Snoring

Snoring is the most frequent nocturnal symptom of OSA, occurring in up to 95% of patients with the condition. Snoring has poor predictive value owing to a high prevalence in the general population. In population surveys, the prevalence of snoring increases progressively with age, yet snoring is a hallmark of OSA, and in its absence, the diagnosis of OSA is unlikely. Snoring occurs after sleep onset, although in some patients with OSA it is present even during drowsiness. Its intensity increases with nighttime alcohol consumption and use of sedative drugs. In general, snoring is loudest in the supine position (dorsal recumbency) and decreases in volume in the side-lying position. Periods of silence interrupting loud snoring may reflect occurrence of pathologic apneas.

Other Nocturnal Signs and Symptoms

Patients with OSA usually fall asleep quickly, although many of them report insomnia and frequent nocturnal awakenings. Insomnia is most likely to reflect the perception of recurrent arousals from sleep and its nonrestorative pattern. Repetitive episodes of airway obstruction can be associated with snorting, gasping, diaphoresis, and restlessness that lead to sleep fragmentation. In severe OSA, choking is reported by more than 30% of patients. Nocturnal awakenings raise a differential diagnosis that should include nocturnal asthma, cardiac failure, and gastroesophageal reflux. Pathologic nocturia (2 episodes or more per night) has a prevalence of 50% among patients with OSA. It is thought to be secondary to hypoxia and atrial stretch, leading to increased atrial natriuretic peptide secretion and subsequent increment in intravascular volume. Effective therapy with continuous positive airway pressure (CPAP) reduces occurrence of these symptoms, thus suggesting a causal relationship between them and OSA.

Bed partners often volunteer witnessing breathing pauses followed by snorting or gasping during sleep, and this is a common reason for referral of the patient to a sleep clinic. Witnessed apneas are considered a good diagnostic predictor of OSA; nevertheless, this finding does not correlate with objective measurements and hence does not predict the severity of the disorder.

Excessive Daytime Sleepiness

Sleepiness is difficult to define and is a subjective feeling of impairment of concentration and increased craving for sleep. Excessive daytime sleepiness (EDS) is a nonphysiologic complaint that is not satisfied by a restorative sleep. Sleepiness is reported by 30% to 50% of the general population, so EDS alone is a poor predictor of OSA and requires a differential diagnosis to exclude many other medical conditions associated with this daytime symptom, such as depression, fibromyalgia, chronic insomnia, or hypothyroidism. Patients with OSA sometimes refer to EDS as abnormal daytime tiredness or lack of energy and convey the impression that they must make stringent efforts to remain alert and awake. It is believed that the loss of the restorative function of sleep due to repetitive arousals is the main mechanism to explain the presence of EDS in OSA. The Epworth Sleepiness Scale (Box 61-2) is the most popular tool for subjective evaluation (self-assessment) of EDS. A score above 10 of 24 is considered to be clinically relevant. The relationship between the Epworth score and the apnea-hypopnea index (AHI) (as a surrogate index of OSA severity) is relatively poor. In fact, 35% patients with severe OSA identified within sleep clinics do not complain of EDS. This discrepancy is partly due to underestimation or intentional underreporting the severity of sleepiness for personal gain, such as to avoid job loss. On the other hand, patients scoring high in the Epworth scale could have just mild to moderate OSA. EDS is the most disabling symptom among patients with OSA. One example is drowsiness while driving, which is associated with a three-fold increase in risk of accidents in patients with OSA. Poor school or job performance also is frequently reported.

Other Daytime Signs and Symptoms

On wakening in the morning, half of sufferers report headaches. Morning headache usually is generalized and lessens as the patient begins the usual activities of the day. This symptom may be due to hypercapnia and associated cerebral vasodilatation with resultant increase in intracranial pressure. Often, morning headaches disappear after effective treatment of OSA. Symptoms related to cognitive impairment such as memory loss, irritability, personality changes, and depression are frequent but nonspecific. Both sleep fragmentation and nocturnal hypoxemia have been advocated to explain decreased vigilance and psychomotor impairment, respectively. One concern is the observation that OSA treated with CPAP causes only partial resolution of those deficits, suggesting a potentially irreversible anoxic brain damage. In men with OSA, sexual dysfunction including impotence and decreased libido have been reported in 30% to 50% of the cases and appears to be fully reversible with effective treatment of the OSA. Past medical history should be obtained, particularly for those conditions that may occur as a result of OSA, such as hypertension, cardiac failure, myocardial infarction, and motor vehicle crashes.