Patient-reported outcomes with hypoglossal nerve stimulation for treatment of obstructive sleep apnea: a systematic review and meta-analysis.

INTRODUCTION: Hypoglossal nerve stimulation (HNS) has recently been introduced as an alternative treatment for patients with OSA. A large number of studies have demonstrated substantial changes in OSA with this therapy by reducing respiratory events and improving symptoms such as daytime sleepiness and quality of life. The objective of this review was to conduct a systematic review and meta-analysis to evaluate patient-reported outcomes and experience with HNS therapy. METHODS: A systematic literature search of MEDLINE, Cochrane, and Web of Science was performed to identify randomized controlled and observational studies reporting subjective outcomes with different HNS systems in patients with OSA. Abstracts of 406 articles were screened and a subset of 55 articles were reviewed for eligibility. Risk of bias was assessed using the ROBINS-I tool. Meta-analysis using RevMan was performed when > 2 studies were identified that reported data on a specific outcome. RESULTS: Thirty-four publications reporting data on 3785 patients with a mean follow-up of 11.8 ± 12.2 months were identified and included in the meta-analysis. The analysis revealed a pooled effect of 4.59 points improvement in daytime sleepiness as measured by the ESS questionnaire (Z = 42.82, p < .001), 2.84 points improvement in daytime functioning as measured by the FOSQ score (Z = 28.38, p < .001), and 1.77 points improvement in sleep quality as measured by the PSQI questionnaire (Z = 2.53, p = .010). Patient-reported experience was consistently positive and revealed additional relevant aspects from this perspective. CONCLUSION: HNS therapy significantly improves quality of life in patients with OSA and reliably produces clinically meaningful effects on daytime sleepiness, daytime functioning, and sleep quality. Treatment regularly meets or exceeds the minimum clinically important differences defined for the respective instruments. Additional research is needed to further investigate effects on quality of life beyond improvements in daytime sleepiness and daytime functioning.

Evaluation of the maximum isometric tongue force of healthy volunteers.

The forces of specific muscle groups have been well described for nearly all parts of the human body. Interestingly, data for the tongue and its forces are rare. In light of ongoing development of systems for managing the tongue (retaining, advancing, suspending or stabilizing), especially in patients with obstructive sleep apnea, knowledge of the maximum tongue force is important for the conceptual design of those systems. The maximum tongue force in a sagittal direction was documented using a custom-built device that included a tongue clamp and a piezoelectric sensor to capture force measurements. Once positioned securely in the device, participants were asked to move the tongue in a posterior sagittal direction, with maximum force, in each of three test positions. Forty-nine healthy volunteers (29 male) were included in the study. Tongue force measurements were collected three times in three different tongue positions. Thirty-three participants had repeated measurements to investigate any potential learning effect. The maximum force of the human tongue in a posterior sagittal direction showed high inter-individual variation and ranged from 3.2 to 52.4 Newton (N; mean 14.1 ± 7.5 N), when measured from a "neutral protrusion or resting" tongue position. The "retracted" and "maximal protrusion" testing positions yielded lower maximum tongue forces. Men (m) showed statistically significantly higher tongue forces than women (w) (m: 16.0 ± 8.4 N, w: 11.0 ± 4.3 N), and there was a positive correlation with BMI and a negative correlation with age. Comparing the first measurement session with the second session (per patient) showed higher mean maximum forces in the second session, but with no statistical significance. The maximum tongue force data showed substantial inter- and intra-individual variability and gender dependency. Some male individuals produced very high forces. These forces should be considered for the future conception and development of tongue management systems and the mechanical stress to which these systems may be exposed.