Digital Signal Processing and System Theory

Talk Janika Puls


jap
Automatische Verifizierung von kognitiven Beeintraechtigungen waehrend epileptischer Aktivitaet

Date: 20.06.2013, 13:30 h - 14:15 h
Room: Aquarium

Janika Puls
CAU, Kiel, Germany,




Details



Clinical monitoring is important to adjust the medication of patients, who suffer from absence epilepsy. Monitoring lasts a few hours and is done by the clinical personal, who observes the EEG measurement and asks the patient questions if an absence is detected. This method creates several problems. The EEG data is not observed during the questioning part, and question and answer are not recorded. This thesis presents a program/method for the automatic detection of absence epilepsy and verification of the cognitive impairment during an absence seizure in real-time.

Therefor the signals of the Electroencephalogram (EEG) are analyzed by extracting different features, which were developed according to the characteristics of the absence seizures. The first feature is the short-term power, which results in high values during an absence and low values during normal EEG-activity. Permutation entropy is another feature, which tracks the dynamical changes of EEG data and presents similar results as the kurtosis. The feature kurtosis is based on the fourth and second moment of a random variable and compares the distribution of a random variable with the normal distribution.

The combination of these features allows a robust detection of absence seizures by using a classification method. In this theses two different classification methods are presented: a threshold method and a codebook. These two methods are evaluated with real EEG data of absence patients by computing the classification errors for absence and non absence data and total classfication error. Both of these methods result in a low classification error.

Once an absence is detected the verification of the cognitive impairment is done by asking the patient a question, which is played by a loudspeaker. Via a microphone the answer of the patient as well as the EEG signals are recorded. The recording is done a few seconds before the absence starts until a few seconds after the absence has ended. This allows a further evaluation of the absence seizures.