title: EEG in adult-onset idiopathic generalized epilepsy.
abstract: OBJECTIVE
  It remains controversial whether adult-onset idiopathic generalized epilepsy (IGE) is a distinct syndrome or a continuum among IGE syndromes. EEG is the only known biologic marker of IGE and helps differentiate many of its classic subsyndromes. In this study, we looked for the differences in the EEG findings of IGE of classic adolescent onset versus adult onset that may suggest syndromic heterogeneity.
  
  
  METHODS
  Seventy-six patients (47 adolescent-onset IGE, 29 adult-onset IGE) with a clinical and EEG diagnosis of IGE were included. We defined IGE with age at onset of 11-20 years as adolescent-onset IGE and age at onset of 20 years or after as adult-onset IGE. Patients with first-decade onset of seizures, delayed EEGs, and no EEG available for review were excluded. The first EEG was performed within 24 h of the seizure, and if negative, a sleep-deprived EEG was done. All EEGs were reviewed in detail with respect to the background activity and the generalized spike-wave (GSW) characteristic.
  
  
  RESULTS
  EEGs (87; 56 adolescent-onset IGE, 31 adult-onset IGE) were systematically reviewed. Background was normal in all patients. The morphology, amplitude, duration, frequency, occurrence, or activation of the GSW pattern did not differ between these two groups.
  
  
  CONCLUSIONS
  No differences of EEG features were found between the classic adolescent-onset and the adult-onset IGE. This supports the hypothesis that they share common biologic determinants and exist along a life-long age spectrum of classic IGE.
authors.affiliation: Epilepsy Research Institute and Department of Medicine (Neurology), University of Melbourne, Austin and Repatriation Medical Centre, Melbourne, Australia.
authors.forename: Suthida
authors.initials: S
authors.lastname: Yenjun
authors.forename: A Simon
authors.initials: AS
authors.lastname: Harvey
authors.forename: Carla
authors.initials: C
authors.lastname: Marini
authors.forename: Mark R
authors.initials: MR
authors.lastname: Newton
authors.forename: Mark A
authors.initials: MA
authors.lastname: King
authors.forename: Samuel F
authors.initials: SF
authors.lastname: Berkovic
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D002540:Cerebral Cortex / Q000473:pathology / Q000503:physiopathology; D002648:Child; D003937:Diagnosis, Differential; D004569:Electroencephalography; D004829:Epilepsy, Generalized / Q000145:classification / Q000175:diagnosis* / Q000503:physiopathology; D005071:Evoked Potentials / Q000502:physiology; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D012189:Retrospective Studies; D013577:Syndrome; D014057:Tomography, X-Ray Computed