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Video

Sleep Medicine

(A1222) Unusual Anatomy of the Hypoglossal Nerve During Upper Airway Stimulation Surgery

Monday, October 13, 2025
12:00 PM - 1:00 PM EDT
Location: OTO EXPO, Posters

    Presenting Author(s)

  • Kevin B. Xiao, MD

    Resident Physician
    University of Missouri, Department of Otolaryngology--Head and Neck Surgery
    Columbia, Missouri, United States

    • Senior Author(s)

  • C.W. David Chang, MD

    Professor
    University of Missouri, Department of Otolaryngology--Head and Neck Surgery
    Columbia, MO, United States

Disclosure(s):
Kevin B. Xiao, MD: No relevant relationships to disclose.
C.W. David Chang, MD: No relevant relationships to disclose.


Introduction: Nerve branches to tongue retractor muscles are excluded from the electrode cuff in upper airway stimulation (UAS). We present a case of abnormal branching patterns where nerves associated with “exclusion” signals emerged from the inferior aspect of the hypoglossal nerve (CNXII).

Methods: Electronic medical review of a patient undergoing UAS was completed. Literature review was completed.

Results: A 65-year-old female with pre-op apnea-hypopnea index (AHI) of 15.5 and no known anatomic abnormality underwent UAS. CNXII was in normal anatomic position. After neurophysiologic intraoperative monitoring stimulation (NIMS) testing and initial cuff placement, system validation showed poor tongue protrusion and retraction. Reevaluation of CNXII demonstrated several distal branches along its inferior aspect producing exclusion signals. No further distal late branches along its superior surface produced exclusion signal. CNXII was reinspected and did not appear twisted. Cuff placement was revised to a more anterior location, excluding C1 and the collection of late inferior CXII branches. Final system validation demonstrated good protrusion on configurations A, B, and C, without retraction. Cuff was placed distally with a very vertical orientation on post-op neck film. Patient had a post-op AHI of 2.6.

Literature review demonstrates variations in terminal CNXII branching are typically related to proximity and takeoff angle to CNXII. Superior branches of CNXII typically produce exclusion signals and inferior branches produce inclusion signals during surgery. The medial belly of the inferior longitudinal muscle is innervated by the medial (distal) aspect of CNXII and could be responsible for retrusion by distal branches. A more vertically oriented distal course of CNXII may change branching patterns.

Conclusions: Nerve branches to be excluded from CNXII stimulation may branch off the inferior aspect of the distal CNXII. Thorough nerve dissection and NIMS confirmation are vital for proper cuff placement. With proper cuff placement, patients can have successful outcomes even in cases of abnormal anatomy.