title: A storm of fast (40-150Hz) oscillations during hypsarrhythmia in West syndrome.
abstract: OBJECTIVE
  Fast oscillations (FOs) were first explored from scalp electroencephalographic (EEG) data from hypsarrhythmia in West syndrome (infantile spasms) to investigate the meaning of FOs in this epileptic encephalopathy.
  
  
  METHODS
  In 17 infants with West syndrome, we conservatively detected fast frequency peaks that stood out from the time-frequency spectral background with square root power > 1µV (spectral criterion) and corresponded to clear FOs with at least 4 oscillations in the filtered EEG traces (waveform criterion) in sleep EEGs.
  
  
  RESULTS
  We found a total of 1,519 interictal FOs that fulfilled both the spectral and waveform criteria. The FOs with a median frequency of 56.6Hz (range = 41.0-140.6Hz) were dense, with a median rate of 66 (range = 24-171) per minute before adrenocorticotropic hormone (ACTH) treatment, which was significantly higher than that in control infants without seizures (median = 1, p < 0.001). The FOs were reduced by treatment. The mean gamma and ripple oscillation rates that were detected using the waveform criterion alone were 40.62/min and 15.75/min, respectively, per channel; these results were 112.8 and 98.4 times higher, respectively, than the previously reported corresponding rates in adult epilepsy patients.
  
  
  CONCLUSIONS
  The observed FOs corresponded to epileptogenicity because of their close relation to the severity of hypsarrhythmia during the course of ACTH treatment. The very high epileptic FO rates in hypsarrhythmia are thought to affect the process of neurodevelopment by interfering with physiological functions in West syndrome, taking into account that high frequencies are also important in physiological higher brain functions.
authors.affiliation: Department of Child Neurology, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences and Okayama University Hospital, Okayama, Japan.
authors.forename: Katsuhiro
authors.initials: K
authors.lastname: Kobayashi
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Akiyama
authors.forename: Makio
authors.initials: M
authors.lastname: Oka
authors.forename: Fumika
authors.initials: F
authors.lastname: Endoh
authors.forename: Harumi
authors.initials: H
authors.lastname: Yoshinaga
mesh_terms: D000324:Adrenocorticotropic Hormone / Q000494:pharmacology / Q000627:therapeutic use; D058256:Brain Waves / Q000187:drug effects / Q000502:physiology*; D004569:Electroencephalography; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D010507:Periodicity; D013036:Spasms, Infantile / Q000188:drug therapy / Q000503:physiopathology*
chemical_list: D000324:Adrenocorticotropic Hormone