Pudendal Nerve Entrapment (PNE) is a condition that results from the compression or pinching of the pudendal nerve.
PNE causes chronic pain in the perianal, perineal and genital areas. Types of pain caused by PNE may include:
- Dysesthesia (spontaneous burning pain)
- Deep pain
- Hyperesthesia (increased sensitivity to physical stimulus)
- Hyperalgesia (exaggerated sensitivity to pain caused by certain stimuli)
- Allodynia (Pain caused by stimuli which don’t typically cause pain)
Symptoms of Pudendal Nerve Entrapment
Pain is aggravated when the patient is sitting, or after they’ve been sitting for a short period of time. Patients don’t feel pain when they are standing, lying down, or sitting on a toilet seat.
Other symptoms of PNE include:
- Difficulty starting a urinal flow
- Frequent urination
- Sudden urge to urinate
- Painful bowel movements
- Sexual dysfunction
- Altered sensation of ejaculation in men
- Recurrent numbness of the vulva or penis and/or scrotum in men
Causes of PNE
The condition may be caused by:
- Repetitive mechanical injury (from cycling for long periods of time)
- Injury sustained during surgery in the pelvic region
- Tumors or lesions in the pelvis
- Conditions such as diabetes or vasculitis that may trigger peripheral neuropathy
Treating PNE with Pudendal Nerve Blocks
A pudendal nerve block can help alleviate pain associated with the pudendal nerve.
Side Effects and Risks
The procedure is typically safe, with few side effects or complications. The most common side effect is discomfort at the injection site.
Less common side effects include bleeding, infection and temporary leg numbness or weakness caused by the medication spreading to the sciatic nerve. Serious (and rare) complications may include pudendal nerve damage or structural injury to the bladder and rectum.
Preparing for the Procedure
Patients should avoid eating six hours before the procedure. Patients taking medication and/or herbal and vitamin supplements should speak to their physician to find out if they should discontinue the medication.
The procedure is contraindicated if the patient has a cold, fever or flu symptoms. Patients should have pain that is at least 4/10 so that the medical team can assess if the injection is effective in relieving their pain.
What to Expect During the Procedure
The patient lies down on the operating table and the targeted area is cleaned with an antiseptic.
The most common approach used to perform a pudendal nerve block for female patients is called the transvaginal approach. Once the patient is positioned in the lithotomy position, the clinician will be guided by ultrasound or fluoroscopy as they identify the ischial spine. A long injection needle will puncture the sacrospinous ligament and the local anesthetic will be injected posteriorly to the ischial spine at the attachment of the sacrospinous ligament.
The procedure may also be performed using the transperineal approach. Once the patient is positioned in the lithotomy position, the clinician will be guided by ultrasound or fluoroscopy as they identify the ischial spine. A long injection needle will puncture the skin transperineally, medial to the ischial tuberosity. The local anesthetic will be injected once the target location is reached.
A third approach is the perirectal approach, which involves the use of a nerve stimulator to elicit contractions of the external anal sphincter.
Patients typically experience pain relief immediately.