers with a spatial and functional organization. These achievements pave the way for further pudendal neuromodulation studies by using a clinically relevant animal model with the potential for translating the findings into clinical applications.

Anatomical Relationships of the Sciatic Nerve and Pudendal Nerve to the Ischial Spine as They Exit the Greater Sciatic Foramen.

OBJECTIVE: Deep gluteal syndrome is a clinical condition in which discomfort may arise due to the pathoanatomy of the subgluteal space. We conducted an anatomical exploration to categorize the relationship of the piriformis muscle, sciatic nerve (SN), and pudendal nerve (PN) to the ischial spine (IS) and sacrospinous ligament. METHODS: We analyzed 22 cadavers. The piriformis muscle, SN, and PN were exposed through either a transgluteal approach or a gluteal flap. The relationship of the neural structures to the IS, sacrospinous ligament, and ischial bone as they exit the greater sciatic foramen was observed, and the exit zones were classified as zone A, medial to the IS (entirely on sacrospinous ligament); zone B, on the IS; and zone C, lateral to the IS (entirely on ischial bone). RESULTS: The SN was observed either in zone B or zone C in all specimens. The PN was found to be in either zone A or zone B in 97.6% of specimens. The most common combinations were SN in zone B and PN in zone A (type I), and SN in zone C and PN in zone B (type II). CONCLUSIONS: The results from this study show clear anatomical differences in the SN-PN relationship, which may play a role in pain seen in deep gluteal syndrome. Moreover, classification of the SN-IS and PN-IS relationships described in this article will help describe different pathologies affecting the deep gluteal area.

Intravenous dexamethasone does not prolong the duration of pudendal nerve block in infants and children undergoing hypospadias surgery: A randomized clinical trial.

BACKGROUND: The administration of intravenous dexamethasone increases the duration of neuraxial block and improves the quality of analgesia. However, little is known about these effects of dexamethasone on peripheral nerve blocks in children. AIMS: In this study, we aimed to investigate the benefit of intravenous dexamethasone for enhancing the effect of pudendal block on postoperative analgesia in children who underwent hypospadias surgery. METHODS: In total, 46 children aged 6-36 months who underwent hypospadias surgery were randomly allocated to either a control group (normal saline, group C) or dexamethasone group (0.5 mg/kg, group D). Pudendal block was performed before the surgery using 0.3 mL/kg of 0.225% ropivacaine on both sides. Parents were instructed to press the patient-controlled analgesia bolus button when their children's pain score was >4 points. The primary outcome measure was the time at which the first patient-controlled analgesia by proxy bolus dose was administered. The secondary outcome measures were pain score, number of patient-controlled analgesia administration by proxy bolus attempts, number of rescue analgesics required, total amount of fentanyl administered, and overall parental satisfaction. RESULTS: The time of first patient-controlled analgesia bolus administration by proxy was not different between the control and dexamethasone groups (5.6 [5.2, 8.8] h versus 6.5 [5.4, 8.1] h, hazard ratio 0.8, 95% confidence intervals 0.43 to 1.47, p = .46). There were no statistically significant differences among the secondary outcomes. CONCLUSIONS: Administration of intravenous dexamethasone did not enhance the duration of pudendal nerve block in infants and children aged 6-36 months who underwent hypospadias surgery.

Pudendal Nerve Block With Liposomal Bupivacaine for Sacrospinous Ligament Suspension.

IMPORTANCE: Pudendal nerve block has been frequently used as a pain management modality for vaginal prolapse surgery. However, studies investigating its efficacy and the type of anesthetic used have had conflicting results. OBJECTIVE: This study aimed to evaluate the effect of intraoperative pudendal nerve block with liposomal bupivacaine on postoperative pain after sacrospinous ligament suspension surgery. STUDY DESIGN: In this single-blinded randomized controlled trial, 83 women undergoing sacrospinous ligament suspension were randomized to receive either intraoperative pudendal nerve block with liposomal bupivacaine or no block. Participants recorded their pain level on postoperative days (PODs) 1-3 and 7, the number of pain medication pills consumed, and the quality of their recovery using a validated questionnaire. RESULTS: There were no significant differences in pain scores between the groups on POD 1 and POD 3: 5 (2-6.25) versus 5.5 (4-8; P = 0.058) and 4 (1-6) versus 5 (2-7; P = 0.146), respectively. On POD 2, the overall pain score was statistically different between the groups, with the block group having lower interquartile ranges. This difference, however, was not clinically significant: 5 (1.75-5) versus 5 (3.25-7.75; P = 0.023). In the subset of participants who underwent a concomitant midurethral sling procedure, POD 2 and POD3 pain scores were significantly lower in those who received the block: 3 (1-5) versus 6 (5-8; P = 0.006) for POD 2 and 3 (1-5) versus 5 (3.250-7; P = 0.042) for POD 3. There were no significant differences in pain medication consumption or the quality of recovery scores. CONCLUSION: Pudendal nerve block with liposomal bupivacaine did not result in significant differences in postoperative pain after sacrospinous ligament suspension, except in those participants who underwent a concomitant midurethral sling procedure.

