There is some controversy about whether upper airway resistance syndrome (UARS) is a distinct disorder or even whether it is part of the spectrum of sleep-related breathing disorders that includes sleep apnea.
Defining Upper Airway Resistance Syndrome
Upper airway resistance syndrome (UARS) is believed to be a disorder of increased airway resistance without the findings suggestive of sleep apnea. Generally, in sleep apnea there is a significant reduction in airflow and associated drops in the oxygen levels of the blood. There may be a complete cessation in breathing -- which is called apnea -- or a partial reduction called a hypopnea. In upper airway resistance there are neither hypopneic or apneic events, and there are no drops in the oxygen levels of the blood.
Nevertheless, there is often snoring and frequent brief arousals noted in sleep with significant excessive daytime sleepiness. It is thought that the frequent arousals associated with the condition lead to the sleepiness. These arousals may be due to a modestly increased effort to breathe, which can be detected with measurement of pressure changes within the esophagus.
Diagnosis and Treatment of UARS
Diagnosis of upper airway resistance syndrome is accomplished with careful documentation of increasingly negative esophageal pressures occurring before the associated arousals. This may be done with adjunctive measurements associated with a standard sleep study called a polysomnogram.
The treatment of UARS is similar to obstructive sleep apnea. Individuals afflicted with UARS may respond to continuous positive airway pressure (CPAP) therapy or other alternative treatments.
Source:
Mowzoon, N et al. “Neurology of Sleep Disorders.” Neurology Board Review: An Illustrated Guide. 2007; 726
