title: Diagnostic yield of five minutes compared to three minutes hyperventilation during electroencephalography.
abstract: OBJECTIVE
  To investigate whether hyperventilation (HV) for 5min increases the diagnostic yield of electroencephalography (EEG) compared to 3min HV.
  
  
  METHODS
  data were evaluated from 1084 consecutive patients, from three European centres, referred to EEG on suspicion of epilepsy. Seizures and interictal EEG abnormalities precipitated during the first 3min and during the last 2min of the HV period (totally 5min) were determined.
  
  
  RESULTS
  Eight hundred seventy-seven patients (81%) completed 5min HV. Seizures were precipitated during the first 3min of HV in 21 patients, and during the last 2min in four more patients. Interictal EEG abnormalities were precipitated in the first 3min of HV in 16 patients, and during the last 2min in 7 more patients. Psychogenic nonepileptic seizures occurred in eight patients during the first 3min of HV and in two more patients during the last 2min. No adverse events occurred during the last 2min of HV, but eight patients (1%) stopped HV during the last 2min because they were not able to hyperventilate further.
  
  
  CONCLUSIONS
  16% of seizures and 30% of interictal EEG abnormalities triggered by HV occurred during the last 2min of HV, suggesting the clinical usefulness of prolonged hyperventilation for 5min. The vast majority of patients (99%) who are able to hyperventilate for 3min can complete 5min HV, without additional adverse events.
authors.affiliation: Department of Clinical Neurophysiology, Danish Epilepsy Centre, Denmark; Department of Neurology, University Hospital, Bucharest, Romania.
authors.forename: Laura
authors.initials: L
authors.lastname: Craciun
authors.affiliation: Department of Neurology, University of Szeged, Hungary.
authors.forename: Edina Timea
authors.initials: ET
authors.lastname: Varga
authors.affiliation: Department of Neurology, University Hospital, Bucharest, Romania.
authors.forename: Ioana
authors.initials: I
authors.lastname: Mindruta
authors.affiliation: Department of Clinical Neurophysiology, Danish Epilepsy Centre, Denmark.
authors.forename: Pirgit
authors.initials: P
authors.lastname: Meritam
authors.affiliation: Department of Neurology, University of Szeged, Hungary.
authors.forename: Zoltán
authors.initials: Z
authors.lastname: Horváth
authors.affiliation: Department of Clinical Neurophysiology, Danish Epilepsy Centre, Denmark.
authors.forename: Daniella
authors.initials: D
authors.lastname: Terney
authors.affiliation: Department of Clinical Neurophysiology, Danish Epilepsy Centre, Denmark.
authors.forename: Elena
authors.initials: E
authors.lastname: Gardella
authors.affiliation: Department of Clinical Neurophysiology, Danish Epilepsy Centre, Denmark.
authors.forename: Jørgen
authors.initials: J
authors.lastname: Alving
authors.affiliation: Department of Neurology, University of Szeged, Hungary; MTA-SZTE Neuroscience Research Group, Szeged, Hungary.
authors.forename: László
authors.initials: L
authors.lastname: Vécsei
authors.affiliation: Department of Clinical Neurophysiology, Danish Epilepsy Centre, Denmark; Department of Clinical Neurophysiology, Aarhus University, Denmark. Electronic address: sbz@filadelfia.dk.
authors.forename: Sándor
authors.initials: S
authors.lastname: Beniczky
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D003291:Conversion Disorder / Q000175:diagnosis / Q000503:physiopathology; D004569:Electroencephalography / Q000009:adverse effects / Q000379:methods*; D004827:Epilepsy / Q000175:diagnosis* / Q000503:physiopathology*; D005260:Female; D006801:Humans; D006985:Hyperventilation; D007223:Infant; D008297:Male; D008875:Middle Aged; D012640:Seizures / Q000175:diagnosis / Q000503:physiopathology; D013997:Time Factors; D055815:Young Adult
keywords: Diagnostic yield; Duration; EEG; Hyperventilation; Provocation