Overview of Pudendal Nerve Block
Pudendal nerve blocks are a popular method used to diagnose and manage long-term (chronic) pain in the pelvic area, particularly when it’s due to pudendal neuralgia – a condition often associated with the trapping of a nerve. This technique, which involves numbing a particular region with anesthetic, is extensively used in procedures related to women’s reproductive health, childbirth, and lower digestive tract.
These nerve blocks are often used to lessen the pain during childbirth, give local pain relief during surgeries, and manage long-term pelvic pain in a range of medical settings.
Anatomy and Physiology of Pudendal Nerve Block
The pudendal nerve is a nerve that comes from the lower part of your spine, specifically from the nerve roots called S2-S4. It’s important as it plays a role in both feeling (sensory) and movement (motor) in certain parts of your body. This nerve travels through a passage in your hip bone, moves around some ligaments in your pelvis before re-entering a region known as the perineum. The perineum is the area between your genitals and your anus. Here, the pudendal nerve is accompanied by an artery and a vein that share its name. It then travels through an area called the ischiorectal fossa and a canal known as Alcock canal, or the pudendal canal.
Inside this canal, the pudendal nerve splits into two parts. One of these, the inferior rectal nerve, provides feeling and controls the muscles around your anus. The other part, the perineal nerve, controls muscles in your pelvic floor and provides feeling to the skin of major sexual organs. Finally, a branch of the nerve called the dorsal nerve supplies feeling to the skin of the clitoris in women and the penis in men.
Damage or disorders that affect the pudendal nerve can have significant impacts on the areas it supplies, particularly causing loss of sensation. The regions this nerve services include the perineum, lower buttocks, anus, and external sexual organs.
The pudendal nerve can get “trapped” or pinched in four common places:
- Type 1: Below a hip muscle (the piriformis muscle) where the nerve emerges from a notch in your hip bone
- Type 2: Between the sacrotuberous and sacrospinous ligaments in your pelvis, it’s the most common place
- Type 3: Inside the Alcock canal
- Type 4: At the terminal or end branches of the nerve which supply regions like the perineum or external sexual organs
Pudendal neuralgia, which is a pain condition involving the pudendal nerve, is typically caused by repetitive actions or excessive use of the muscles in the pelvic region. This can occur from activities such as sitting for extended periods of time, continuous cycling, car accidents, falls, surgeries involving the pelvic area, radiation therapy and childbirth. Other causes include health conditions such as diabetes, herpes zoster, HIV, endometriosis, and multiple sclerosis. Often, childbirth and post-surgery complications are the most prevalent causes for this condition.
Why do People Need Pudendal Nerve Block
A pudendal nerve block is a type of local anesthesia that is commonly used in certain medical procedures to numb the area around the genitals and anus. Traditionally, it has been used in childbirth, certain types of vaginal repairs, and surgeries to treat hemorrhoids. It’s also useful for some urological procedures, such as prostate biopsies guided by ultrasound, removal of the prostate through the urethra, implanting an inflatable penile prosthesis, and for patients experiencing discomfort from a urinary catheter.
This type of nerve block is effective at reducing pain and can decrease the need for strong painkillers known as opioids, which are often required after surgery. For instance, in patients receiving an inflatable penile prosthesis, pudendal nerve blocks can sufficiently control pain and reduce the need for opioids, which is particularly beneficial for those where it’s important to limit opioid use. There have also been some cases where these nerve blocks have helped manage ongoing genital arousal disorder.
Apart from this, pudendal nerve blocks are also used to manage and help diagnose pudendal neuralgia, a condition that causes chronic pain in the area that this nerve serves. This pain may be described as a burning sensation, or as a tingling, aching, stabbing, or electric-shock-like discomfort in the external genitals and perineal area (the area between the anus and the genitals). This pain typically worsens when sitting and improves when standing, and it often intensifies after ejaculation. Some people may also experience urinary symptoms such as urgency and frequent urination, as well as problems getting or keeping an erection.
Pudendal neuralgia most commonly affects one side of the body, although there have been cases where cyclists have reported experiencing it on both sides. It’s not always easy to diagnose this condition, as its symptoms can be quite nondescript, leading to misdiagnosis and delay in treatment. That’s why it’s suggested that anyone with unresponsive chronic pelvic pain should be evaluated for possible pudendal nerve entrapment. A successful pudendal nerve block is often a key test in diagnosing pudendal nerve entrapment and neuralgia. If the pain relief is significant after the nerve block, it could be repeated on a monthly basis to manage long-term pain. Research also showed that adding a medication called dexamethasone intravenously (into a vein) could enhance the pain-relieving effects of pudendal nerve blocks in children undergoing surgery for a condition called hypospadias, where the opening of the urethra is on the underside of the penis.
When a Person Should Avoid Pudendal Nerve Block
A pudendal block is generally very safe, but there are a few situations where it might not be the best option:
First, if you’ve had an allergic reaction to the numbing medicine that’s being used, you shouldn’t get a pudendal block.
Second, if you are fighting off an infection or have a serious illness called sepsis, this could also prevent you from getting this procedure. This is also true if there’s an infection in your skin or tissue where the injection would be given.
Third, if your blood isn’t clotting properly (“uncorrected coagulopathies”) or if you’ve had surgery in the same area before and the local anatomy has been changed, a pudendal block may not be a good choice.
Equipment used for Pudendal Nerve Block
To carry out a procedure aimed at numbing the pudendal nerve (a nerve in the pelvis), certain items are needed. These include germ-killing solutions like chlorhexidine or povidone-iodine, disposable sterile sheets used to cover the patient and operating area, sterile gloves, sterile sponges for wiping, sterile syringes and needles, and a selected numbing solution. The needle often used is 20 cm long and 20-gauge in size.
