Definition

Although the definition of snoring may differ depending on the “ear of the beholder,” it is defined by the Random House Dictionary of the English Language as “breathing during sleep with hoarse or harsh sounds as caused by the vibrating of the soft palate.”⁵ The International Classification of Sleep Disorders: Diagnostic and Coding Manual defines primary snoring (ICSD 786.09) as “loud upper airway breathing sounds in sleep, without episodes of apnea or hypoventilation.”⁶

Prevalence

It is clearly recognized that snoring is common in the general population, but estimates vary widely of its prevalence in different populations. These differences mainly are due to subjective perception, depending on who is reporting the snoring (the snorer or the bed partner) and how the question is asked by the clinician. Overall, snoring is reported to affect 19% to 37% of the general population and more than 50% of middle-aged men.⁷ Male predominance has been noted in all snoring epidemiologic studies, possibly due to the differences in perception of snoring by men and women. Other possible reasons for increased male predominance include differences in pharyngeal anatomy and function, hormonal differences and their effects on upper airway muscles, and differences in body fat distribution.

Pathophysiology

Snoring is a result of the changes in the configuration and properties of the upper airway (from the nasopharynx to the laryngopharynx) that occurs during sleep. This sound can be produced by any membranous portion of the airway that lacks cartilaginous support, including the soft palate, uvula, and the pharyngeal walls. Snoring is usually an inspiratory sound, but it can also occur in expiration.⁸ Snoring can occur during any stage of sleep but is more common during stages 2, 3, and 4. This is because airway elastance and muscle tone due to sympathetic activity and neural output to the upper airway walls are different during rapid eye movement (REM) and non-REM sleep. Multiple predisposing factors can lead to a snoring abnormality, including age (middle or advanced), regional obesity, body posture, use of alcohol and muscle relaxants, retrognathia, nasal blockage, and smoking.⁹

Signs and Symptoms

A primary snorer is usually asymptomatic and does not suffer from cardiovascular disease. Snoring in this population is usually an annoyance to the bed partner, and the snorer might deny any symptoms of daytime somnolence or difficulty with concentration. In contrast, snoring also can occur in conjunction with a disordered sleep pattern and may be associated with a range of symptoms, including overt OSAHS.

Bed partners, family members, or friends who have shared a room with the sleeping patient initially might complain of loud or disruptive noises. Patients sometimes complain of snoring themselves, a feeling of tiredness on waking, excessive sleepiness during the day, poor work performance, and difficulty with concentration.

Diagnosis

A complete history and careful physical examination are paramount in assessing whether sleep apnea is present in a patient with snoring symptoms. The history and examination results also guide the clinician in deciding whether a nocturnal polysomnogram is necessary and in determining appropriate treatment.

The history should be obtained in the presence of the bed partner, who usually initiates the visit, because the snorer often is unaware of snoring. The clinician also should assess the degree of social disruption caused by the snoring. He or she should ask the bed partner the number of years’ duration of the snoring, frequency of snoring (every night or intermittent), postural dependence (lying on side or back), and the association of posture with cessation of breathing.

The patient’s risk factors should be assessed, including male gender, increase in weight, ingestion of alcohol, allergies, nasal obstruction, trauma, use of muscle-relaxing medications, and smoking. An assessment of daytime functioning, including concentration levels, work performance, and sleepiness, should be documented. The Epworth Sleepiness Scale (Table 1), which assesses the level of daytime sleepiness, has been used to distinguish primary snoring from OSAHS.¹⁰ A history should be sought of previous surgery or trauma to the upper airways (any site between the nose and the larynx) because the compliance of the airways may be affected. A family predisposition to snoring has been described, and many snorers admit to other family members of having a history of snoring if asked.¹¹

Table 1 The Epworth Sleepiness Scale

Laboratory tests for hypothyroidism or acromegaly are indicated only if clinical signs suggest the presence of these disorders. The decision to order other laboratory investigations should be based on the possible medical consequences of the patient’s snoring, the probability that apnea is present, and factors that can influence successful treatment.

