Preterm EEG: A Multimodal Neurophysiological Protocol

Abstract

Since its introduction in early 1950s, electroencephalography (EEG) has been widely used in the neonatal intensive care units (NICU) for assessment and monitoring of brain function in preterm and term babies. Most common indications are the diagnosis of epileptic seizures, assessment of brain maturity, and recovery from hypoxic-ischemic events. EEG recording techniques and the understanding of neonatal EEG signals have dramatically improved, but these advances have been slow to penetrate through the clinical traditions. The aim of this presentation is to bring theory and practice of advanced EEG recording available for neonatal units.In the theoretical part, we will present animations to illustrate how a preterm brain gives rise to spontaneous and evoked EEG activities, both of which are unique to this developmental phase, as well as crucial for a proper brain maturation. Recent animal work has shown that the structural brain development is clearly reflected in early EEG activity. Most important structures in this regard are the growing long range connections and the transient cortical structure, subplate. Sensory stimuli in a preterm baby will generate responses that are seen at a single trial level, and they have underpinnings in the subplate-cortex interaction. This brings neonatal EEG readily into a multimodal study, where EEG is not only recording cortical function, but it also tests subplate function via different sensory modalities. Finally, introduction of clinically suitable dense array EEG caps, as well as amplifiers capable of recording low frequencies, have disclosed multitude of brain activities that have as yet been overlooked.In the practical part of this video, we show how a multimodal, dense array EEG study is performed in neonatal intensive care unit from a preterm baby in the incubator. The video demonstrates preparation of the baby and incubator, application of the EEG cap, and performance of the sensory stimulations.

Evaluation of somatosensory cortical processing in extremely preterm infants at term with MEG and EEG

“…The routine EEG recording is performed with a NicOne (Cardinal Healthcare/Natus, USA) system and EEG caps (sintered Ag/AgCl electrodes; Waveguard, ANT-Neuro, Germany), which include 21 electrodes positioned according to the international 10-20 standard. For further details of the recording multichannel newborn EEG, please see (Vanhatalo et al, 2008;Stjerna et al, 2012) and http://www.nemo-europe.com/en/educationaltools.php/. The signals were collected at 2000 Hz, and we used Cz as a recording reference.…”

Spatial patterning of the neonatal EEG suggests a need for a high number of electrodes

“…Sixty-four channel hdEEG caps were used (Waveguard, ANT B.V., Enschede, The Netherlands, www.ant-neuro.com; see also Stjerna et al, 2012). A video clip showing an EEG recording of this kind is shown in the link www.nemo-europe.com/en/educational-tools.php.…”

“…Functional assessment of neonatal brain activity is currently severely hampered by the poor spatial resolution provided by conventional neonatal EEG recording (Andre et al, 2010), which hardly suffices to distinguish brain lobes from each other. In order to meet the need for better spatial parcellation, several methods have been recently devised to enable recording of high density EEG (hdEEG) from the neonatal head in the laboratory environment (Fifer et al, 2006;Roche-Labarbe et al, 2008;Vanhatalo et al, 2008), and even in the neonatal intensive care unit (Stjerna et al, 2012;Vanhatalo et al, 2008).…”

Overcoming the practical challenges of electroencephalography for very preterm infants in the neonatal intensive care unit

“…Stjerna et al. used an EEG cap for preterm EEG monitoring and reported an effective technique of EEG application in preterm infants . An electrode cap array is undoubtedly an attractive option for infants, but a number of sizes are required for all gestational ages, and ideally, these hats need to be sterile and disposable.…”