New laparoscopic approach to the pudendal nerve for neuromodulation based on an anatomic study

AIMS

The aim was to develop a new laparoscopic technique for placement of a pudendal lead.

METHODS

Development of a direct, feasible and reliable minimal‐invasive laparoscopic approach to the pudendal nerve (PN). Thirty‐one embalmed human specimens were dissected for the relevant anatomic structures of the pelvis. Step‐by‐step documentation and analysis of the laparoscopic approach in order to locate the PN directly in its course around the medial part of the sacrospinous ligament and test this approach for feasibility. Landmarks for intraoperative navigation towards the PN as well as the possible position of an lead were selected and demonstrated.

RESULTS

The visible medial umbilical fold, the intrapelvine part of the internal pudendal artery, the coccygeus muscle and the sacrospinous ligament are the main landmarks. The PN traverses the medial part of the sacrospinous ligament dorsally, medially to the internal pudendal artery. The medial part of the sacrospinous ligament has to be exposed in order to display the nerve. An lead can be placed ventrally on the nerve or around it, depending on the lead type or shape.

CONCLUSIONS

A precise and reliable identification of the PN by means of laparoscopy is feasible with an easy four‐step approach: (1) identification of the medial umbilical fold; (2) identification of the internal iliac artery; (3) identification of the internal pudendal artery and incision of the coccygeus muscle (‘white line’, arcuated line); and (4) exposition of the medial part of the sacrospinous ligament to display the PN.     

Contribution of the pudendal nerve to sensation of the distal rectum

BACKGROUND: Anal and rectal sensory mechanisms and pudendal nerve function are important in the control of faecal continence. The contribution of the pudendal nerve to sensation of the distal rectum was investigated. METHODS: Heat thresholds in the anal canal, distal and mid rectum were measured using a specially designed thermoprobe. Rectal sensory threshold volumes were measured using the balloon distension method. Needle electrodes were inserted into the external anal sphincter. Pudendal nerve block was performed through a perineal approach, and completeness assessed by loss of electromyographic activity. Heat and rectal volume thresholds were measured again following unilateral and bilateral pudendal nerve block. RESULTS: The technique was successful in four of six volunteers. Bilateral pudendal nerve block produced complete anaesthesia to heat in the anal canal (P = 0.029), but had no effect on heat thresholds in the distal or mid rectum. Rectal sensory threshold volumes were also unaffected by pudendal nerve anaesthesia. CONCLUSION: Anal canal sensation is subserved by the pudendal nerve, but this nerve is not essential to nociceptive sensory mechanisms in the distal or mid rectum. The transition between visceral control mechanisms in the lower rectum and somatic mechanisms in the anal canal may have functional importance in the initiation of defaecation and the maintenance of continence.     

Surgical anatomy of the somatic terminal innervation to the anal and urethral sphincters: role in anal and urethral surgery

PURPOSE: The gross anatomy of the pudendal nerve branches was studied to identify more precisely the neuroanatomical relationship in the region of the anal canal, bladder neck and proximal urethra. Such knowledge is essential for the development of surgical techniques that avoid nerve injury in sphincteroplasty for anal and urinary stress incontinence, and in pudendal canal decompression. MATERIALS AND METHODS: The pudendal nerve terminal branches were dissected in 7 female and 5 male formalin fixed cadavers, including 6 fully mature neonates and 6 adults, a mean age of 37.6 years. The nerves were traced from the pudendal nerve to their termination in the anal and urethral sphincters, and pelvic floor muscles. RESULTS: The inferior rectal nerve occupied the lower half of the ischiorectal fossa. Immediately after emerging from the pudendal canal it extended a motor branch to the levator ani muscle and the cutaneous perianal and scrotal branches. The nerve terminated in the external anal sphincter at the 3 and 9 o'clock positions. Inside the pudendal canal the perineal nerve gave rise to a scrotal branch which joined the scrotal branch of the inferior rectal nerve to form the common scrotal nerve. About 2 to 3 cm. from the pudendal canal the perineal nerve extended a branch to the bulbocavernosus muscle and divided into the terminal scrotal and motor branches, which penetrated the striated urethral sphincter at the 3 and 9 o'clock positions. The deep dorsal nerve of penis or clitoris coursed forward into the ischiorectal fossa, emerged from the deep perineal pouch and penetrated the suspensory ligament to the dorsum of the penis or clitoris. CONCLUSIONS: The identification of the precise anatomical relation of the somatic nerve termination to the anal and urethral sphincters seems vital to avoid sphincter denervation during surgery for the correction of fecal and stress urinary incontinence.     

