TY - JOUR
T1 - Subclinical rhythmic electrographic discharges of adults (SREDA) revisited
T2 - A study using digital EEG analysis
AU - O'Brien, Terence J.
AU - Sharbrough, Frank W.
AU - Westmoreland, Barbara F.
AU - Busacker, Neil E.
PY - 1998/12/1
Y1 - 1998/12/1
N2 - Previous descriptions of the subclinical rhythmic electrographic discharges of adults (SREDA) have been based entirely on visual analysis of analog electroencephalographic (EEG) recordings. The introduction of digital electroencephalograms (EEGs) and advances in digital signal processing provide an opportunity to restudy in more depth the nature of SREDA. We identified nine patients who had SREDA diagnosed on a routine EEG recording since the introduction of digital EEG to our laboratory in August 1995. Following careful rereview using standard montages, six of these patients were determined to fulfill the traditional requirements for the diagnosis of SREDA, whereas three were believed to have other benign discharges. Review with Laplacian montages demonstrated that the site of the SREDA activity was maximal in the parietal region or parietocentrotemporal regions, whereas it was maximal in the temporal or frontotemporal regions in the non-SREDA discharges. Frequency analysis, using both the conventional fast Fourier transform (FFT) and time-frequency mapping with the Wigner FFT variant, demonstrated that the SREDA consisted of a complex mixture of multiple rapidly shifting frequencies which showed little spatial and temporal correlation. In contrast, the non-SREDA all consisted of a single dominant well-organized rhythmic frequency spectrum that remained stable throughout space and time.
AB - Previous descriptions of the subclinical rhythmic electrographic discharges of adults (SREDA) have been based entirely on visual analysis of analog electroencephalographic (EEG) recordings. The introduction of digital electroencephalograms (EEGs) and advances in digital signal processing provide an opportunity to restudy in more depth the nature of SREDA. We identified nine patients who had SREDA diagnosed on a routine EEG recording since the introduction of digital EEG to our laboratory in August 1995. Following careful rereview using standard montages, six of these patients were determined to fulfill the traditional requirements for the diagnosis of SREDA, whereas three were believed to have other benign discharges. Review with Laplacian montages demonstrated that the site of the SREDA activity was maximal in the parietal region or parietocentrotemporal regions, whereas it was maximal in the temporal or frontotemporal regions in the non-SREDA discharges. Frequency analysis, using both the conventional fast Fourier transform (FFT) and time-frequency mapping with the Wigner FFT variant, demonstrated that the SREDA consisted of a complex mixture of multiple rapidly shifting frequencies which showed little spatial and temporal correlation. In contrast, the non-SREDA all consisted of a single dominant well-organized rhythmic frequency spectrum that remained stable throughout space and time.
KW - Digital EEG
KW - EEG
KW - Frequency spectral analysis
KW - SREDA
UR - http://www.scopus.com/inward/record.url?scp=0032438569&partnerID=8YFLogxK
U2 - 10.1097/00004691-199811000-00008
DO - 10.1097/00004691-199811000-00008
M3 - Article
C2 - 9881922
AN - SCOPUS:0032438569
SN - 0736-0258
VL - 15
SP - 493
EP - 501
JO - Journal of Clinical Neurophysiology
JF - Journal of Clinical Neurophysiology
IS - 6
ER -