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Oral Appliances in Snoring and Obstructive Sleep Apnea

Sleep-Disordered Breathing

Sleep-disordered breathing (SDB) is characterized by repetitive upper airway obstruction and consequent oxyhemoglobin desaturation during the deeper stages of sleep.
The proposed etiology is a combination of both abnormal upper airway anatomy and a yet-to-be determined aberrant afferent/efferent somatosensory loop.

The health-related consequences of SDB are well documented by large prospective cohort studies and chiefly include hypertension, myocardial infarction, stroke, diabetes, depression, excessive daytime fatigue, and a greater risk of motor vehicle accidents. These associated medical problems place an enormous financial burden on society. Because of the high prevalence of this condition, cost-effective management is essential.

Fortunately, a number of viable management options are available. The most common initial treatment for SDB is a continuous positive airway pressure (CPAP) device.
However, CPAP devices can prove annoying and discomforting to many patients, and, for some patients, may be entirely intolerable.

Thus, CPAP is effective only for patients who can tolerate the device and, unfortunately, affords no permanent cure.

Surgical intervention is an alternative form of treatment and involves anatomic reconstruction of the airway.
Although more expensive from the outset, it has long-lasting effects, because surgical intervention results in a permanent alteration of the airway. However, the prospect of surgery may not appeal to all patients. As a result, prosthetic devices are available as effective and low-cost treatment options for those patients that cannot tolerate CPAP and do not wish to undergo surgery.

See also Sleep-Disordered Breathing and CPAP and Surgical Approach to Snoring and Sleep Apnea.

Relevant anatomy, etiology, and pathophysiology

Although primary hypoventilation may be an underlying cause of SDB, the most important factor is the anatomy of the upper airway. In general, obstruction of the airway may be found at three primary sites (ie, nose, velopharynx, hypopharynx). During normal awake respiration, the obstructive tendency of the negative inspiratory pressure within the upper airway is balanced by the outward force of pharyngeal dilator muscle activity under central nervous system (CNS) control. Reduction of tone in this musculature and loss of compensatory reflex dilator mechanisms during deep sleep result in the airway obstruction.

Snoring, a common symptom of SDB, is a repetitive sound caused by vibration of upper airway structures during sleep. Snoring is a good indicator of increased upper airway resistance.

Patients who have obstructive sleep apnea (OSA) generally have smaller upper airways than normal individuals. Increased parapharyngeal fat, a large tongue, an elongated palate, thickened lateral pharyngeal walls, as well as maxillofacial skeletal deficiencies may all play a role in OSA. Lateral pharyngeal wall encroachment by the peritonsillar pillars and tonsillar tissue is also an important etiology of OSA. This tissue bulk may direct the airway anteroposteriorly, as opposed to the normal lateral orientation, forcing the pharyngeal muscles to act at a disadvantage. Greater pharyngeal length increases collapsibility, which may explain why men are more susceptible to OSA than women.

See also Upper Airway Evaluation in Snoring and Obstructive Sleep Apnea and Physiologic Approach in Snoring and Obstructive Sleep Apnea.

SDB evaluation

The symptom and physical findings in patients with SDB, as well as tests used to diagnose this disorder, are briefly discussed below.

Symptoms

Patients with SDB generally present with symptoms of loud snoring or with struggling efforts to breathe, often reported by their sleep partner; choking episodes during sleep; awakening with early morning headaches
; chronic fatigue, feeling of drowsiness, or needing frequent napping during the day; depressed mood; falls or automobile accidents, in serious cases; bedwetting in children; and/or nocturia (rare).

Physical findings

Affected patients typically exhibit increases in body mass index (BMI) (about 75% of patients), blood pressure, and neck circumference and waist-hip ratio.

The upper airway should be examined to evaluate for a low hanging, bulky soft palate; large tonsils; large tongue; dental malocclusion; low hyoid position; or maxillomandibular deficiency.

Diagnostic tests/studies

The Epworth Sleepiness Scale (ESS) is a questionnaire used to screen for sleep apnea that relies on the patient’s description of symptoms.

Polysomnography (testing in a sleep laboratory) is the gold standard test used to establish the diagnosis of SDB.

The multiple sleep latency test (MSLT) is used to establish how rapidly the patient falls asleep, to distinguish from narcolepsy.

Lateral cephalometric radiographs reveal the dimensions of the airway column, the position of the hyoid bone, and the craniofacial skeleton for any maxillomandibular deficiencies.

Flexible fiberoptic nasopharyngoscopy examines in real-time the three-dimensional (3-D) structure of the airway revealing any anatomic sites of obstruction.

See also Obstructive Sleep Apnea, Childhood Sleep Apnea, and Obstructive Sleep Apnea and Home Sleep Monitoring.

Sleep positioning and nasal airway obstruction

The patient’s position during sleep can affect simple snoring in patients with significant SDB. In patients whose snoring is primarily due to nasal airway obstruction, surgical or prosthetic intervention may be of benefit.

Nonsupine position

Positioning of the patient during sleep is a useful method to control simple snoring. In mild cases, snoring is often resolved when the patient assumes a nonsupine position, which may relieve the obstruction. The physiology is intuitively simple: the soft palate and tongue fall posteriorly due to gravity and relaxation of the genioglossus. When the mouth opens, the tongue is even more retrodisplaced. Airway obstruction may result in oxyhemoglobin desaturation if apnea occurs. The effect of positioning is demonstrated by polysomnography, which often shows more frequent and severe disordered breathing events when the patient is supine.

The classic remedy of attaching a tennis ball to the back of the individual’s pajamas may help some patients with mild cases. However, most patients with significant SDB show apnea in all positions. Thus, this technique is seldom useful for patients with more than simple snoring.

A snoring pillow may help some patients with snoring problems. Used appropriately, the pillow positions the head so that the mouth is closed and the jaw is held forward. Unfortunately, movement during sleep minimizes the pillow’s effectiveness.

Nasal airway obstruction

In the normal airway, the limen nasi is the site of the highest resistance to airflow. Collapsed alae, a severely deviated septum, or hypertrophied turbinates may affect airflow substantially. Nasal valve surgery has been demonstrated to improve snoring for many patients whose primary problem is nasal airway obstruction.

Although surgical therapy is effective for treating nasal valve obstruction, devices that splay the alae (externally or internally) have also demonstrated success in improving nasal airflow and decreasing snoring.
However, studies disagree on whether significant improvement occurs. Although anecdotal reports describe patients whose sleep apnea may have been controlled by alar splaying devices, no statistical difference in patients using the devices compared with controls has been demonstrated. These devices are benign, inexpensive, and available at any pharmacy. For patients with minimal problems and noticeable nasal airway obstruction, devices that splay the alae are easy to obtain for an at-home trial.

Nasal trumpets may be useful for short-term management in select patients. Trumpets are commonly used in postanesthesia airway management. These devices bypass any nasal, soft-palate, and, often, tongue-base obstructions. However, few patients are willing to use the trumpets nightly to control SDB.

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