Chapter 62: Pudendal Nerve Block

INTRODUCTION

Pudendal pain can often be difficult to diagnose and harder to treat. The majority of patients suffering from this malady are female; chronic pelvic pain affects approximately 1 in 7 women.¹ Frequently, they have been to various doctors with a complaint of chronic perineal pain that may be localized to the rectum, anus, urethra, or genitalia. This usually causes them multiple diagnoses and treatment without resolution of symptoms. For years, patients with chronic neuropathic perineal pain were assigned a “psychosomatic vulvovaginitis” diagnosis by exasperated physicians.² Finally, this elusive presentation has been recognized to have a valid biomechanical and a neuropathic basis that allow multiple modalities for its treatment. Current treatments can improve a patient’s quality of life, and research continues to improve outcomes.

DIAGNOSIS

The pudendal nerve is a mixed motor/sensory nerve having numerous potential entrapment sites. Therefore, the clinical presentation varies.

• The pain of pudendal neuralgia (PN) typically waxes and wanes and is often described as burning, tearing, stabbing, sharp, electrical, and shooting along with feelings of a lump or foreign body in the vagina or rectum.³

• Symptoms include abnormal temperature sensations, constipation, pain and straining with bowel movements, straining or burning when urinating, painful intercourse, and sexual dysfunction (including uncomfortable arousal or decreased sensation). PN presents most commonly as unilateral.

• The symptoms are usually aggravated by sitting or cycling and are absent or relieved by standing, recumbent position, and sitting on a toilet seat.⁴

Indications

Pudendal nerve blocks are used to diagnose and manage patients with chronic pain with possible pudendal origin. Local anesthetic blocks can be used to diagnose pain problems. If the local anesthetic removes the pain, the pain generator is presumed to be distal to this pathology. They can also be used to predict results of surgical neurolysis, pudendal nerve stimulation, and as a direct treatment.

Contraindications

• Systemic infection

• Infections at the skin, injection site, ischiorectal space, rectum, vagina, or perineum

• Coagulopathy

• Contrast allergy (when used)

• Immunocompromised patient

• Metastatic cancer in the area

• Lack of understanding or cooperation with the procedure

Relevant Anatomy

Rising from the sacral plexus and formed from contributions of the second, third, and fourth sacral nerve roots, the pudendal nerve is a sensory and motor nerve. There are 3 branches of the nerve on each side of the body:

• Rectal branch

• Perineal branch

• Penile/clitoral branch

Pudendal neuropathy occurs when the nerve or one of its branches becomes damaged, inflamed, or entrapped.

• The pudendal canal runs from the lesser sciatic notch to the posterior edge of the perineal membrane.

• A space within the obturator fascia, the pudendal (Alcock’s) canal, is bound by the medial aspect of the obturator internus muscle and the lateral wall of ...