EEG and cerebral blood flow in newborns during quiet sleep

Abstract

Cerebral blood flow (CBF) alterations in the newborns (NB) can lead to brain damage by a decrease in the supply of oxygen and glucose. Aiming at contributing to an understanding of the mechanisms involved, the association between the EEG (right front-temporal derivation) and Doppler velocimetry of the middle cerebral artery from term NB has been investigated. These signals were simultaneously collected from 20 NB and then epochs during quiet sleep (Tracé Alternant, TA, and High Voltage Slow, HVS) were selected. EEG power in theta band (Pthet, 4-8 Hz), was estimated each second. For CBF, obtained from velocimetry, the average velocity (V) was extracted for each heart cycle. To investigate the association in the time (cross correlation function - CCF) and frequency domains (magnitude square coherence - MSC) signal processing techniques were developed that can deal with interruptions in the data (missing samples). During TA, the CCF between Pthet and V resulted in a maximum value around -5 s (Pthet leading V) in 85% of the NBs with p≤ 0.05 (significance was tested by Monte Carlo simulations). The maximum of the MSC occurred around 0.10 Hz in 92 % of the NB (p≤ 0.05). These findings indicate association between the neuronal activity and CBF during TA. The high coherence could be interpreted as TA influencing CBF or another physiologic variable influencing both the CBF and the neuronal activity.