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Distinct behavioral and EEG topographic correlates of loss of consciousness in absences

Jallon, P.
Published in Epilepsia. 2000, vol. 41, no. 6, p. 687-693
Abstract PURPOSE: To describe the behavioral and EEG topographic correlates of absences with 3-Hz generalized spike-waves and partitioned impairment of consciousness. METHODS: Two adult women had so-called "phantom" absences, characterized by brief and mild impairments of consciousness that were previously inconspicuous to both patient and physician. Neuropsychological examination was performed under video-EEG monitoring during absence status. EEG topographic mapping of spike-wave discharges was obtained in the two cases. RESULTS: Only mild attentional and executive disturbances were observed during absence status despite prolonged discharges. Spike-wave bursts were associated with selective impairment in the initiation of response and self-generated action, whereas short-term storage of external information during discharges was fully preserved. This is consistent with a predominant involvement of frontomesial cortex demonstrated by topographic mapping of spike-wave discharges in the two cases. By contrast, in two other patients with typical absences and a complete lack of retention for information given during the discharges, topographic mapping found a more lateral frontal involvement by spike-wave activity. CONCLUSIONS: Different types of absence seizures may impair distinct components of conscious behavior. A predominant involvement of frontomesial thalamocortical circuitry may underlie an "inconspicuous" disorder of consciousness as seen in phantom absences with selective loss of initiation and goal-oriented behavior, whereas involvement of more lateral frontal areas in typical absences may additionally disrupt working memory processes.
Keywords AdultAgedBrain MappingCerebral Cortex/physiology/physiopathologyCognition/physiologyElectroencephalography/ statistics & numerical dataEpilepsy, Absence/diagnosis/ physiopathologyFemaleFrontal Lobe/ physiopathologyFunctional Laterality/physiologyGyrus Cinguli/physiopathologyHumansMemory, Short-Term/physiologyMiddle AgedNeural Pathways/physiology/physiopathologyNeuropsychological Tests/statistics & numerical dataSensation/physiologyThalamus/physiology/physiopathologyUnconsciousness/diagnosis/ physiopathology
Stable URL http://archive-ouverte.unige.ch/unige:10490
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PMID: 10840400
Research group Neuropsychologie et neurologie comportementale (951)
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