A method for ultrasonographic visualization and injection of the superior laryngeal nerve: volunteer study and cadaver simulation.

Superior laryngeal nerve block is a valuable technique for provision of upper airway anesthesia. In bilateral scans of 20 volunteers, we developed a technique for ultrasonographic visualization of the superior laryngeal nerve and key anatomical structures using a hockey stick-shaped 8 to 15 MHz transducer (HST15 to 8/20 linear probe, Ultrasonix, Richmond, BC, Canada). Subsequently, we simulated superior laryngeal nerve scanning and injection in bilateral injections in 2 cadavers. Ultrasound-guided in-plane advancement of a needle toward the superior laryngeal nerve and injection of 1 mL of green dye was achieved in all 4 attempts and confirmed by a postprocedural dissection performed by an anatomist. We conclude that ultrasound-guided superior laryngeal nerve block in humans may be feasible.