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Ictal cerebral haemodynamic characteristics during typical absence seizures, compared to focal seizures with brief alteration of awareness.

To investigate ictal cerebral haemodynamic characteristics during spontaneous typical absence seizures (TAS) and hyperventilation-evoked absence seizures in paediatric patients, relative to brief complex partial seizures (BCPS). All children diagnosed with seizures using real-time transcranial doppler ultrasonography (TCD) and sleep-deprived video-EEG (vEEG) from 2015 to 2017 in our hospital were included. The seizures were diagnosed based on the video and EEG findings. Mean cerebral blood flow velocity (CBFVm) of the unilateral middle cerebral artery was measured using TCD. TCD and vEEG data were integrated for a synchronous assessment of CBFVm changes and epileptic status. Baseline and peak CBFVm for TAS and BCPS were compared by T-test. Six children (two boys and four girls) with TAS and two girls with BCPS were enrolled. A total of 15 spontaneous TAS, 14 hyperventilation-evoked absence seizures, and six BCPS were recorded using real-time TCD-vEEG monitoring. During spontaneous TAS, whether awake or asleep, the CBFVm decreased by 20-40% compared to baseline. During hyperventilation-evoked absence seizures and BCPS, the CBFVm increased by 50-150% and 20-30% over baseline levels, respectively. The haemodynamic characteristics during TAS and BCPS are distinct, and thus our results may provide a new method to diagnose typical absence seizures using dynamic CBFVm curves. Ictal cerebral haemodynamic characteristics during spontaneous typical absence seizures and hyperventilation-evoked absence seizures may reflect different pathophysiological mechanisms and networks compared with BCPS.