Pudendal nerve entrapment
Encyclopedia
Pudendal nerve entrapment (PNE), also known as Alcock canal syndrome, is an uncommon source of chronic pain
, in which the pudendal nerve
(located in the pelvis
) is entrapped or compressed. Pain is positional and is worsened by sitting. Other symptoms include genital numbness, fecal incontinence and urinary incontinence.
The term pudendal neuralgia (PN) is used interchangeably with "pudendal nerve entrapment", but a 2009 review study found both that "prevalence of PN is unknown and it seems to be a rare event" and that "there is no evidence to support equating the presence of this syndrome with a diagnosis of pudendal nerve entrapment," meaning that it is possible to have all the symptoms of pudendal nerve entrapment (otherwise known as pudendal neuralgia) based on the criteria specified at Nantes in 2006, without having an entrapped pudendal nerve.
and scrotum
after prolonged cycling, or an altered sensation of ejaculation
, with disturbance of micturition (urination) and reduced awareness of defecation
. Nerve entrapment syndromes, presenting as genitalia numbness, are amongst the most common bicycling associated urogenital problems.
The pain is typically caused by sitting, relieved by standing, and is absent when recumbent (lying down) or sitting on a toilet seat. If the perineal pain is positional (changes with the patient's position, for example sitting or standing), this suggests a tunnel syndrome. Anesthesiologist John S. McDonald of UCLA reports that sitting pain relieved by standing or sitting on a toilet seat is the most reliable diagnostic parameter.
Other than positional pain and numbness, the main symptoms are fecal incontinence
and urinary incontinence
.
Differential diagnosis
should consider the far commoner conditions chronic prostatitis/chronic pelvic pain syndrome
and interstitial cystitis
.
may be useful. In patients with unilateral pudendal entrapment in the Alcock's canal, it is typical to see asymmetric swelling and hyperintensity affecting the pudendal neurovascular bundle.
, scarring due to surgery
, accidents and surgical mishaps. Anatomic abnormalities can result in PNE due to the pudendal nerve being fused to different parts of the anatomy, or trapped between the sacrotuberous and sacrospinalis ligament
s. Heavy and prolonged bicycling
, especially if an inappropriately shaped or incorrectly positioned bicycle seat is used, may eventually thicken the sacrotuberous and/or sacrospinous ligaments and trap the nerve between them, resulting in PNE.
has helped decrease pain levels for some people, but is generally ineffective. Chiropractic adjustments to the lower back have also helped some patients with pudendal nerve issues.
(like gabapentin
), antidepressant
s (like amitriptyline
), and palmitoylethanolamide
.
hydrochloride) and a corticosteroid
(e.g. methylprednisolone
) are injected to provide immediate pudendal anesthesia
. The injections may also bring a long-term response because the anti-inflammatory effects of the steroid
and steroid-induced fat necrosis
can reduce inflammation in the region around the nerve and decrease pressure on the nerve itself. This treatment may be effective in 65–73% of patients.
has been successful in treating a refractory case of PNE.
in its Guidelines on Pelvic Pain said that expert centers in Europe have found no cases of PNE and that surgical success is rare:
Three types of surgery have been done to decompress the pudendal nerve: transperineal, transgluteal, and transichiorectal. A follow-up of patients of this surgery after 4 years found that 50% felt their pain had improved to various extents, although control patients were not followed up for comparison.
If surgery does bring relief of symptoms, patients will mostly experience it within 4 weeks of surgery.
Chronic pain
Chronic pain has several different meanings in medicine. Traditionally, the distinction between acute and chronic pain has relied upon an arbitrary interval of time from onset; the two most commonly used markers being 3 months and 6 months since the initiation of pain, though some theorists and...
, in which the pudendal nerve
Pudendal nerve
The pudendal nerve is a sensory and somatic nerve in the pelvic region which is a large branch of the sacral plexus that innervates the external genitalia of both sexes, as well as sphincters for the bladder and the rectum...
(located in the pelvis
Pelvis
In human anatomy, the pelvis is the lower part of the trunk, between the abdomen and the lower limbs .The pelvis includes several structures:...
) is entrapped or compressed. Pain is positional and is worsened by sitting. Other symptoms include genital numbness, fecal incontinence and urinary incontinence.
The term pudendal neuralgia (PN) is used interchangeably with "pudendal nerve entrapment", but a 2009 review study found both that "prevalence of PN is unknown and it seems to be a rare event" and that "there is no evidence to support equating the presence of this syndrome with a diagnosis of pudendal nerve entrapment," meaning that it is possible to have all the symptoms of pudendal nerve entrapment (otherwise known as pudendal neuralgia) based on the criteria specified at Nantes in 2006, without having an entrapped pudendal nerve.