Decompression and transposition of the pudendal nerve in pudendal neuralgia: a randomized controlled trial and long-term evaluation

BACKGROUND: We assess that pudendal neuralgia is a tunnel syndrome due to a ligamentous entrapment of the pudendal nerve and have treated 400 patients surgically since 1987. We have had no major complication. We conducted a randomized controlled trial to evaluate our procedure. METHODS: A sequential, randomized controlled trial to compare decompression of the pudendal nerve with non-surgical treatment. Patients aged 18-70, had chronic, uni/bilateral perineal pain, positive temporary response to blocks at the ischial spine and in Alcock's canal. They were randomly assigned to surgery (n=16) and control (n=16) groups. Primary end point was improvement at 3 months following surgery or assignment to the non-surgery group. Secondary end points were improvement at 12 months and at 4 years following surgical intervention. RESULTS: A significantly higher proportion of the surgery group was improved at 3 months. On intention-to-treat analysis 50% of the surgery group reported improvement in pain at 3 months versus 6.2% of the non-surgery group (p=.0155); in the analysis by treatment protocol the figures were 57.1% versus 6.7% (p=.0052). At 12 months, 71.4% of the surgery group compared with 13.3% of the non-surgery group were improved, analyzing by treatment protocol (p=.0025). Only those randomized to surgery were evaluated at 4 years: 8 remained improved at 4 years. No complications were encountered. CONCLUSIONS: In this study we demonstrate that decompression of the pudendal nerve is an effective and safe treatment for cases of chronic pudendal neuralgia that have been unresponsive to analgesia and nerve blocks. Following surgery, other medical interventions may be necessary.     

Intra-abdominal laparoscopic pudendal canal decompression – A feasibility study

BACKGROUND: Pudendal canal syndrome (PCS) is induced by the compression or the stretching of the pudendal nerve within Alcock's canal. METHODS: Considering the difficulty and possible complications involved in exposing the pudendal canal and nerve by either transperineal, transgluteal or transischiorectal approaches, an intra-abdominal laparoscopic pudendal canal decompression (ILPCD) was employed. For this technique, 30 male adult human cadavers were examined. RESULTS: Measurements revealed an adequate working space in 16 (80%) of the 20 cadavers, while in four specimens the ischiococcygeus muscle was too large to be mobilized sufficiently. The mean working space was 24 mm with a range of 18 to 31 mm. It was considered that a working space of less than 20 mm would not be sufficient for manipulation of the instruments. With regards to pudendal nerve compression, it was observed that 7 (35%) of the 20 cadavers exhibited anatomic signs of PCS. In five (25%) specimens, the compression was observed between the sacrospinous and sacrotuberous ligaments, while the other two (10%) exhibited a broader compression, by the falciform portion of the sacrotuberous ligament. Under the guidance of a laparoscope, the peritoneum was cut laterally to the bladder, and fascia pelvis was identified. The latter was split and the internal iliac vein was traced to the opening of the pudendal canal allowing clear visualization of its contents. Subsequently, either the sacrospinous or sacrotuberous ligament was cut. CONCLUSIONS: Considering that none of the surgical procedures currently used are known to completely improve all the symptoms of PCS, ILPCD could theoretically reduce stretching of the pudendal nerve.     

