Actas Urologicas Espanolas Review – MISTURICTION DYSFUNCTION Update on pudendal nerve entrapment syndrome: an anatomical and surgical approach, diagnosis and therapy

Introduction: The syndrome of pudendal nerve entrapment (SANP) is widely unknown and often misdiagnosed or confused with other diseases. It was first described by Amarenco in 1987. The classic clinical manifestation is pudendal neuralgia, a neuropathic pain in the genital area. Objectives: To make known its existence to the urology professionals through a systematic review of existing literature and its potential for diagnosis and treatment. Materials and methods: We performed a literature search through the database "Pubmed" using the terms "Pudendal nerve", "Pudendal nerve entrapment syndrome", "Pelvic floor neuropathic pain", "Pelvic floor myofascial syndrome," "Pudendal nerve decompression". Also, selected works in English, Spanish and French, also reviewing the articles relate this work. Results: We develop the highlights of the syndrome: anatomy, etiology, pathophysiology, clinical diagnosis, ecodoppler of internal pudendal artery, electrophysiological studies, diagnostic criteria, medical therapy, physical therapy treatments and surgery. Conclusion: It is an uncommon cause of pain in the pelvic floor and greatly affects quality of life of patients. Today, we have diagnostic and therapeutic tools that allow us to treat this disabling syndrome with good results. Introduction Pudendal nerve entrapment syndrome was described by Dr. Amarenco in 1987. He came across this syndrome when a cyclist visited him complaining of pain in the pudendal area. He would run some electrophysiological tests to determine the anomaly. At first, he called it perineal paralysis of cyclists (1).Soon after, in 1991, Dr. Shafik would describe the technique for pudendal nerve decompression. The procedure is simple and ambulatory. It lasts 510 minutes in expert hands, with no complications except for infections, small hematomas and postoperative pain (2).The main reason for patients to consult the doctor is pain in the anal and perineal area. This pain particularly appears when sitting down, relieves when getting up and disappears when lying in bed. Among its neuropathy symptoms we can find hypoesthesia, numbness, perineal tingling and even severe electrical shocks (3).In a retrospective study, Benson shows that we are dealing with an entity few practitioners think of. This will lead to a significant pilgrimage of patients before being correctly diagnosed. Moreover, we can find cases in which neurophysiologic findings showed values within normal limits, increasing the difficulty of the problem (4).Similarity between PNE symptoms and myofascial pain syndrome of the pelvic floor will be constant. Sometimes they will co-exist and sometimes one of these entities will lead to the other; distinctive pains of both syndromes are overlapped or some of them stand out on the others, making their diagnosis and later treatment more difficult (5).As for epidemiological records, there are not too many in the existing literature. The average time of diagnosis is 4 years, ranging from 1 to 15 years. Doctors visited before diagnosis range from 10 to 30. Sex of course is important, being more females affected. Seven out of ten are women.The actual impact of this condition is still unknown. Objectives: to make known its existence to the urology professionals through a systematic review of existing literature and its potential for diagnosis and treatment. Materials and methods: We performed a literature search through the database "Pubmed" using the terms such as "Pudendal nerve", "Pudendal nerve entrapment syndrome", "Pelvic floor neuropathic pain", "Pelvic floor myofascial syndrome," "Pudendal nerve decompression". We also selected works in English, Spanish and French, reviewing articles related to this topic too. Finally, we chose between those works that better fit the PNE profile, ruling out second ones and successive manuscripts by the same author or authors that did not add up any relevance to the treated subject. Results: we developed the highlights of the syndrome: anatomy, etiology, pathophysiology, clinical diagnosis, Doppler ultrasound in internal pudendal artery, electro-physiological studies, diagnostic criteria, medical therapy, physical therapy treatments and surgery. Brief anatomic-surgical summary The pudendal nerve (PN) (picture 1) as it follows its path, goes through some intricate passages; this is the reason why nerve entrapment easily occurs (6). Picture 1. Pudendal Nerve pathway. PN anatomy has profusely been