Superior laryngeal nerve block: An anatomical study comparing two techniques

Study Objective: To determine whether an anterior approach is as successful as the conventional posterior approach to superior laryngeal nerve block.Design: Prospective observational study.Setting: University anatomy laboratory.Patients: 20 formalin-fixed adult human cadavers.Measurements: Simulated superior laryngeal nerve blocks were performed by a single operator using 3mL of 0.01%analine blue dyewith a 23-gauge Quincke tip needle. Two different landmark techniqueswere used on each undissected cadaver: 1) the conventional posterior approach using the hyoid bone as a palpable landmark, with injection at the posterior third of the thyrohyoid membrane; and 2) the anterior approach, using the anterior thyroid notch of the thyroid cartilage, with injection at the anterior third of the thyrohyoid membrane. The spread of analine dye was observed. An injection was deemed successful if the entire paraglottic space was stained or the superior laryngeal nerve stained as it entered the paraglottic space.Main Results: Both techniques were equally successful after 40 injections.Conclusion: There was no significant difference in success in staining the superior laryngeal nerve in human cadavers between the conventional posterior approach and an anterior approach.