Symptoms
There are no specific clinical signs or complementary test results for this condition. The typical symptoms of PNE or PN are seen, for example, in male competitive cyclists (it is often called "cyclist syndrome), who can rarely develop recurrent numbness of the penisPenis
The penis is a biological feature of male animals including both vertebrates and invertebrates...
and scrotum
Scrotum
In some male mammals the scrotum is a dual-chambered protuberance of skin and muscle containing the testicles and divided by a septum. It is an extension of the perineum, and is located between the penis and anus. In humans and some other mammals, the base of the scrotum becomes covered with curly...
after prolonged cycling, or an altered sensation of ejaculation
Ejaculation
Ejaculation is the ejecting of semen from the male reproductory tract, and is usually accompanied by orgasm. It is usually the final stage and natural objective of male sexual stimulation, and an essential component of natural conception. In rare cases ejaculation occurs because of prostatic disease...
, with disturbance of micturition (urination) and reduced awareness of defecation
Defecation
Defecation is the final act of digestion by which organisms eliminate solid, semisolid or liquid waste material from the digestive tract via the anus. Waves of muscular contraction known as peristalsis in the walls of the colon move fecal matter through the digestive tract towards the rectum...
. Nerve entrapment syndromes, presenting as genitalia numbness, are amongst the most common bicycling associated urogenital problems.
The pain is typically caused by sitting, relieved by standing, and is absent when recumbent (lying down) or sitting on a toilet seat. If the perineal pain is positional (changes with the patient's position, for example sitting or standing), this suggests a tunnel syndrome. Anesthesiologist John S. McDonald of UCLA reports that sitting pain relieved by standing or sitting on a toilet seat is the most reliable diagnostic parameter.
Other than positional pain and numbness, the main symptoms are fecal incontinence
Fecal incontinence
Fecal incontinence is the loss of regular control of the bowels. Involuntary excretion and leaking are common occurrences for those affected. Subjects relating to defecation are often socially unacceptable, thus those affected may be beset by feelings of shame and humiliation...
and urinary incontinence
Urinary incontinence
Urinary incontinence is any involuntary leakage of urine. It is a common and distressing problem, which may have a profound impact on quality of life. Urinary incontinence almost always results from an underlying treatable medical condition but is under-reported to medical practitioners...
.
Differential diagnosis
Differential diagnosis
A differential diagnosis is a systematic diagnostic method used to identify the presence of an entity where multiple alternatives are possible , and may also refer to any of the included candidate alternatives A differential diagnosis (sometimes abbreviated DDx, ddx, DD, D/Dx, or ΔΔ) is a...
should consider the far commoner conditions chronic prostatitis/chronic pelvic pain syndrome
Chronic prostatitis/chronic pelvic pain syndrome
Chronic nonbacterial prostatitis or chronic prostatitis/chronic pelvic pain syndrome is a pelvic pain condition in men, and should be distinguished from other forms of prostatitis such as chronic bacterial prostatitis and acute bacterial prostatitis...
and interstitial cystitis
Interstitial cystitis
Interstitial cystitis or bladder pain syndrome is a chronic, oftentimes severely debilitating disease of the urinary bladder...
.
Imaging
Imaging studies using MR neurographyMagnetic resonance imaging
Magnetic resonance imaging , nuclear magnetic resonance imaging , or magnetic resonance tomography is a medical imaging technique used in radiology to visualize detailed internal structures...
may be useful. In patients with unilateral pudendal entrapment in the Alcock's canal, it is typical to see asymmetric swelling and hyperintensity affecting the pudendal neurovascular bundle.
Causes
PNE can be caused by pregnancyPregnancy
Pregnancy refers to the fertilization and development of one or more offspring, known as a fetus or embryo, in a woman's uterus. In a pregnancy, there can be multiple gestations, as in the case of twins or triplets...
, scarring due to surgery
Surgery
Surgery is an ancient medical specialty that uses operative manual and instrumental techniques on a patient to investigate and/or treat a pathological condition such as disease or injury, or to help improve bodily function or appearance.An act of performing surgery may be called a surgical...
, accidents and surgical mishaps. Anatomic abnormalities can result in PNE due to the pudendal nerve being fused to different parts of the anatomy, or trapped between the sacrotuberous and sacrospinalis ligament
Ligament
In anatomy, the term ligament is used to denote any of three types of structures. Most commonly, it refers to fibrous tissue that connects bones to other bones and is also known as articular ligament, articular larua, fibrous ligament, or true ligament.Ligament can also refer to:* Peritoneal...
s. Heavy and prolonged bicycling
Cycling
Cycling, also called bicycling or biking, is the use of bicycles for transport, recreation, or for sport. Persons engaged in cycling are cyclists or bicyclists...
, especially if an inappropriately shaped or incorrectly positioned bicycle seat is used, may eventually thicken the sacrotuberous and/or sacrospinous ligaments and trap the nerve between them, resulting in PNE.
