Upper Airway Resistance Syndrome (UARS): Diagnosis and Treatment
Upper airway resistance syndrome is now classified as a form of obstructive sleep apnea (OSA) and should be diagnosed using polysomnography with esophageal pressure monitoring and arousal-based scoring, including respiratory effort-related arousals (RERAs) in the respiratory disturbance index (RDI). 1
Diagnostic Approach
Current Classification
UARS is no longer a separate diagnosis—it has been subsumed under OSA in the ICSD-3 classification due to shared pathophysiology and treatment response 1. Patients who exclusively have RERAs (previously labeled as UARS) are now diagnosed with OSA when they meet criteria.
Diagnostic Criteria
Polysomnography is the standard diagnostic test and must include:
- Arousal-based scoring that recognizes hypopneas associated with EEG arousals (with or without oxygen desaturation) 1
- RERAs in the RDI calculation: RDI = (apneas + hypopneas + RERAs) × 60 / total sleep time 1
- Esophageal pressure monitoring remains the gold standard for detecting increased upper airway resistance and RERAs 2, 3, 4
The diagnosis requires ≥5 predominantly obstructive respiratory events per hour with symptoms, or ≥15 events per hour regardless of symptoms 1.
Key Diagnostic Features
Look for these specific characteristics:
- AHI <5 events/hour with oxygen saturation ≥92% 5
- RERA index ≥5 5
- Elevated negative intrathoracic pressure (mean around -36.7 cm H₂O) 6
- Frequent EEG arousals disrupting sleep architecture 3
Clinical Presentation
Patients typically present with:
- Excessive daytime sleepiness and chronic fatigue (not just snoring) 2, 6
- Functional somatic syndromes—many are initially seen by psychiatrists rather than sleep specialists 2, 4
- Non-obese young adults with no strong sex predominance 4
- Craniofacial abnormalities: excessive palatal tissue, narrowed oropharynx/hypopharynx 6
Critical pitfall: These patients often remain undiagnosed because they don't fit the classic OSA profile and may not report sleep complaints as their primary concern 2.
Treatment
First-Line Therapy
Continuous positive airway pressure (CPAP) is the most efficacious treatment 3, though patient compliance may be challenging.
Practical Implementation
- Split-night polysomnography can effectively diagnose UARS and initiate CPAP titration in a single study, reducing the delay in treatment (which otherwise averages 72 days) 7
- This approach does not diminish diagnostic accuracy or CPAP titration success 7
Alternative Treatments
When CPAP compliance is poor:
- External nasal dilation reduces stage 1 sleep and desaturation time, though effects on overall sleep architecture are modest 8
- Positional therapy: Lateral sleeping position significantly reduces AHI and desaturation compared to supine position 8
- Surgical options: Palatal surgery and jaw distraction osteogenesis show promise 2, 6, with reported improvement in Epworth Sleepiness Scale scores from 12.0 to 3.4 post-operatively 6
- Radiofrequency ablation and oral appliances require further validation 3
Clinical Significance
Quality of Life Impact
Patients with UARS have 5.5 times greater probability of low quality of life compared to the general population—similar to the 6.2-fold increase seen in OSA 5. Quality of life is further impaired by muscle pain, obesity, depression, and psychotropic medication use 5.
Prognosis and Complications
- Hypertension is an important sequela, likely from autonomic changes induced by increased negative intrathoracic pressure 3, 4
- Potentially reversible if treated early due to intact local neurologic function 2
- Risk of progression to frank OSA if left untreated 4
The key to successful management is early recognition using proper polysomnography with arousal-based scoring, followed by prompt CPAP initiation, ideally through split-night protocols to minimize treatment delays.