title: Frontal lobe seizures: from clinical semiology to localization.
abstract: OBJECTIVE
  Frontal lobe seizures are difficult to characterize according to semiologic and electrical features. We wished to establish whether different semiologic subgroups can be identified and whether these relate to anatomic organization.
  
  
  METHODS
  We assessed all seizures from 54 patients with frontal lobe epilepsy that were explored with stereoelectroencephalography (SEEG) during presurgical evaluation. Semiologic features and concomitant intracerebral EEG changes were documented and quantified. These variables were examined using Principal Component Analysis and Cluster Analysis, and semiologic features correlated with anatomic localization.
  
  
  RESULTS
  Four main groups of patients were identified according to semiologic features, and correlated with specific patterns of anatomic seizure localization. Group 1 was characterized clinically by elementary motor signs and involved precentral and premotor regions. Group 2 was characterized by a combination of elementary motor signs and nonintegrated gestural motor behavior, and involved both premotor and prefrontal regions. Group 3 was characterized by integrated gestural motor behavior with distal stereotypies and involved anterior lateral and medial prefrontal regions. Group 4 was characterized by seizures with fearful behavior and involved the paralimbic system (ventromedial prefrontal cortex ± anterior temporal structures). The groups were organized along a rostrocaudal axis, representing bands within a spectrum rather than rigid categories. The more anterior the seizure organization, the more likely was the occurrence of integrated behavior during seizures. Distal stereotypies were associated with the most anterior prefrontal localizations, whereas proximal stereotypies occurred in more posterior prefrontal regions.
  
  
  CONCLUSIONS
  Meaningful categorization of frontal seizures in terms of semiology is possible and correlates with anatomic organization along a rostrocaudal axis, in keeping with current hypotheses of frontal lobe hierarchical organization. The proposed electroclinical categorization offers pointers as to the likely zone of organization of networks underlying semiologic production, thus aiding presurgical localization. Furthermore, analysis of ictal motor behavior in prefrontal seizures, including stereotypies, leads to deciphering the cortico-subcortical networks that produce such behaviors.
authors.affiliation: INSERM UMR 1106, Institut de Neurosciences des Systèmes, Marseille, France; Faculty of Medicine, Aix-Marseille University, Marseille, France.
authors.forename: Francesca
authors.initials: F
authors.lastname: Bonini
authors.forename: Aileen
authors.initials: A
authors.lastname: McGonigal
authors.forename: Agnès
authors.initials: A
authors.lastname: Trébuchon
authors.forename: Martine
authors.initials: M
authors.lastname: Gavaret
authors.forename: Fabrice
authors.initials: F
authors.lastname: Bartolomei
authors.forename: Bernard
authors.initials: B
authors.lastname: Giusiano
authors.forename: Patrick
authors.initials: P
authors.lastname: Chauvel
mesh_terms: D000293:Adolescent; D000328:Adult; D016000:Cluster Analysis; D004569:Electroencephalography / Q000379:methods*; D017034:Epilepsy, Frontal Lobe / Q000175:diagnosis* / Q000503:physiopathology* / Q000601:surgery; D005260:Female; D006801:Humans; D008297:Male; D025341:Principal Component Analysis; D012640:Seizures / Q000175:diagnosis* / Q000503:physiopathology* / Q000601:surgery; D055815:Young Adult
keywords: Epileptic seizures; Frontal lobe; Semiology; Stereoelectroencephalography; Stereotypies