Upper Airway Resistance Syndrome-One Decade Later

Gang Bao; Christian Guilleminault


Curr Opin Pulm Med. 2004;10(6) 

In This Article

Abstract and Introduction

Purpose of Review: The term upper airway resistance syndrome (UARS) was coined to describe a group of patients who did not meet the criteria for diagnosis of obstructive apnea-hypopnea syndrome and thus were left untreated. Today, most of the patients with UARS remain undiagnosed and are left untreated.
Recent Findings: Today, the clinical picture of UARS is better defined. We have learned that patients usually seek treatment with a somatic functional syndrome rather than sleep-disordered breathing or even a disorder of excessive daytime sleepiness. Therefore, most of these patients are seen by psychiatrists. In addition, recent technologic advances have allowed a better recognition of the problem. We have learned that obstructive apnea-hypopnea syndrome is associated with a local neurologic impairment that is responsible for the occurrence of the hypopnea and apneas. In contrast, patients with UARS have an intact local neurologic system and have the ability to respond to minor changes in upper airway dimension and resistance to airflow. New treatment options including internal jaw distraction osteogenesis are used and are promising for treatment of patients with UARS.
Summary: The clinical presentation of patients with UARS is similar to the presentation of subjects with functional somatic syndrome. To diagnose UARS, nocturnal polysomnography should include additional measurement channels.

Upper airway resistance syndrome (UARS) was first recognized in children in 1982.[1] The term UARS, however, was not used until adult cases were reported in 1993.[2] The description of UARS brought clinicians' attention to a group of patients left undiagnosed and untreated despite severe impairment. Since the original description, the syndrome has been recognized in patients with clinical and polysomnography presentations different from that of obstructive sleep apnea syndrome (OSAS). However, controversies exist regarding the syndrome. Some have rejected it as a distinct clinical entity or even doubted its existence;[3] others have considered it part of a spectrum that includes benign snoring, UARS, obstructive hypopnea syndrome, OSAS, and hypoventilation. The term sleep-disordered breathing (SDB) is used widely today, often without clear definition by the authors. Supposedly it includes all these breathing abnormalities in sleep, including central apnea and hypoventilation. Clinically, the disease entity of SDB is often called sleep-related breathing disorders. In clinical practice, a label of SDB or sleep-related breathing disorders is applied when a breathing abnormality is found in sleep but no clear distinction between UARS and obstructive apnea-hypopnea syndrome (OSAHS) is attempted or can be made. In the past few years, there have been at least two review articles published on UARS in general[4] and in children.[5] This review is aimed at coverage of recent progress progresses in recognition and understanding of UARS, with greater emphasis on data published over the period of the past 2 years.

Since the first description of a polygraphic pattern called obstructive sleep apnea in the Pickwickian syndrome in 1965,[6,7] sleep medicine has undergone an evolution. UARS was born as part of the efforts to describe a generally unrecognized patient population that is nonobese with clinical features not matching those reported with OSAHS. Unfortunately, many sleep breathing abnormalities are still ignored because of the belief that SDB is synonymous with OSAHS and that patients must be obese. Such limited views have already led to the underdiagnosis and undertreatment of OSAS in women (the forgotten sex).[8] With use of new techniques, such as the esophageal catheter for esophageal pressure measurement (Pes)[9] and nasal cannula/pressure transducer,[10] it has become more convenient to identify subtle changes in breathing patterns during sleep. Recently, UARS has been linked to many somatic, psychiatric, or psychosomatic conditions, including parasomnias, attention deficit disorder or attention deficit hyperactivity disorder, fibromyalgia, and chronic insomnia. Also, to many clinicians, the distinction between UARS and OSAS lies in the clinical severity, such as apnea-hypopnea index (AHI) and level of oxygen desaturation, but research in recent years supports the presence of a different pathophysiology in the two syndromes.


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