Ear Anesthesia

Anesthesia of the ear is useful for repair of lacerations, hematoma incision and drainage, and other painful procedures of the ear.

Anatomy

The ear is composed of 3 compartments: the external ear, the middle ear, and the inner ear. For the purpose of local anesthesia, this article focuses on the external ear which comprises the auricle, or pinna, and the ear canal. The auricle (visible part of ear) is composed mainly of cartilage covered by skin and consists of the helix, antihelix, lobule, tragus, and concha.

Anatomy of the ear is shown below.

Anatomy of the ear.

Four sensory nerves supply the external ear: (1) greater auricular nerve, (2) lesser occipital nerve, (3) auricular branch of the vagus nerve, and (4) auriculotemporal nerve. Knowledge of the nerve anatomy is critical in understanding anesthesia of the ear. For more information about the relevant anatomy, see Trigeminal Nerve Anatomy, Facial Nerve Anatomy, and Vagus Nerve Anatomy.

Anatomy of the sensory nerves of the external ear are shown in the image below.

Anatomy of sensory nerves in the external ear.

See the list below:

• The greater auricular nerve is a branch of the cervical plexus. It innervates the posteromedial, posterolateral, and inferior auricle (lower two-thirds both anteriorly and posteriorly).

• The lesser occipital nerve innervates a small portion of the helix.

• The auricular branch of the vagus nerve innervates the concha and most of the area around the auditory meatus.

• The auriculotemporal nerve originates from the mandibular branch of the trigeminal nerve. It innervates the anterosuperior and anteromedial aspects of the auricle.

• The external auditory canal and tympanic membrane have separate innervation. Indications for anesthetizing these areas are distinct from those for performing an auricular block.

For more information about the relevant anatomy, see Ear Anatomy.

Anesthetizing the ear may be required in the following situations:

• Suture of a large laceration of the ear or the skin surrounding the ear[1]

• Painful procedures of the ear, such as incision and drainage of an abscess or hematoma[2, 3] (For more information, see Medscape Reference article Auricular Hematoma Drainage.)

Avoid anesthetizing the ear if the patient has cellulitic periauricular skin or a severe allergy to the chosen anesthetic.

Local anesthetic agents (eg, lidocaine 1% [Xylocaine], bupivacaine 0.25% [Marcaine]) may be used.

If a regional block is performed, lidocaine mixed with epinephrine can be used; however, epinephrine is contraindicated in direct infiltration of the ear.[4]

For more information, see Local Anesthetic Agents, Infiltrative Administration and Local Anesthesia and Regional Nerve Block Anesthesia.

The following equipment is needed:

• Syringe, 5-10 mL

• Needle, 25-gauge or 27-gauge (5-7 cm in length)

• Parenteral anesthetic agent

• Light source

Position the patient so that both clinician and patient are comfortable and the ear to be anesthetized is easily accessible.

Laying the patient supine is usually the optimal position.

The choice of technique depends on the area of the ear that requires anesthesia.

Ring block technique

The ring block, shown in the image below, provides anesthesia to the entire ear, excluding the concha and external auditory canal.

Ring block technique.

Steps for this technique are as follows:

• Disinfect skin with an alcohol swab.

• Insert the needle into the skin just inferior to the attachment of the earlobe to the head. Do not insert the needle into the earlobe itself. Advance the needle just anterior to the tragus, aspirating as the needle advances.

• Aspirate and then inject 2-3 mL of anesthetic while withdrawing the needle slowly back toward the puncture site without removing it.

• Once just under the skin at the puncture site, redirect and advance the needle posteriorly along the inferior posterior auricular sulcus, aspirating as it is advanced.

• Aspirate and inject 2-3 mL of anesthetic while withdrawing the needle.

• Remove the needle and reinsert it just superior to the attachment of the helix to the scalp. Direct and advance the needle just anterior to the tragus, aspirating as it is advanced.

• Aspirate and inject 2-3 mL of anesthetic while withdrawing the needle toward your puncture site without removing it. Remember to inject the subcutaneous tissue, not the ear cartilage.

• Once just under the skin at your puncture site, redirect and advance the needle posteriorly along the superior posterior auricular sulcus, aspirating as it is advanced.

• Aspirate and inject 2-3 mL of anesthetic while withdrawing the needle.

• Be aware that the superficial temporal artery, located medial to the ear, crosses over the zygomatic arch. If the artery is cannulated, maintain firm pressure with gauze for at least 20-30 minutes.

Field block technique

This field block, depicted below, provides anesthesia to the earlobe and lateral helix (greater auricular and lesser occipital nerve branches).

Technique to anesthetize the earlobe and lateral helix.

Steps for this technique are as follows:

• Disinfect the skin with an alcohol swab.

• Insert the needle just posterior to the inferior attachment of the the auricle (behind the earlobe). Aspirate and inject a total of 3-4 mL of anesthetic while advancing the needle superiorly, following the curvature of the posterior sulcus. See the video below.

  Ear anesthesia. Courtesy of Hamid R Djalilian, MD.

Auriculotemporal nerve block

This technique, shown in the image below, provides anesthesia to the helix and tragus (auriculotemporal nerve).

Technique to anesthetize the helix and tragus.

Steps for this technique are as follows:

• Disinfect the skin with an alcohol swab.

• Insert the needle anteriorly and superiorly to the tragus.

• Aspirate and inject 3-4 mL of anesthetic.

Since adequate anesthesia of the auditory canal and tympanic membrane is difficult to obtain, consult an ENT specialist for painful procedures involving these areas.

Do not inject cellulitic skin.

Do not inject any anesthetic containing epinephrine directly into the auricle.

Complications may include the following:

• Infection[5]

• Allergic reactions

• Inadequate anesthesia[6]

• Cannulation of the superficial temporal artery