title: EEG-LORETA endophenotypes of the common idiopathic generalized epilepsy syndromes.
abstract: OBJECTIVE
  We tested the hypothesis that the cortical areas with abnormal local EEG synchronization are dissimilar in the three common idiopathic generalized epilepsy (IGE) phenotypes: IGE patients with absence seizures (ABS), juvenile myoclonic epilepsy (JME) and epilepsy with generalized tonic-clonic seizures exclusively (EGTCS).
  
  
  METHODS
  Groups of unmedicated ABS, JME and EGTCS patients were investigated. Waking EEG background activity (without any epileptiform potentials) was analyzed by a source localization method, LORETA (Low Resolution Electromagnetic Tomography). Each patient group was compared to a separate, age-matched group of healthy control persons. Voxel-based, normalized broad-band (delta, theta, alpha, and beta) and very narrow band (VNB, 1Hz bandwidth, from 1 to 25Hz) LORETA activity (=current source density, A/m(2)) were computed for each person. Group comparison included subtraction (average patient data minus average control data) and group statistics (multiple t-tests, where Bonferroni-corrected p<0.05 values were accepted as statistically significant).
  
  
  RESULTS
  Statistically not significant main findings were: overall increased delta and theta broad band activity in the ABS and JME groups; decrease of alpha and beta activity in the EGTCS group. Statistically significant main findings were as follows. JME group: bilaterally increased theta activity in posterior (temporal, parietal, and occipital) cortical areas; bilaterally increased activity in the medial and basal prefrontal area in the 8Hz VNB; bilaterally decreased activity in the precuneus, posterior cingulate and superior parietal lobule in the 11Hz and 21-22Hz VNBs. ABS group: bilaterally increased theta activity emerged in the basal prefrontal and medial temporal limbic areas. Decreased activity was found at 19-21Hz in the right postcentral gyrus and parts of the right superior and medial temporal gyri. EGTCS group: decreased activity was found in the frontal cortex and the postcentral gyrus at 10-11Hz, increased activity in the right parahippocampal gyrus at 16-18Hz.
  
  
  CONCLUSIONS
  Increased theta activity in the posterior parts of the cortex is the endophenotype for JME. Increased theta activity in the fronto-temporal limbic areas is the endophenotype for ABS. Statistically not significant findings might indicate diffuse biochemical abnormality of the cortex in JME and ABS.
  
  
  CONCLUSIONS
  EEG-LORETA endophenotypes may correspond to the selective propensity to generate absence and myoclonic seizures in the ABS and JME syndromes.
authors.affiliation: Kenézy Hospital Ltd., Department of Neurology, Bartók Béla út 3, Debrecen, Hungary. bela.clemens@yahoo.com
authors.forename: B
authors.initials: B
authors.lastname: Clemens
authors.forename: S
authors.initials: S
authors.lastname: Puskás
authors.forename: M
authors.initials: M
authors.lastname: Besenyei
authors.forename: M
authors.initials: M
authors.lastname: Emri
authors.forename: G
authors.initials: G
authors.lastname: Opposits
authors.forename: S A
authors.initials: SA
authors.lastname: Kis
authors.forename: K
authors.initials: K
authors.lastname: Hollódy
authors.forename: A
authors.initials: A
authors.lastname: Fogarasi
authors.forename: I
authors.initials: I
authors.lastname: Kondákor
authors.forename: K
authors.initials: K
authors.lastname: Füle
authors.forename: K
authors.initials: K
authors.lastname: Bense
authors.forename: I
authors.initials: I
authors.lastname: Fekete
mesh_terms: D000293:Adolescent; D004569:Electroencephalography / Q000379:methods*; D055590:Electromagnetic Phenomena; D058068:Endophenotypes; D004829:Epilepsy, Generalized / Q000175:diagnosis* / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D014054:Tomography / Q000379:methods*; D055815:Young Adult