Obstructive Sleep Apnea (OSA) is a disorder where the upper airway repeatedly collapses during sleep, disrupting rest and reducing blood oxygen levels. The standard treatment for moderate to severe OSA is Continuous Positive Airway Pressure (CPAP), which uses pressurized air delivered through a mask to mechanically splint the airway open. Many patients struggle with CPAP compliance due to discomfort, mask fit issues, or claustrophobia, creating a need for alternative therapies. For those unable to tolerate CPAP, a fully implanted system exists that treats the underlying cause of airway collapse, eliminating the need for an external air delivery device.
Understanding the Implanted Technology
This alternative is a neurostimulation system, known as an Upper Airway Stimulator, that addresses the muscular dynamics of the throat. It functions by delivering mild electrical impulses to the hypoglossal nerve, which controls tongue movement. Stimulating this nerve causes the genioglossus muscle—the main muscle of the tongue—to move forward. This stabilization prevents the tongue from collapsing backward and blocking the pharyngeal airway during sleep.
The implanted system consists of three primary components that synchronize nerve stimulation with the patient’s breathing cycle. The first is a small, pacemaker-like implantable pulse generator (IPG) containing the battery and electronics, typically placed beneath the skin in the upper chest. The second component is a sensing lead, a thin wire placed near the ribs, which detects the subtle movements of the chest wall as the patient inhales.
When the sensing lead registers the beginning of an inspiration, it signals the IPG. The IPG then transmits an electrical impulse through the third component, the stimulation lead, which is placed around a branch of the hypoglossal nerve under the jaw. This stimulation stiffens and protrudes the tongue and surrounding throat muscles, opening the airway for the duration of the breath. The process is synchronized with the patient’s natural breathing pattern, ensuring the airway remains open without external air pressure.
Patient Selection and Eligibility Requirements
To be considered for the implantable neurostimulator, a patient must have a documented history of moderate to severe OSA and an inability to tolerate CPAP therapy. Severity is measured using the Apnea-Hypopnea Index (AHI); eligible patients generally have an AHI between 15 and 100 events per hour. The sleep apnea must also be predominantly obstructive, meaning central or mixed apneas account for less than 25% of the total AHI events.
A defining criterion for candidacy is the Body Mass Index (BMI). While older guidelines required a BMI of less than 32 kg/m², current indications allow for a BMI up to 35 kg/m² or even 40 kg/m², though outcomes are better in patients with lower BMI. The treatment is intended for adults 18 years of age or older, sometimes 22 or older, depending on regulatory guidelines.
The final step in the selection process is Drug-Induced Sleep Endoscopy (DISE). During DISE, the patient is placed under light sedation to mimic natural sleep, allowing a surgeon to use a flexible scope to visualize the pattern of airway collapse. The neurostimulator is effective only if the collapse at the soft palate level is not a complete concentric blockage, as this pattern is less responsive to tongue protrusion. If the DISE reveals a favorable pattern of collapse, the patient is cleared for surgery.
The Surgical Procedure and Recovery
The implantation of the upper airway stimulator is an outpatient surgical procedure performed under general anesthesia, lasting two to three hours. The surgeon makes three small incisions to place the components in their designated anatomical locations. The implantable pulse generator is positioned in a subcutaneous pocket created just below the collarbone in the upper chest, similar to a cardiac pacemaker.
A second incision, usually under the jaw, allows placement of the stimulation lead around the branch of the hypoglossal nerve. The third incision, made near the ribs, is used to place the sensing lead, which is tunneled beneath the skin to connect to the IPG. Most patients can return home the same day following the procedure.
Initial recovery involves managing mild pain and swelling at the incision sites, which subsides within a few days to a week. Patients should avoid strenuous activities for a few weeks, but normal activities can be resumed quickly. The implant remains inactive for four to six weeks to allow the surgical sites to fully heal and minimize the risk of infection before the device is activated.
Activation, Daily Use, and Expected Efficacy
Device activation occurs approximately one month after surgery, ensuring the body has healed around the implanted components. During this appointment, the clinician uses a programming system to check the device’s function and set the initial stimulation parameters. The patient receives a handheld remote control that manages the system’s daily operation.
The daily routine is straightforward: the patient uses the remote to turn the system on before sleeping and off upon waking. The device includes a slight delay before stimulation begins, allowing the patient to fall asleep comfortably. Over the following weeks, the patient and clinician work through titration, gradually adjusting the stimulation level. This process finds the optimal setting that eliminates airway collapse while remaining comfortable.
Hypoglossal nerve stimulation has demonstrated therapeutic success, with long-term studies showing the treatment reduces the AHI by an average of 68% to 79% in appropriate candidates. This reduction in breathing events improves quality of life, including a decrease in daytime sleepiness measured by the Epworth Sleepiness Scale. Patient satisfaction rates are high, and many report a near-complete elimination of loud snoring.