title: Acquired auditory agnosia in childhood and normal sleep electroencephalography subsequently diagnosed as Landau-Kleffner syndrome: a report of three cases.
abstract: OBJECTIVE
  We report three cases of Landau-Kleffner syndrome (LKS) in children (two females, one male) in whom diagnosis was delayed because the sleep electroencephalography (EEG) was initially normal.
  
  
  METHODS
  Case histories including EEG, positron emission tomography findings, and long-term outcome were reviewed.
  
  
  RESULTS
  Auditory agnosia occurred between the age of 2 years and 3 years 6 months, after a period of normal language development. Initial awake and sleep EEG, recorded weeks to months after the onset of language regression, during a nap period in two cases and during a full night of sleep in the third case, was normal. Repeat EEG between 2 months and 2 years later showed epileptiform discharges during wakefulness and strongly activated by sleep, with a pattern of continuous spike-waves during slow-wave sleep in two patients. Patients were diagnosed with LKS and treated with various antiepileptic regimens, including corticosteroids. One patient in whom EEG became normal on hydrocortisone is making significant recovery. The other two patients did not exhibit a sustained response to treatment and remained severely impaired.
  
  
  CONCLUSIONS
  Sleep EEG may be normal in the early phase of acquired auditory agnosia. EEG should be repeated frequently in individuals in whom a firm clinical diagnosis is made to facilitate early treatment.
authors.affiliation: Department of Paediatric Neurology, Hôpital Erasme, Université Libre de Bruxelles, Brussels, Belgium.
authors.forename: Patrick
authors.initials: P
authors.lastname: van Bogaert
authors.forename: Mary D
authors.initials: MD
authors.lastname: King
authors.forename: Philippe
authors.initials: P
authors.lastname: Paquier
authors.forename: Catherine
authors.initials: C
authors.lastname: Wetzburger
authors.forename: Catherine
authors.initials: C
authors.lastname: Labasse
authors.forename: Jean-Marie
authors.initials: JM
authors.lastname: Dubru
authors.forename: Thierry
authors.initials: T
authors.lastname: Deonna
mesh_terms: D000377:Agnosia / Q000209:etiology* / Q000503:physiopathology; D000893:Anti-Inflammatory Agents / Q000627:therapeutic use; D001921:Brain / Q000000981:diagnostic imaging / Q000503:physiopathology; D002675:Child, Preschool; D057210:Delayed Diagnosis; D004569:Electroencephalography; D005260:Female; D006801:Humans; D006854:Hydrocortisone / Q000627:therapeutic use; D018887:Landau-Kleffner Syndrome / Q000150:complications* / Q000175:diagnosis* / Q000188:drug therapy / Q000503:physiopathology; D008297:Male; D049268:Positron-Emission Tomography; D012189:Retrospective Studies; D012890:Sleep; D017211:Treatment Failure; D016896:Treatment Outcome; D014851:Wakefulness
chemical_list: D000893:Anti-Inflammatory Agents; D006854:Hydrocortisone