Surgical anatomy of the hypoglossal nerve: A new classification system for selective upper airway stimulation

Background: Selective upper airway stimulation (UAS) has shown effectiveness in treating patients with obstructive sleep apnea (OSA). The terminating branches of the hypoglossal nerve show a wide complexity, requiring careful discernment of a functional breakpoint between branches for inclusion and exclusion from the stimulation cuff electrode. The purpose of this study was to describe and categorize the topographic phenotypes of these branches. Methods: Thirty patients who received an implant with selective UAS from July 2015 to June 2016 were included. All implantations were recorded using a microscope and resultant tongue motions were captured perioperatively for comparison. Results: Eight different variations of the branches were encountered and described, both in a tabular numeric fashion and in pictorial schema. Conclusion: The examinations showed the complex phenotypic surgical anatomy of the hypoglossal nerve. A schematic classification system has been developed to help surgeons identify the optimal location for cuff placement in UAS.