Lumbosacral plexus and pudendal nerve magnetic resonance tractography: A systematic review of the clinical applications for pudendal neuralgia.

Diffusion tensor imaging (DTI) is commonly used to establish three-dimensional mapping of white-matter bundles in the supraspinal central nervous system. DTI has also been the subject of many studies on cranial and peripheral nerves. This non-invasive imaging technique enables virtual dissection of nerves in vivo and provides specific measurements of microstructural integrity. Adverse effects on the lumbosacral plexus may be traumatic, compressive, tumoral, or malformative and thus require dedicated treatment. DTI could lead to new perspectives in pudendal neuralgia diagnosis and management. We performed a systematic review of all articles or posters reporting results and protocols for lumbosacral plexus mapping using the DTI technique between January 2011 and December 2023. Twenty-nine articles published were included. Ten studies with a total of 351 participants were able to track the lumbosacral plexus in a physiological context and 19 studies with a total of 402 subjects tracked lumbosacral plexus in a pathological context. Tractography was performed on a 1.5T or 3T MRI system. DTI applied to the lumbosacral plexus and pudendal nerve is feasible but no microstructural normative value has been proposed for the pudendal nerve. The most frequently tracking parameters used in our review are: 3T MRI, b-value of 800 s/mm2, 33 directions, 3 × 3 × 3 mm3, AF threshold of 0.1, minimum fiber length of 10 mm, bending angle of 30°, and 3DT2 TSE anatomical resolution. Increased use of DTI could lead to new perspectives in the management of pudendal neuralgia due to entrapment syndrome, whether at the diagnostic, prognostic, or preoperative planning level. Prospective studies of healthy subjects and patients with the optimal acquisition parameters described above are needed to establish the accuracy of MR tractography for diagnosing pudendal neuralgia and other intrapelvic nerve entrapments.

Development of an ultrasound-guided transgluteal injection of the pudendal nerve in cats: a cadaveric study.

OBJECTIVE: To develop an ultrasound-guided interfascial plane technique for injection of the pudendal nerve near its sacral origin in cats. STUDY DESIGN: Prospective, randomized, anatomical study. ANIMALS: A group of 12 feline cadavers. METHODS: Gross and ultrasound anatomy of the ischiorectal fossa, the pudendal nerve relationship with parasacral structures, and the interfascial plane were described. Computed tomography was employed to describe a cranial transgluteal approach to the pudendal nerve. Bilateral ultrasound-guided injections were performed in eight cadavers using low [(LV) 0.1 mL kg-1] or high volume [(HV) 0.2 mL kg-1] of ropivacaine-dye solution. Dissections were performed to determine successful staining of the pudendal nerve (>1 cm) and inadvertent staining of the sciatic nerve, and any rectal, urethral, or intravascular puncture. Pudendal nerve staining in groups LV and HV were compared using Fisher's exact and Wilcoxon rank-sum test as appropriate (p = 0.05). RESULTS: The pudendal nerve and its rectal perineal and sensory branches coursed through the ischiorectal fossa, dorsomedial to the ischiatic spine. The pudendal nerve was not identified ultrasonographically, but the target plane was identified between the sacral transverse process, the ischiatic spine, the pelvic fascia and the rectum, and it was filled with dye solution. Both branches of the pudendal nerve were completely stained 75% and 87.5% in groups LV and HV, respectively (p = 1.00). The dorsal aspect of the sciatic nerve was partially stained in 37% of injections in group HV. Rectal or urethral puncture and intravascular injection were not observed. CONCLUSIONS AND CLINICAL RELEVANCE: In cats, ultrasound-guided cranial transgluteal injection successfully stained the pudendal nerve in at least 75% of attempts, regardless of injectate volume. Group HV had a greater probability of sciatic nerve staining.

Ultrasound-Guided Pudendal Nerve Block Combined with Propofol Deep Sedation versus Spinal Anesthesia for Hemorrhoidectomy: A Prospective Randomized Study.