Low-dose caudal versus dorsal penile nerve block for postoperative analgesia after circumcision: a randomized comparative study.

INTRODUCTION: Paediatric male circumcision is a painful surgical procedure, which is usually carried out under general anaesthesia. Regional analgesic techniques, including dorsal penile nerve block (DPNB) and caudal nerve block (CNB), are superior to opioid and non-opioid systemic analgesia for postoperative pain control after circumcision. MATERIAL AND METHODS: The purpose of our study was to compare the efficacy, duration of postoperative analgesia, and complications of DPNB, CNB, and the combination of 2 blocks. Eighty-one male patients aged from 3 to 12 years scheduled for circumcision were distributed into 3 groups, each consisting of 27 patients; group 1 (DPNB group), group 2 (CNB group), and group 3 for combined blockade. This study compared the 3 groups in terms of intraoperative vital signs: heart rate and blood pressure, postoperative Wong-Baker score, and complications (nausea, vomiting, pruritus, urinary retention, and constipation). RESULTS: The intraoperative haemodynamics did not differ between the 3 groups of the study. There is significant difference in the Wong-Baker scale postoperatively at 1, 3, and 24 hours, being significantly less in the CNB group and combined blockade group than in the DPNB group, but there was no significant difference between the CNB group and the combined blockade group. The incidence of complications showed no significant intergroup difference, except for urinary retention being lower with DPNB. CONCLUSIONS: Both caudal and combined blockade were superior to DPNB for intraoperative and postoperative analgesia after circumcision. CNB and combined blockade was associated with significantly higher incidence of urinary retention compared to DPNB. Also, there was no additional benefit to the analgesic efficacy from combining both blocks.

Bloqueos Nerviosos. Bases Anatómicas del Dolor Somático Abdomino-Pélvico / Nerve Blocks. Anatomy of the Somatic Innervation of the Abdomino-Pelvic Cavity

El dolor abdominal es una de las sintomatologías que afectan con frecuencia la cavidad abdomino-pélvica. Dicha cavidad posee una inervación somática en la que intervienen del séptimo a doceavo nervios intercostales, ramos colaterales y terminales del plexo lumbar y el nervio pudendo; siendo objetivo de este trabajo la descripción anatómica del dolor abdominopélvico a través del plexo lumbar, nervios intercostales y nervio pudendo, sus diferentes patrones y variaciones de conformación, y las implicancias de éstas últimas en las distintas maniobras clínico-quirúrgicas. Se realizó un estudio descriptivo, observacional y morfométrico de la inervación somática de la cavidad abdomino-pélvica, en 50 preparaciones cadavéricas, fijadas en solución de formaldehído, de la Tercera Cátedra de Anatomía, Facultad de Medicina, Universidad de Buenos Aires, entre Agosto/2017-Diciembre/2019. La descripción clásica del plexo lumbar se encontró en 35 casos; la presencia del nervio femoral accesorio en ningún caso; así como también la ausencia del nervio iliohipogástrico en ningún caso; el nervio obturador accesorio se halló en 2 casos; el nervio genitofemoral dividiéndose dentro de la masa muscular del psoas mayor en 6 casos; el nervio cutáneo femoral lateral emergiendo únicamente de la segunda raíz lumbar en 6 casos y por último se encontró la presencia de un ramo del nervio obturador uniéndose al tronco lumbosacro en un caso. Los nervios intercostales y el nervio pudendo presentaron una disposición clásica en todos los casos analizados. Es esencial un adecuado conocimiento y descripción del plexo lumbar, nervios intercostales y nervio pudendo para un adecuado abordaje de la cavidad abdomino-pélvica en los bloqueos nerviosos.

