Upper airway resistance syndrome
Upper airway resistance syndrome is a rare sleep disorder characterized by the narrowing of the airway that can cause disruptions to sleep. The primary symptoms include excessive fatigue and chronic insomnia. UARS can be diagnosed by polysomnography, and can be treated with lifestyle changes, dental devices, or CPAP therapy. UARS is similar to certain types of sleep apneas.
|Upper airway resistance syndrome|
Signs and symptoms
Symptoms of UARS are similar to those of obstructive sleep apnea, but not inherently overlapping. Fatigue, daytime sleepiness, unrefreshing sleep, and frequent awakenings during sleep are the most common symptoms.
Many patients experience chronic insomnia that creates both a difficulty falling asleep and staying asleep. As a result, patients typically experience frequent sleep disruptions. Loud snoring also serves as a possible indicator of the syndrome, but is not a symptom required for diagnosis.
Some patients experience hypotension, which may cause lightheadedness, and patients with UARS are also more likely to experience headaches and irritable bowel syndrome.
Upper airway resistance syndrome is caused when the upper airway narrows without closing. Consequently, airflow is either reduced or compensated for through an increase in inspiratory efforts. This increased activity in inspiratory muscles leads to the arousals during sleep which patients may or may not be aware of.
A typical UARS patient is not obese and possesses a triangular face and misaligned jaw, which can result in a smaller amount of space behind the base of the tongue. Patients may have other anatomical abnormalities that can cause UARS such as deviated septum, inferior turbinate hypertrophy or nasal valve collapse. UARS affects equal numbers of males and females. It is unclear as to whether UARS is merely a phase that occurs between simple snoring and sleep apneas, or whether UARS is a syndrome that describes a deviation from normal upper airway physiology.
Polysomnograms can be used to help diagnose UARS. Patient who have UARS typically show multiple EEG arousals during the sleep study and little to no polygraphic evidence of obstructive sleep apnea or decreased levels of oxygen. UARS arousals, or respiratory-effort related arousals, typically last for one to three breaths. These arousals may be due to snoring, but patients do not need to snore in order to have UARS. Polysomnogram patterns must exhibit no evidence of apneas or hypopneas in order to lead to a diagnosis of UARS. Even with polysomnography, diagnosis of UARS may be difficult because of insufficient means of measuring changes in airflow. This lack of sensitivity in detection may lead to misdiagnosis, as minor undetectable changes in airflow may still be responsible for the arousals. In order to definitively diagnose UARS, there must be a demonstrated pattern of greater negative esophageal pressures which are then followed by a rapid change to a more positive level with a sleep arousal. This can be confirmed with invasive polysomnography that uses an esophageal balloon transducer and full pneumotachograph.
Behavioral modifications include getting at least 7–8 hours of sleep and various lifestyle changes, such as positional therapy. Sleeping on one's side rather than in a supine position or using positional pillows can provide relief, but these modifications may not be sufficient to treat more severe cases. Avoiding sedatives including alcohol and narcotics can help prevent the relaxation of airway muscles, and thereby reduce the chance of their collapse. Avoiding sedatives may also help to reduce snoring.
Positive airway pressure therapy
Positive airway pressure therapy is similar to that in obstructive sleep apnea and works by stenting the airway open with pressure, thus reducing the airway resistance. Use of a CPAP mask can help ease the symptoms of UARS. Therapeutic trials have shown that using a CPAP mask with pressure between four and eight centimeters of water can help to reduce the number of arousals and improve sleepiness. CPAP masks are the most promising treatment for UARS, but effectiveness is reduced by low patient compliance.
Oral appliances to protrude the tongue and lower jaw forward have been used to reduce sleep apnea and snoring, and hold potential for treating UARS, but this approach remains controversial. Oral appliances may be a suitable alternative for patients who cannot tolerate CPAP.
Though less common methods of treatment, various surgical options including uvulopalatopharyngoplasty (UPPP), hyoid suspension, and linguloplasty exist. These procedures increase the dimensions of the upper airway and reduce the collapsibility of the airway. One should also be screened for the presence of a hiatal hernia, which may result in abnormal pressure differentials in the esophagus, and in turn, constricted airways during sleep. Palatal tissue reduction via radiofrequency ablation has also been successful in treating UARS.
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