Le nerf pudendal : morphogenèse,anatomie, physiopathologie,clinique et thérapeutique

The pudendal is the king of the perineum. Most often originating in the S3 root, it is responsible for the teguments of the perineum (glans penis, clitoris, scrotum, and the labia majora, the skin of the central fibrous perineal body, anus), but also the erector muscles and the striated sphincters. The social nerve, it controls erection and the voluntary sphincters. It is also the nerve of the beginnings of sexual sensation and masturbation. Its injury is expressed in perineal pain, which, when positional, suggests a tunnel syndrome. The compression points have become well known: ligament pinching between the sacrotuberous and sacrospinous ligaments, the falciform process and the pudendal canal (Alcock canal). The data from questioning the patient, the results of the neurological exam, and the at least momentary response to infiltration define the Nantes criteria, which confirm the diagnosis. Treatment is medical, physical therapy, infiltration, and, as a last resort, surgery. The results have improved because of new technical norms, with 75% of operated patients benefiting from surgery. This disorder has become well known and should be remembered, thus sparing the patient from years of suffering and needless consultations for patients who do not present with organ disease, too often implicated instead of a true canal neuropathy, whose clinical manifestation and treatment have now been validated.     

Penile and perianal pudendal nerve somatosensory evoked potentials in the diagnosis of erectile dysfunction.

Neurophysiologic examinations in differential diagnosis of erectile dysfunction comprise electromyogramme of the pelvic floor, pudendal nerve terminal motor latency (PNTML) and evaluation of pudendal somatosensory evoked potentials (SSEP). We focused our interest on comparing diagnostic importance of penile and perianal pudendal nerve SSEP. We examined 20 patients suffering from erectile dysfunction and 20 patients without any manifestation of impotence. The stimulus was administered using penile ring electrodes at the base of the penis (cathode) and distally on the penis shaft (anode), as well as a perianal surface electrode applied at 3 o'clock in lithotomy position and 5 cm laterally on the gluteal skin. The potentials were recorded with intradermal needle electrodes at C(z)-2 cm (different) and F(z) (indifferent). 500 stimuli were averaged for a single tracing. The stimulus strength was set at an average of 3-4 times the stimulus threshold. Cortical latency of P 40 ranged from 39.0 to 45.6 ms (penile) and from 33.6 to 43.2 ms (perianal) in the control group, in the patient group latencies ranged from 38.8 to 51.6 (penile) and 34.0 to 44.8 ms (perianal). In two patients no potential was recordable after perianal stimulation, one patient showed a marked prolongation of the penile response with a normal perianal latency. Penile and perianal latencies of P 40 were significantly prolonged in the patient group compared to the control group (P<0.05). The combination of penile and perianal pudendal SSEP may provide valuable additional information in differential diagnosis of erectile dysfunction, especially allowing to identify different sites of neurogenic lesions. In contrast to perianal pudendal SSEP, penile stimulation may help to discover pathologic changes in the distal course of the pudendal nerve, especially the dorsal nerve of the penis.     

Feasibility of real-time ultrasound for pudendal nerve block in patients with chronic perineal pain

BACKGROUND AND OBJECTIVES: Compared with conventional fluoroscopic-guided pudendal nerve block, ultrasonography has potential advantages for visualizing anatomical landmarks such as the internal pudendal artery and nerve, the sacrospinous and sacrotuberous ligaments, and local anesthetic spread. We examined the clinical utility of performing pudendal nerve block under real-time ultrasound guidance. METHODS: Seventeen patients were studied. With the patient lying prone, a 2 to 5 MHz curved array ultrasound probe was placed at the level of the ischial spine to capture the transverse view of the ischial spine, the sacrospinous and sacrotuberous ligaments (SSL and STL), the internal pudendal artery (confirmed with color Doppler), and the pudendal nerve. A 22-gauge needle was advanced under real-time ultrasound guidance to reach the pudendal nerve in the plane between the STL and SSL. Following confirmation of spread of dextrose 5% solution in the interligamentous plane, a mixture of 5 mL 0.25% bupivacaine with 1:200,000 epinephrine and 40 mg Depo-Medrol (Pharmacia & Upjohn, Kalamazoo, MI) was injected. Assessment included the ease of identification of anatomical structures and local anesthetic spread with ultrasound, and the degree of sensory block in the perineum. RESULTS: The ischial spine, SSL, STL, internal pudendal artery, and pudendal nerve were easily identifiable with ultrasound in the majority of patients. Local anesthetic spread was seen as a hypoechoic collection around the nerve and expanding between the STL and SSL. All patients developed perineal sensory block following the procedure. CONCLUSIONS: Pudendal nerve block at the ischial spine level can be reliably performed under real-time ultrasound guidance.     

