Hypoglossal Nerve Stimulator Outcomes for Patients Outside the U.S. FDA Recommendations. 
The hypoglossal nerve stimulator (HGNS) is currently approved for the treatment of obstructive sleep apnea (OSA) in patients with an apnea-hypopnea index (AHI) of >15 to ≤65 events/hour, and a central apnea index (CAI) <25% of the AHI, no complete concentric collapse on drug-induced sleep endoscopy, and a recommended body mass index (BMI) <32 kg/m2 .  We present 18 patients implanted as a salvage procedure despite being outside these guidelines.  We included all patients who underwent HGNS but who did not meet all FDA guidelines.  Demographic data, previous OSA treatments, polysomnographic (PSG) parameters from baseline and HGNS titration PSG, Epworth sleepiness score (ESS), and BMI were compared before and after surgery.  Eighteen patients were identified: 94.4% male, median age 63 years.  Seven underwent previous sleep surgery.  Four had an AHI <15 (mean 10.5 events/hour), four had an AHI >65 (mean 86.9 events/hour), two had an elevated CAI (mean 31.3% of AHI), and 12 had a BMI >32 kg/m2 (range 32.1-39.1).  Median AHI decreased from 25.3 to 3.75 events/hour on titration polysomnography (P = .0006), oxyhemoglobin saturation nadir increased from 82% to 88.5% (P = .0001) and median ESS dropped from 11 to 7.5 (P = .0016).  Fifteen (83.3%) patients achieved surgical success (decrease in AHI >50% and AHI <20 events/hour) and 12 (66.7%) had an AHI <5 events/hour.  Neither patient with CAI >25% was successfully treated.  Median adherence = 33.5 hours/week.  Our success rate for patients outside the Food and Drug Administration guidelines for HGNS (67%) was similar to the 1-year STAR trial results (66%).  Future studies are necessary to consider expansion of these guidelines.  4 Laryngoscope, 2019.