18.1.1 Anatomy

In a penile root block, the two dorsal nerves of penis are blocked. The dorsal nerves of the penis are terminal branches of the pudendal nerve (S2–S4), which run through the subpubic space caudal to the symphysis slightly paramedian up to the dorsal side of the penis. This subpubic space is bordered cranially by the symphysis, caudally by the corpora cavernosa penis, and anteriorly by the fascia of Scarpa (inner membranous layer of the superficial abdominal fascia; Fig. 18.1). The nerves are located lateral to the dorsal arteries of penis and the unpaired deep dorsal vein of penis. This neurovascular bundle runs between the fascia of Buck (deep fascia of penis) and the tunica albuginea (Fig. 18.2). Cranially, there is a connection between the fascia of Buck and the fascia of Scarpa.

The dorsal penile nerves supply sensory innervation to the glans penis and the distal two thirds of the penile skin. The proximal third of the penile skin receives its sensory supply from the genitofemoral nerves and iliohypogastric nerves.

18.1.2 Technique of Penile Root Block

Procedure

The skin caudal to the symphysis is disinfected, then the symphysis is palpated and the penis is pulled slightly caudally or alternatively fixed caudally with an adhesive bandage across the thigh. An incision is made with a short-bevel needle (25 or 27 G) paramedian (0.5–1 cm lateral to the midline) just caudal to the symphysis (Dalens et al 1989). The needle is advanced in a slight mediocaudal direction (Fig. 18.3) into the subpubic space until the fascia of Scarpa is perforated (clear “fascia click”). After negative aspiration, the local anesthetic is injected. Then a further injection is made on the opposite side using the same technique.

18.1.3 Indications and Contraindications

18.1.4 Complications, Side Effects, Method-Specific Problems

18.1.5 Remarks on the Technique

Burke et al (2000) report on temporary ischemia of the glans penis after using ropivacaine 0.75% (7.5 mg/mL). Due to the vasoconstrictive properties of ropivacaine, the scientific working group for pediatric anesthesia of the German Society of Anesthesia and Intensive Medicine (DGAI) has currently reached no conclusive assessment of the use of ropivacaine in end-arterial areas (Mader et al 2007).

As an alternative to the technique described above, the block can also be made by a single median puncture (Bacon 1977). After bone contact with the symphysis, the needle is withdrawn slightly and advanced directly caudal to the symphysis. After aspiration, the local anesthetic is applied. This technique increases the risk of a hematoma (see above).

18.2.1 Anatomy

The iliohypogastric nerve (T12, L1) and ilioinguinal nerve (L1) descend from the lateral border of the psoas major muscle between the renal capsule and the quadratus lumborum muscle. Both nerves run parallel and cranial to the iliac crest between the internal oblique muscle and the transversus abdominis muscle (Fig. 18.4) and supply sensory innervation to the skin of the lateral hip region, the mons pubis, and the anterior upper part of the scrotum or the labia majora.

18.2.2 Sonoanatomy

A linear transducer is placed on the lateral abdominal wall medial or slightly craniomedial to the anterior superior iliac spine and the iliohypogastric and the ilioinguinal nerves are visualized in the short axis (Fig. 18.5). The nerves can be visualized within a “lenticular” double fascia between the internal oblique muscle and the transversus abdominis muscle as hypoechoic structures surrounded by the hyperechoic fascia (Fig. 18.6).

18.2.3 Technique of Ilioinguinal Nerve Block

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15 General Overview 17 Lower Limb 16 Upper Limb 5 Suprascapular Nerve Block 4 Supraclavicular and Infraclavicular Techniques of Brachial Plexus Block 9 Psoas Block