[Quantitative analysis of background activity using ambulatory EEG monitoring system]

We studied a possibility of the quantitative analysis of background activities using ambulatory EEG monitoring system (AEEG). (1) This recorder system had a stable frequency characteristics from 1.0 Hz to 20 Hz, in which range the background activities on EEG were organized, and also had a good lineality of amplitude until 150 microV. Therefore, this system had no hindrance in quantitative analysis of EEG background activities. (2) We selected the method of continuous spectrum array (CSA) to analyse the records using AEEG. The CSAs at awakening, light sleep and deep sleep respectively revealed the characteristic patterns of spectrum. And, in the long-term examination of CSA during sleep, the dynamic alternation of spectrum was well recognized depending on the change of sleep stages. This method was useful to the evaluation of sleep cycle as well as the judgement of consciousness level. The AGGE has many advantages compared with the other long-term EEG systems. Major advantages are as follows: 1) The patient can move freely with this equipment. 2) A whole day's record can be stored on a cassette. 3) The operative technique is easy. The clinical and research application of AEEG may be more expanded to combine with the various computer analysing methods.