Characteristics of slow waves on EEG associated with epileptic spasms.
OBJECTIVE
The high-voltage slow waves (HVSs) on EEG associated with epileptic spasms were investigated to clarify their characteristics and their relation to the pathophysiology of spasms in West syndrome and related disorders.


METHODS
In 14 patients, digitally recorded EEG segments showing the ictal HVSs were extracted and their traces were overlaid by using an average reference. The ictal HVSs were also averaged to build maps for investigation of the pattern of potential distribution over the scalp.


RESULTS
In a total of 685 recorded spasms, 346 (50.5%) with minimal artifacts were selected to demonstrate that the ictal HVSs had a largely consistent waveform and distribution in each patient. The ictal HVSs were symmetrical in 10 patients and asymmetrical in the other four, and were relatively negative over the posterior region and positive over the frontal or temporal regions in 11 patients. Two symptomatic patients showed a marked deviation of the distribution of HVSs to the pathologically more involved hemisphere. An infant with Aicardi syndrome had two different types of spasms, each type showing a consistent pattern of HVSs with a lateralized distribution.


CONCLUSIONS
The patterns of distribution of the ictal HVS may be related to the abnormal activation of the brain in the generation of spasms.
Kobayashi
Katsuhiro
K
Department of Child Neurology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, and Okayama University Hospital, 5-1 Shikatacho 2-chome, Okayama 700-8558, Japan. k_koba@md.okayama-u.ac.jp
Oka
Makio
M
Inoue
Takushi
T
Ogino
Tatsuya
T
Yoshinaga
Harumi
H
Ohtsuka
Yoko
Y
D001921:Brain / Q000503:physiopathology*; D001931:Brain Mapping / Q000379:methods; D002540:Cerebral Cortex / Q000503:physiopathology; D002675:Child, Preschool; D004569:Electroencephalography / Q000379:methods / Q000706:statistics & numerical data*; D004829:Epilepsy, Generalized / Q000175:diagnosis / Q000503:physiopathology; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007223:Infant; D008297:Male; D008959:Models, Neurological; D013036:Spasms, Infantile / Q000175:diagnosis* / Q000503:physiopathology