Upper airway resistance syndrome - Central electroencephalographic power and changes in breathing effort

Upper airway resistance syndrome (UARS) is defined by excessive daytime sleepiness and tiredness, and is associated with increased breathing effort. Its polygraphic features involve progressive increases in esophageal pressure (Pes), terminated by arousal (AR) as defined by the American Sleep Disorders Association (ASDA). With the arousal there is an abrupt decrease in Res, called Res reversal. However, Res reversal can be seen without the presence of an AR. We performed spectral analysis on electroencephalographic data from a central lead for both AR and nonarousal IN-AR) events obtained from 15 UARS patients (eight men and seven women). Delta band activity was increased before and surrounding Res reversal regardless of the presence or absence of AR. In the period after Res reversal, alpha, sigma, and beta activity showed a greater increase in AR events than in N-AR events. The Res measures were identical leading up to the point of reversal, but showed a longer-lasting and significantly greater decrease in respiratory effort after an AR. The data indicate that substantial electroencephalographic changes can be identified in association with Res events, even when ARs cannot be detected according to standard criteria; however, visually identifiable electroencephalographic arousals clearly have a greater impact on ongoing inspiratory effort.