# Ultrasonographic Tongue Base Motion Does Not Correlate With Hypoglossal Nerve Stimulation Outcomes

## TL;DR

Ultrasonography of tongue base movement during hypoglossal nerve stimulation does not predict treatment success in sleep apnea patients.

## Contribution

This study is the first to show that visible tongue motion via ultrasound does not correlate with treatment outcomes in hypoglossal nerve stimulation.

## Key findings

- No significant correlation was found between AHI reduction and anterior tongue displacement in axial or sagittal planes.
- Tongue shape and symmetry were not predictive of treatment success.
- Ultrasound-visible tongue motion does not reliably reflect functional airway improvement.

## Abstract

To evaluate whether tongue base motion patterns, assessed by submental ultrasonography during unilateral hypoglossal nerve stimulation (HNS), are associated with treatment response in obstructive sleep apnea patients.

This cross‐sectional study included 64 patients with unilateral HNS. Standardized submental B‐mode ultrasound was performed to assess tongue‐base motion under awake stimulation. Two independent, blinded raters evaluated the magnitude of anterior tongue base movement in the axial and sagittal planes. Further, the symmetry of bilateral tongue protrusion and tongue shape was classified. The primary endpoint was the correlation between apnea‐hypopnea (AHI) reduction and ultrasonographic findings.

Ultrasonographic assessment showed substantial to excellent agreement between the two raters. No significant correlation was found between AHI reduction and anterior tongue displacement in either the axial (Spearman's ρ = 0.20, p = 0.12) or sagittal plane (ρ = −0.08, p = 0.64). Clinically meaningful bilateral activation was present in 33% of patients but was not associated with treatment outcome (ρ = 0.03, p = 0.84). Neither tongue shape was predictive of AHI improvement (buckling p = 0.13 and trough sign p = 0.79). Tongue movement patterns were not associated with stimulation voltage.

Ultrasonographic assessment of tongue base motion under HNS does not correlate with treatment response. Neither symmetry, magnitude, nor qualitative shape was associated with AHI reduction. These findings suggest that visible tongue motion may not reliably reflect functional improvement in the airway. Future research should define the role of ultrasound in HNS evaluation and optimization.

3b.

ClinicalTrials.gov Identifier: NCT06154577

Ultrasonographic tongue‐base motion during hypoglossal nerve stimulation showed no meaningful association with treatment response in obstructive sleep apnea. Neither displacement magnitude, symmetry, nor qualitative tongue shape correlated with AHI reduction, despite good interrater agreement. Ultrasound‐visible tongue motion therefore appears to have limited value for predicting or assessing HNS efficacy.