The numbing solutions primarily used are Lidocaine 1% and Bupivacaine 0.25%. In some cases, a mixture of Lidocaine, Bupivacaine, and a steroid called triamcinolone is used for longer-lasting relief, providing over 30 days of comfort.
Although the numbing procedure can be performed without the help of an imaging device, it is highly suggested to use ultrasound or fluoroscopy (imaging techniques to see the body’s structures and functions). There should also be equipment nearby to monitor the patient’s heart rate and blood pressure during the procedure.
Who is needed to perform Pudendal Nerve Block?
A team typically conducts pudendal nerve blocks, a type of procedure to help reduce pain in the lower part of your body. This team is usually made up of a doctor and a nurse who both have special training in doing these procedures. Also, if a particular type of medical imaging is used during the procedure, a skilled technician who knows how to handle this machine would be there too.
Preparing for Pudendal Nerve Block
Before starting any medical procedure, doctors go through a process to make sure patients fully understand what will happen. They’ll explain exactly what the procedure involves, the benefits it’s expected to provide, any potential risks, and the other options you might consider instead. Once you understand all this, they’ll ask for your permission to go ahead with the procedure.
The doctor will then make sure all the necessary equipment and medications for the procedure are in the room. This is an important step to ensure everything goes smoothly. A “time-out” is then conducted – a safety protocol where all members of the medical team check they’re about to carry out the right procedure on the right patient.
Once all the checks are complete, you’ll be positioned comfortably, and the doctor will clean the area where they will perform the procedure. They will then cover this area with sterile drapes to keep it clean and prevent infections. The room should also be equipped with a specific imaging device if this is being used in the procedure. This could be something like an X-ray or ultrasound machine to help the doctor see better under your skin.
How is Pudendal Nerve Block performed
A pudendal nerve block is a procedure that aims to temporarily numb the pudendal nerve, which provides sensation to the lower part of your body like your buttocks and genital area. This procedure is often used to relieve pain during childbirth or certain medical procedures like surgery. The nerve is located near the ligament that connects the sacrum (part of your lower back) to the ischial spine (part of your hip bone), and there are a few ways doctors can reach it to administer the anesthetic.
One common method to numb the pudendal nerve is a transvaginal approach, often used for childbirth and gynecological procedures. It involves the following steps:
1. The patient lies down on their back with their legs up and open (a position called lithotomy).
2. The doctor feels for a bony projection on the inside of the pelvis (the ischial spine) or the ligament next to it (sacrospinous ligament).
3. Then, they gently insert a needle guide through the vagina, aiming to reach a point near the ischial spine.
4. After that, the doctor punctures the ligament using a needle, which may be preceded by injecting a small amount of local anesthetic to reduce discomfort.
5. Finally, once the needle position is confirmed (either by the loss of resistance or using imaging techniques), the anesthetic is injected, numbing the nerve.
Two other methods are the transperineal and perirectal approaches, commonly used for operations on the lower abdomen or pelvic region, and for patients with pudendal nerve pain, especially in men. Both of these involve similar steps as above but vary in terms of the patient’s position and entry point for the needle.
There’s also a transgluteal approach, performed through the hip region, which can be used regardless of gender. It’s mostly similar to the other methods but might benefit from using imaging techniques to guide the injection, particularly in a canal-like area where the pudendal nerve passes.
Regardless of the technique used, the anesthetic’s effect is almost immediate, but it might take up to 20 minutes for the full effect. While these procedures are generally effective, they might not always succeed on the first try, often because the anesthetic didn’t have enough time to take effect. Around 20% of pudendal nerve blocks don’t fully numb both sides, often due to problems with the procedure. If this happens, doctors might need to inject additional anesthetic.
Possible Complications of Pudendal Nerve Block
Getting a pudendal nerve block, which is a type of injection to reduce pain, most often results in discomfort where the injection was given. Less often, it could cause bleeding or an infection. Serious but rare complications can include damage to the pudendal nerve itself, or injury to nearby organs like the bladder and rectum. There is also a very small chance that if the pudendal artery is accidentally punctured during the injection and anesthetics (drugs that numb the area) are injected into the bloodstream, it could cause an extremely serious condition called systemic local anesthetic toxicity, which can be life-threatening.
What Else Should I Know About Pudendal Nerve Block?
A pudendal nerve block is a type of medical procedure that can be used to diagnose pudendal neuralgia, a condition that causes pain in the pelvic area. To test for this, doctors primarily use local anesthetics. If patients experience significant pain relief from this, it’s a sign that they may benefit from further treatment. This might mean getting additional pudendal nerve blocks using a combination of corticosteroids (a type of medication that reduces inflammation) and local anesthetics for longer-term pain relief. However, the effects of this treatment can vary – they may last anywhere from weeks to months. Doctors generally consider pudendal nerve block testing for patients who have pelvic pain that hasn’t improved with initial treatment.
Compared to other pain-control methods such as general or neuraxial anesthetic methods, pudendal nerve blocks have shown to provide a high level of pain control. What’s more, patients undergoing this procedure require fewer pain medications. Like other types of regional anesthesia techniques (which numb only a specific part of the body), pudendal nerve blocks can reduce the risk of complications often associated with general anesthesia, which can lead to slowing down of the heart and lungs, and side effects related to neuraxial anesthesia like difficulty in passing urine.
It’s important to note, though, that pudendal nerve blocks are not widely used, especially in men. This is usually due to the discomfort patients might feel during the injections, fears about possible injury to important body structures, and lack of sufficient training in this technique among urology and gynecology doctors.
