Effects of uvulopalatopharyngoplasty on the daytime sleepiness associated with sleep apnea syndrome.
Pre- and post-treatment nocturnal polysomnography and multiple sleep latency tests (MSLT) were done in thirty-one patients with obstructive sleep apnea syndrome who underwent uvulopalatopharyngoplasty. The treatment reduced by half the frequency of apneas and hypoxemia occurring during sleep and improved the excessive daytime sleepiness, but not all patients responded similarly. Among patients classified as responders, the frequency of apnea was reduced to a level seen in healthy adults of the same age, measures of sleep approached normal, and excessive sleepiness was eliminated. In nonresponders, frequency of apneas and consequent disruption of sleep was not reduced, but hypoxemia was improved. The MSLT differentiated responders from nonresponders who showed no MSLT improvement, although 70% reported a subjective improvement in excessive sleepiness. Measures of the apneas' disruptive effect on sleep and not its hypoxemic consequences were most predictive of improvement in excessive sleepiness.