title: Evolution of epilepsy and EEG findings in Angelman syndrome.
abstract: OBJECTIVE
  To evaluate the evolution of epileptic seizures and EEG features in a large group of patients with Angelman syndrome (AS).
  
  
  METHODS
  Thirty-six patients with AS with a proven chromosome 15q11-13 deletion were retrospectively analyzed with regard to their epilepsy and EEG findings by examination of patient files and EEGs. AIJ EEGs were reviewed by one of the authors. A logistic regression model, with a follow-up from 1 to 39 years (mean, 15 years), was used for statistical analysis.
  
  
  RESULTS
  Epileptic seizures had occurred in 30 (83%) patients. In 43% of them, the initial symptoms of epilepsy were febrile convulsions in infancy. In childhood, epilepsy could start with almost any type of seizure. Atypical absences and myoclonic seizures prevailed in adulthood. Epileptic seizures were present in 92% of the adult patients. The most typical EEG findings were rhythmic triphasic delta waves of high amplitude with a maximum over the frontal regions, identified in 99 (66%) of 150 EEGs, and continuously or intermittently, in 30 (83%) of 36 patients with AS. In 47% it was present even before a clinical diagnosis of AS was considered. High-amplitude rhythmic 4-6/s slow activity, seen in 44 (29%) of 150 EEGs, was not present after the age of 12 years.
  
  
  CONCLUSIONS
  In contrast to previous reports suggesting a decreasing frequency of epileptic seizures with age, we found that 92% of the adult patients with AS continued to have epileptic seizures. The most typical EEG finding in AS, in both children and adults, was the presence of frontal triphasic delta waves. In mentally retarded patients, this EEG pattern should point the physician in the direction of AS.
authors.affiliation: Department of Neurology, Leiden University Hospital, The Netherlands.
authors.forename: L A
authors.initials: LA
authors.lastname: Laan
authors.forename: W O
authors.initials: WO
authors.lastname: Renier
authors.forename: W F
authors.initials: WF
authors.lastname: Arts
authors.forename: I M
authors.initials: IM
authors.lastname: Buntinx
authors.forename: I J
authors.initials: IJ
authors.lastname: vd Burgt
authors.forename: H
authors.initials: H
authors.lastname: Stroink
authors.forename: J
authors.initials: J
authors.lastname: Beuten
authors.forename: K H
authors.initials: KH
authors.lastname: Zwinderman
authors.forename: J G
authors.initials: JG
authors.lastname: van Dijk
authors.forename: O F
authors.initials: OF
authors.lastname: Brouwer
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D017668:Age of Onset; D017204:Angelman Syndrome / Q000175:diagnosis* / Q000503:physiopathology; D000818:Animals; D001921:Brain / Q000503:physiopathology; D002648:Child; D002675:Child, Preschool; D003700:Delta Rhythm; D004569:Electroencephalography / Q000706:statistics & numerical data; D005500:Follow-Up Studies; D006801:Humans; D007223:Infant; D016015:Logistic Models; D012189:Retrospective Studies