title: [Clinical correlation of hypnagogic hypersynchrony during sleep in normal children and those with learning disability].
abstract: BACKGROUND
  One of the electroencephalographic (EEG) patterns that can be mistaken for paroxysmal clinical activity, when not taken into account and especially in children, is hypnagogic hypersynchrony (HH). This consists in generalised, paroxysmal, synchronic, symmetrical, slow, high voltage waves lasting 2 8 seconds, which appear in drowsiness and in stage I. It was observed that this pattern often appeared in children with learning disability (LD). AIMS. To correlate clinical data with the presence of HH during sleep in normal children and those with LD.
  
  
  METHODS
  We assessed 180 children between the ages of 6 12 years with normal neurological development, 130 of which suffered LD and 50 who did not have LD. EEG was performed with sleep deprivation, following the International Federation of Clinical Neurophysiology guidelines.
  
  
  RESULTS
  The presence or absence of HH, together with its characteristics, was assessed. Of the children with LD, 35.38% displayed HH and of the children without LD, only 4% displayed HH. Since the characteristics of HH in the children with LD were different to previous descriptions, we put forward criteria with which to evaluate those differences.
  
  
  CONCLUSIONS
  HH appeared more often in children with LD than in normal children. Qualitative, quantitative (p< 0.05) and morphological changes were found in the paroxysmal activity of HH during the stages of sleep in children with LD.
authors.affiliation: Instituto de Investigaciones de Problemas de Aprendizaje, AC, México DF, México. frairemarianes@aol.com
authors.forename: G
authors.initials: G
authors.lastname: Olmos G  de Alba
authors.forename: M I
authors.initials: MI
authors.lastname: Fraire-Martínez
authors.forename: R
authors.initials: R
authors.lastname: Valenzuela-Romero
mesh_terms: D002648:Child; D004569:Electroencephalography; D006801:Humans; D007859:Learning Disabilities / Q000503:physiopathology*; D012892:Sleep Deprivation; D012894:Sleep Stages / Q000502:physiology*
vernacular_title: Correlación clínica de la hipersincronía hipnagógica durante el sueño, en niños normales y con problemas de aprendizaje.