An unusual content of the inguinal canal: The external pudendal vein

Summary In a 43-year-old male cadaver the external pudendal vein ran an abnormal course in both inguinal regions. On each side the vein passed through the superficial inguinal ring, and after a short course in the canal pierced the inguinal ligament and drained into the femoral vein. The significance of this rare relation between the external pudendal vein and the inguinal canal is discussed from the embryological, surgical and diagnostic point of view.     

Painful ejaculation

We reviewed previous publications on post-orgasmic pain with reference to prevalence, epidemiology and treatment options, using the Ovid and PubMed (updated May 2006) databases to comprehensively search MEDLINE for reports on post-orgasmic pain that included peer-reviewed English-language articles. Official proceedings of internationally known scientific societies were also assessed. Because of the heterogeneity of the studies we did not apply meta- analytic techniques to the data. The incidence of post-orgasmic pain is 1-9.7%. The ejaculatory pain is associated with prostatitis, chronic pelvic pain syndrome, benign prostatic hyperplasia, and ejaculatory duct obstruction; it is also described in patients after procedures like radical prostatectomy. Aetiopathogenic theories include those referring to bladder neck closure and pudendal neuropathy. The treatment options vary from self-care, a 'perineal hyperprotection programme' to medication with the alpha-blocker, topiramate, and even surgical procedures like removing a section of the sacrotuberous ligament, neurolysis of the pudendal nerve or removing a section of the sacrospinous ligament. This is the first update of the subject, with reference to prevalence, epidemiology and treatment options. There is a need for adequately powered, prospective randomized trials on aetiology and treatment options.     

Functional sphincter ani externus reconstruction for treatment of fecal stress incontinence using free latissimus dorsi muscle transfer with coaptation to the pudendal nerve: preliminary experimental study in dogs

The external anal sphincter (EAS) is a skeletal muscle capable of voluntary contraction to prevent accidental defecation. Current reconstructive options for a severely damaged EAS using local muscle flaps are not always adequate for functional repair. The present preliminary experimental model was designed to assess the feasibility of a neuromicrovascular latissimus dorsi muscle transfer for functional external spincter muscle reconstruction. In nine mongrel dogs, the anal sphincter muscles were totally resected, leaving a mucosal canal in place. A segmental latissimus dorsi muscle was shaped around the anal canal in a circular fashion, with coaptation to the pudendal nerve, and vessel anastomosis at the ischiorectal fossa. Functional evaluation was performed using electromyogram, sphincter manometry, video documentation, and histologic examination with standard and immunohistochemical staining. After 8 months, the remaining three eligible dogs were continent. Muscle function was verified by means of electromyogram, sphincter manometry, and a video record. Histologic and immunohistochemical examination confirmed the functional results, showing only minor zones of fatty and fibrous degeneration. Transplantation of a segmental latissimus dorsi muscle with vascular anastomosis and coaptation to the pudendal nerve has proved to be successful in restoring (voluntary) anal continence experimentally in dogs. Its feasibility for perfect orientation as a neosphincter seems to be superior to any pedicled muscle flap. However, these preliminary results deserve further investigation prior to considering application in humans.     

