Neurological perspective on obstructive and nonobstructive sleep apnea.

One of every 15 adults in the United States has at least moderate sleep apnea. The true prevalence is higher, as approximately 0.3 to 5% of adults with sleep apnea are undiagnosed. Sleep apnea has major health consequences; therefore, neurologists must recognize and treat sleep apnea syndromes appropriately. There are three main categories of sleep apnea: obstructive sleep apnea (OSA), central sleep apnea (CSA), and mixed sleep apnea. OSA results from upper airway obstruction, and CSA is due to lack of inspiratory muscle effort; mixed apnea results from a combination of these factors. Sleep apnea syndromes can present within the spectrum of "typical" neurological complaints, including forgetfulness, headaches, sleepiness, fatigability, seizures, and muscle and nerve weakness. A good sleep history, a nocturnal polysomnogram, and multiple sleep latency test are important in elucidating the diagnosis and validating the complaints of sleepiness. The gold standard for treatment of OSA is positive airway pressure, although some patients may benefit from surgical interventions designed to bypass the site of airway obstruction. With CSA, treatment is directed toward the underlying disorder. Patients with CSA may also benefit from several types of nasal positive airway pressure treatment, while some require mechanical ventilation.