| Abstract [eng] |
The onset of sleep under normal circumstances in young adult humans is normally through Non-REM sleep after 15 minutes of being awake. The abnormal entry into sleep through REM sleep can be diagnostic in patients with narcolepsy. One important investigation in diagnosing narcolepsy is the Multiple Sleep Latency Test (MSLT), where onset of sleep and occurrence of REM – if any is measured 4 times per day. This test is traditionally scored by visual analysis of sleep onset and onset of REM sleep. There is tight relation between sleep and epilepsy. During sleep epileptiform activity is frequent and seizures make influence on the quality of sleep ant it’s phases. In some types of epilepsy (e.g. idiopathic focal) seizures occur during onset of sleep, in others (juvenile myoclonic) – short time after awaking. Detection of sleep onset is very important for the evaluation of the sleep quality of epilepsy patient’s and for accurate diagnosis of narcolepsy. EEG interpretation strongly depends on the skills of the EEG reader. Therefore automatic sleep onset detection could be useful diagnostic tool for EEG interpretation. We have found it of interest to investigate if an automatic analysis amplitude – integrated electroencephalography (aEEG) method could reliable identify sleep onset by comparing it with visual analysis in 25 narcolepsy patients, who were treated in Copenhagen University hospital and 23 children with epilepsy (idiopathic focal and juvenile myoclonic), who were treated in Vilnius University Child Hospital. The aEEG method is based on filtered and compressed EEG that enables evaluation of long-term changes and trends in electrocortical background activity by pattern recognition. The EEG processing includes a band pass filter (8-12Hz), semilogarithmic amplitude compression, rectifying, smoothing, and time compression. It was found that aEEG method could be additional diagnostic tool for sleep onset detection. The difference between the aEEG method and visual analysis is not highly significant and the onset of sleep with aEEG method was detected earlier than by visual inspections (average 52 ± 170 sec.). There are no gender or age differences. Also short time Furje transformation could be used for sleep onset detection but this method is not practical in clinical EEG evaluation due to its long and multiplex processing. |
