title: Pseudotemporal ictal patterns compared with mesial and neocortical temporal ictal patterns.
abstract: OBJECTIVE
  This study analyzes falsely localizing pseudotemporal ictal EEG patterns, to test if it is possible to differentiate them from those in "true" temporal lobe epilepsy.
  
  
  METHODS
  We retrospectively studied 33 patients who had epilepsy surgery and a favorable outcome (Engel I), belonging to three groups: 10 patients (37 seizures) with pseudotemporal ictal patterns (PT), 12 patients (45 seizures) with mesial temporal epilepsy because of hippocampal sclerosis (HS), and 11 patients (41 seizures) with neocortical temporal epilepsy (NT). Ictal EEGs were analyzed visually according to predetermined criteria and by using a source localization program (BESA5.1). The topographies of interictal discharges were compared among the three groups.
  
  
  RESULTS
  Ictal patterns and locations overlapped across all the groups. The initial onset patterns in NT were less likely to localize to one temporal region as compared with the other groups (P < 0.008). Rhythmic temporal theta as later pattern was seen significantly more frequently in HS than in NT (P < 0.001). All seizures in PT spread to the contralateral side compared with 73 of 86 (85%) of "true temporal" seizures (P < 0.05). Source analysis of the ictal discharge and topographic distribution of interictal discharges were not able to separate the three groups.
  
  
  CONCLUSIONS
  Pseudotemporal ictal patterns are morphologically indistinguishable from true temporal ictal patterns. Although statistically more common in hippocampal sclerosis, rhythmic theta pattern can be seen as a result of propagation from extratemporal sites.
authors.affiliation: Epilepsy Center, Cleveland Clinic, Cleveland, Ohio 44195, USA.
authors.forename: Sherif A
authors.initials: SA
authors.lastname: Elwan
authors.forename: Norman K
authors.initials: NK
authors.lastname: So
authors.forename: Rei
authors.initials: R
authors.lastname: Enatsu
authors.forename: William E
authors.initials: WE
authors.lastname: Bingaman
mesh_terms: D000293:Adolescent; D000328:Adult; D001931:Brain Mapping / Q000706:statistics & numerical data*; D002540:Cerebral Cortex / Q000503:physiopathology*; D002648:Child; D003937:Diagnosis, Differential; D004569:Electroencephalography / Q000706:statistics & numerical data*; D004833:Epilepsy, Temporal Lobe / Q000175:diagnosis* / Q000453:epidemiology / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009820:Ohio / Q000453:epidemiology; D015995:Prevalence; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D055815:Young Adult