Who is a candidate for Inspire (Upper Airway Stimulation) therapy for obstructive sleep apnea (OSA)?

Who is a Candidate for Inspire (Hypoglossal Nerve Stimulation)?

Inspire therapy is indicated for adults with moderate-to-severe obstructive sleep apnea (AHI 15-65 events/hour) who have failed or cannot tolerate CPAP, with BMI <32 kg/m², and absence of complete concentric collapse at the soft palate level on drug-induced sleep endoscopy. 1

Mandatory Eligibility Criteria

Age and Disease Severity

• Age ≥18 years is required for hypoglossal nerve stimulation 1
• AHI between 15-65 events per hour documented on polysomnography within 24 months 1
• The Veterans Administration/Department of Defense guidelines specifically recommend AHI 15-65/h as the therapeutic window 1
• Success rates drop significantly with AHI >50, falling from 100% in patients with AHI <30 to only 50% in those with AHI >50 1

Body Mass Index Requirements

• BMI must be <32 kg/m² according to the most stringent guideline recommendations 1
• Some guidelines allow BMI <40 kg/m², but the stricter <32 kg/m² threshold predicts better anatomical features and surgical efficacy 1
• Patients with BMI <30 kg/m² have shorter anterior cranial base, smaller mandible, and retroposition that creates narrower velopharyngeal spaces—anatomical features that predict better surgical outcomes 2, 1

CPAP Failure Documentation

• Documented CPAP intolerance or failure is mandatory before considering hypoglossal nerve stimulation 1
• Comprehensive CPAP optimization must be attempted, including mask refitting, pressure adjustments, heated humidification, and behavioral interventions 1
• A trial of BPAP should be considered if high CPAP pressures were the primary intolerance issue 1
• The American Academy of Sleep Medicine strongly recommends against delaying definitive treatment with prolonged attempts at CPAP optimization once true intolerance is documented 1

Critical Anatomical Assessment

Drug-Induced Sleep Endoscopy (DISE)

• DISE is required to confirm absence of complete concentric collapse at the soft palate level, as this anatomical pattern predicts failure of hypoglossal nerve stimulation 1
• Nasofibroscopy and complete clinical examination must evaluate the three major anatomic regions: nose, palate (oropharynx), and base of tongue (hypopharynx) 2
• The Friedman staging system should be used to score palate position and tonsil size 2, 1

Favorable Anatomical Features

• Minimal tonsil tissue and tongue position that improves with jaw thrust maneuver indicate favorable anatomy 1
• Patients without obvious micrognathia or bony anatomic abnormalities respond better 2
• Hypopharyngeal obstruction at the base of tongue (present in 80% of surgical candidates) is typically amenable to hypoglossal nerve stimulation 2

Absolute Contraindications

Medical Exclusions

• Central or mixed sleep apnea patterns are absolute contraindications 1
• History of respiratory or cardiac failure within the past year excludes patients from surgical intervention 2
• Active smoking is a contraindication; patients must stop smoking at least 1 month prior to surgery 2

Anatomical Exclusions

• Complete concentric collapse at the soft palate level on DISE predicts failure 1
• Obvious micrognathia or bony anatomic abnormalities predict insufficient response 2
• Previous failed uvulopalatopharyngoplasty (UPPP) surgery suggests poor surgical candidacy 2

Dental Contraindications

• Severe periodontal disease, severe temporomandibular disorders, inadequate dentition, or severe gag reflex contraindicate mandibular advancement devices but not hypoglossal nerve stimulation 1

Treatment Algorithm Position

First-Line Therapy

• CPAP remains the gold standard first-line treatment for moderate-to-severe OSA 1
• Educational and behavioral interventions should accompany PAP therapy initiation 1
• BPAP is offered for patients unable to tolerate CPAP due to high pressure requirements 1

Second-Line Consideration

• Hypoglossal nerve stimulation is a second-line therapy reserved for documented CPAP failure or intolerance 1
• The European Respiratory Society issued a conditional recommendation against hypoglossal nerve stimulation as first-line treatment 1
• Mandibular advancement devices are less effective than CPAP and inappropriate for moderate-to-severe OSA (AHI >30); they would represent a therapeutic step-down 1

Third-Line Options

• Multilevel surgery is reserved for hypoglossal nerve stimulation failure and has higher morbidity including velopharyngeal insufficiency, dysphagia, and mandibular fracture 1

Important Clinical Considerations

Pre-Operative Requirements

• Polysomnography within 24 months is mandatory 1
• Multidisciplinary evaluation by maxillofacial surgeon, neurophysiologist, and pulmonologist may be beneficial 2
• Weight reduction should be pursued concurrently with planning, as lower BMI predicts better outcomes 1

Common Pitfalls to Avoid

• Do not delay definitive treatment with prolonged weight loss attempts when the patient has symptomatic moderate-to-severe OSA 1
• Do not cycle through additional PAP variants after documented CPAP and BPAP failure 1
• Do not assume positional therapy is adequate without documentation that OSA is predominantly positional 1
• Only about 10% of screened patients typically meet all criteria, highlighting the need for careful patient evaluation 1

Expected Outcomes

• Surgical success (AHI decrease >50% and overall AHI ≤20) occurs in 66% of implanted subjects 3
• Long-term follow-up data (≥5 years) confirms sustained safety and efficacy 1
• Adherence to hypoglossal nerve stimulation is superior to CPAP 1
• Significant improvements in quality of life measures and Epworth Sleepiness Scale scores are documented 1, 4