Neurostimulation in the Management of Obstructive Sleep Apnea

Purpose of Review: Neurostimulation is an electrical therapy for obstructive sleep apnea and is now an approved therapy option for patients whom positive airway pressure (PAP) therapy is not tolerated. This review describes its implementation, efficacy and safety, the available multi-year clinical outcomes for stimulation devices, and future prospects. Recent Findings: The clinical literature on upper airway neurostimulation was surveyed from July 2014 to December 2021, with a focus on the origins of new therapies, the components of devices, evidences for clinical utility, and adverse events. The basic science literature began as demonstrations of muscle actions leading to neurostimulator prototypes that brought industry interest to clinical therapy. Currently, Inspire® and Nyxoah Genio® are the only two neurostimulators available in the USA. Inspire®, FDA-approved in 2014 as first-in-class therapy, is a hypoglossal nerve (cranial nerve XII) stimulator that is time-coordinated with breathing to prevent upper airway collapse, and its use has the longest experience in the clinic. Given the general narrow inclusion criteria (BMI < 35, ideally < 32), AHI 15–65/h, and a favorable anterior–posterior velopharyngeal collapse pattern on drug-induced sleep endoscopy (DISE), ~ 65% of patients intolerant to PAP therapy achieve clinical success (AHI < 20/h with a reduction of < 50% in AHI) with Inspire® across many centers. In addition to symptomatic relief, adverse events are mild and self-limited after the initial implant surgery, with rarely needed adjustment or replacement of the implantable generator and electrode. The Nyxoah Genio® (2021 FDA approval as a breakthrough device) is strategically different, placing the electrode near the insertion of CNXII bilaterally into the genioglossus muscle and utilizing an external power generator with proprietary programming and activation patterns, Nyxoah Genio® was approved to address concentric collapse, and it is in phase III trials. Summary: Hypoglossal nerve stimulation is a reasonable second-in-line alternative for selected patients when first-in-line therapeutic options fail. Considering the recent technological advances in micro implantation for smart remote programming and surveillance, the next generation of neurostimulation devices will be more compact, especially when efferent co-activation and/or afferent-efferent patterning seems feasible.