title: Clinical characteristics and brain PET findings in 3 cases of dissociative amnesia: disproportionate retrograde deficit and posterior middle temporal gyrus hypometabolism.
abstract: BACKGROUND
  Precipitated by psychological stress, dissociative amnesia occurs in the absence of identifiable brain damage. Its clinical characteristics and functional neural basis are still a matter of controversy.
  
  
  METHODS
  In the present paper, we report 3 cases of retrograde autobiographical amnesia, characterized by an acute onset concomitant with emotional/neurological precipitants. We present 2 cases of dissociative amnesia with fugue (cases 1 and 2), and one case of focal dissociative amnesia after a minor head trauma (case 3). The individual case histories and neuropsychological characteristics are reported, as well as the whole-brain voxel-based 18FDG-PET metabolic findings obtained at group-level in comparison to 15 healthy subjects.
  
  
  RESULTS
  All patients suffered from autobiographical memory loss, in the absence of structural lesion. They had no significant impairment of anterograde memory or of executive function. Impairment of autobiographical memory was complete for two of the three patients, with loss of personal identity (cases 1 and 2). A clinical recovery was found for the two patients in whom follow-up was available (cases 2 and 3). Voxel-based group analysis highlighted a metabolic impairment of the right posterior middle temporal gyrus. 18FDG-PET was repeated in case 3, and showed a complete functional brain recovery.
  
  
  CONCLUSIONS
  The situation of dissociative amnesia with disproportionate retrograde amnesia is clinically heterogeneous between individuals. Our findings may suggest that impairment of high-level integration of visual and/or emotional information processing involving dysfunction of the right posterior middle temporal gyrus could reduce triggering of multi-modal visual memory traces, thus impeding reactivation of aversive memories.
authors.affiliation: Plein Ciel, Lyon & laboratoire EMC, université Lyon 2, 75, rue Bataille, 69008 Lyon, France. Electronic address: c.thomas-anterion@orange.fr.
authors.forename: C
authors.initials: C
authors.lastname: Thomas-Antérion
authors.affiliation: Département de neurologie, CHU d'Angers, Angers, France.
authors.forename: F
authors.initials: F
authors.lastname: Dubas
authors.affiliation: Service de médecine nucléaire, CHU Nord, Saint-Étienne, France.
authors.forename: M
authors.initials: M
authors.lastname: Decousus
authors.affiliation: Service de médecine nucléaire, CHU d'Angers, Angers, France.
authors.forename: C
authors.initials: C
authors.lastname: Jeanguillaume
authors.affiliation: Service central de biophysique et médecine nucléaire, CHU Timone, AP-HM, centre européen de recherche en imagerie médicale (Cerimed), INT CNRS UMR 7289, université Aix-Marseille, France.
authors.forename: E
authors.initials: E
authors.lastname: Guedj
mesh_terms: D000328:Adult; D000648:Amnesia, Retrograde / Q000000981:diagnostic imaging / Q000209:etiology / Q000378:metabolism*; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008297:Male; D049268:Positron-Emission Tomography; D013315:Stress, Psychological / Q000150:complications*; D013702:Temporal Lobe / Q000000981:diagnostic imaging / Q000378:metabolism*; D055815:Young Adult
chemical_list: D019788:Fluorodeoxyglucose F18
keywords: Amnésie dissociative; Amnésie rétrograde; Behavioral neurology; Brain PET metabolism; Conversion; Disproportionate retrograde amnesia; Dissociative amnesia; Métabolisme cérébral; Neurologie comportementale; Neuropsychiatrie; Neuropsychiatry; PET-scan