Sleep apnea syndromes: overview and diagnostic approach.

The two broad categories of sleep apnea syndrome are associated with obstructive or mixed events on the one hand, and central events on the other. The pathogenesis of both seems to involve periodic reduction in respiratory drive, although obstructive apneas may also involve an anatomic abnormality of the upper airway. Patients with obstructive sleep apnea syndrome most commonly exhibit resuscitative snoring and daytime sleepiness. Snoring is generally less prominent in the central sleep apnea syndromes; those with daytime hypercapnia generally complain of daytime sleepiness, whereas those without hypercapnia complain of disturbed sleep. The overnight polysomnogram is the preferred method of diagnosing both disorders.