The two main studies usually used to evaluate snoring are nocturnal polysomnography and an airway assessment. In a position statement, the American College of Chest Physicians and the Association of Sleep Disorders Centers have declared that only snorers suspected of having sleep apnea syndrome should undergo polysomnography.¹² The American Thoracic Society has declared in its position statement that snoring alone is not an indication for a sleep study.¹³

In symptomatic snorers with daytime somnolence, reduced performance, reduced attention, and tiredness, a full nocturnal polysomnogram is needed to establish a diagnosis of sleep apnea or UARS. Nocturnal polysomnography with a recording of sleep architecture and arousals is necessary.

Polysomnography remains the gold standard for diagnosing SDB. A complete polysomnography is often termed a full sleep study. Sleep is recorded from a number of electrophysiologic signals as well as from breathing and limb movement electrodes. This includes an electroencephalogram (EEG) with two leads, electromyography, electro-oculography, respiratory signals from airflow measurements from nasal pressure, nasal temperature, expired carbon dioxide, ventilation from thoracoabdominal movements or nasal pressure, oxygenation levels, and possibly esophageal balloon pressures. Other signals include an electrocardiogram tracing during sleep, pulse rate, position, esophageal pH, and video recording. A detailed airway assessment of upper airway volume and area is not done routinely because it does not predict successful surgical outcomes in a nonapneic snorer. If surgery is being considered, further radiographic imaging can provide an airway assessment and may include cephalometric measurements, computed tomography, or magnetic resonance imaging.

Treatment

Because snoring and sleep apnea are contained within a spectrum of disease states, the treatment of snoring and sleep apnea can overlap. Treatment of snoring should be directed at improving sleep apnea or UARS. In the snorer without sleep apnea or in the primary snorer, initiation of treatment can improve quality of life. Lifestyle modification should be addressed in all patients who snore, including reduction of risk factors such as obesity, alcohol consumption, and use of muscle relaxants.

Noninvasive treatments should be recommended initially, including nasal dilators, tongue-retaining devices, and mandibular advancement appliances that can be fixed or adjusted. Used to treat apneic snorers, tongue-retaining devices hold the tongue in a forward position by applying negative pressure. Subsequently, obstruction at the base of the tongue is relieved and nasal breathing is promoted. In 1995, the Task Force for the Standards of Practice Committee of the American Sleep Disorders Association recommended offering oral appliances to all nonapneic snorers.¹⁴

Nonsurgical methods such as treating coexisting allergies or nasal congestion, reducing weight, changing sleeping positions, and using ear plugs have met with limited success. Although many of these modalities are anecdotally successful, their efficacy has not been demonstrated in a randomized controlled setting.¹⁵

Patients should be counseled that CPAP carries the greatest guarantee that snoring will be abolished. Application of nasal CPAP via a nasal mask has significantly altered the medical treatment of sleep apnea, because CPAP can almost completely eliminate snoring. Most nonapneic snorers are reluctant to commit to nasal CPAP, and compliance can become an issue that leads to limited efficacy in this population.

Surgical approaches should be discussed only with patients who suffer from obvious anatomic abnormalities, including nasal or pharyngeal obstruction. Discussions in conjunction with a surgical team should focus on improvement of symptoms; patients should not expect complete resolution of snoring through surgical techniques. Nasal surgery for the relief of nasal obstruction due to septal deviation or polyps may be associated with improvement in snoring in up to 75% of patients.¹⁶ It is believed that nasal surgery alone is unlikely to cure snoring, but it can improve breathing, allowing patients to better tolerate therapies such as nasal CPAP. Uvulopalatopharyngoplasty (UPPP) (Fig. 1) and laser-assisted palatal surgery each have reported success rates of greater than 70% for primary snoring.¹⁷

Figure 1 Reduction in posterior pharyngeal tissue and absence of the uvula are seen following uvulopalatopharyngoplasty.

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