Continuous positive airway pressure (CPAP) is a highly effective treatment for moderate-to-severe obstructive sleep apnoea (OSA), but suffers significantly from poor patient adherence. This paper reports the three-year outcomes of a prospective multicentre cohort study examining the effect of hypoglossal nerve upper airway stimulation (UAS) on OSA. This treatment is FDA-approved and deemed cost-effective in the USA. Patients with BMI >32 kg/m2 were excluded from the trial, along with those suffering from concurrent other sleep disorders, psychiatric disorders, or severe cardiac / pulmonary disease. All participants had an initial apnoea-hypopnoea index (AHI) of between 20 and 50 events/hr. Patients underwent implantation of a stimulating electrode on the distal hypoglossal nerve, connected to a pulse generator in the subclavicular region, and a respiratory effort sensor in the fourth intercostal space. The tongue base is thereby stimulated in synchrony with inspiration. Of 126 patients receiving the implant, only three required implant removal. Follow-up at 36 months was completed by 116 patients.
Treatment response was defined a priori as a decline in AHI by >50%, to <20 events/hr. By this measure, 74% of patients achieved a treatment response. Mean AHI for the cohort declined from 32 initially to 11.5 at 36 months.
Self-reported Epworth sleepiness scores and Functional Outcomes of Sleep Questionnaires (FOSQ) improved in a sustained fashion over the same period. Common adverse events included tongue abrasions from repetitive tongue movements over the dentition, and discomfort from electrical stimulation, although both declined significantly over the 36-month trial period. This longitudinal trial demonstrates the efficacy of this novel treatment for OSA, which merits further examination in controlled and comparative studies. The study is limited by its lack of a control group and significant individual differences, but UAS may represent a viable alternative in selected patients not tolerating CPAP.
