Hypoglossal Nerve Stimulator

Hypoglossal nerve stimulators are an effective treatment option for patients with moderate to severe obstructive sleep apnea who have failed treatment with positive airway pressure. An implantable pulse generator is implanted into the right chest, with a lead to the hypoglossal nerve and a respiratory sensing lead. The device generates electrical impulses by detecting respiratory efforts and simulating the hypoglossal nerve. The hypoglossal nerve innervates all extrinsic (genioglossus, hyoglossus, styloglossus) and intrinsic tongue muscles except for the palatoglossus muscle. During the procedure, the surgeon will test the hypoglossal nerve to determine the inclusion and exclusion branches for stimulation cuff electrode placement. The inclusion fibers supply the genioglossus and the geniohyoid muscles, which protrude from the tongue. The exclusion fibers supply the hyoglossus and the styloglossus muscles, which retrude the tongue and should therefore be kept out of the stimulation cuff. During an obstructive event, the sensing lead over the internal intercostal muscle fails to recognize a breath/chest rise and sends a signal to the impulse generator, which then stimulates the protrusive fibers of the hypoglossal nerve, thereby relieving the obstruction. Hypoglossal nerve stimulation is not for every obstructive sleep apnea patient. Indications for such therapy include adults 18 years or older, obstructive apnea with an AHI range from 15 to 65 events/h, failed CPAP, BMI of less than 36, and appropriate airway anatomy determined by a drug-induced sleep endoscopy. Contraindications for such therapy include concentric airway collapse noted on drug-induced sleep endoscopy, > 25% central and mixed apneas, preexisting compromised neurological control of the upper airway, and patients who cannot operate the hypoglossal nerve stimulator remotely. The purpose of this chapter is to review pearls and pitfalls in the hypoglossal nerve stimulator procedure.