Nerve Block, Dorsal Penile, Neonatal

Circumcision is an age-old practice, described in stone-age cave sketches and depicted in Egyptian hieroglyphics. Today, it is commonly performed to fulfill religious commandments, mark transition into adulthood, change cosmetic appearance and, arguably, affect health outcomes. Traditionally, practitioners have believed that the neurological system of the neonate was not sufficiently developed to permit the neonate to feel pain during this surgical procedure. However, studies have shown that neonate undergo changes in the cardiovascular system, hormonal levels, and behavioral changes during the circumcision procedure. ^{[1, 2, 3]}

Circumcision in neonates was the most commonly performed surgical procedure in the United States prior to 1978; it was performed on more than 80% of neonatal males. The procedure was typically completed without pain-relieving anesthesia. The landmark 1978 Pediatrics article first describing dorsal penile nerve block (DPNB) initiated a slow but steady change in clinical practice regarding this neonatal surgical procedure. ^[4] Numerous studies have revealed not only biochemical changes related to cortisol levels but also the obvious psychological signs involving respirations and tissue oxygenation changes. ^[1] Facial changes, crying, and gross motor movements confirm the painfulness of the procedure. Despite the obvious signs of an neonate's discomfort and pain during the procedure, tradition had held that the use of anesthetic was unnecessary and unwise.

Today, 9 out of 10 residency-trained physicians use anesthesia during this procedure. ^[5] Much of this change was first fueled by the American Academy of Pediatrics (AAP) in their 1999 recommendation that some method of pain relief should be used during circumcisions and that such pain relief is associated with very little risk. ^[6] This policy statement was updated and affirmed by the 2012 Pediatrics Task Force on Circumcision, which also states that non-pharmacological techniques such as positioning and sucrose pacifiers, although helpful, are inadequate alone for anesthesia and should be used only as analgesic adjuncts to improve infant comfort. ^[7]  Additional supports followed when several physician groups, including the AAP, the American College of Obstetricians and Gynecologists (ACOG), and the American Academy of Family Physicians (AAFP), recommended universal use of local or topical anesthesia for pain relief during circumcision. The technical specifics of the dorsal penile block procedure can be readily taught and learned and have proven to be highly effective. ^[8]

Dorsal penile nerve block is one of several methods of providing pain relief during neonatal circumcision, thereby reducing the associated risks of psychological stress, aspiration, and psychological trauma that may result from the procedure.

Dorsal penile block offers an effective way of relieving the signs and symptoms of patient distress that occur during circumcision. ^[9] This indication is in compliance with the published guidelines and policies of the both the AAP and the AAFP.

Contraindications to the dorsal penile block are similar to those of the neonatal circumcision procedure.

• Instability or illness of neonate

• Prematurity of neonate

• Fewer than 12 hours passed since birth

• Anatomical abnormalities, such as hypospadias (For information on the diagnosis and treatment of hypospadias, please see Medscape Reference Pediatrics article Hypospadias.)

This article describes the dorsal penile nerve block performed with lidocaine 1% (without epinephrine).

For more information, see the Technique section.

The equipment needed includes the following:

• Parental consent (Consent for the dorsal penile nerve block should be obtained separately from the consent obtained for the circumcision procedure.)

• Restraining device (such as papoose board or a Strang circumcision chair)

• Sterile gloves

• Alcohol preparation pad

• Syringe, 27 gauge (ga), 1.22 mL, with a 0.75-inch needle

• Lidocaine 1% (without epinephrine)

Place the neonate in a warm environment on papoose board or similar restraint device (see image below).

Papoose (restraint) board.

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Expose the genitalia for the procedure.

Use of a pacifier may help quiet the neonate for the injection.

Anatomy

The nerves to the penis are derived from the pudendal and cavernous nerves. The pudendal nerves supply somatic motor and sensory innervation to the penis. The cavernous nerves are a combination of parasympathetic and visceral afferent fibers and provide the nerve supply to the erectile tissue. The cavernous nerves run in the crus and corpora of the penis, primarily dorsomedial to the deep penile arteries. For more information about the relevant anatomy, see Penis Anatomy.

• The penis contains 2 dorsal penile nerves that provide sensation to the foreskin glands and shaft of the penis. The nerves are located between the Buck fascia and the corpora cavernosa. See anatomy images below.

  Penile nerve anatomy.

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  Cross-sectional penile nerve anatomy.

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• At the 10-o'clock and 2-o'clock positions on the penile shaft, these nerves lay approximately 3-5 mm beneath the skin at the root of the penis and course distally toward the glands to a more superficial location of 1-3 mL beneath the skin.

• The lidocaine is injected subcutaneously below the Buck fascia in the 10- and 2-o'clock positions found approximately 0.5-1 cm distal to the base of the penis (see image below).

  Injection sites for dorsal penile nerve block.

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Technique

See the list below:

• Undress the neonate from the waist down and place him in a neonate restraint.

• Prepare the base of the penis with alcohol or povidone-iodine solution (eg, Betadine).

• If topical anesthetics such as lidocaine/prilocaine and EMLA are used, due to a higher incidence of skin irritation in low birth weight infants, dorsal penile nerve block should be used alone or instead. ^[7]

• Palpate the penile root with gloved fingers.

• Apply gentle traction to the penis to secure and straighten the shaft.

• Pierce the skin with the 27-ga needle at the 10-o'clock position, slightly distal to where the penile and pubic skin meet (see image below).

  Left side penile nerve block.

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• Advance the needle tip is in a posterior medial angle of 25 degrees to an area 0.5 cm distal to the penile root.

• After confirming that the needle tip is freely movable, attempt aspiration to avoid intravascular injection. Then, slowly inject 0.4 mL of plain 1% lidocaine.

• Apply immediate light pressure to any bleeding or swelling.

• Repeat the procedure on the opposite side of the penis, at the 2-o'clock position (see image below).

  Right side penile nerve block.

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• After 5 minutes, circumcision is performed.

Always provide clear informed consent to parents regarding indications and potential adverse effects of the nerve block. This consent should be separate from consent to the circumcision procedure itself.

Keep the neonate warm and calm as long as possible.

A sucrose pacifier may provide additional comfort to the neonate. ^[10]

Make sure the tip of the needle is freely movable and not in the body of the penis.

Apply immediate light pressure to any bleeding or swelling.

Be sure to allow at least 5 minutes to pass between the time of the injection and the beginning of the circumcision procedure.

In general, the dorsal penile nerve block is a very safe and effective procedure. Some minor complications have been encountered.

• The most common complication is penetration of the superficial dorsal vein, which causes some bruising and bleeding. ^[11] If this occurs, immediate pressure should be placed on the area. The subcutaneous swelling and discoloration should resolve in about 24 hours.

• If the needle is inserted too deeply in a vertical direction, the anesthetic is injected into the actual body of the penis or erectile tissue.

• Another common complication is that of partial block, where only partial anesthesia of the foreskin is obtained. The occurrence of this complication seems to lessen with time and experience of the operator.

• Complications can also be caused by the anesthetic itself. Patients may be allergic to lidocaine. Skin necrosis has been reported when certain long-acting anesthetics are used (eg, bupivacaine), suggesting that these anesthetics should be avoided. ^{[12, 13]} Systemic toxicity has been reported with bupivacaine causing lethargy, altered consciousness, and hypotonia. ^[14] Care should be taken with the choice of anesthetic agent and the age and weight of the infant, with appropriate adjustments of the concentration and volume used.

• For more information, see Infiltrative Administration of Local Anesthetic Agents.