RESUMEN
A new way of processing and presenting multichannel EEG recordings is introduced, called dynamic imaging frequency analysis (DIFA). Firstly power spectral analysis is applied to 14 EEG signals simultaneously. The cross-power spectra or transfer functions of 13 EEG signals are calculated in relation to the 14th EEG signal, thus obtaining not only the average amplitude but also the relative phase of diffusely occurring frequencies. The information per electrode obtained in this way can be presented in a numerical form, for quantification and statistical evaluation. Also, the information from 14 electrodes per significant frequency can be presented as a dynamic image display (frequency animation) yielding immediate information on the average amplitude and relative phase of the average activity per frequency of the EEG record. Application of the DIFA technique to several dozen patients demonstrates the value of phase information in EEG analysis.
Asunto(s)
Presentación de Datos , Electroencefalografía/métodos , Adulto , Niño , Femenino , Humanos , MasculinoRESUMEN
In the past two years the above computerisations have been applied as a routine in over 2500 EEG recordings in our department. From the experience gained with this type of registration, processing and presentation of the EEG signals it appears that the scope of electro-encephalographic examination has been considerably extended. This is evident from the following examples 1. Communication between EEG specialists and non-EEG specialists over electro-encephalographic examination is improved considerably by means of this way of data reduction and topographical presentation. 2. As far as the discriminating power is concerned, it appears that, for example, small differences in frequency of cerebral activities in for example slight unilateral or local disorders of the circulation in the brain can be indicated by the computer analysis, even if it is invisible to the naked eye [10]. 3. Further statistical analysis of various parameters has become possible by distinguishing between normal and abnormal importance in distinguishing between normal and abnormal EEG's of one and the same patient, the difference can be indicated both objectively and quantitatively. 4. By means of electrical filing of EEG signals simultaneous with the usual paper filing, there is the possibility of applying newly developed statistical and mathematical computer programs to the stored EEG data of patients whose brain disorders have been definitively diagnosed.