Analyzing EEG maturation in preterm infants: the value of a quantitative approach

Despite increase in survival of very low birth weight infants, the number of infants who experience neuromotor or neurocognitive problems later in life is still high. Therefore, accurate documentation of the brain development in these infants is indicated. Electroencephalography (EEG) may be a valuable tool to monitor brain development during the intensive care period. However, our knowledge on EEG maturation is based on visually determined patterns. Since there are no exact reference values, conclusions on EEG maturation are difficult to establish and may vary between investigators. Also, most knowledge concerning EEG maturation is derived from relatively old studies in the "pre-digital" era. New digital EEG recorders provide the opportunity towards a quantitative approach of EEG maturation. This approach may lead to a more objective and uniform description of EEG maturation. In this article we review the most important aspects of EEG maturation, i.e. changes in discontinuity, development of age specific waveforms, inter-hemispheric synchrony/correlation and the development of sleep-wake cycles, and qualitative or semi-quantitative studies concerning EEG maturation and outcome. We discuss the concept of an EEG analyzing algorithm and propose several quantitative analyzing techniques which may be incorporated in such an algorithm.