A new method for ultrasound-guided superior laryngeal nerve block

Objective: A block of the internal branch of the superior laryngeal nerve (ibSLN) is performed to facilitate awake intubation in patients with a difficult airway. The technique is usually done blindly using landmarks. We delineate a new method using ultrasound guidance while performing a superior laryngeal nerve block. Materials and Methods: After approval by the ethics committee and with permission from the involved families, six unembalmed fresh human cadavers were used for the study. In each cadaver, bilateral ibSLN blocks were performed using ultrasound guidance. The probe was placed longitudinally over the submandibular area to produce a sagittal view. After identification of the greater horn of the hyoid bone and thyroid cartilage, 2 mL methylene blue dye was injected using an out-of-plane method. Another anatomist dissected the tissue to determine if the nerve was bathed in the dye. Results: All except one of the 12 ibSLNs were bathed in the dye. Ultrasound-guided nerve block was successful in 11 of 12 ibSLN. Conclusion: Ultrasound may be an alternative method to identify the greater horn of the hyoid bone and thyroid cartilage as landmarks while performing an ibSLN block. Copyright (C) 2013, Buddhist Compassion Relief Tzu Chi Foundation. Published by Elsevier Taiwan LLC. All rights reserved.