Abstract

STUDY OBJECTIVES: The major goal of the study was to determine whether changes in tongue morphology under selective hypoglossal nerve therapy for OSA were associated with alterations in airway patency during sleep when specific portions of the hypoglossal nerve were stimulated.METHODS: This case series was conducted at the Johns Hopkins Sleep Disorders Center at Johns Hopkins Bayview Medical Center. Twelve apneic patients implanted with a multi-channel targeted hypoglossal nerve stimulating system underwent mid-sagittal ultrasound tongue imaging during wakefulness. Changes in tongue shape were characterized by measuring its vertical height and polar dimensions between tongue surface and genioglossi origin in the mandible. Changes in patency were characterized by comparing airflow responses between stimulated and adjacent unstimulated breaths during NREM sleep.RESULTS: Two distinct morphologic responses were observed. Anterior tongue base and hyoid-bone movement (5.4(0.4) to 4.1(1.0)cm (median, IQR)) with concomitant increases in tongue height (5.0(0.9) to 5.6(0.7)cm) were associated with decreases in airflow during stimulation. In contrast, comparable anterior hyoid movement (tongue protrusion from 5.8(0.5) to 4.5(0.9)cm) without significant increases in height (5.2(1.6) to 4.6(0.8)cm) were associated with marked increases in in airflow during sleep.CONCLUSIONS: Tongue protrusion with preservation of tongue shape predicted increases in patency, whereas anterior movement with concomitant increases in height were associated with decreased pharyngeal patency. These findings suggest that pharyngeal patency can be best stabilized by stimulating lingual muscles that maintain tongue shape while protruding the tongue, thereby preventing it from prolapsing posteriorly during sleep.

View details for DOI 10.5664/jcsm.10474

View details for PubMedID 36727502