Upper Airway Resistance Syndrome
A form of sleep-disordered breathing where increased breathing effort causes arousals and fragmented sleep, without meeting criteria for sleep apnea.
What is Upper Airway Resistance Syndrome?
Upper Airway Resistance Syndrome (UARS) is a form of sleep-disordered breathing characterized by repetitive increases in upper airway resistance during sleep that lead to brief arousals, but without the apneas or hypopneas that define obstructive sleep apnea. Despite not meeting OSA criteria, patients with UARS experience significant symptoms including excessive daytime sleepiness and fatigue. UARS represents a middle ground on the spectrum between primary snoring and obstructive sleep apnea.
Prevalence
UARS is less well-studied than OSA, and prevalence estimates vary widely. It appears to be more common in younger patients and women compared to OSA. Some studies suggest it may affect up to 10-15% of patients evaluated for sleep-disordered breathing. UARS is often underdiagnosed because standard sleep study scoring may miss it.
Causes
UARS is caused by partial upper airway narrowing during sleep that increases the effort required to breathe. The airway doesn't fully collapse (as in OSA), but the increased resistance triggers arousals that fragment sleep. Contributing factors include subtle anatomical abnormalities, low arousal threshold (waking easily to breathing difficulty), chronic nasal congestion, and genetic factors. UARS may be a precursor to OSA in some patients.
Symptoms
Excessive daytime sleepiness
Despite the absence of significant apneas, sleep fragmentation from repeated arousals causes pronounced daytime fatigue and sleepiness.
Unrefreshing sleep
Patients wake feeling unrefreshed regardless of sleep duration due to frequent brief arousals disrupting sleep architecture.
Mild or no snoring
Unlike OSA, patients with UARS may have minimal or no snoring, which can lead to delayed diagnosis.
Chronic fatigue
Persistent fatigue that doesn't improve with more sleep time, often misdiagnosed as chronic fatigue syndrome.
Insomnia symptoms
Difficulty maintaining sleep, with frequent awakenings throughout the night.
Morning headaches
Headaches upon waking, though often less severe than those associated with OSA.
Functional somatic syndromes
UARS has been associated with conditions like fibromyalgia, irritable bowel syndrome, and chronic pain syndromes.
Diagnosis
Self-Assessment Questions
If you answer yes to any of these questions, consider consulting a sleep specialist:
- 1Do you feel excessively tired during the day despite sleeping enough hours?
- 2Do you wake frequently during the night for no apparent reason?
- 3Do you have symptoms of fatigue that haven't been explained by other conditions?
- 4Have you been told you snore only lightly or not at all, yet feel unrefreshed?
- 5Do you have chronic pain, headaches, or symptoms of fibromyalgia or irritable bowel syndrome?
Diagnosis of UARS requires careful attention during polysomnography to detect respiratory effort-related arousals (RERAs) that may be missed by standard scoring. Esophageal pressure monitoring or pneumotachography may be needed for definitive diagnosis.
Polysomnography with RERA Scoring
A sleep study that specifically looks for respiratory effort-related arousals (RERAs), not just apneas and hypopneas. This may require more sensitive analysis than routine studies.
Esophageal Pressure Monitoring
A catheter measuring pressure changes in the esophagus can detect increased respiratory effort that triggers arousals. This is the gold standard but is invasive and not routinely used.
Nasal Pressure Transducer
High-sensitivity measurement of nasal airflow can detect flow limitation (flattening of the inspiratory waveform) that indicates increased airway resistance.
Cyclic Alternating Pattern (CAP) Analysis
Specialized EEG analysis that may reveal sleep instability and microarousals not captured by standard sleep staging.
Treatment
Treatment for UARS is similar to OSA treatment but may be effective at lower intensities. Many patients respond to conservative measures, though some require PAP therapy or other interventions.
Nasal CPAP or BiPAP
Positive airway pressure therapy is effective for UARS, often at lower pressures than required for OSA. It prevents airway narrowing and eliminates arousals.
Oral Appliances
Mandibular advancement devices may be particularly effective for UARS, advancing the jaw to open the airway without requiring PAP therapy.
Nasal Surgery
If chronic nasal obstruction contributes to UARS, surgical correction (septoplasty, turbinate reduction) may provide relief.
Palatal Procedures
Radiofrequency ablation or other procedures to stiffen the soft palate may reduce airway resistance in selected patients.
Myofunctional Therapy
Exercises to strengthen the tongue and throat muscles may help maintain airway patency during sleep.
Lifestyle Adjustments
- •Maintain a healthy weight (though UARS patients are often normal weight)
- •Avoid alcohol and sedatives before bed
- •Treat allergies and nasal congestion aggressively
- •Sleep on your side
- •Practice good sleep hygiene
- •Avoid sleeping pills that may deepen sleep and worsen arousals
- •Consider nasal strips or nasal dilators
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