described by significant anatomists, but the electro-physiological records show that the origins of the different branches differ with those mentioned by the conventional anatomy which agrees with Bisschop et al's anatomic and neurophysiologic investigations (7). Shafik tells us about surgical anatomy and its implications, in a revealing article, after having examined 26 corpses; following transperineal and transgluteal paths that we will see in the surgical treatment area later on (8). Robert et al, through anatomic investigation on corpses, believe that critical points to find entrapments at PN would be: the point between the sacrotuberous and sacrospinous ligaments, Alcock’s canal and the falciform process (9). We find ourselves before a complex anatomy, however necessary to explain the pathology caused by the entrapment. PN has its origin at the sacral spinal segments: S2, S3 y S4. The anatomy of nerve endings is very complex and has many variants. However, we will be able to relate the pain to its possible pudendal origin if we know the sensory areas innervated by the pudendal nerve. PN has got 3 terminal branches: inferior rectal nerve, perineal nerve and dorsal nerve of penis and clitoris. PN innervates the bulbospongiosus and ischiocavernosus muscles, external anal sphincter, levator ani and superficial and deep perienal nerve. Variability in the innervation of the levator ani muscle expressed by Grigoriescu after studying 17 corpses should put us on the alert for its clinical and surgical repercussions (10). The 3 terminal branches have a different proportion of motor, sensory and autonomic fibers. Therefore, their entrapment can cause signs or symptoms in any of its 3 areas. In total, it is estimated that 30% will be autonomic and 70% will be somatic (50% sensory and 20% motor). Pudendal nerve innervations will be (6), (11): • Sensitive: perineal skin and genitals. • Motor: external anal sphincter, levator ani muscle, bulbospongiosus and ischiocavernosus muscles, urethral striated sphincter and superficial and deep perienal nerve. • Vegetative: erection and sense of urgency to urinate. Etiology and events that lead to injury Bautrant et al analyzed the possible causes that might lead to PNE. They found out that childbirth, direct falls on the tail-bone, cycling and pelvic surgery are frequent triggers for this nosologic condition (12). Cycling is the common reason mentioned by Amarenco in order to suffer from nerve entrapment and we figure out that similar sports might produce the same results(1); temporary erectile dysfunction is a frequent companion to amateur cyclists (13).Chronic constipation and perineal descent are given as one of the first causes to trigger off PNE (14).In a very interesting article Shafik mentions the importance of rectal prolapse and rectal incontinence to cause PNE. He finds abnormal electromyographic and electroneurographic values, along with perineal hypoesthesia. He treats it with decompression and obtains encouraging results (15).Vulvar pain associated with chronic constipation and incontinence may be connected to PN entrapment as Shafik showed in his study of idiopathic vulvodynia. 9 out of 11 patients experienced no pain after decompression (16).Surgery involving vaginal dissection may produce compressive neuropathy of the PN as Benson will tell (17).The practice of sport during adolescence may lead to an inadequate development of the spinous process of the ischium that will end up in an ulterior compressive neuropathy over the years (18).After all this, it will be easy to understand that repetitive micro-trauma injuries to the perineal area can lead us to PNE (19).Only by passing through a muscle anywhere on the body, a nerve of that segment may be trapped and cause an injury or nerve dysfunction (20). Lien et al describe nerve stretch during childbirth as a possible etiology (21).The episiotomy can be the source of some cases of neuropathy of the PN, therefore we will be very vigilant when carrying it out, as evidenced by a report of Soga et al based on the observation of 15 elderly female corpses (22). Pathophysiology of nerve entrapment Three main factors can be identified in the development and pathology of the nervous system: vascular, ionic and mechanical. There is no agreement about which one of them is predominant, particularly in the early stages of the compression. Today it is thought that vascular factors predominate over the others (23).Nerve fibers depend on a continuous blood supply for their normal functioning. Pe lvis Región glutes Calnal de Alcok Espacio perineal profundo Cara dorsal del pene