SUMMARY: Abdominal pain is one of the symptoms that affect the abdominal-pelvic cavity. The abdominal-pelvic cavity has a somatic innervation involving the seventh to twelfth intercostal nerves, collateral and terminal branches of the lumbar plexus and the pudendal nerve. The objective of this work is the description of the lumbar plexus, intercostal nerves and pudendal nerve, its different patterns and structure variations, as well as its implications during pain management in patients. A descriptive, observational, and morphometric study of patterns and structure variations of the lumbar plexus, intercostal nerves and pudendal nerve was conducted in 50 formalin-fixed cadaveric dissections of the Third Chair of Anatomy at the School of Medicine in the Universidad de Buenos Aires from August 2017 to December/2019. The standard description of the lumbar plexus was found in 35 cases; accessory femoral nerve was not present in any of the cases; absence of the iliohipogastric nerve was also not found in any case, while the accessory obturating nerve was found in 2 cases; genitofemoral nerve dividing within the muscle mass of psoas in 6 cases; lateral femoral cutaneous nerve emerging only from the second lumbar root in 6 cases and finally, presence of a branch of the obturating nerve was found joining the lumbosacral trunk in one case. The pudendal and intercostal nerve patterns presented a typical pathway in all cases. Adequate knowledge and description of the lumbar plexus, intercostal nerves and pudendal nerve is essential for an adequate approach of the abdominal-pelvic cavity in nerve blocks.

Novel implantation technique for pudendal nerve peripheral nerve stimulation for treatment of chronic pelvic pain.

BACKGROUND: Chronic pelvic pain (CPP) is a pervasive, difficult to treat condition affecting up to 26% of the global female and 8.2% of the global male population. Considered a form of chronic regional pain syndrome (CRPS), it is medically complex and often refractory to multimodal management. Neuromodulation has become increasingly popular in treatment of chronic neuropathic pain conditions, including CPP and CRPS. Dorsal column spinal cord stimulation and dorsal root ganglion stimulation have had some success for managing CPP meanwhile peripheral nerve stimulators (PNS) have been suggested as another viable option. However, few studies in the literature have reported successful use of PNS in treatment of CPP. Here, we detail a possible technique for pudendal PNS lead placement for management of CPP. METHOD: This article describes a novel cephalad to caudad fluoroscopic guided technique for pudendal nerve PNS lead placement and implantation. RESULTS: A cephalad to caudal-medial fluoroscopic guided approach as described within to successfully implant a percutaneous pudendal nerve PNS for management of CPP. CONCLUSIONS: The pudendal nerve PNS lead placement technique noted within can be used to avoid many of the important neurovascular structures near the pelvic outlet. Further studies are needed to validate the safety and efficacy of this therapy modality but it may be a viable management option for patients with medically refractory CPP.

Role of opioid and ß-adrenergic receptors in bladder underactivity induced by prolonged pudendal nerve stimulation in cats.

AIMS: To determine the role of opioid and ß-adrenergic receptors in bladder underactivity induced by prolonged pudendal nerve stimulation (PNS). METHODS: In α-chloralose anesthetized cats, 30-min PNS was applied repeatedly for 3-9 times to induce poststimulation or persistent bladder underactivity. Then, naloxone (opioid receptor antagonist, 1 mg/kg, IV) or propranolol (ß-adrenergic receptor antagonist, 3 mg/kg, IV) was given to reverse the bladder underactivity. After the drug treatment, an additional 30-min PNS was applied to counteract the drug effect. Repeated cystometrograms were performed by slowly (1-2 mL/min) infusing the bladder with saline via a urethral catheter to determine the bladder underactivity and the treatment effects. RESULTS: Prolonged (2-4.5 h) PNS induced bladder underactivity evident as a large bladder capacity (169 ± 49% of control) and a reduced amplitude of bladder contraction (59 ± 17% of control). Naloxone fully reversed the bladder underactivity by reducing bladder capacity to 113 ± 58% and increasing the amplitude of bladder contraction to 104 ± 34%. After administration of naloxone an additional 30-min PNS temporarily increased the bladder capacity to the underactive bladder level (193 ± 74%) without changing the amplitude of the bladder contraction. Propranolol had no effect on bladder underactivity. CONCLUSIONS: A tonic enkephalinergic inhibitory mechanism in the CNS plays a critical role in the bladder underactivity induced by prolonged PNS, while the peripheral ß-adrenergic receptor mechanism in the detrusor is not involved. This study provides basic science evidence consistent with the clinical observation that comorbid opioid usage may contribute to voiding dysfunction in patients with Fowler's syndrome.

First case-series of robot-assisted pudendal nerve release: technique and outcomes.