Background and Objectives. Several anesthesia techniques were applied to hemorrhoidectomy, but postoperative pain and urinary retention were still two unsolved problems. The aim of this prospective randomized study was to evaluate the effect of ultrasound-guided pudendal nerve block (PNB) combined with deep sedation compared to spinal anesthesia for hemorrhoidectomy. Methods. One hundred and twenty patients undergoing Milligan-Morgan hemorrhoidectomy were randomized to receive PNB combined with deep sedation using propofol (Group PNB, n = 60) or spinal anesthesia (Group SA, n = 60). Pain intensity was assessed using the visual analogue scale (0: no pain to 10: worst possible pain). The primary outcome was pain scores recorded at rest at 3, 6, 12, 24, 36, and 48 h and on walking at 12, 24, 36, and 48 h postoperatively. Secondary outcomes were analgesic consumption, side effects, and patient satisfaction after surgery. Results. Ultrasound-guided bilateral PNB combined with deep sedation using propofol could successfully be applied to Milligan-Morgan hemorrhoidectomy. Postoperative pain intensity was significantly lower in Group PNB compared to Group SA at rest at 3, 6, 12, 24, 36, and 48 h (p < 0.001) and during mobilization at 12, 24, 36, and 48 h (p < 0.001) postoperatively. Sufentanil consumption in Group PNB was significantly lower than that in Group SA, during 0-24 h (p < 0.001) and during 24-48 h (p < 0.001) postoperatively. Urinary retention was significantly lower in Group PNB compared to Group SA (6.9% vs 20%, p=0.034). The patients in Group PNB had higher satisfaction compared to Group SA (p < 0.001). Conclusions. Ultrasound-guided PNB combined with propofol sedation is an effective anesthesia technique for Milligan-Morgan hemorrhoidectomy.

Accuracy of Ultrasound-Guided Pudendal Nerve Block in the Ischial Spine and Alcock's Canal Levels: A Cadaveric Study.

BACKGROUND: Blockade of the pudendal nerve (PN) using ultrasound (US) guidance has been described at the levels of the ischial spine and Alcock's canal. However, no study has been conducted to compare anatomical accuracy between different approaches in targeting the PN. OBJECTIVE: To investigate the accuracy of US-guided injection of the PN at the ischial spine and Alcock's canal levels. This study also compared the accuracy of the infiltrations by three sonographers with different levels of experience. SUBJECTS: Eight Thiel-embalmed cadavers (16 hemipelvises). METHODS: Three physiatrists trained in musculoskeletal US imaging with 12 years, five years, and one year of experience performed the injections. Each injected a 0.1-mL bolus of colored dye in both hemipelvises of each cadaver at the ischial spine and Alcock's canal levels under US guidance. Each cadaver received three injections per hemipelvis. The accuracy of the injection was determined following hemipelvis dissection by an anatomist. RESULTS: The injections were accurate 33 times out of the total 42 attempts, resulting in 78% accuracy. Sixteen out of 21 injections at the ischial spine level were on target (76% accuracy), while the approach at Alcock's canal level yielded 17 successful injections (81% accuracy). The difference between the approaches was not statistically significant. There was also no significant difference in accuracy between the operators. CONCLUSIONS: US-guided injection of the PN can be performed accurately at both the ischial spine and Alcock's canal levels. The difference between the approaches was not statistically significant.

Visualizing the autonomic and somatic innervation of the female pelvis with 3D MR neurography: a feasibility study.

BACKGROUND: Treatment of female pelvic malignancies often causes pelvic nerve damage. Magnetic resonance (MR) neurography mapping the female pelvic innervation could aid in treatment planning. PURPOSE: To depict female autonomic and somatic pelvic innervation using a modified 3D NerveVIEW sequence. MATERIAL AND METHODS: Prospective study in 20 female volunteers (n = 6 normal, n = 14 cervical pathology) who underwent a modified 3D short TI inversion recovery (STIR) turbo spin-echo (TSE) scan with a motion-sensitive driven equilibrium (MSDE) preparation radiofrequency pulse and flow compensation. Modifications included offset independent trapezoid (OIT) pulses for inversion and MSDE refocusing. Maximum intensity projections (MIP) were evaluated by two observers (Observer 1, Observer 2); image quality was scored as 2 = high, 1 = medium, or 0 = low with the sciatic nerve serving as a reference. Conspicuity of autonomic superior (SHP) and bilateral inferior hypogastric plexuses (IHP), hypogastric nerves, and somatic pelvic nerves (sciatic, pudendal) was scored as 2 = well-defined, 1 = poorly defined, or 0 = not seen, and inter-observer agreement was determined. RESULTS: Images were of medium to high quality according to both observers agreeing in 15/20 (75%) of individuals. SHP and bilateral hypogastric nerves were seen in 30/60 (50%) of cases by both observers. Bilateral IHP was seen in 85% (34/40) by Observer 1 and in 75% (30/40) by Observer 2. Sciatic nerves were well identified in all cases, while pudendal nerves were seen bilaterally by Observer 1 in 65% (26/40) and by Observer 2 in 72.5% (29/40). Agreement between observers for scoring nerve conspicuity was in the range of 60%-100%. CONCLUSION: Modified 3D NerveVIEW renders high-quality images of the female autonomic and pudendal nerves.

