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Session: Eye
Session starts: Thursday 26 January, 14:30
Presentation starts: 14:45
Room: Room 558

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Valentina Barone (University of Twente)
Maria Carla Piastra ()
Hans van Dijk ()
Mariette Debeij-van Hall ()
Michel van Putten ()

Abstract:
Absence seizures impact 10% to 17% of all cases of childhood epilepsy. Literature and clinical evidence show that absence seizures affect visual attention and eye movements variably. Possibly, dissimilarity of symptoms in these patients is reflected by differences in neurophysiological parameters and brain networks activation. Ten pediatric patients (7-18 years old, 5 females) with generalized absences recruited at Kempenhaeghe performed a 40-minutes-long computerized choice reaction time task, while EEG and eye tracking were synchronously recorded (number of absences 1-14). To study in detail the variability of visual attention and eye movements during absences, we investigated differences in markers of attention (i.e. RT, number of errors), EEG features (i.e. power spectra density, dominant frequency, amplitude), neural sources and brain networks involved in the generation and propagation of seizures (i.e. dipole fit density maps, phase connectivity and graph analysis). Observing diverse patterns of eye movements during seizures, subjects were divided into two groups: five patients had preserved eye movements (i.e. preserved group) and five patients showed unpreserved eye patterns (i.e. unpreserved group). We further tested the variability of the groups with EEG features, source reconstruction and graph theory. In the unpreserved group, EEG amplitude was higher in the posterior channels (p< .05, mean difference: 193 µV), while peak frequency was 0.3 Hz slower (p< .05). Source reconstruction using dipole fitting indicated an overall higher involvement of fronto-central areas for the unpreserved group (i.e. 35% vs 21% of the total number of dipoles were positioned in fronto-central areas). Lastly, graph analysis revealed different connections density of specific channels, i.e. C4 and Fz for the unpreserved group, and Cz for the preserved group. We show that the degree of impairment of visual attention and eye movements varies among patients with absences, depending on EEG parameters and networks activation too. In particular, fronto-central areas related to production and maintenance of visual attention seem to be activated and connected differently in the two groups. A fast assessment of visuospatial attention can be usefully employed in clinical practice to deliver advice tailored to the individual patient and for characterization and prognostication of patients with absences.