OBJECTIVE: Pudendal Nerve Entrapment (PNE) may determine chronic pelvic pain associated with symptoms related to its innervation area. This study aimed to present the technique and report the outcomes of the first series of robot-assisted pudendal nerve release (RPNR). PATIENTS AND METHODS: 32 patients, who were treated with RPNR in our centre between January 2016 and July 2021, were recruited. Following the medial umbilical ligament identification, the space between this ligament and the ipsilateral external iliac pedicle is progressively dissected to identify the obturator nerve. The dissection medial to this nerve identifies the obturator vein and the arcus tendinous of the levator ani, which is cranially inserted into the ischial spine. Following the cold incision of the coccygeous muscle at the level of the spine, the sacrospinous ligament is identified and incised. The pudendal trunk (vessels and nerve) is visualized, freed from the ischial spine and medially transposed. RESULTS: The Median duration of symptoms was 7 (5, 5-9) years. The median operative time was 74 (65-83) minutes. The median length of stay was 1 (1-2) days. There was only a minor complication. At 3 and 6 months after surgery, a statistically significant pain reduction has been encountered. Furthermore, the Pearson correlation coefficient reported a negative relationship between the duration of pain and the improvement in NPRS score, - 0.81 (p = 0.01). CONCLUSIONS: RPNR is a safe and effective approach for the pain resolution caused by PNE. Timely nerve decompression is suggested to enhance outcomes.

Fiber counts and architecture of the human dorsal penile nerve.

The human penis transmits behaviorally important sensory information via the dorsal penile nerve, which is required for initiation and maintenance of erection. The human penis differs from the penes of other hominids. The lack of a baculum makes the human penis dependent on erectile tissue, which is under control of neural signals activated by tactile stimulation. Accordingly, the penile sensory innervation is crucial for human sexual behavior. To clarify penile innervation, we analyzed the architecture of the dorsal penile nerve of five male subjects who donated their body. We stained the sensory fibers in the penile dorsal nerve with anti-neurofilament H antibody, and identified myelinated axons with Luxol fast blue staining. Furthermore, we visualized nerve bundles as they travel along the shaft of the penis by performing microfocus computed tomography scans after counterstaining penes with iodine. Our results show that the dorsal penile nerve is organized in 25-45 loosely packed nerve bundles, running mediodorsally in the shaft of the penis. This organization corresponds to that in penes of other mammalian species, but differs from the organization of the other peripheral sensory nerves. Around half of the dorsal penile nerve fibers were myelinated and a human hemipenis contained a total of 8290 ± 2553 (mean ± SD) axons. Thus, the number of sensory axons in the human dorsal penile nerve is higher than in other species described so far. The large fraction of unmyelinated nerve fibers suggests that the conduction speed is not a crucial aspect of penile sensory transmission.

Pudendal nerve block for circumcision of pediatric patient with Pierre Robin Sequence: case report

Abstract Pierre Robin Sequence (PRS) is a congenital condition characterized by micrognathia, glossoptosis, and cleft palate that presents with airway obstruction and developmental delay with or without other congenital anomalies. These patients' anesthesia management is challenging because of difficult ventilation and intubation. Regional anesthesia methods should be considered for these patients on a case-by-case basis. This report presents primary use of regional anesthesia for circumcision of a 9-year-old boy with PRS.

Pudendal Nerve Block Analgesia at the Time of Vaginal Surgery: A Randomized, Double-Blinded, Sham-Controlled Trial.

IMPORTANCE: Effective opioid-sparing postoperative analgesia requires a multimodal approach. Regional nerve blocks augment pain control in many surgical fields and may be applied to pelvic floor reconstruction. OBJECTIVE: This study aimed to evaluate the impact of pudendal nerve block on postoperative pain control and opioid consumption after vaginal surgery. STUDY DESIGN: In this randomized, double-blind, sham-controlled trial, we enrolled women undergoing pelvic reconstruction, excluding patients with chronic pelvic pain or contraindications to nonnarcotic analgesia. Patients were randomized to transvaginal pudendal nerve block (9 mL 0.25% bupivacaine and 1 mL 40 mg/mL triamcinolone) or sham injection (10 mL normal saline). Primary outcomes were pain scores and opioid requirements. Sixty patients were required to show a 20-mm difference on a 100-mm visual analog scale (VAS). RESULTS: We randomized 71 patients: 36 pudendal block and 35 sham. Groups were well matched in baseline characteristics and surgery type. Prolapse repairs were most common (n = 63 [87.5%]), and there was no difference in anesthetic dose or operative time. Pain scores were equivalent in the postanesthesia care unit (mean VAS, 53.1 [block] vs 56.4 [sham]; P = 0.517) and on postoperative day 4 (mean VAS, 26.7 [block] vs 35.5 [sham]; P = 0.131). On postoperative day 1, the intervention group reported less pain, but this did not meet our 20 mm goal for clinical significance (mean VAS, 29.2 vs 42.5; P = 0.047). A pudendal block was associated with lower opioid consumption at all time points, but this was not statistically significant. CONCLUSIONS: Surgeon-administered pudendal nerve block at the time of vaginal surgery may not significantly improve postoperative pain control or decrease opioid use.