Evaluating the discordant relationship between Tarlov cysts and symptoms of pudendal neuralgia.

BACKGROUND: Pudendal neuralgia is a painful neuropathic condition involving the pudendal nerve dermatome. Tarlov cysts have been reported in the literature as another potential cause of chronic lumbosacral and pelvic pain. Notably, they are often located in the distribution of the pudendal nerve origin at the S2, S3, and S4 sacral nerve roots and it has been postulated that they may cause similar symptoms to pudendal neuralgia. Literature has been inconsistent on the clinical relevance of the cysts and if they are responsible for symptoms. OBJECTIVE: To evaluate the prevalence of S2-S4 Tarlov cysts at the pudendal nerve origin (S2-S4 sacral nerve roots) in patients specifically diagnosed with pudendal neuralgia, and establish association of patient symptoms with location of Tarlov cyst. STUDY DESIGN: A retrospective study was performed on 242 patients with pudendal neuralgia referred for pelvic magnetic resonance imaging from January 2010 to November 2012. Dedicated magnetic resonance imaging review evaluated for presence, level, site, and size of Tarlov cysts. Among those with demonstrable cysts, subsequent imaging data were collected and correlated with the patients' clinical site of symptoms. Statistical analysis was performed using χ2, Pearson χ2, and Fisher exact tests to assess significance. RESULTS: Thirty-nine (16.1%) patients demonstrated at least 1 sacral Tarlov cyst; and of the 38 patients with complete pain records, 31 (81.6%) had a mismatch in findings. A total of 50 Tarlov cysts were identified in the entire patient cohort. The majority of the Tarlov cysts were found at the S2-S3 level (32/50; 64%). Seventeen patients (44.7%) revealed unilateral discordant findings: unilateral symptoms on the opposite side as the Tarlov cyst. In addition, 14 (36.8%) patients were detected with bilateral discordant findings: 11 (28.9%) had bilateral symptoms with a unilateral Tarlov cyst, and 3 (7.9%) had unilateral symptoms with bilateral cysts. Concordant findings were only demonstrated in 7 patients (18.4%). No significant association was found between cyst size and pain laterality (P = .161), cyst volume and pain location (P = .546), or cyst size and unilateral vs bilateral pain (P = .997). CONCLUSION: The increased prevalence of Tarlov cysts is likely not the etiology of pudendal neuralgia, yet both could be due to similar pathogenesis from part of a focal or generalized condition.

Role of 3 Tesla MR Neurography and CT-guided Injections for Pudendal Neuralgia: Analysis of Pain Response.

