Haemodynamic changes during seizure-like activity in a neonate: a simultaneous AC EEG-SPIR and high-resolution DC EEG recording.

OBJECTIVE: We sought to define the interaction between neonatal epileptic discharges and the haemodynamic activities in a control situation (i.e. in the absence of cardiorespiratory perturbation or any interaction with normal, ongoing, synchronized neuronal activity).
METHOD: Alternating-current electroencephalography (AC EEG), near-infrared spectroscopy (NIRS), and high-resolution direct-current (HR DC) EEG were performed in a curarized, ventilated neonate with a flat interictal EEG. The seizure-like discharges (SLD) first spike was used as a trigger for further averaging of NIRS, AC and DC EEG. Source localization was performed on the averaged spike and the averaged, negative DC shift.
RESULTS: SLD were of maximal amplitude in centroparietal areas and induced a change in local haemodynamic parameters characterized by a first increase in [HHb] followed by an increase in [HbO(2)] and [HbT]. [HHb] returned to baseline at the end of the seizure and decreased thereafter. The negative DC shift started before the first spike and the increase in haemodynamic parameters. It then became positive and returned to baseline at the end of the seizure. Source localization revealed different positions for the first spike and the negative DC shift. DISCUSSION: Pure SLD in neonates might induce a negative blood oxygen level-dependent (BOLD) effect on the cortex, which occurs after the negative DC shift and which has a closer temporal relationship with the neuronal discharge than a positive BOLD effect.