[The usefulness of an alternative EEG scoring system in obstructive sleep apnea]

Careful analysis of the EEG in obstructive sleep apnea (OSA) patients according to the Rechtschaffen and Kales (R & K) criteria indicates that obstructive apneas (OA) are more frequently observed during stage 1 and 2 sleep than during slow wave sleep. However it is also obvious that OA can be recognised during R & K wakefulness stage (St W). The purpose of the present study was to see whether further partition of R & K St W could define a wakefulness stage during which no apneas occur. Ten patients with predominantly OSA were studied (OA-Index 20 +/- 5). Patients EEG were scored according to classic R & K and to modified criteria which further divided R & K St W. Three additional stages were defined (STW-a, STW-b, STW-c). The partitioning of STW of R & K allowed us to define a W-stage (STW-a) during which no apneas occur, and to identify alpha (STW-b) and drowsiness (STW-c) during which OA occur frequently.