Pudendal nerve entrapment syndrome

What is pudendal nerve entrapment? syndrome?

Pudendal nerve entrapment syndrome is an unusual condition that arises from compression of the pudendal nerve (S2) and causes chronic pain at saddle sites: the perineal, perianal and genital areas

It is a form of vulvodynia (in women). Pudendal nerve entrapment syndrome can also affect men.

Pudendal nerve entrapment syndrome is also called Alcock syndrome.

What causes pudendal nerve entrapment syndrome?

Pudendal nerve entrapment syndrome is caused by compression of the pudendal nerve as it exits or enters the pelvis in various tunnels created by adjacent muscles, tendons or bone and ligament tissues.

In this condition, the nerve is most often compressed in:

• The space between the sacrotuberous and sacrospinous ligaments (~ 70% of cases)
• Within Alcock's pudendal canal (~ 20% of cases)
• While the falciform process of the sacrotubertal ligament extends through the pudendal nerve and its branches
• Anywhere along the course of the pudendal nerve or its branches

Changes in the shape and position of the ischial spine are believed to occur in young cyclists. This predisposes them to pudendal nerve entrapment in later years, especially if they continue to cycle for long periods.

The most common causes of pudendal nerve entrapment syndrome include:

• Repeated mechanical injuries (eg, sitting in bicycle seats for prolonged periods over many years or months)
• Trauma to the pelvic area, for example during childbirth
• Damage to the nerve during surgical procedures in the pelvic or perineal regions.
• Compression of lesions or tumors arising in the pelvis.
• Any cause for the development of peripheral neuropathy (for example, diabetes or vasculitis)

What are the symptoms of pudendal nerve entrapment syndrome?

The symptoms of pudendal nerve entrapment syndrome arise from changes in nerve function and structural changes in the nerve that arise from the mechanical effects of compression. These changes result in neuropathic pain or cutaneous dysesthesia at perineum, genital and anorectal areas.

Neuropathic pain has many manifestations, most commonly spontaneous or evoked burning pain (also called "dysesthesia") with or without an acute (sudden, "electrical") pain component. Other manifestations of “neuropathic pain” include deep pain / pain sensation, increased appreciation of a sensation to any physical stimulus (“hyperesthesia”), exaggerated sensation of pain for a given stimulus (“hyperalgesia”), sensation of pain that occurs with stimulation that normally does not cause pain (“allodynia") Or an unpleasant, exaggerated and prolonged response to pain (" hyperpathy ").

The characteristic feature of pudendal nerve entrapment syndrome is an aggravation of symptoms when assuming a sitting position, often after a short session duration. Symptoms are usually relieved by standing and are generally absent when you lie down or sit on the toilet seat.

In some cases, other symptoms may occur, for example, urinary hesitancy (difficulty starting the flow of urine), frequency (frequent need to urinate), urgency (sudden sensation of urination), constipation / painful bowel movements, decreased awareness of defecation (the evacuation process), sexual dysfunction, recurrent numbness of the penis and / or scrotum (or vulva in women) after a prolonged cycle, impaired ejaculation sensation and impotence in men.

Chronic pudendal neuralgia is associated with generalized pain syndromes

How is pudendal nerve entrapment syndrome diagnosed?

Pudendal nerve entrapment syndrome is primarily a clinical diagnosis based on:

• History
• Characteristic symptoms and aggravating or relieving factors.
• Typical location of symptoms.

The 'skin roll test' can be a useful clinic sign. In this test, a thick roll (or fold) of skin just below and side he pinches his anus and then rolls forward. If pain is caused, this suggests that the pudendal nerve is compressed.

It is important to exclude injuries to the pelvis that could compress the nerve by a ultrasound, computed tomography (Connecticut) scan or magnetic resonance image (Magnetic resonance) Sometimes special studies of the nerves (electrophysiological studies) can be helpful. Local anesthetic Pudendal nerve blocks can be helpful in confirming the diagnosis in some cases if it demonstrates complete abolition of symptoms after a nerve block.

What is the treatment for pudendal nerve entrapment syndrome?

The condition can be amenable to treatment in a number of ways. General measures may include:

• Avoid prolonged periods of sitting, particularly in cyclists who have this condition.
• Use a foam cushion so there is no pressure in the center when sitting
• Avoid straining when urinating or opening the intestines.
• See a physical therapist to learn relaxation techniques for the pelvic floor.

Various medical treatments can be tried to relieve neuropathic pain, including nerve stabilizing agents. These may include:

• Tricyclic antidepressants such as amitriptyline.
• Anticonvulsants such as carbamazepine and sodium valproate.
• Nerve stabilizers such as gabapentin and pregabalin.

When medical treatments are not successful in alleviating symptoms, surgical treatments can be tried. Surgical treatments include Local anesthesia nerve blocks, botulinum toxin injections to relieve pelvic floor spasm, corticosteroid injections to reduce swelling, and inflammationand surgical decompression of the pudendal nerve.

Surgical decompression of the nerve can be variably effective. Surgery may not be completely effective in all cases for various reasons, for example irreversible nerve damage due to the effects of prolonged or severe nerve compression, processes that irreversibly affect nerve function (such as poorly controlled diabetes mellitus for long long time), inadequate decompression surgery, surgical wrong-site decompression, and chronic pain syndromes.