Greater Auricular Nerve Block

The great auricular nerve is the largest sensory branch of the cervical plexus and arises mainly from the third cervical nerve (C3) with irregular contributions from the second cervical nerve (C2). The first part of its course is deep to the sternocleidomastoid muscle between the deep and superficial layers of the cervical fascia. At a point just inferior and lateral to the lesser occipital nerve, the Greater auricular nerve pierces the cervical fascia and passes superiorly and forward and then curves around the posterior border of the sternocleidomastoid muscle. It then winds around the posterior border of the sternocleidomastoid muscle and perforates the superficial fascial layer to reach the lateral surface of the muscle. Before bifurcation into anterior and posterior branches, the nerve ascends almost vertically towards the auricle, initially covered by the platysma in most individuals. It provides cutaneous sensory innervation to both surfaces of the auricle, the external auditory canal, the angle of the jaw and the skin overlying a portion of the parotid gland.

It provides sensory innervation to segments of the external ear including the tail of the helix, the antitragus, and the lobule of the auricle with variable supply to the spine of the helix, the tragus, and the concha. Although the greater auricular nerve block was described over five decades ago, it has traditionally involved the blockade of the entire superficial cervical plexus at the border of the sternocleidomastoid muscle utilizing large local anaesthetic volumes rather than the selective procedure. Landmark techniques for selective blockade of this nerve have been attempted with varying degrees of success with different volumes of local anaesthetic. The greater auricular nerve ranges in diameter from 1.4-2.0 mm with a median size of 1.7 mm in anatomical studies. The wide availability and utilization of ultrasound has provided physicians with the ability to directly image small peripheral nerves and perform blockade with reduced volumes of local anaesthetic. Because of its superficial location on the anterior surface of the sternocleidomastoid muscle, ultrasound acquisition of the GAN is relatively easy to perform yielding excellent imaging. Thallaj and colleagues noted a success rate of 100% in identifying the GAN using ultrasound imaging with a block success rate of near 100% when pinprick testing was performed and compared to the contralateral ear.

Painful conditions that can be managed by greater auricular nerve block include greater auricular neuralgia, red ear syndrome, post-herpetic neuralgia, Ramsay Hunt syndrome, acute herpes zoster and primary yawning headache.

The procedure is usually done on an outpatient basis. Ultrasound can reliably be used for infiltration of the greater auricular nerve. This will improve the safety as well as the diagnostic utility of the procedure. The first identification of the great auricular nerve is best achieved when it lies deep and medial to the sternocleidomastoid muscle near its dorsal border. After initial probe placement, the transducer has to be adjusted in a slightly oblique (‘transverse-oblique’) manner for clear identification of its deep course. The nerve is visible twice as a round or oval hypoechoic structure in positions deep and superficial to the sternocleidomastoid muscle in one image. The superficial part of the great auricular nerve is known as the ‘nerve point’ and roughly coincides with its piercing of the superficial cervical fascia.

Local anaesthetic and steroid can be injected under real-time ultrasound guidance targeting the Greater Auricular nerve in the neck. A positive response confirms the diagnosis of Great auricular neuralgia and can also provide therapeutic benefits lasting weeks to months.

Pulsed radiofrequency treatment can be applied to the Greater Auricular nerves in patients who get a positive response to the local anaesthetic blocks. Pulsed radiofrequency can provide sustained pain relief in patients with auricular neuralgia and nerve entrapment.

Injections are generally avoided in patients with systemic infection or skin infection over the puncture site, bleeding disorders or coagulopathy, allergy to local anaesthetics or any of the medications to be administered.

Complications are rare, particularly if injections are performed under ultrasound guidance. Severe allergic reactions to local anaesthetics are uncommon. Post-procedural pain flare-up can occur in some patients especially if steroids are used in the injection.