BACKGROUND: Magnetic resonance neurography (MRN) has an increasing role in the diagnosis and management of pudendal neuralgia, a neurogenic cause of chronic pelvic pain. OBJECTIVE: The objective of this research was to determine the role of MRN in predicting improved pain outcomes following computed tomography (CT)-guided perineural injections in patients with pudendal neuralgia. STUDY DESIGN: This study used a retrospective cross-sectional study design. SETTING: The research was conducted at a large academic hospital. METHODS: Patients: Ninety-one patients (139 injections) who received MRN and CT-guided pudendal blocks were analyzed. INTERVENTION: A 3Tesla (T) scanner was used to evaluate the lumbosacral plexus for pudendal neuropathy. Prior to receiving a CT-guided pudendal perineural injection, patients were given pain logs and asked to record pain on a visual analog scale. MEASUREMENT: MRN findings for pudendal neuropathy were compared to the results of the CT-guided pudendal nerve blocks. Injection pain responses were categorized into 3 groups - positive block, possible positive block, and negative block.Statistical Tests: A chi-square test was used to test any association, and a Cochran-Armitage trend test was used to test any trend. Significance level was set at .05. All analyses were done in SAS Version 9.4 (SAS Institute, Inc., Cary, NC). RESULTS: Ninety-one patients (139 injections) who received MRN were analyzed. Of these 139 injections, 41 were considered positive (29.5%), 52 of 139 were possible positives (37.4%), and 46 of 139 were negative blocks (33.1%). Of the patients who had a positive pudendal block, no significant difference was found between the MRN result and the pudendal perineural injection response (P = .57). Women had better overall response to pudendal blocks, but this response was not associated with MRN findings (P = .34). However, positive MRN results were associated with better pain response in men (P = .005). Patients who reported bowel dysfunction also had a better response to pudendal perineural injection (P = .02). LIMITATIONS: Some limitations include subjectivity of pain reporting, reporting consistency, absence of a control group, and the retrospective nature of the chart review. CONCLUSION: Pudendal perineural injections improve pain in patients with pudendal neuralgia and positive MRN results are associated with better response in men. KEY WORDS: MRI, MRN, CT injection, pudendal neuralgia, pudendal nerve, pelvic pain, chronic pelvic pain, pudendal neuropathy.

Ultrasound-guided pudendal nerve block in children: A new technique of ultrasound-guided transperineal approach.

BACKGROUND: Transperineal pudendal nerve block guided by nerve stimulator is used in pediatric anesthesia as an alternative to caudal analgesia in perineal surgery. The risk of rectal puncture or intravascular injection is inherent to this blinded technique. We described a new technique of transperineal pudendal nerve block, with ultrasound guidance, to improve safety of the technique. AIMS: The first goal of this study was to describe this new technique and to test its feasibility. The second objective was to evaluate intra operative effectiveness and postoperative pain control. METHODS: After parental and children consent, this prospective descriptive study included children aged 1-15 years, ASA status I-III, scheduled for general anesthesia associated with bilateral pudendal nerve block for an elective perineal surgery. After standardized general anesthesia, the anesthesiologist performed pudendal nerve block under ultrasound guidance with "out of plane" approach and evaluated the visualization of anatomical structures (ischial tuberosity, rectum, and pudendal artery), of the needle and of the local anesthetic spread. Pudendal nerve block failure was defined as an increase in mean arterial blood pressure or heart rate more than 20% compared to baseline values after surgical incision. In the postoperative period, the need for rescue analgesia was noted. RESULTS: During the study period, 120 blocks were performed in 60 patients, including 59 boys. Quality of the ultrasonographic image was good in 81% of blocks, with easy visualization of ischium and rectum in more than 95% of cases. Localization of the tip of the needle was possible for all pudendal nerve blocks, directly or indirectly. The spread of local anesthetic was seen in 79% of cases. The block was effective in 88% of cases. CONCLUSION: The new technique of ultrasound-guided pudendal nerve block, described in this study, seems to be easy to perform with a good success rate, and probably improves safety of the puncture and of the injection by real-time visualization of anatomical structures and local anesthetic spread.

Postpartum hemorrhage from non-uterine arteries: clinical importance of their detection and the results of selective embolization.

Background Identification of the source of postpartum hemorrhage (PPH) is important for embolization because PPH frequently originates from non-uterine arteries. Purpose To evaluate the clinical importance of identifying the non-uterine arteries causing the PPH and the results of their selective embolization. Material and Methods This retrospective study enrolled 59 patients who underwent embolization for PPH from June 2009 to July 2016. Angiographic findings and medical records were reviewed to determine whether non-uterine arteries contributed to PPH. Arteries showing extravasation or hypertrophy accompanying uterine hypervascular staining were regarded as sources of the PPH. The results of their embolization were analyzed. Results Of 59 patients, 19 (32.2%) underwent embolization of non-uterine arteries. These arteries were ovarian (n = 7), vaginal (n = 5), round ligament (n = 5), inferior epigastric (n = 3), cervical (n = 2), internal pudendal (n = 2), vesical (n = 1), and rectal (n = 1) arteries. The embolic materials used included n-butyl cyanoacrylate (n = 9), gelatin sponge particles (n = 8), gelatin sponge particles with microcoils (n = 1), and polyvinyl alcohol particles (n = 1). In 13 patients, bilateral uterine arterial embolization was performed. Re-embolization was performed in two patients with persistent bleeding. Hemostasis was achieved in 17 (89.5%) patients. Two patients underwent immediate hysterectomy due to persistent bleeding. One patient experienced a major complication due to pelvic organ ischemia. One patient underwent delayed hysterectomy for uterine infarction four months later. Conclusion Non-uterine arteries are major sources of PPH. Detection and selective embolization are important for successful hemostasis.

