title: EEG features in idiopathic generalized epilepsy: clues to diagnosis.
abstract: OBJECTIVE
  To investigate the EEG profile and its contribution for diagnosis and management in a group of patients with a clinical diagnosis of idiopathic generalized epilepsy (IGE) who were referred to a tertiary hospital.
  
  
  METHODS
  We retrospectively studied clinical and EEG features of 180 consecutive patients with IGE. Eighty patients were diagnosed with juvenile myoclonic epilepsy (JME), 35 had absence epilepsy (AE), 13 had generalized tonic-clonic seizures on awakening (GTCS-A), 28 had generalized tonic-clonic seizures only (TCS), and 24 had adult-onset idiopathic generalized epilepsy (AIGE). The EEGs were classified in typical (synchronous generalized spike or polyspikes-and-wave discharges with normal background), atypical (with clear focalities or asymmetries), and normal.
  
  
  RESULTS
  The 493 EEG exams were analyzed. The first EEG was normal in 45% of the 180 patients, and only 33% had typical abnormalities. AE had a higher proportion of typical examinations and needed fewer sequential examinations to register a typical abnormality compared with the other groups. By contrast, the serial EEG profile of TCS and AIGE showed a higher proportion of normal and atypical EEG findings.
  
  
  CONCLUSIONS
  These findings support previous recommendations that IGE patients should be treated with appropriate therapy based on clinical history. Waiting for a typical abnormal EEG pattern can generate an unacceptable delay in the correct diagnosis and treatment of these patients. In patients with long-term epilepsy, the diagnosis may be difficult. Furthermore, serial EEGs can help to elucidate the syndromic diagnosis, especially in patients with TCS and AIGE.
authors.affiliation: Department of Neurology, University of Campinas. Unicamp, Campinas SP, Brazil.
authors.forename: Luiz Eduardo
authors.initials: LE
authors.lastname: Betting
authors.forename: Susana Barreto
authors.initials: SB
authors.lastname: Mory
authors.forename: Iscia
authors.initials: I
authors.lastname: Lopes-Cendes
authors.forename: Li M
authors.initials: LM
authors.lastname: Li
authors.forename: Marilisa M
authors.initials: MM
authors.lastname: Guerreiro
authors.forename: Carlos A M
authors.initials: CA
authors.lastname: Guerreiro
authors.forename: Fernando
authors.initials: F
authors.lastname: Cendes
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002540:Cerebral Cortex / Q000503:physiopathology*; D002648:Child; D003937:Diagnosis, Differential; D004569:Electroencephalography / Q000145:classification / Q000706:statistics & numerical data*; D004829:Epilepsy, Generalized / Q000145:classification / Q000175:diagnosis* / Q000503:physiopathology; D004830:Epilepsy, Tonic-Clonic / Q000175:diagnosis / Q000503:physiopathology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D013997:Time Factors