Anal Canal Carcinoma with Pagetoid Spread: Report of a Case

A 70-year-old man with a history of colon polyps was found to have a semipedunculated polyp in the anal canal. The patient was asymptomatic. The lesion was 14 mm in diameter and located 5 mm from the dentate line. Histological examination of biopsy specimens revealed well-differentiated adenocarcinoma of the anal canal. During transanal local excision of the tumor, an abnormality of the perianal skin was recognized. Although intraoperative frozen section of the perianal skin did not show malignancy, permanent sections of the perineal skin revealed Paget's cells in the epidermis. Pathological examination of the anal canal carcinoma revealed submucosally invasive well-differentiated adenocarcinoma with a positive distal surgical margin. Thus, we performed additional wide local excision of the perianal skin including the distal margin of the previous local excision. Pathological examination revealed continuance within the epidermis between the anal canal adenocarcinoma and Paget's cells in the perianal skin lesion. Scattered Paget's cells also formed some glandular structures. Thus, we concluded that the perianal skin lesion was Pagetoid spread of anal canal adenocarcinoma. This report shows that the perianal skin should be examined carefully in patients with anal canal carcinoma.     

Pelvic osteotomies: anatomic pitfalls at the ischium

Pelvic osteotomies for acetabular dysplasia include an osteotomy of the ischium. The potential anatomical hazards of three different osteotomies of the ischium were assessed by performing a triple osteotomy in a series of 8 fresh cadaver pelvises. An oblique osteotomy above the sacrospinous ligament using a posterior approach requires that the inferior gluteal and pudendal neurovascular bundles be mobilised and retracted. A transverse osteotomy below the sacrospinous ligament using a posterior approach can be performed in a relatively safe area between the pudendal and sciatic nerves. A transverse osteotomy from anterior can be performed through a modified Smith Peterson approach. The pudendal nerve medially, the sciatic nerve laterally and the medial circumflex artery distally are not visualised and are prone to damage. Received: 4 August 1997     

End-to-side pudendal nerve anastomosis for the creation of a new reinforcing anal sphincter in dogs

BACKGROUND: An ideal reinforcing neo-sphincter should be innervated by the pudendal nerve to work in coordination with the external anal sphincter. The aim of this study was to create a skeletal muscle innervated by the pudendal nerve without inducing external anal sphincter morbidity. METHODS: Seven dogs were used. On the right side of each dog, the distal end of the transected nerve innervating the biceps femoris muscle was anastomosed to the perineural window of the pudendal nerve, where the epineurium was excised over a small area without injuring the funiculus. Reinnervation was studied 5 months after the operations. The left side of the dogs was used as a control. RESULTS: For all 7 dogs, there was no macroscopic difference detected in the external anal sphincter. For 6 dogs, the biceps femoris muscle was preserved after end-to-side pudendal nerve anastomosis. After the pudendal nerve central to the anastomosis site was electrically stimulated, the external anal sphincter contracted in all dogs. After end-to-side pudendal nerve anastomosis, the biceps femoris muscle contracted with the evoked potential in 5 dogs (71%) and demonstrated electric activity at rest in 3 dogs (43%), but there was no reflex activity after anal stimulation. The ratio of type 1 to type 2 muscle fiber in the biceps femoris muscle after end-to-side pudendal nerve anastomosis significantly changed and became the same as that in the external anal sphincter. The diameter of type 2 muscle fibers in the biceps femoris muscle significantly decreased after surgery. In addition, regenerated myelinated axons were observed in a cross section of the anastomosed nerve in 6 dogs. CONCLUSIONS: End-to-side pudendal nerve anastomosis is a promising technique for the creation of an anal sphincter in patients who have fecal incontinence. The technique preserved the original external anal sphincter and created a skeletal muscle that was innervated by the pudendal nerve in 71% of the dogs studied. This newly innervated skeletal muscle was capable of contracting in coordination with the original external anal sphincter on electric stimulation and also demonstrated characteristics closely similar to those of the external anal sphincter.     

Perianal complications of Crohn disease

Perianal Crohn's diseases (PCD) means perianal skin lesions, affection of anal canal and onset of fistula-in-ano. These manifestations are present in 10-82 per cent of patients suffered from the Crohn's disease (CD). Fistula-in-ano is the most serious complications which significantly threaten a quality of life. Contemporary treatment of this kind of fistula-in-ano includes administration of immunosuppressive drugs, steroids, antimycotics and combination of enteral and parenteral nutrition, with long term local treatment. Successful results are obtained in 40-80%.     