[Magnetic resonance neurography for the identification of pudendal neuralgia]. / Neurografía por resonancia magnética para la identificación de la neuralgia del nervio pudendo.

The pudendal nerve entrapment is an entity understudied by diagnosis imaging. Various causes are recognized in relation to difficult labors, rectal, perineal, urological and gynecological surgery, pelvic trauma fracture, bones tumors and compression by tumors or pelvic pseudotumors. Pudendal neuropathy should be clinically suspected, and confirmed by different methods such as electrofisiological testing: evoked potentials, terminal motor latency test and electromyogram, neuronal block and magnetic resonance imaging. The radiologist should be acquainted with the complex anatomy of the pelvic floor, particularly on the path of pudendal nerve studied by magnetic resonance imaging. High resolution magnetic resonance neurography should be used as a complementary diagnostic study along with clinical and electrophysiological examinations in patients with suspected pudendal nerve neuralgia.

Neurografía por resonancia magnética para la identificación de la neuralgia del nervio pudendo / Magnetic resonance neurography for the identification of pudendal neuralgia

La neuralgia del nervio pudendo (NP) es una entidad poco estudiada por imágenes. Se reconocen varias causas, tales como compresión a través de su paso por estructuras ligamentarias; estiramiento por partos laboriosos; lesiones secundarias a cirugías rectales, perineales, urológicas y ginecológicas, traumatismos con o sin fractura de huesos pelvianos; procesos inflamatorios/autoinmunes; tumores del NP, y, compresión/desplazamiento por tumores o seudotumores de pelvis. El diagnóstico de neuralgia del NP se sospecha por la clínica y se confirma por diferentes métodos, tales como las pruebas electrofisiolológicas: potenciales evocados, test de latencia motora terminal y electromiograma, y, a través de bloqueos neurales y resonancia magnética. La neurografía por resonancia magnética de alta resolución, debería ser empleada como estudio diagnóstico complementario junto a la clínica y exámenes electrofisiológicos, en los pacientes con sospecha de neuralgia del NP.

The pudendal nerve entrapment is an entity understudied by diagnosis imaging. Various causes are recognized in relation to difficult labors, rectal, perineal, urological and gynecological surgery, pelvic trauma fracture, bones tumors and compression by tumors or pelvic pseudotumors. Pudendal neuropathy should be clinically suspected, and confirmed by different methods such as electrofisiological testing: evoked potentials, terminal motor latency test and electromyogram, neuronal block and magnetic resonance imaging. The radiologist should be acquainted with the complex anatomy of the pelvic floor, particularly on the path of pudendal nerve studied by magnetic resonance imaging. High resolution magnetic resonance neurography should be used as a complementary diagnostic study along with clinical and electrophysiological examinations in patients with suspected pudendal nerve neuralgia.

Ultrasound-guided dorsal penile nerve block performed in a case of zipper entrapment injury.

Injury to the penis resulting from zipper entrapment is a painful condition that presents a unique anesthetic challenge to the emergency physician and may even require procedural sedation for removal. In this case report, we describe successful removal of zipper entrapment from the penis of a 34-year-old patient after the application of an ultrasound-guided dorsal penile nerve block. We discuss the anatomy, sonographic features, and steps required for the nerve block procedure. © 2017 Wiley Periodicals, Inc. J Clin Ultrasound 45:589-591, 2017.

Pudendal nerve and branch neuropathy: magnetic resonance neurography evaluation.

Pudendal neuralgia is being increasingly recognized as a cause of chronic pelvic pain, which may be related to nerve injury or entrapment. Due to its complex anatomy and branching patterns, the pudendal nerve abnormalities are challenging to illustrate. High resolution 3 T magnetic resonance neurography is a promising technique for the evaluation of peripheral neuropathies. In this article, the authors discuss the normal pudendal nerve anatomy and its variations, technical considerations of pudendal nerve imaging, and highlight the normal and abnormal appearances of the pudendal nerve and its branches with illustrative case examples.