Treatment
Optional treatments include behavioral modifications, physical therapy, analgesics and other medications, pudendal nerve block, and surgical nerve decompression. A newer form of treatment is pulsed radiofrequency.Physical therapy
There are stretches and exercises which have provided reduced levels of pain for some people. There are different sources of pain for people since there are so many ligament, muscles and nerves in the area. Sometimes women do pelvic floor exercises for compression after childbirth. However, there have been cases where the wrong stretches make the constant pain worse. Some people need to strengthen the muscles, others should stretch, while for some people it is purely neurological. There have been cases where doing stretches have helped bicyclists. A helpful stretch for some is bending over and touching your toes. Another stretch includes bringing your knee to your chest on the compressed side while laying on your back. One more possibly helpful stretch for bicyclists include sitting in the lotus position and moving your head to the ground supporting yourself with your hands and keeping your buttocks up. Stretches should not be held long (about 8 seconds) and be spread out through the day. AcupunctureAcupuncture
Acupuncture is a type of alternative medicine that treats patients by insertion and manipulation of solid, generally thin needles in the body....
has helped decrease pain levels for some people, but is generally ineffective. Chiropractic adjustments to the lower back have also helped some patients with pudendal nerve issues.
Medications
Drugs used include anti-epilepticsAnticonvulsant
The anticonvulsants are a diverse group of pharmaceuticals used in the treatment of epileptic seizures. Anticonvulsants are also increasingly being used in the treatment of bipolar disorder, since many seem to act as mood stabilizers, and in the treatment of neuropathic pain. The goal of an...
(like gabapentin
Gabapentin
Gabapentin is a pharmaceutical drug, specifically a GABA analogue. It was originally developed for the treatment of epilepsy, and currently is also used to relieve neuropathic pain...
), antidepressant
Antidepressant
An antidepressant is a psychiatric medication used to alleviate mood disorders, such as major depression and dysthymia and anxiety disorders such as social anxiety disorder. According to Gelder, Mayou &*Geddes people with a depressive illness will experience a therapeutic effect to their mood;...
s (like amitriptyline
Amitriptyline
Amitriptyline is a tricyclic antidepressant . It is the most widely used TCA and has at least equal efficacy against depression as the newer class of SSRIs...
), and palmitoylethanolamide
Palmitoylethanolamide
Palmitoylethanolamide is an endogenous fatty acid amide, belonging to the class of endocannabinoids. PEA has been demonstrated to bind to a receptor in the cell-nucleus and exerts a great variety of biological functions related to chronic pain and inflammation. The main target is thought to be...
.
Injections
Alcock canal infiltration with corticosteroids is a minimally invasive technique which allows for pain relief and could be tried when physical therapy has failed and before surgery. A long-acting local anesthetic (bupivacaineBupivacaine
Bupivacaine is a local anaesthetic drug belonging to the amino amide group. AstraZeneca commonly markets it under various trade names, including Marcain, Marcaine, Sensorcaine and Vivacaine.-Indications:...
hydrochloride) and a corticosteroid
Corticosteroid
Corticosteroids are a class of steroid hormones that are produced in the adrenal cortex. Corticosteroids are involved in a wide range of physiologic systems such as stress response, immune response and regulation of inflammation, carbohydrate metabolism, protein catabolism, blood electrolyte...
(e.g. methylprednisolone
Methylprednisolone
Methylprednisolone is a synthetic glucocorticoid or corticosteroid drug. It is marketed in the USA and Canada under the brand names Medrol and Solu-Medrol. It is also available as a generic drug....
) are injected to provide immediate pudendal anesthesia
Anesthesia
Anesthesia, or anaesthesia , traditionally meant the condition of having sensation blocked or temporarily taken away...
. The injections may also bring a long-term response because the anti-inflammatory effects of the steroid
Steroid
A steroid is a type of organic compound that contains a characteristic arrangement of four cycloalkane rings that are joined to each other. Examples of steroids include the dietary fat cholesterol, the sex hormones estradiol and testosterone, and the anti-inflammatory drug dexamethasone.The core...
and steroid-induced fat necrosis
Necrosis
Necrosis is the premature death of cells in living tissue. Necrosis is caused by factors external to the cell or tissue, such as infection, toxins, or trauma. This is in contrast to apoptosis, which is a naturally occurring cause of cellular death...
can reduce inflammation in the region around the nerve and decrease pressure on the nerve itself. This treatment may be effective in 65–73% of patients.
Pulsed radiofrequency
Pulsed radiofrequencyPulsed radiofrequency
Pulsed radiofrequency is the technique where by radio frequency oscillations are gated at a rate of pulses per second . Radio frequency energies occupy 1.0 X 104Hz to 3.0 X 1011HZ of the electromagnetic spectrum...
has been successful in treating a refractory case of PNE.
Surgical
Decompression surgery is a "last resort", according to surgeons who perform the operation. The surgery is performed by a small number of surgeons in a limited number of countries. The validity of decompression surgery as a treatment and the existence of entrapment as a cause of pelvic pain are highly controversial. While a few doctors will prescribe decompression surgery, most will not. Notably, in February 2003 the European Association of UrologyEuropean Association of Urology
The European Association of Urology is a non-profit organisation committed to the representation of urology professionals worldwide...
in its Guidelines on Pelvic Pain said that expert centers in Europe have found no cases of PNE and that surgical success is rare:
Three types of surgery have been done to decompress the pudendal nerve: transperineal, transgluteal, and transichiorectal. A follow-up of patients of this surgery after 4 years found that 50% felt their pain had improved to various extents, although control patients were not followed up for comparison.
If surgery does bring relief of symptoms, patients will mostly experience it within 4 weeks of surgery.