title: Sonographic evaluation of tongue motions during upper airway stimulation for obstructive sleep apnea-a pilot study.
abstract: BACKGROUND
  The objective was to evaluate the feasibility of sonographic evaluation of functional tongue motion as a tool to evaluate postoperative outcomes in human subjects using breathing-synchronized stimulation of the hypoglossal nerve-a novel therapy option for patients with obstructive sleep apnea (OSA).
  
  
  METHODS
  Sixteen patients with OSA (n = 16, age 60.4 ± 10.2, BMI 28.7 ± 2.4, AHI 35.0 ± 11.8) underwent sonographic evaluation of tongue motion after initiation of therapy with the Inspire II Upper Airway Stimulation system. Sonographic examination was performed in four different planes (A = floor of the mouth frontal, B = base of the tongue horizontal, C = floor of the mouth parallel to mandible, and D = floor of the mouth median sagittal) in an attempt to visualize tongue surface, tongue and hyoid motion, and the distance of protrusion.
  
  
  RESULTS
  Identification of the tongue surface was achieved in all cases in planes B, C, and D and 81 % of patients in plane A. Tongue motion was evident on the right (implant) side in 63 % in plane A and 75 % in plane B. Distance of protrusion was measured in plane B at 1.04 cm (±0.51), in plane C at 1.08 cm (±0.47), and in plane D at 0.96 cm (±0.45). Hyoid protrusion was measured in plane C or D and was 0.57 cm (±0.39). Significant correlations among the three planes were observed, but there was no correlation to the reduction of apnea-hypopnea index.
  
  
  CONCLUSIONS
  The results indicate feasibility of sonography to identify tongue and hyoid motions during upper airway stimulation. Useful sonographic planes and landmarks, which allow visualization of dynamic effects of upper airway stimulation, could be established. The evaluation of the tongue in a horizontal (B) and in a sagittal plane (D) appears to be superior to the other investigated planes. The approximate tongue protrusion needed to generate a significant reduction of AHI and ODI was 1 cm.
authors.affiliation: Otorhinolaryngology/Head and Neck Surgery, Klinikum rechts der Isar, Technical University of Munich, Ismaningerstr. 22, 81675, Munich, Germany. b.hofauer@tum.de.
authors.forename: Benedikt
authors.identifier: http://orcid.org/0000-0002-3126-2877
authors.initials: B
authors.lastname: Hofauer
authors.affiliation: Division of Pulmonary, Critical Care, and Sleep Medicine, Louis Stokes Cleveland Veterans Affairs Medical Center and Case Medical Center, Case Western Reserve University, Cleveland, OH, USA.
authors.forename: Kingman
authors.initials: K
authors.lastname: Strohl
authors.affiliation: Otorhinolaryngology/Head and Neck Surgery, Klinikum rechts der Isar, Technical University of Munich, Ismaningerstr. 22, 81675, Munich, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Knopf
authors.affiliation: Otorhinolaryngology/Head and Neck Surgery, Klinikum rechts der Isar, Technical University of Munich, Ismaningerstr. 22, 81675, Munich, Germany.
authors.forename: Murat
authors.initials: M
authors.lastname: Bas
authors.affiliation: Otorhinolaryngology/Head and Neck Surgery, Klinikum rechts der Isar, Technical University of Munich, Ismaningerstr. 22, 81675, Munich, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Wirth
authors.affiliation: Nephrology/II. Medical Department, Klinikum rechts der Isar, Technical University Munich, Munich, Germany.
authors.forename: Konrad
authors.initials: K
authors.lastname: Stock
authors.affiliation: Otorhinolaryngology/Head and Neck Surgery, Klinikum rechts der Isar, Technical University of Munich, Ismaningerstr. 22, 81675, Munich, Germany.
authors.forename: Clemens
authors.initials: C
authors.lastname: Heiser
mesh_terms: D000368:Aged; D004599:Electric Stimulation Therapy / Q000295:instrumentation*; D005240:Feasibility Studies; D006801:Humans; D006928:Hyoid Bone / Q000503:physiopathology; D007002:Hypoglossal Nerve / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D017286:Polysomnography; D020181:Sleep Apnea, Obstructive / Q000000981:diagnostic imaging* / Q000601:surgery*; D014059:Tongue / Q000000981:diagnostic imaging / Q000294:innervation* / Q000503:physiopathology*; D014061:Tongue Habits; D014463:Ultrasonography
keywords: Continuous positive airway pressure; Hypoglossal nerve; Intolerance; Obstructive sleep apnea; Sonography; Upper airway stimulation