Bladder voiding by combined high frequency electrical pudendal nerve block and sacral root stimulation

AIMS: Uncoordinated contraction of the external urethral sphincter is prevalent in individuals with spinal cord injury and can prevent bladder voiding. The aim of this study was to demonstrate that complete and reversible sinusoidal high frequency alternating current (HFAC) conduction block of the pudendal nerves (PN) can eliminate external urethral sphincter activation and produce low residual bladder voiding. METHODS: In four cats, tripolar nerve cuff electrodes were implanted bilaterally on both pudendal nerves and on both extradural S2 roots. Bladder and urethral pressures, bladder volumes and flow were recorded. Bilateral HFAC was applied to determine voltage and frequency parameters resulting in bilateral PN conduction block. Sacral root stimulation provided bladder activation. Randomized sets of voiding trials were conducted with and without HFAC PN block. Additional voiding trials were conducted following bilateral PN neurotomy to eliminate somatic sphincter resistance and provide an estimate of voiding with complete block. RESULTS: Effective bilateral PN block and voiding was obtained in three of four animals. Application of bilateral PN HFAC stimulation improved voiding from 2 +/- 4% to 77 +/- 18% of the initial bladder volume and significantly (P < 0.001) reduced maximum bladder pressure during voiding. Voiding in trials with PN block was not significantly different from voiding following PN neurotomy (82 +/- 19%, P = 0.51). CONCLUSIONS: These results demonstrate that bilateral HFAC block of the PN can produce effective voiding. Neural prostheses using this approach may provide an alternative method for producing micturition for people with spinal cord injury.     

Alcock's canal releasing for pudendal artery syndrome resulting from gunshot injury

A 21-y-old man applied to hospital with a complaint of erectile dysfunction, which started soon after a gunshot injury. The entry of the bullet was at the middle right gluteal region without any exit hole. A pelvic X-ray revealed the bullet and the scattered particles. On penile Doppler ultrasonography, the peak systolic velocities (PCV) of the right and the left cavernosal arteries were 19 and 29 cm/s, respectively. Pudendal angiography revealed poor visualization of the right pudendal artery below the level of the bullet. The patient underwent a right-sided Alcock's canal releasing surgery. After the operation, on control penile Doppler ultrasonography, PCV on the right and the left cavernosal arteries were 53 and 35 cm/s, respectively. The control angiography revealed a normal right pudendal artery. The patient was fully potent 2 y after the operation. Not only the entrapment of pudendal nerve but also the pudendal artery may cause Pudendal canal syndrome. A gunshot injury may cause such a condition due to the reaction caused by the bullet. Pudendal canal decompression is a simple and effective treatment for pudendal canal syndrome.     

Diagnostic criteria for pudendal neuralgia by pudendal nerve entrapment (Nantes criteria)

AIMS: The diagnosis of pudendal neuralgia by pudendal nerve entrapment syndrome is essentially clinical. There are no pathognomonic criteria, but various clinical features can be suggestive of the diagnosis. We defined criteria that can help to the diagnosis. MATERIALS AND METHODS: A working party has validated a set of simple diagnostic criteria (Nantes criteria). RESULTS: The five essentials diagnostic criteria are: (1) Pain in the anatomical territory of the pudendal nerve. (2) Worsened by sitting. (3) The patient is not woken at night by the pain. (4) No objective sensory loss on clinical examination. (5) Positive anesthetic pudendal nerve block. Other clinical criteria can provide additional arguments in favor of the diagnosis of pudendal neuralgia. Exclusion criteria are also proposed: purely coccygeal, gluteal, or hypogastric pain, exclusively paroxysmal pain, exclusive pruritus, presence of imaging abnormalities able to explain the symptoms. CONCLUSION: The diagnosis of pudendal neuralgia by pudendal nerve entrapment syndrome is essentially clinical. There are no specific clinical signs or complementary test results of this disease. However, a combination of criteria can be suggestive of the diagnosis.