title: High-frequency EEG activity in epileptic encephalopathy with suppression-burst.
abstract: OBJECTIVE
  We explored high-frequency activity in the suppression-burst (SB) pattern of interictal electroencephalogram (EEG) in early infantile epileptic encephalopathy including Ohtahara syndrome (OS) and early myoclonic encephalopathy (EME) to investigate the pathophysiological characteristics of SB.
  
  
  METHODS
  Subjects included six patients with the SB EEG pattern related to OS or EME (Group SB). The results were evaluated in comparison to tracé alternant (TA) observed during the neonatal period in nine patients to rule out possible nonspecific relationships between high-frequency activity and periodic EEG patterns (Group TA). EEG was digitally recorded with a sampling rate of 500Hz and the analysis was performed in each of the particular bipolar channel-pairs. We visually selected 20 typical consecutive burst sections and 160 inter-burst sections for comparison from the sleep record of each patient and performed the time-frequency analysis. We investigated the maximum frequencies of power enhancement in each derivation in both groups.
  
  
  RESULTS
  In Group SB, a significant increase in power at a frequency of 80-150Hz was observed in association with the bursts, particularly in the bilateral parieto-occipital derivations, in all patients. In Group TA, on the contrary, no significant increase in high-frequency power was found. The maximum frequencies of power enhancement were significantly higher in Group SB than in Group TA (p<0.001 by repeated-measures ANOVA).
  
  
  CONCLUSIONS
  Interictal high frequencies of up to 150Hz were detected in the suppression-burst EEG patterns in epileptic encephalopathy in early infancy. Further studies will be necessary to identify the role of the interictal high-frequency activity in the pathophysiology of such early epileptic encephalopathy.
authors.affiliation: Department of Child Neurology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences and Okayama University Hospital, Okayama, Japan; Department of Pediatrics, School of Medicine, University of Tokushima, Tokushima, Japan.
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Toda
authors.affiliation: Department of Child Neurology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences and Okayama University Hospital, Okayama, Japan. Electronic address: k_koba@md.okayama-u.ac.jp.
authors.forename: Katsuhiro
authors.initials: K
authors.lastname: Kobayashi
authors.affiliation: Department of Child Neurology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences and Okayama University Hospital, Okayama, Japan.
authors.forename: Yumiko
authors.initials: Y
authors.lastname: Hayashi
authors.affiliation: Department of Child Neurology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences and Okayama University Hospital, Okayama, Japan.
authors.forename: Takushi
authors.initials: T
authors.lastname: Inoue
authors.affiliation: Department of Child Neurology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences and Okayama University Hospital, Okayama, Japan.
authors.forename: Makio
authors.initials: M
authors.lastname: Oka
authors.affiliation: Department of Child Neurology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences and Okayama University Hospital, Okayama, Japan.
authors.forename: Fumika
authors.initials: F
authors.lastname: Endo
authors.affiliation: Department of Child Neurology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences and Okayama University Hospital, Okayama, Japan.
authors.forename: Harumi
authors.initials: H
authors.lastname: Yoshinaga
authors.affiliation: Department of Child Neurology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences and Okayama University Hospital, Okayama, Japan; Asahigawaso Rehabilitation and Medical Center, Okayama, Japan.
authors.forename: Yoko
authors.initials: Y
authors.lastname: Ohtsuka
mesh_terms: D000704:Analysis of Variance; D001921:Brain / Q000503:physiopathology*; D058256:Brain Waves / Q000502:physiology*; D004569:Electroencephalography; D004576:Electromyography; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D013036:Spasms, Infantile / Q000503:physiopathology*; D013997:Time Factors
keywords: Early myoclonic encephalopathy; High-frequency oscillations; Ohtahara syndrome; Time–frequency analysis; Tracé alternant