Pudendal Neuralgia is a problem that I see more and more frequently in the office and that most patients usually come after having seen different specialists (urologist, gynecologist, surgeon, neurologist) without a clear diagnosis or a treatment guideline.
The Pudendal Nerve
The pudendal nerve arises from the anterior branches of the medullary segments S2, S3 and S4. This plexus rests on the coccygeus muscle and exits the pelvis below the pyramidal muscle. It then circles the sciatic spine and re-enters the pelvis along the lateral wall of the ischiorectal fossa. It continues along the inner aspect of the ischial tuberosity, where it joins the pudendal vessels in Alcock’s canal or pudendal duct of Alcock’s canal, and runs through the canal following the direction of the sacro-tuberous ligament.
Subsequently, the pudendal nerve divides into three branches:
1. perineal nerve (inferior branch), arises at the exit of Alcock’s canal and runs along the internal border of the deep transverse muscle of the perineum. On its way, it gives off a lateral perineal branch to the superficial transverse muscle which gives rise to branches to the scrotum (in the case of men) or to the labia majora (in women), where the superficial perineal branch also arrives. Subsequently, the perineal nerve gives off another deep or bulbourethral branch. The deep branch pierces the medial aponeurosis of the perineum and gives rise to branches for the superficial and deep transverse muscles of the perineum. This deep branch dies into two: the bulbar branch (which penetrates the bulbospongiosus muscle) and the urethral branch (which runs along the underside of the corpus spongiosum and ends at the glans/vestibular bulb). In women, it innervates the ischiocavernosus and bulbocavernosus muscles, ending in the vestibular bulb. Thus, its sensory branches innervate the lower third of the vagina and the urethra, as well as the labia. On the other hand, the motor branches of the perineal nerve pass through the perineal membrane and die in the striated sphincter of the urethra.
2. Inferior rectal nerve. Generally, it also arises in Alcock’s canal. Its branches innervate the anal canal, the caudal third of the rectum, the skin of the posterior vulvar fork and peri-anal with inconsistent cutaneous perineal endings in the dorsal area. Its motor branches terminate in the levator ani and external anal sphincter.
3. Dorsal clitoral/penile nerve. Like the rest, it also arises in Alcock’s canal. It runs together with the internal pudendal vessels inside the fascia pundenda, crosses the anterior aspect of the transverse ligament of the perineum and passes under the symphysis pubis until it reaches the dorsal aspect of the penis or clitoris through the suspensory ligament. The dorsal clitoral nerve generates two branches. The clitoridian branch runs along the pubic branch and has endings from the pubic arcade to the inguinal canal. These inconsistent endings may explain some painful symptoms in the inguinal area and occasionally in the lower iliac cavity.
Symptoms of Neuralgia Pudendalis
The main symptom of Pudendal neuralgia is usually perianal or genital pain, which may be accompanied by burning, prickling, constipation, sexual dysfunction (e.g., painful intercourse), stinging, or pain during urination or defecation. Symptoms may appear on both sides or be unilateral. They are usually worse when sitting and better when standing.
Causes of Pudendal Neuralgia
The causes of the pain may not be so clear. Most of the time it is due to an entrapment or compression of the nerve in its pathway and this may be due to surgery (episiotomy during childbirth), trauma or accidents, sports such as cycling or weight lifting, infections (prostatitis); many times it may be due to spending a long time sitting and in other cases the specialists in the Pain Unit are unable to find the cause.
It is important to know the anatomy of the pudendal nerve to explain the pain and accompanying symptoms.
Thus, as a summary the pudendal innervation will be:
- Sensitive: skin of the perineum and genitals.
- Motor (mainly perineal nerve): levator ani, superficial and deep transverse perineal, bulbospongiosus, ischiocavernosus, striated urethral sphincter and anterior portion of the external anal sphincter.
- Autonomous: erection and urge to urinate.