title: Interictal epileptogenic fast oscillations on neonatal and infantile EEGs in hemimegalencephaly.
abstract: OBJECTIVE
  Hemimegalencephaly is an epileptic encephalopathy which presents during the neonatal period. Our aims are to analyze interictal fast oscillations and EEG patterns in neonates and infants with hemimegalencephaly.
  
  
  METHODS
  We collected scalp EEGs and applied multiple band frequency analysis (MBFA) to analyze frequency and power of interictal fast oscillations (FOs).
  
  
  RESULTS
  We studied 18 scalp EEGs in 7 patients with catastrophic epilepsy secondary to hemimegalencephaly, between 3 days and 24 months of age. Maximum frequency of FOs (22-57 Hz; mean, 42 Hz) on the hemimegalencephalic side was significantly higher than those (8-27 Hz; mean, 18 Hz) in the unaffected side (p<0.05). Differences in maximum FOs remained within 1-8 Hz (mean, 3 Hz) across consecutive EEGs. We found four EEG patterns: (1) suppression burst pattern (7 EEGs, 6 patients), (2) continuous triphasic complex pattern (5 EEGs, 3 patients), (3) continuous high amplitude slow waves with spikes (3 EEGs, 2 patients) and (4) frequent spike and slow waves (3 EEGs, 2 patients). Five patients with multiple EEG recordings showed changing EEG patterns.
  
  
  CONCLUSIONS
  We confirmed the interictal epileptogenic FOs in neonatal EEGs of patients with hemimegalencephaly. The frequency of epileptogenic FOs remains stable from the neonates through increasing age while the patterns of EEG changed during brain maturation.
authors.affiliation: Division of Neurology, The Hospital for Sick Children, Toronto, ON, Canada.
authors.forename: Madoka
authors.initials: M
authors.lastname: Yamazaki
authors.forename: Derrick
authors.initials: D
authors.lastname: Chan
authors.forename: Zulma
authors.initials: Z
authors.lastname: Tovar-Spinoza
authors.forename: Cristina
authors.initials: C
authors.lastname: Go
authors.forename: Katsumi
authors.initials: K
authors.lastname: Imai
authors.forename: Ayako
authors.initials: A
authors.lastname: Ochi
authors.forename: Bill
authors.initials: B
authors.lastname: Chu
authors.forename: James T
authors.initials: JT
authors.lastname: Rutka
authors.forename: James
authors.initials: J
authors.lastname: Drake
authors.forename: Elysa
authors.initials: E
authors.lastname: Widjaja
authors.forename: Masato
authors.initials: M
authors.lastname: Matsuura
authors.forename: O Carter
authors.initials: OC
authors.lastname: Snead
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Otsubo
mesh_terms: D001921:Brain / Q000503:physiopathology*; D004569:Electroencephalography; D004827:Epilepsy / Q000209:etiology* / Q000473:pathology; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D054220:Malformations of Cortical Development / Q000150:complications* / Q000473:pathology; D012815:Signal Processing, Computer-Assisted; D013057:Spectrum Analysis