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Brown: Atlas of Regional Anesthesia, 3rd ed., Copyright © 2006 Saunders, An Imprint of Elsevier
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PLACEMENT

Anatomy.

The superior laryngeal nerve is a branch of the vagus nerve. After it leaves the main vagal trunk, it courses through the neck and passes medially, caudal to the greater cornu of the hyoid bone, at which point it divides into an internal branch and an external branch. The internal branch is the nerve of interest during a superior laryngeal nerve block, and it is blocked where it enters the thyrohyoid membrane just inferior to the caudal aspect of the hyoid bone ( Fig. 29-1 ).

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Figure 29-1  Superior laryngeal nerve block: anatomy.


Position.

The patient is placed supine, with the neck extended. The anesthesiologist displaces the hyoid bone toward the side to be blocked by grasping it between the index finger and the thumb ( Fig. 29-2 ). A 25-gauge, short needle is then inserted to make contact with the greater cornu of the hyoid. The needle is walked off the caudal edge of the hyoid and advanced 2 to 3 mm so the needle tip rests between the thyrohyoid membrane laterally and the laryngeal mucosa medially. The drug (2–3 mL) is then injected; an additional 1 mL is injected while the needle is being withdrawn.

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Figure 29-2  Superior laryngeal nerve block: technique.


Potential Problems.

It is possible to place the needle in the interior of the larynx with this approach, although it should not result in long-term problems. If the block is carried out as described, intravascular injection should be infrequent despite the presence of the superior laryngeal artery and vein, which pierce the thyrohyoid membrane with the internal laryngeal nerve.

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