Sacrotuberous Ligament Healing following Surgical Division during Transgluteal Pudendal Nerve Decompression: A 3-Tesla MR Neurography Study.

Pelvic pain due to chronic pudendal nerve (PN) compression, when treated surgically, is approached with a transgluteal division of the sacrotuberous ligament (STL). Controversy exists as to whether the STL heals spontaneously or requires grafting. Therefore, the aim of this study was to determine how surgically divided and unrepaired STL heal. A retrospective evaluation of 10 patients who had high spatial resolution 3-Tesla magnetic resonance imaging (3T MRI) exams of the pelvis was done using an IRB-approved protocol. Each patient was referred for residual pelvic pain after a transgluteal STL division for chronic pudendal nerve pain. Of the 10 patients, 8 had the STL divided and not repaired, while 2 had the STL divided and reconstructed with an allograft tendon. Of the 8 that were left unrepaired, 6 had bilateral surgery. Outcome variables included STL integrity and thickness. Normative data for the STL were obtained through a control group of 20 subjects. STL integrity and thickness were measured directly on 3 T MR Neurography images, by two independent Radiologists. The integrity and thickness of the post-surgical STL was evaluated 39 months (range, 9-55) after surgery. Comparison was made with the native contra-lateral STL in those who had unilateral STL division, and with normal, non-divided STL of subjects of the control group. The normal STL measured 3 mm (minimum and maximum of absolute STL thickness, 2-3 mm). All post-operative STL were found to be continuous regardless of the surgical technique used. Measured at level of Alcock's canal in the same plane as the obturator internus tendon posterior to the ischium, the mean anteroposterior STL diameter was 5 mm (range, 4-5 mm) in the group of prior STL division without repair and 8 mm (range, 8-9 mm) in the group with the STL reconstructed with grafts (p<0.05). The group of healed STLs were significantly thicker than the normal STL (p<0.05). We conclude that a surgically divided STL will heal spontaneously and will be significantly thicker after healing.

Transischiorectal fossa approach for resection of pudendal nerve schwannoma: case report.

Pudendal nerve schwannomas are very rare, with only two cases reported in the English-language literature. The surgical approaches described in these two case reports are the transgluteal approach and the laparoscopic approach. The authors present the case of a patient with progressive pelvic pain radiating ipsilaterally into her groin, vagina, and rectum, who was subsequently found to have a pudendal schwannoma. The authors used a transischiorectal fossa approach and intraoperative electrophysiological monitoring and successfully excised the tumor. This approach has the advantage of direct access to Alcock's canal with minimal disruption of the pelvic muscles and ligaments. The patient experienced complete relief of her pelvic pain after the procedure.

Ultrasound-Guided Pudendal Nerve Block at the Entrance of the Pudendal (Alcock) Canal: Description of Anatomy and Clinical Technique.

BACKGROUND AND OBJECTIVES: Ultrasound-guided techniques for pudendal nerve block have been described at the level of the ischial spine and transperineally. Theoretically, however, blockade of the pudendal nerve inside Alcock canal with a small local anesthetic volume would minimize the risk of sacral plexus blockade and would anesthetize all 3 branches of the pudendal nerve before they ramify in the ischioanal fossa. This technical report describes a new ultrasound-guided technique to block the pudendal nerve. The technique indicates an easy and effective roadmap to target the pudendal nerve inside the Alcock canal by following the margin of the hip bone sonographically along the greater sciatic notch, the ischial spine, and the lesser sciatic notch. METHODS: The technique was applied bilaterally in 3 patients with chronic perineal pain. The technique described was also used to locate the pudendal nerve within Alcock canal and inject dye bilaterally in 2 cadavers. RESULTS: Complete pinprick anesthesia was obtained in the pudendal territory of the perineum in all 3 patients. Pain was effectively alleviated or reduced in all patients with no affection of the sacral plexus nerve branches. In the 2 cadavers, all 4 pudendal nerves were successfully targeted and colored. CONCLUSIONS: This new technique is based on easily recognizable sonoanatomical patterns. It probably implies no risk of sacral plexus blockade, and the pudendal nerve is anesthetized before any branches ramify from the main trunk. This promising new technique must be validated in future clinical trials.